Conseil International pour l' Exploration de laMer

CHARLOTTENLUND SLOT- DANEMARK

ANNALES BIOLOGIQUES

Prix: kr. 55.00

VOLUME NO. 24

REDIGE PAR

H. T AMBS-L YCHE

1967

En Commission chez

ANDR. FRED. H0ST & FILS

COPEN HAGUE

Septembre rg68

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TABLE OF CONTENTS

Page

Preface, by H. TAMBS-LYCHE 7

Part I. HYDROGRAPHY

Hydrographic conditions in Icelandic waters in June 1967- Sv.-AA. MALM-BERG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Some result of hydrographic investigations with R. V. "Anton Dohrn" in October/November 1967 around Iceland- K. EHRICKE . . . . . . . . . zo

Water temperature of the Norwegian Sea in 1967- V. V. PENIN, L. R. SoLO-NITSINA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Hydrographic conditions off Spitsbergen in the summers of 1966 and 1967 -R R. DICKSON, T. c. DODDINGTON . . . . . . . . . . . . . . . . . . 24

Water temperature of the southern Barents Sea in 1967- A. I. MuKHIN 30 Surface temperature and salinity observations at English sampling stations

during 1967- D. J. ELLETT, S. R. JoNES, GLYNIS READ . . . . . . . . 32 Temperature observations at English and Welsh coastal stations during 1967

- T. C. DODDINGTON, S. R. JONES . . . . . . . . . . . . . . . . . . 46 Polish hydrographical observations off South Ireland and in the central part

of the North Sea in 1967- J. FILARSKI . . . . . . . . . . . . . . . . 48 Hydrographic and chemical observations in the Southern Bight, August and

November 1967- S. B. TIJSSEN . . . . . . . . . . . . . . . . . . . 52 Hydrography of the south-eastern North Sea 1967, Danish observations-

H. THOMSEN . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Hydrography of the Skagerak and Kattegat areas, Swedish observations 1967

- A. Sv ANSSON . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Hydrography of the Kattegat area 1967, Danish observations- H. THOMSEN 57 Danish observations in the Great Belt and the Baltic, 1967- H. THOMSEN 57 Polish hydrographical observations in the southern Baltic in 1967- A. GLO-

WINSKA ................ · · · · · .. · · · · · · · 59 Observations at Swedish lightships and in the central Baltic 1967- S. H. Fon-

SELl US 65

Part II. PLANKTON AND BENTHOS

Some optical measurements at Ocean ·weather Station A-M.P. VISSER . . 70 Beam transmittance measurements in Icelandic waters in May and June 1967

- Sv.-AA. MALMBERG . . . . . . . . . . . . . . . . . . . . . . . 70 The Continuous Plankton Recorder Survey: plankton in the Irminger Sea region

during 1967 - R. S. GLOVER, G. A. RoBINSON . . . . . . . . . . . . . 76 Sebastes in continuous plankton records in 1967- G. T. D. HENDERSON . . 77 Plankton distribution in the Norwegian Sea in the spring-summer of 1967 -

A. F. TIMOKHINA . . . . . . . . . . . . . . . . . . . . . . . . . . 77

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Page

Phytoplankton investigations from Aberdeen in 1967- D. D. SEATON . . . 79 Zooplankton investigations from Aberdeen in 1967- J. H. FRASER . . . 8o Chlorophyll a and zooplankton standing crop in the central and northern

North Sea- J. A. ADAMS, I. E. BAIRD . . . . . . . . . . . . . . . . 8r The Continuous Plankton Recorder Survey. Plankton around the British Isles

during 1967- R. S. GLOVER, G. A. RoBINSON . . . . . . . . . . . . . 8r Zooplankton investigations on Rockall Bank, May, June and September 1967

-D. D. SEATON . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Part III. THE FISH

Gadoid Fish

Cod

Introduction, by A. HYLEN . . . . . . . . . . . . . . . . . . . 92 The spawning stock of Icela:o.dic cod in 1967- J. JONSSON . . . . . 94 Soviet investigations of the age- and size composition of cod stock in

the Barents Sea in 1967- V. P. PoNOMARENKO . . . . . . . . . 94 Scottish investigations on cod of the West Coast stock, 1964 to 1967-

D. F. S. RAITT, M. GROVES . . . . . . . . . . . . . . . . . . 96 Scottish investigations on the North Sea stock of cod in 1967- D. F. S.

RAITT, M. GROVES . . . . . . . . . . . . . . . . . . . . . . 98 German investigations on cod in the western Baltic 1967- F. THUROW 99 Polish cod investigations in the southern Baltic in the years 1966 and

1967 - M. KosiOR . . . . . . . . . . . . . . . . . . . . . . ror

Haddock

Saithe

Soviet investigations on young haddock of the 0, I, II and III age groups in the Barents Sea - Z. P. BARANOVA . . . . . . . . . . roz

The length-age composition and growth rate of the Arcto-Norwegian haddock- M. A. SoNINA . . . . . . . . . . . . . . . . . . . ro4

Scottish investigations on the Faroe stock of haddock in rg67- R. Jo-NES, A. S. jERMYN . . . . . . . . . . . . . . . . . . . . . . I05

Scottish investigations on the West Coast stock of haddock in 1967 -R. jONES, A. S. jERMYN . . . . . . . . . . . . . . . . . . . I05

Scottish investigations on the North Sea stock of haddock in rg66 and I967- R. JONES, A. S. jERMYN . . . . . . . . . . . . . . . . I07

Soviet investigations on the North Sea stock of haddock in 1967- A. S. PoLONSKY . . . . . . . . . . . . . . . . . . . . . . . . . rog

Distribution of young saithe (Pollachius virens) in the Barents Sea in rg67 - T. S. BERGER . . . . . . . . . . . . . . . . . . . . III

Whiting

Scottish investigations on the West Coast stock of whiting in rg67-J. R. G. HISLOP, A. S. jERMYN . . . . . . . . . . . . . . . . IIZ

Scottish investigations on the North Sea stock of whiting in rg66 and rg67- J. R. G. HISLOP, A. S. jERMYN . . . . . . . . . . . . . II3

Soviet investigations on the North Sea stock of whiting in 1967- A. S. PoLONSKY . . . . . . . . . . . . . . . . . . . . . . . . . rr4

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Page

Clupeoid Fish

Herring

Introduction, by ]. ]. ZIJLSTRA . . . . . . . . . . . . . . . . . rr6 Icelandic herring investigations 1967- H. VILHJALMSSON,]. jAKOBSSON rr8 German investigations on the Atlanto-Scandian herring- K. SCHUBERT 123 Norwegian herring investigations 1967. The mature herring- F. DE-

VOLD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 Norwegian adult herring fisheries 1967- 0. DRAGESUND . . . . . . rz8 Norwegian investigations in 1967 on eggs and larvae, small and fat her­

ring- 0. DRAGESUND . . . . . . . . . . . . . . . . . . . . 131 Norwegian herring tagging experiments and tag returns- 0. DRAGE-

SUND, S. HARALDSVIK . . . . . . . . . . . . . . . . 133 Scottish herring fisheries, 1967- G. McPHERSON, A. SAVILLE . . . . 135 Scottish fisheries on adolescent herring 1967 - A. SA VILLE . . . . . 145 Polish herring catches on the slopes of the Norwegian Channel in the

years 1965-1967-]. SOSINSKI . . . . . . . . . . . . . . . . 146 The Norwegian herring fisheries in the North Sea and Skagerak rg67-

S. HARALDSVIK . . . . . . . . . . . . . . . . . . . . . . . rso The Polish herring fisheries in the North Sea in rg67-]. PoPIEL, J. So­

SINSKI . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 The English herring fisheries in rg67- R. J. WooD, W. G. PARNELL . r6z The herring fisheries of the Netherlands rg67 - ]. ]. ZIJLSTRA, K. H.

PosTUMA . . . . . . . . . . . . . . . . . . . . . . . . . . r66 Growth data for herring of the Southern Bight, derived by back-calcu­

lation of scales. The 1967 East Anglian samples- T. D. ILEs . . . 168 Notes sur le hareng de la region du Pas-de-Calais; observations pour la

periode de rg63 a rg67- M. A. MAUCORPS . . . . . . . . . . . 170 The Dunmore East herring fishery, rg66j67 and rg67j68-]. P. MoL-

LOY . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 Changes in herring stocks in the western and central Baltic- 0. RECH-

LIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 Polish herring fisheries in the Baltic in rg67- J. PoPIEL, K. STRZYZEWSKA 176

Sardine

Sprat

The English sprat fisheries, results of the rg67j68 season- P. 0. JOHNSON 179

Scombriform Fish

Mackerel

English mackerel investigations- G. C. BoLSTER . . . . . . . . . r86 Netherland's mackerel fishery in the North sea in 1967- K. H. PosTUMA r86

Anadromous and Catadromous Fish

Salmon

Investigations of saimon and sea trout of the river Axe, Devon, 1967 -A. SWAIN . . . . . . . . . . . . . . . . . . . . . . . . . . 188

Smolt tagging programme in the rivers U sk, Wye and Severn~ A. SwAIN 188 German investigations on salmon 1967 - F. THUROW . . . . . . . . r88

Flatfishes

Greenland Halibut

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Investigations on and fisheries for Greenland halibut north of Iceland

Page

in the summer of 1967 - K. KoNSTANTINOV . . . . . . . . . . 192

Other Fishes

Redfish

Distribution of young redfish, 5. mentella and 5. marinus, in the Barents Sea in 1967 - T. S. BERGER, R. A. CHEREMISINA. . . . . . . . . 193

Sand eels

The German sandeel fishery in 1967 - K. TrEws 196

Grenadier

Feeding of Macrurus rupestris in the Iceland area-S. G. PODRAZHANS-KAYA 197

Cutlass Fish

Biology of the cutlass fish, Lepidopus caudatus - L. N. DoMANEVSKY 198

Rare Fishes

Rare fishes recorded by the Marine Research Institute in Reykjavik during 1967- G. JONSSON . . . . . . . . . . . . . . 201

Scottish records of rare fishes 1967- B. B. RAE, S. F. PIRIE 201 English observations on rare fish in 1967- R. W. BLACKER . 202

Shellfish

Prawns

On the biology and distribution of Pandalus borealis in the offshore waters of the Barents Sea- V. F. BRYAZGIN . . . . . . . . . . 204

Shrimps

By-catch in the German shrimp fishery (Crangon crangon) in 1967- K. TIEWS. . . . . . . . . . . . . . . . . . . . . . . . . . . . 205

APPENDIX

Report on the joint meeting of Soviet and Icelandic investigations on the Atlanto-Scandian herring distribution in relation to oceanographic conditions, held at Akureyri 18.-19. June 1967 . . . . . . . . . 206

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PREFACE

The very few changes in the arrangement of contributions to the present volume are reflected in the "Table of Contents". They have been introduced in order to make the set-up clearer, and also to simplify references to the chapters.

Mr. A. HYLEN has written an introduction to the information available on cod, and Mr. J. J. ZIJLSTRA one on herring. Both are hereby gratefully acknowledged.

Joint efforts by all concerned has made it possible to issue this volume almost four months earlier than the last one, and the editor thanks all who have contributed to this. A few reports were received too late for inclusion in the present volume; they will eventually be published in Volume 25 together with information for 1968.

A nnales Biologiques and Statistical News Letters are to some extent complementary. General reference is therefore hereby given to the following numbers of Statistical News Letters (issued, in print or under preparation) where detailed statistical data, relevant to information presented in this volume, will be found:-

No. 39: Herring. Nominal Catch and Fishing Effort 1967. No. 40: Herring. Stock Record Data 1967. No. 41: Nominal Catch and Fishing Effort by Months 1967, as reported on

STANA forms. No. 42: Demersal Species. Nominal Catch and Fishing Effort, Stock Record

Data 1967.

The observations, reported for 1967 may be very briefly summarized as follows:-

Hydrography

There is no information in this volume from Greenland waters. In Icelandic waters the ice conditions in the spring of 1967 were extremely unfavourable. Temperatures in the upper soo m layer west of Iceland were about I 0 below normal; salinities were normal. No Atlantic influx was observed east of Kogur, and both temperature and salinity values were generally the lowest in the are since observations started in I949· Temperatures in the upper roo metres were about 4° below normal. An unusually large proportion of polar water was observed in the East Icelandic Current, temperatures were characterized as unusually low in June. This was confirmed by Soviet observations.

A report on three hydrographical sections around Iceland in October-November is found on pp. 20-22.

Soviet observations of temperature conditions in the Norwegian Sea showed that the heat transport by the Atlantic Current was below normal during the first half of the year. Temperatures of the Norwegian Current at 63°N were in June the lowest since 1954, and all over the area were found temperatures below the normal ones. From July on, however, the influx of warm Atlantic water increased, and tempe­ratures in the eastern part of the area were usually higher than in 1964, when they were near to normal. At the same time, the temperature of the East Icelandic Cur­rent remained unusually low.

Detailed observations from waters around Spitsbergen in the late summers of 1966 and 1967 are reportes on pp. 24-29. Waters east of Bear Island were very much colder and less saline in 1967 than in the previous year, and the same trend was found on the Spitsbergen Bank and east of Sorkap.This indicated an increased Arctic influence east of the Sorkap-Bear Island line. West of this line the Atlantic influence was stronger in 1967 than in r966, with warmer and more saline waters.

As to the Barents Sea, Soviet observations showed that the unusually low heat content at the end of r966 influenced the thermal regime also in the first part of r967.

- 8 -

Already in spring, however, (March to May) surface temperatures had reached the long-term mean values at the Murman coast, while temperatures in medium depths and at the bottom remained lower than usual. At the end of the summer (August to September) the temperatures in the o to 50 metre layer were above normal in the southern part of the sea, and in the o to zoo metre layer they reached the long-term mean in September. As far east as the Kola meridian the temperature anomaly was positive in September, and at the end of the year, temperatures in the southern Barents Sea were generally slightly higher than normal.

Detailed British observations at English coasts and in the North Sea and the Channel showed that the North Sea was generally warm during rg67, especially during the summer.

Negative temperature anomalies were found on the Dogger Bank at the end of the year, while positive anomalies were at the same time found in the German Bight and off the Danish west coast. During the last half of the year, high salinity ano­malies were found on the Leiht-Copenhagen route.

At the western entrance to the English Channel, temperatures were above or close to the normal values, in the eastern part of the Channel waters were relatively warmer in the first part of the year than in the second. Salinity values varied more irregularly. At the southern entrance to the Irish Sea, temperatures were generally low, and salinity anomalies negative. Additional Polish observations from the southern part of the Irish Sea are reported on pp. 48-50.

Polish investigations in the central and northern parts of the North Sea in summer and autumn showed that bottom layers were considerably more influenced by Atlantic waters than in rg66.

Dutch observations in the Southern Bight gave values above normal both for temperature and salinity in August and November. Distribution charts for oxygen and phosphate values in the same area and time are presented on pp. 54-55. A little further north, at the "Vyl" light-vessel, salinities were generally below normal during the first 9 months of the year. Temperatures varied more irregularly.

SwE'dish observations from Skagerak showed that the temperatures in the deeper parts were increasing slowly, but steadily since the large and sudden drop which occurred in rg66.

In the Belt Sea was found an exceptionally high salinity in March. Polish and Swedish reports give details of the hydrography of different parts of

the southern and central Baltic. There was an influx of highly saline bottom water into the Arkona Basin in February, and other less pronounced in July and October. The first influx reached the Bornholm Basin as well as the Gdansk Deep in May and the Gotland Deep in July, again lifting the layer containing H 2S above a layer with oxygen along the bottom.

Plankton and Benthos

Optical measurements in the Irminger Sea and in Icelandic waters are reported on pp. 70-75, and reference is also given to the map on Figure 173 (p. zog). It is hopes that such investigations will be continued and reported on an annual basis, so year-to-year developments may be followed.

The pring outbreak of phytoplankton was exceptionally rich both in the eastern and western parts of the Irminger Sea, but it occurred earlier and lasted longer in the western part. This was also reflected in the peak of occurrence of copepods. The young stages of Sebastes were also exceptionally abundant in the western part, but it seems that the main "spawning" started late.

Soviet investigations on plankton in the Norwegian Sea showed that the "bio­logical o:pring" occurred later than in rg66 in the western part, while it came earlier in the eastern part. Over the whole area, however, the plankton biomass was lower

-g-

in rg67 than in the two preceding years. Further observations on plankton in the Norwegian Sea and Icelandic waters in relation to hydrography and herring in­vestigations are found on pp. zo6-214.

There are several reports giving details of plankton distribution and development around the British Isles. The main result is that the spring outbreak was late and low everywhere except in the west-central and southern North Sea. In the second half of the year, however, there was a recovery, and phytoplankton was more abundant than usual in most areas. Copepods also attained their spring maximum later than usual in all areas except the southern North Sea.

Special investigations were carried out on the Rockall Bank in May, June and September, and interesting results are summarized on pp. 86-go.

There were no information available for this volume on plankton conditions in the Baltic in 1967, nor on investigation on benthos.

The Fish Cod

Reference is given to Mr. A. HYLEN's summary on pp. 92-93.

Haddock

Soviet investigations in the southern Barents Sea confirmed that the rg64 year class is of medium strength, and that the 1965 one is weak. The same is obviously the case with the 1966 year class. The young of those two year classes were not met with at all in the Bear Island-Spitsbergen area.

Interesting information on the influence of different growth-rates upon the distri­bution pattern of haddock in the Barents Sea is found on pp. I04-105.

The catch rate in Faroese waters declined slightly from the high values of the year before. In the North Sea the very strong 1962 year class was still well represented in the catche:::, especially in the northern parts, where catch rates increased from the year before. The rg66 year class is also characterized as very strong, although it appears to be only a quarter of the strength of the rg6z one. The year classes between these two were poorly represented in the catches. Soviet investigations in the North Sea confirmed these results, and also indicated that the 1967 year class may be a strong one.

Saithe

In rg67 young saithe of IZ-I5 em length were found in unusually large quantities in the Bear Island area and along the warm West Spitsbergen Current. Young saithe were also found, although in smaller numbers, over most of the Barents Sea. It is suggested that the year class in question may be among the most abundant ones, and also that the hydrographical conditions had facilitated its approach to West Spitsbergen as well as its wide distribution in the Barents Sea.

Whiting

The 1962 year class was still abundant in the North Sea, and it was confirmed that the 1965 and rg66 ones were of average strength. There are not yet any safe estimates as to the strength of the 1967 year class.

Herring

Reference is given to Mr. J. J. ZIJLSTRA's summary on pp. rr6-rr7.

Sprat

Again there is only information on British sprat fisheries. The report gives, how­ever, information as to the stocks of sprat over most of the southern and central

-10-

North Sea as well as along the English coasts. The problems connected with size distribution within year classes, discussed in last years contribution, is further elucidated. It appears that the 1967 year class is a strong one over most of the area.

Mackerel

It is regretted that not more information is available on this species, in spite of its great importance in the fisheries in recent years. It appears, however, from English investigations that the 1962, 1963 and 1964 year classes are strong, and from Dutch investigations that the same is the case with the 1965 one.

Salmon and Sea-Trout

British reports include catches in Greenland waters of fish tagged in English rivers. German investigations on salmon in the Baltic also included tagging experiments. An interesting result is that fish released in the Danzig Deep area were recaptured in Swedish and Finnish rivers, but not a single specimen in Soviet or Polish ones.

Greenland Halibut

This was the only flatfish reported upon this year. The distribution of this species north of Iceland was found to follow the boundary between warm and cold waters, and dense concentrations were found in a. narrow band only. Tagging experiments indicated that the species is relatively stationary in this area.

Redfish

The year classes 1962, 1963 and 1964 are considered to be abundant in the Bear Island-Spitsbergen area. In the southern Barents Sea the 1966 year class seemed to be very abundant.

Data on pelagic Sebastes larvae from Continuous Plankton Recorder Surveys are found on p. 77·

Other Fish

There are notes on the German sandeel fishery in 1967 (p. 196) with data. on by­catches; on investigations on the feeding of grenadier (Macrurus rupestris) in the Icelandic area (p. 197), and on the biology of the cutlass fish (Lepidopus caudatus) in West African waters (p. 198).

There is further information on captures of rare fish from Icelandic (p. 201), Scottish (p. 201) and English (p. 202) laboratories.

Shellfish

There is a report on good Soviet catches of Pandalus borealis in the Hopen area and in West Spitsbergen waters, together with data on size and age, and notes on environmental factors.

There is also a report on German catches - and by-catches - in their fishery for shrimps (Crangon crangon) in 1967.

HANS TAMBS-LYCHE

Hydrographical conditions in Icelandic waters in June 1967

(Figures r-rr; Tables 1--2) 1)

A hydrobiological survey was carried out in the waters west, north and north-east of Iceland from 29. May to 5- June. Figures 1-2 show the location of the stations, the drift ice limit and the distribution of temperature and salinity at 20 m. Figures 3-7 show the vertical

"l ... ~ ,,r .. I

64°

t°C, 20m

29/5- 516,1967

20° -,-----,

ICE LIMIT

12-

distribution of temperature and salinity in the sections off Smefellsnes, Litrabjarg, Siglunes, Langanes-NE and Langanes-E (for location see Figure I). Figure 8 shows the location of the 0°-isotherm at 50 min June 1966 and 1967. Figure 9 shows t-S diagrams for all available hydro­graphic observations (with temperatures below 2° C) made in June in the uppermost 200m within latitude 67° to 69°N and longitude II 0 to I5°W in the years 1950, 1952, 1953, 1954, 1955, 1956,

15° 10·

o· _ls· j• u '

~·

(. \.Ju. j•

l

• HYDROGRAPHIC ST.

o BT ST

Figure r. Temperature, 20m, 29. May to 5- June 1967.

Table I. The temperature and salinity means within latitude 67-69°N and longitude II-15°'N' in June 1950, -52, -53, -54, -55, -56, -57, -58, -64, -65, -66, -67; the number of observations and the means for the periods 1950-1958

and 1964-1967

1950 1952 1953 No. of No. of No. of No. of No. of No. of

Depth in m toe obs. S Ofoo obs. toe obs. S Ofoo obs. toe obs. S Ofoo obs.

0 ..... 3-02 2 34·85 2 I.23 4 34-83 4 4-25 4 34-70 4 10 ..... 2.82 2 86 2 1.37 4 82 4 4·25 4 7I 4 25 ..... 2-53 2 87 2 I.I7 4 Sr 4 3-II 4 74 4 so ..... 1.30 2 ss 2 I.OO 4 81 3 0.29 4 78 4

roo ..... 0.35 2 83 2 0.00 4 ss 4 -0.30 4 So 4 rso ..... 0.08 2 84 2 -0.43 4 88 4 -o.rs 4 ss 4 200 ..... -0.02 2 84 2 -o.sr 4 88 4 -o.os 4 87 4 300 ..... - 0-37 2 8s 2 -0.63 4 89 3 -0.36 4 88 4 400 ..... -0.27 2 87 2 --o.6o 4 90 4 -o.sr 4 90 4 soo ..... - - - --0-44 I -o.s6 4 90 4 Total no. of obs. .. r8 r8 37 34 40 40

') Tables r and 2 appeared in previous papers, published in "1EGIR", Nos. 12 and q, and have since then been amended.

------ ~---~--~·---- - -- -'"'"""·=><<--""'~ .. ,~~'==-'""'''-="

Depth in m

0 IO

2S so

IOO

ISO 200

300 400 soo Total no. of obs ...

Depth in m

0

10 2S so

IOO ISO 200

300 400 soo Total no. of obs ...

Depth in m

0

10 25 so

100 ISO 200

300 400 soo Total no. of obs ...

toe

4·03 3.S2 2.69 1.04 0.3S 0.02

0.04 -0.31 -0.44 -0.57

toe

2.go 2.64 2-54 1.40

-0.02

--0.26 -0.23 --O.I6 -0.22

--0.32

t°C

2.26 2.1S

-0.01 -O.S3 -o.g2

0-45

o.15 -0.10

-13- Hydrography

1954 No. of

obs. S Oj00

4 34·S3 4 S1 4 So 4 S2 4 S2 4 S3 4 S7 4 90 4 92 4 92

40

Ig57 No. of

obs. S o/oo 2 34-So 2 So 2 So 2 S1 2 ss

S7 2 ss 2 go 2 g1 2 g1

1g

1g65 No. of

obs. S %o 6 6 6 6 6

6

2

39

34-Ig 03 25 4g 70

S7

g3 g3

No. of obs.

4 4 4 4 4 4 4 4 4 4

40

No. of obs.

2

2

2

2

2

2

2

2

2

2

20

No. of obs.

6 6 6 6 6

6

2

3g

Table 1 (continued).

toe

4-43 4-4I 3-41 1.33 o.6g o.1g

-0.01 -o.oS -0.25 -0.4S

toe

2.gg 3.01 1.9S o.So

-0.11 -o.2S -0.32 -0.3S -0.24 -0.32

toe

3-16 2.gS 1.26

-0.37 -o.S6

-0.26

1gss No. of

obs. S Ofoo

5 34-S1 5 S1 5 s4 5 S7 5 ss 5 S7 5 S6 4 Sg 4 gr

44

195S No. of

obs. SOfoo

34-ss ss SJ S7 ss Sg

3 3 3 3 3 3 2 go

go 2 92

2 g3

25

1g66 No. of

obs. S 0/oo

2

2

2

2

2

II

34-62 62 6s 6S 77

go

No. of obs.

5 4 5 5 5 5 5 5 3

42

No. of obs.

3 3 3 3 3 3 2

2

2

25

No. of obs.

2

2

2

2

2

2

I2

toe

1.56 L3g r.r6 0.72

··-0.07 -0-40 -0.24 -0.27 -0.31 -0.36

toe

3-24 3.0g 2.66 0.3g

-o.os o.os 0.13

-0.02

-0.24 -0.33

toe

o.s6 0.52

-o.g4 -r.2S -o.Ss -o.6r -0-42

rgs6 No. of

obs. SOfoo

34-SS s4 s4 S6

2

2

2

2

2 go g1

2 92

2 92 2 92

2 g3

rg

1g64 No. of

obs. SOfoo

34-57 56 57 6r

3 3 3 3 3 3 3 3 3 3

30

S3 Sg 92 g1 g2 g2

1g67 No. of

obs. S 0/oo

4 4 4 4 4 4 4

z8

34-14 14 56 68 76 7g 87

Mean of 1g5o-1g5S Mean of 1g64-1g67

No. of No. of No. of No. of Depth in m t oe obs. S 0/ 00 obs. toe obs. S o/oo obs.

0 . . . . . 3-05 26 34-SZ 26 2.31 15 34·3S 15 ro . . . . . z.g6 z6 S2 25 2.1g IS 34 1 5 25 . . . . . 2.32 z6 S2 z6 0.74 15 51 15 so . . . . . o.gg z6 S3 25 -0.52 15 62 15

roo . . . . . 0.12 26 ss z6 -0.67 15 77 IS 150 . . . . . -0.15 24 S7 25 --o.2S 7 s4 7 zoo . . . . . -0.17 25 SS z6 -0.03 14 Sg 15 300 . . . . . -0.32 23 Sg 23 -0.02 3 gr 3 400 . . . . . -0.36 24 gr 23 -o.os 4 gz 4 500 . . . . . -0-44 I6 g2 14 -0.22 5 g2 5

Total no. of obs ... 242 23g ro8 10g

No. of obs.

2

2

2

2

2

2

2

2

2

1g

No. of obs.

3 3 3 3 3 3 3 3 3 3

30

No. of obs.

4 4 4 4 4 4 4

z8

I4

~0 c...~ 20° 15° 10° 5"

. . . . \ . I I I I I . . . . . ; .

35.15

34.7 ~-~ 34.6

349

L ICE LIMIT 1( \ .\ \ \ \ ~.

./ I 346 347 348 349 350

e HYDROGRAPHIC ST.

, ~ ~~··· J Figure 2. Salinity, 20 m, 29. ::viay to 5· June 1967.

Table 2. The temperature and salinity deviations within latitude 67-69°N and longitude II-I5°W in June 1950, -52, --53, -54, -55, -56, -57, -58, -64, -65, -66, -67 from the mean values of the period rgso-58

toe

Depth in m 1950 I9S2 I9S3 19S4 19SS I9S6 19S7 r9s8 1964 1965 1966 1967 0 ..... -0.03 -1.82 !.20 0.98 1.38 -1.49 -O.IS -o.o6 0.19 -0.79 O.II -2.49

IO ..... -o.q -I.S9 1.29 0.86 I.4S -I.S7 -0.32 0.05 0.13 -0.78 0.02 -2-44 2S ..... 0.21 -I.1S 0.79 0.37 1.09 -r.r6 0.22 -0.34 -0.34 -2.33 -r.o6 -3.26 so ..... 0.31 0.01 -0.70 o.os 0.34 -0.27 0-41 -0.19 -o.6o -1.82 -1.36 -2.27

roo ..... 0.23 -0.12 -0-42 0.26 o.s7 -0.19 -o.q -0.23 -0.17 -1.04 -0.98 -0.97 ISO ..... 0.23 -0.28 0.00 0.17 0.34 -0.25 -O.II -0.13 0.20 - -0-46 zoo ..... 0.15 -0.34 0.12 0.21 o.r6 -0.07 -o.o6 -O.IS 0.30 0.62 -0.09 -0.2S 300 ..... -o.os -0.31 -0.04 O.OI 0.24 o.os o.r6 -o.o6 0.30 400 ..... 0.09 -0.24 -O.IS -o.o8 O.II o.os 0.14 0.12 0.12 O.S1 soo ..... 0.00 -0.!2 -0.13 -0.04 0.08 0.!2 0.12 O.II 0.34

S Ofoo Depth in m 19SO I9S2 I9S3 1954 19SS r9s6 I9S7 1958 1964 r96s 1966 1967

0 ..... 0.03 O.OI -0.12 O.OI -O.OI 0.03 -0.02 0.06 --0.25 -0.63 -0.20 -o.68 IO ...... 0.04 0.00 -O.II -0.01 -0.01 0.02 -0.02 0.06 -0.26 -0.79 -0.20 -o.68 2S ..... 0.05 -O.OI -o.o8 -·0.02 0.02 0.02 -0.02 o.os -o.zs -O.j7 -0.17 -0.26 so ..... 0.02 -0.02 -0.05 -0.01 0.04 0.03 -0.02 0.04 -0.22 -0.34 -O.IS -O.IS

roo ..... -0.02 0.00 -o.os -0.03 0.03 0.05 0.00 0.03 -0.02 -O.IS -o.o8 -0.09 ISO ..... -0.03 O.OI -0.02 -0.04 0.00 0.04 0.00 0.02 0.02 - -o.o8 200 ..... -0.04 0.00 -O.OI -0.01 -0.02 0.04 0.00 0.02 0.04 -0.01 0.02 -0.01 300 ..... -0.04 0.00 -O.OI O.OI 0.00 0.03 O.OI 0.01 0.02

400 ..... -0.04 -0.01 -0.01 0.01 0.00 0.01 0.00 0.01 0.01 0.02

6oo ..... - -0.02 0.00 - O.OI -0.01 0.01 0.00 0.01

-IS-

ST8 7 4

35.0 349 0 r-r-···-·-·- ·-"!·---,-- ----~. ---~35~~ ml' •

1

• ~· • i: : : : : . : •:: r . . . . 35.15 • • • • .

I ~ ~, .· : .. ,.= ." : .\ :I J~

r~35/ I

IOOn.m.

'!:

50

S%o

29-30/5 1967

STB

~I:

500

I: , 6.5"

~ .

6.1' /

'=lt IQQ,, .. , ..

Figure 3· Section west of Sn::efellsnes

ST 9

r1·~

60

500f- /

90n.m

10 II 12

50

a) Temperature b) Salinity

13 14 ST 9 10 r-- . m o . /"~ n ,.

r

"" -i ::0 l> ~

3515 l> J ::0

/ "'

500

_IT

30/5,1967

0 90n.m.

Figure 4- Section west of Latrabjarg a) Temperature b) Salinity

&

II

! . . .

50

J 50

12 352

:

4

Hydrography

r \',~ :

......... ~------6.5" -:------.

~

29-30/5,!967

13

S%o

30/5,1967

r

"" -i ::0 l> ~ !iJ "'

0

0

- r6-

ST. 24 25 26 27

01( !c... ......... ~7!

(f)

ST. 24 25 26 27 34.0

o f\ 1'::: i L_34"i:j I m ·. •

345-;

20

0/ ;o ~ 349

500

1°C

1/6,1967

On.m.

ST33 34

[:] '\i""" 2COf::i ~

"' ~ 2-3/6,!967 _J

35

o·

500

40 On.m.

Figure 5· Section north of Siglunes

a) Temperature b) Salinity

36 37 38

·t• ,~-- . ~" .<-1.50 )

~

:~

·:\: ·::

S 01oo

1/6,1967

40

39

c::; <-J.So

'·~-t·. •'-·o.5• ~ -·· -o.5·-·

3QQL---~----~----L---~-~~J_ ____ L---~----~----L---_i----~----L----L----~--~ 0 n. m. 50 100 150

51:33 34 35 36 37 38 39

--- =! 348

On.m. 50 300 150 100

Figure 6. Section north-east of Langanes a) Temperature b) Salinity

1957, 1958, 1964, 1965, 1966 and 1967, July observations from 1948 and 1949 and August observations from 1951. In 1959 to 1963 no hydro­graphic observations were made in the area

mentioned. Table r gives the temperature and salinity means for June for the years 1950-58 and 1964-67, the means for the two periods, and finally the number of observations. The tern-

- IJ-

ST50 49 48 47 46 45 44

z· , •. ____ __..;._

' <-o.so '\ o•

~ ..

-o.5•

On.m 50 100 150

500

5150 49 48 47 46 45 44 34.2 -~-f"'ri I _! =: . !__.......---- I ··=·. • 345 • ---------=---

348 •

S%.

4-5/6,1967

Hydrography

~

-o.5·

200

43

350 •

\___:_

1000 ... ~--~-~--_j On.m. 50 100 150 200

Figure 7· Section east of Langanes a) Temperature b) Salinity

perature and salinity means for the two periods are also shown in Figure ro. The deviations from the 1950-58 mean for June are shown in Table 2 and the deviations for the years 1964-67 are also shown in Figure II.

The main features of the hydrographic conditions

in the waters west, north and north-east of Iceland in June 1967 were as follows:

In the spring of 1967 ice conditions in North Icelandic waters were extremely unfavourable and comparable with the situation in rg65. The ice limit was in June less than 15 n. m. off the north-west

69I·ro_·--.---,---.----.--~'s~·---.---.---.--~--~~o~·---.---.----

~"" 0" C ISOTHERM, 50m

JUNE.

6~L_~~~---L--~--~~~~~~--~---L--~--~~

Figure 8. The position of the 0°-isotherm at so m in June rg66 and 1967

peninsula, about 30-40 n. m. off the north coast, extending east toward Skjalfandi where it bent northward.

The June temperatures in the uppermost soo m off the west coast of Iceland were S-7° C, which is about I 0 below normal, 2° lower than in I964 and I 0 lower than in I965. The salinity distribution in the area was normal, with salinities about 35-ISOfoo·

No Atlantic influx was observed in June east of Ki.igur. Due to ice, only the coastal area north of Iceland could be investigated. Generally, the temperature and salinity values found in the area were the lowest since observations began in I949 and comparable only with the values found in I965. Temperatures in the uppermost IOO m ranged from o-2° C, which is about 4° below normal. The salinities ranged from 34-0---34.8°/00, increasing towards bottom, but this salinity range indicates the presence of polar water. At intermediate depths, between IOO and 300 m, the temperature off Siglunes was only 2° C in June and the salinity about 34.8-34-90foo (Icelandic winter water) and off Langanes the temperature was about 0.5° C and the salinity less than 34.8%0 (polar water and/or arctic water). The corresponding temperature values in the extremely cold year I965 were 4° and 3° C, indicating a slight Atlantic influx into the shelf area north of Iceland in June that year, whereas in June I967 there was no trace of an influx.

The temperature and salinity distribution be­low 300-500 m west, north and north-east of Iceland was about normal in June.

r8-

In the oceanic area off the north-east coast of Iceland low temperatures reached depths of ISO m in June, the minimum temperatures being - r.8° C and the salinities ranging from 34-5 to 34-7%0, as also observed in I965. Thus low tem­peratures and salinities observed in this area since I964 (MALMBERG, I967) were also found this year, as demonstrated in Table I and 2 and Figures 8-II. The extremely low tem­perature and salinity values of the years I965 and I967 are the most prominent features of these tables and figures, indicating an unusually large proportion of polar water in the arctic water of the East Icelandic Current. The low temperatures, without corresponding low salinities, observed in June I952 and I956 (Tables I and 2) are also worth noticing.

The conditions in the East Icelandic Current here mentioned are in agreement with conditions observed in the North Atlantic reported on by several authors and summarized by A. J. LEE (see ICNAF's Redbook I967, Part IV). These specific conditions are assumed to be connected with anomalous atmospheric circulation, and what is more, are expected to predominate over a long

2 •• 0 1948-1958 • • \

0 1964

• 1965 0 .. 1966 • o•[ !::, 1967 .,lf !::, ·~ T°CI ~ ~ • ~ t::,fD

Of- .. b 0 " • o•~ • .!::, • 0

• !::, !::,

• !::,·~ -II-

!::, • !::,

• •••• !::, ~ !::,

!::, !::,

!W -2

33.5 34.0 345 35.05%0

Figure g. T-S diagrams of observations within latitude 67--69°N and longitude rr--I5°W in June 1950, 1952, 1953, 1954, 1955, 1956, 1957, 1958, 1964, 1965, 1966, 1967,

in July 1948--49 and in August 1951

---- --~---- ·---~~-- ----------------------

- rg -- Hydrography

":f " r =~C--~~~~:,::- '~

200~ • 1964-67 l \

l I ~ I ' (

; l°C S%o ! :

~0 i \ I . \

I I i I.

i . \ 1' ' J \ sooL. ---'----- ---.....L...--~ ______j__------....J..__i_______l

Figure ro. The temperature and ;;alinity means within latitude 67 --69°N and longitude r r-I5°VV in June during the periods 1950-58 and 1964--67.

-30 -zo -10 0 -------,----------,---,·

100

ZOJ

300

1965

1967

oo 10 ·10 -0.5 0 0.5

400L 500 ' __j

Figure r r. The deviations for temperature and salinity within latitude 67-69°N, and longitude II--I5°W in June 1964, 1965, 1966, 1967 from the mean values of the period rgso-58.

period (RoDEWALD, rg67). In view of these ab­normal atmospheric conditions, the changes ob­served in the Irminger water (HERMANN, 1967) and polar water (BLINDHEIM, 1967) fractions in the waters off West Greenland since rg63 are of special interest.

On the whole, it may be concluded that in June rg67 temperatures in the uppermost 500 m were below normal (r 0 C) off the west coast of Iceland,

but far below normal (4° C) off the north and north­east coasts. No influx of Atlantic water was observed east of Kogur. The influence of arctic water and polar water was, on the other hand, stronger than previously found in the area north­east of Iceland, even stronger than in rg65. Thus low temperatures and salinities observed in the East Icelandic Current since rg64 still prevail in rg67.

References

Contributions in I.C.N.A.F.'s Red Book, Part IV, 1967 by:

BLINDHEIM, J. "Hydrographic fluctuations off 'West­Greenland during the years 1959-1966".

HERMANN, F. "Temperature variations in the West Greenland area since 1950".

LEE, A. ] . "Fluctuations in sea and air temperature in the ICNAF area since 1950".

RoDEWALD, M. "Recent variations of North Atlantic sea surface temperatures (SST) and the "Type-Tendencies" of the atmospheric circulation".

MALMBERG, Sv. AA., 1967. "Hydrographic conditions in Icelandic waters in June 1966". Annis bioi., Copenh., 23: 23-7·

S.v AA. MALMBERG

Hafranns6knastofnunin, Skulagata 4, Reykjavik, Iceland.

20-

Some results of hydrographic investigations with R. V. "Anton Dohrn" in October/Nov­

ember 1967 around Iceland (Figures 12-18)

In October/November 1967 the R.V. "Anton Dohrn" carried out investigations around Ice­land. The main subjects for investigations were fishery biology and fishery hydrography.

Three hydrographic sections were made, their locations are shown in Figure rz. Section I was made across the Iceland-Faroe Ridge. The first and last stations of this section were done in positions where the depth to bottom exceeded rooo metres.

The temperature-section (see Figure 13) and salinity-section (Figure 14) clearly show the in­fluence of the Iceland-Faroe Ridge. It separates the Arctic deepwater (Station 953; temperature about --:--- 0.5°C, salinity about 34·9ZOfo0) and the

27° 25° zoo 15° 10° S0

680 680

979

][

o987

9708 0 986

CELANO

0197

6 977

II

72

0 971

o970

0969

o968

953

64°f-----f-------f"""""''--~.---t--------rL_J_~~ ;o---~~~-~--~-----~64°

1003 oo9~9

100S0 I o1004

10080

1Q09o 1'1,10

o1025 1030o o 01021 o1019

./ 0 1017 1020

10 961

l016

62°N 62° 27°E 25° 20° 15° 10° S0

Figure rz. Track chart. • Hydrographical stations, o Fishing stations.

- ZI -- Hydrography

0 m

200

400

600 ~ 800

1000

i:LCO

~ : Okm 50 100 150 200 250

Figure r3. Distribution of temperature on section I.

m

200

400

600

800

1000

Okm 50 100 150 200 250

Figure q. Distribution of salinity on section I.

Atlantic water (Station 96r; temperature about 9°C, salinity about 35·30fo0). The overflow over the ridge (DIETRICH, r956; r96o) is indicated in both sections. Except for the low values of salinity at Stations 956 and 955 and of temperature at Station 956 the present data correspond quite well with earlier measurements (DIETRICH, r957).

200

400

60T <- 0.5

BOO

1000

0 km 50 100

Figure 15. Distribution of temperature on section II.

It is obvious that the values of low salinity and temperature are caused by a branch of the East Icelandic Current.

This water was also found in section II, which was carried out from the Icelandic shelf region until depths again exceeded rooo metres. Tempera­ture and salinity distributions are shown in Figures I5 and r6. On one hand the special feature of section II is the relatively warm water with low salinity over the shelf (Station 972 and 973). It belongs to the North Icelandic Current. On the other hand the Arctic deep water can be identified (Station 975 and 976) by its well-known values of salinity and temperature. On section III R.V. "Anton Dohrn" worked from the Icelandic shelf in the

-22

m

~

200

400

>34.9

600

800

1000

0 km 50 100

Figure r6. Distribution of salinity on section II.

direction of the Denmark-Strait as shown in Figure 12. The temperature and salinity distribution is mainly influenced by the watermasses of the East Greenland Current. The temperature (Fi­gure 17) was less than- I.5°C within the region of the current (Station 979 and 980). The salinity (Figure 18), however, was exceptionally low due to intensive melting of icefields, which were ob­served a few nautical miles northwest of Station 979·

K. EHRICKE Institut fur Meereskunde der Universitat Kiel, 23 Kiel,

Niemannsweg II, Germany.

References DIETRICH, G., 1956. "Uberstromung des lsland-Faroer­

Ruckens in Bodennahe nach Beobachtungen mit dem Forschungsschiff "Anton Dohrn" 1955(56". Dt. hydrogr. Z., 9: 78-89.

St.Nr. 979 983 984

~1<-d i -~

200 ) -7.0

400

__.---/ 0

/

600

800

0kC"1 50 100 150

Figure 17. Distribution of temperature on section III.

m

200

600

/

evo

Okm 50 100 150

Figure r8. Distribution of salinity on section III.

DIETRICH, G., I960. "Die Uberstromung des Island­Faroer-Ruckens, eine Voruntersuchung zum inter­nationalen "Overflow-Program" im Juni 1960". Kieler Meeresforsch., 16: 9-12.

DIETRICH, G., 1957. "Schichtung und Zirkulation der Irminger-See im J uni I955". Ber. dtsch. Wiss. Kommn Meeresforsch., 14: (4) 255-312.

-23

Water temperature of the Norwegian Sea in 1967

(Figures rg-zo)

During the first half of 1967 heat transport by the Atlantic Current into the Norwegian Sea was below normal. Water temperatures of the Norwegian Current and its branches were also below normal in the winter-spring period and lower than the mean temperatures observed in 1966.

In June 1967 the waters of the North Atlantic Current in the Faroe-Shetland Channel had a small negative temperature anomaly, amounting to - o.r2 in the o-200 m layer. The mixed waters in the western part of the channel were characterized by lower temperatures, the anomaly amounting to - O.JI

0 in the 0-200 m layer. On the section at 63°0o'N in the Norwegian

Current the mean temperature of the o-200 m layer in June 1967 was the lowest one for the period since 1954. The negative anomaly was - 0.84°.

In waters of the East Icelandic Current the temperature anomaly of the o-200 m was- 1.74°. No such temperature decrease had been observed in this area before.

On the section at 65°45'N the temperature deviation of the eastern branch in June 1967 was -0.39° as compared with the normal for the o-200 m (Figure 19). On the other hand, an increased heat content was registered in the western branch on this parallel. The deviation of the average temperature from the norm in the o-200 m layer was+ 0.2J

0•

In the waters of the East Icelandic Current a small negative temperature anomaly was recorded in the 0-200 m layer (- 0.19°).

In the eastern branch of the section along 67°30'N as well as on the previous one there was also registered a high negative temperature anomaly amounting to -0.55° in the o-200 m layer. In the western branch at this latitude the mean temperatures of both the o-50 and the o-200 m layers were 0.5° below normal.

In the East Icelandic Current the mean tempera­ture anomaly, compared with the norm also amoun­ted to- 0.5°.

On the section along 69°2o'N the mean tempera­ture of the 0-200 m layer in the eastern branch showed a negative anomaly of -0.23°. In the western branch the temperature deviation of the o-200 m reached - 1.04°, and in the north­western branch the mean temperature of the 0-200 m was 0.54° below normal. On the section

Hydrography

0.8

o I ·\ -·?" < ::::> :fQ,'\:

- 0.4

- 0.8

- 1.2

-1.6 L---~----~~--~----~--~--~--~--~~-­F. s. Channel 63°00' 65°45' 67°30' 69°20' 71°10' 1tso' 74°30' 76°30' 78°00'

-1960 -+-1962 -·-·-1964 --- 1965 -1966 -Ll.-1967

Figure rg. Temperature anomalies of the o-zoo m layer of the eastern branch of the Norwegian Current in June

rg6o, rg6z, 1964, rg65-r967.

at 74°30'N in the eastern and western branches, temperature anomalies amounted to - 0.34 ° and - 0.53° respectively. On the Cape Langanes­J an Ma yen section the northern branch of the Irminger Current was characterized by a very low temperature, in the o-50 m layer the anomaly was - 1.94°. In the East Icelandic Current the temperature of the 0-200 m was 0.5° C below the normal (Figure 20).

In July 1967 waters with a surface temperature of 1I.2° C or 0.3° higher than in the nearly normal 1961, entered the Norwegian Sea across the Faroe­Shetland Channel. At the same time, on the section at 69°2o'N the warming up of the eastern branch of the Norwegian Current was registered with the result that the o-50 m layer was o.6° and the o--200 m r.6° warmer than in 1966.

In August 1967 in the Faroe-Shetland Channel the water temperature of the Atlantic Current in the 0-50 m layer was 0.5° higher than in August 1964. The o-200 m layer in the southern part of the sea was as warm as in 1964.

In the northern Norwegian Sea (section along 69°2o'N), in August as in July temperatures of the eastern branch of the Norwegian Current in all layers were 0.3° to 0-4° higher, and in the middle branch 0.9 to I.1° higher than in 1964, when the water temperatures of the Norwegian Current in this part of the sea were about normal.

It is typical that in July, August and September 1967 the Atlantic waters in the Norwegian Sea had a temperature in the o--50 m layer 0.5° higher than in 1964. In the 0-200 m layer it was similar to that in 1964 (10.2° C). In September in the northern part of the sea the warming up of the Norwegian Current was observed from the surface to the depth of 500 m. Its temperature became 0.3 to 0.9° higher than in 1964. In the

1.2

0.4

- 0.4

- 0.8

- 1.2

- 1.6

- 2.0

- 2.4

- 2.8

•-•o-so ) . lrm1nger Current --- o-2oo

II . \ \ \

.\ \ ~ . \ '· I ' .... r\ ·, \ ........ i \-i ....... i .,\ " . .. \ I I \' i i ., \ \ i \ \ .\ i \ \ i \

x-x0-200 East-Icelandic Curr12nt o-o0-50 } v . -- -·200-500

Z4-

temperatures were at the level of the unusually cold rg65.

V. V. PENIN, L. R. SOLONITSINA

The Polar Research Institute of Marine Fisheries and Oceanography (PINRO), 6 Knipovich Street, Murmansk,

USSR.

Hydrographic conditions off Spitsbergen in the summers of 1966 and 1967

(Figures 21-29; Tables 3-4)

1960 1961 1962 1963 1964 1965 1966 1967

In rg66 and rg67, as part of the British con­tribution to the International 0-Group Fish Surveys of the Barents Sea, R. V. "Ernest Holt" carried out two hydrographic surveys of the banks around Spitsbergen. Four sections were worked during the first survey (30. August-4. September, rg66) and five during the second (z4. August-4. September, rg67), the three southernmost sections of the first survey being repeated as closely as possible during the second (Figure zr).

Figure zo. T3mperature anomalies of the East Icelandic and Irminger Currents on the Cape Langanes-Jan Mayen

section in June !960-1967.

waters of the continental shelf west of the Bear Island area the temperature was r.o to I.5° C higher than in rg64.

In October-November the temperature of the East Icelandic Current remained low. Thus, on the section at 65°45'N in the o-so m layer it was 0.3° below the temperature of the unusually cold rg65. In the o-zoo m the same low temperature (z.zo C) was registered as in rg65 (Z-3° C). Compared with rg66 the waters of the East Icelandic Current were 0.6° to o.8° colder in rg67. In December the strengthening of the Norwegian Current continued in the south and central parts of the sea, and its temperature in the o-zoo m layer was 0.3° higher than in the previous cold years.

The temperature of the East Icelandic Current was as low as in the unusually cold rg65 (in the o-so m layer it was z.Z° C, and in the o-zoo m layer I.9° C).

Thus, in the autumn-winter of rg67 a strengthen­ing of the warm advection by the Norwegian Current was expected. Maximum temperatures during the second half of the year were recorded in the eastern branch of the Norwegian Current in the northern part of the sea (sections at 6g 0 ZO' and 74o3o'N). At the same time in the western N onvegian Sea the strengthening of the cold East Icelandic Current was observed and its

From the distributions of temperature and salinity that were observed (Figures zz-zs), it is clear that hydrographic conditions were markedly dissimilar during the two surveys.

Figures zz and Z3 show that the waters imme­diately to the east of Bear Island were very much colder and less saline in rg67 than in the previous year. Water temperatures of < -roC were com­monly observed at depths of between 30 and roo metres in rg67 (the minimum being - r:48°C), whereas nowhere in rg66 did the temperature fall below- r°C, and only one subzero observation was recorded. Again, in rg67 salinities of < 34-S%0 were commonly encountered in the uppermost layers to the east of Bear Island (the minimum recorded value being 33-Zg60Jo0), whereas in rg66 water of salinity < 34-S%0 was very limited in extent, and no values < 34-3°/00 were recorded.

Hydrographic changes of the same trend can be seen to have occurred along the Spitsbergen Bank section (Figures z4 and zs). In rg66 temperatures were (with one exception) always higher than Z°C and salinities were never less than 34-ZS60fo0 ; in rg67 the majority of the bank was covered by water of temperature < Z°C and salinity < 340foo, the respective minima being r.o8°C and 33.637%0-

In the shallower waters of the S0rkapp section, east of S0rkapp Bank, there was again a marked tendency for the surface layers to be colder and less saline in rg67 than in rg66 (Figures z6 and ZJ).

-25- Hydrography

61,0' 5' 10' 15' 20' 25' 30' 35~1'

BO'

79'

7B'

___]J ~~0~--~ ~G ~~ ~2

!u~

Ill

ifkr

~- ""U:tRLES

lr

~

"---? I HOP EN ISLAND

)

o;(,""t7 ~

BO'

30 ~

~

3G

Stations occupied during 1966 Stations occupied during 1967

o:;('~ ~J o'/_,18 JC_,

64 ""15 ,;;; ~

~;;.' ;: ' 6~ 16

ISr::Ji3'0/" ;, 6 ·x-

9

73' 73' o' 5' 10' 15' 20' 25' 3D' 35'

Figure zr. Hydrographic sections worked by R. V. "Ernest Holt" during the international 0-group fish surveys of rg66 and rg67.

Despite the fact that there was a slight variation in the alignment of this part of the section between the two surveys, this tendency appears to be a real one, since the distribution of properties at such stations as were common to both surveys indicate that a cooling and freshening of the surface layers was general throughout the area in the summer of rg67 ( cf. stations 26jrg66 and ss/r967; stations 2rjrg66 and 59/r967).

From the above it appears that, with respect to the first survey, hydrographic conditions at the time of the second survey indicate an increased arctic influence in the shallow waters east of the S0rkapp-Bear Island line.

West of this line it appears to be equally clear that the prevailing Atlantic influence was also more intense during the second of the two surveys. Figures 26 and 27 show that along the S0rkapp

200

300

400

200

300

400

8 7 6

5 6" +6 + \• ~ +

~ _:.._______ ~ 4 + + +

~· ~ +

T'C

19 6 6 30-31/VIII ~·

z6-

r•c

196 7 24-26/VIII

Figure 22. East Bear Island section- temperature.

s 0! 00

19 6 6 30- 31/VII

/ I \

"

/:-------:;.-----:-

05~51

" \. __ /

.._____ ....__

3505 • I

/ I I. /~....__ I I " I I \ I I \ I I \ \ I \ \ I • \ • ,. / "-"- / ....._

<35-05 ....__

So I oo

19 6 7 24-26/VIII

Figure 23. East Bear Island section- salinity.

/ 350/

I \

\

g

3------

11

~ ~ - :::--:--- : I -3505--/ + ---.:-

\ +

\ "­

'-.... ....____

--..__ --..

Contours are drawn at intervals of o.r 0/ 00 above 34·5°/00 and at intervals of 0.5°/00 below 34-5°/00 •

12 13 15 17 18 19 21

+ + + + + + + + + + + + + +

50~ + 19 66

+ +

31/VIII-1/X T0 e

I 100

20/66 65 64 63 61 50 59 I I $ I I L, 2 l + -=2 + >2 + + + + 2 + + + 2 +

50f--~96; + ~

~ 4 I I X Toe

100

Figure 24. Spitsbergen bank section- temperature.

section west of S0rkapp bank, the bed of warm water bounded by the soc isotherm was much more extensive and reached a higher core temperature in rg67 than in the previous year; similarly the rather narrow subsurface bed of high salinity water bounded by the 3S.I%0 isohaline was more extensive during the rg67 survey, and penetrated to the east of S0rkapp Bank, while its core salinities of > 3S.z%0

contrast with a maximum value of 3s.rr6°j00

found in rg66.

As regards the remaining three sections worked off west Spitsbergen - called, for convenience, the "diagonal" section, the "Krossfjord" section and the "Isfjord" section - the same general conclusion can be drawn that conditions were warmer and more saline during the rg67 survey than during that of rg66, despite the fact that Krossfjord section, worked in September rg66, does not coincide with either of the two rg67 sections. Along this rg66 section, temperatures of > soc were nowhere observed (the maximum being 4.92°C) and with only one exception (3s.ror0fo0)

salinities were lower than 3S.r0Jo0 . Yet, during the rg67 survey, temperatures of > soc and salinities of > 3S.r0fo0 were commonly found above 200 m depth along the "diagonal" section worked to the north of the Krossfjord section. Indeed, core temperatures exceeded 6°C in two cases. The Isfjord section of rg67 was worked well to the south of the Krossfjord section and comparisons between the two are therefore of less significance. However, salinities in the upper zoo m off Isfjord

27- Hydrography

12

f>34·3

~ 1966 31/VIII-1/X

S 0/oo

20/66 t-

T >33-7

50r~ " + 1967 4 /IX S 0 /oo

Figure 25. Spitsbergen bank section- salinity. Contours are drawn at intervals of o.r 0 / 00 .

were certainly higher than were observed in rg66 on the S0rkapp section farther south.

The computations of volume transport provide further evidence of an increased Atlantic influence west of Spitsbergen during the later survey. All volume transport observations that could be made, relative to the 8oo m level, are listed below.

Table 3·

Volume Direction Inter-1966 Stations transport (to) station

(ro6 tons distance per sec) (km)

Sorkapp 32-30 0.09 s 79·7 section ... 30-29 0.36 N 73·6

Krossfjord section ... 39--38 0-41 s 29.9

1967 so-sr I.I7 N 75·3

Sorkapp SI-52 O.I I s 75·3 section ... 52-53 0.28 N 39-4

Isfjord section ... 32-·31 0.83 N 50-4

Diagonal section ... 35-36 0.78 N 37·7

These figures certainly suggest a stronger north­ward flow along the west coast of Spitsbergen during the rg67 survey, but do not fully describe the transport since, on the S0rkapp section at least, some part of the flow takes place along the edge of the banks where no calculation of volume trans-

Station

1001-~

200

E

--=o·s <0

~ 1500

2000

Min ·91

2500

32 .~-

<]50 -350

100

200

300

400

500

[:''"~I E •

---1000 /. 34·95_1

>]4·9

~ 1500

2000

2500

numbers

1956 1-2 I IX

-28-

\ \ \ \

S t a t i o n

\_ ~ '---- ---os-

/fv\

Figure 26. Sorkapp section- temperature.

\

S'/,.

1966 1-2 !IX

\ \

\ "'-M \ \ \ \

\ /

\ 34·95 '-.::_.........-

. / /

/

>3495

numbers

T'C

1967 2-4/IX

S'/,.

1967 2-41 IX

Figure 27. Sorkapp section- salinity. Contours are drawn at intervals of o.r 0

/ 00 above 34·5°/00 and at intervals of 0.5°/00

below 34·5°/00

.

o3JJ 100

2000

2500

1967 30-31/Vlll

Oi agonal sect 10n

I

T'C

19 66 2-4/ IX

Kross fJord sectiOn

I \~I

l .I

- zg

T'C

19 67 29/ VIII

lsfjord section

Figure 28. Sections off north-west Spitsbergen-temperature.

port has been made, due to the absence of a suitable reference level at 8oo m. However, as a basis for comparison, the volume transports relative to the 300- and zoo-metre levels are listed below for the S0rkapp section, and these tend to confirm the greater transport of water northwards during rg67.

1966

1967

Table 4·

Volume Volume transport transport

Stations rel. to rel. to Direction 300 m zoo m (to)

( ro6 tons ( r o6 tons per sec) per sec)

32-30 0.02 O.OI s 30-29 0.27 o.rs N 29-28 - 0.06 s 50-51 O.IO 0.05 N 51-52 0.02 0.01 N 52-53 O.IO 0.07 N 53-54 0.33 0.21 N

Inter­distancE

(Km)

79·7 73·6 36·9 75-3 75-3 39-4 37·6

The monthly ice charts published by the Marine Division of the Meteorological Office, Bracknell, provide further evidence that during the rg67 survey, the arctic influence east of Spitsbergen and the Atlantic influence to the west of Spitsbergen

Hydrography

300

400

500

350

10001

II 1500

2000

2500

1 S'/oo

1967 30-31/Vlll

Diagonal section

>350

3 50

J495 " \

I "· S'foo

1966 2-4/IX

Krossfjord section

r,D \ I

I "' I S'/oo

("--/ 1967 29/Vlll

JsfJord section

Figure 29. Sections off north-west Spitsbergen-salinity.

·350

Contours are drawn at intervals of o.r 0 / 00 above 35.o0 j 00 , at

intervals of 0.5°/00 above 34.o0 j00 and at intervals of r.o0 / 00

below 34.0°/00 .

were both more intense than during the survey of rg66. In August and September, rg67 "close or very close pack" was reported as far south as the southern tip of Edge Island- a marked extension from the previous year - while to the north-west and north of Spitsbergen, the southern limit of this pack ice was somewhat further north than in August and September, rg66.

Putting these observations into the broader context of hydrographic change over the Barents Sea as a whole, the unpublished preliminary reports of the two International 0-Group Fish Surveys suggest that conditions were warmer in rg67 than rg66 along all the Atlantic current branches in the Barents Sea, although data from the Kola section would suggest that the higher values of rg67 are in fact close to the long-term average and that the exceptional conditions were those of rg66.

R. R. DICKSON, T. C. DoDDINGTON

Fisheries Laboratory, Lowestoft, Suffolk, England.

-30-

74 2

s· 72°

70°

B

68° 20° 30 40° 20° so· 40°

Figure 30. The distribution of water temperature near bottom in March, A) in 1967 B) long-term mean

Water temperature of the southern Barents Sea in 1967

(Figures 30-32; Table 5)

Unusual low heat content of water masses during 1966, when the annual water temperature anomaly on the Kola Meridian was - 1-4° had influenced the thermal regime of the sea at the beginning of 1967.

In the winter 1966/1967 easterly winds prevailed. Air temperature above the sea in J anuary-Fe­bruary was 1° to 3° below and in March-April 2° to 4° higher than the long-term mean.

As a result of the comparatively light cooling of the surface, the significant negative temperature anomaly in the 0-50 m layer was sharply reduced in January-March and in May the temperature in this layer had reached the many-years mean value. At the surface it had already reached the mean in March. Along the Murman coast the temperature minimum was registered in February, that is one month earlier than usual.

A considerable and sharp decrease was observed i.n the negative anomalies of the water temperature in the o-200 m layer, on all sections in the southern part of the sea, from January to April. Thus, the temperature in waters of the North Cape Current reached the long-term mean in April, in the core of the Murmansk Current the negative anomaly decreased from 1.3° in January to o.6° in April, and along the coastal branch of the Murmansk Current it was reduced from I. 5° to 0.7° respectively. However, the temperature of the near bottom water layer was, as usual, low, and approximately the same as during the cold 1966.

Temperature distribution near the bottom in March 1967 compared with the mean distribution, calculated for many years, is shown in Figure 30.

Hence, in spite of the tendency of warming, the heat content of water masses in the southern Barents Sea continued to be low in the period of winter cooling.

In the beginning of the spring-summer warming­up period (May-June), winds of eastern directions prevailed, and the air temperature above the sea was nearly normal. In July-September westerly winds were predominant, and therefore, the air temperature was around the many-years mean or slightly higher.

The rate of warming of the o-so m layer all over the sea reached, as a whole, the long-term mean. It was very high, however, in the shallow south-eastern part of the sea and up to the end of August the water temperature was 3-4 ° higher than normal in this area. The temperature maxi­mum in this layer was in all sections found in September instead of in August, and it was 0-4° to 0.7° higher than the long-term mean.

Temperatures of the 0-200 m layer on the section across the North Cape Current were o.1-o.2°C below normal during the whole warm period and only in September did they reach the long-term mean.

The expected reduction of the positive tempera­ture anomaly in the beginning of the year in the branch of the Murmansk Current continued during the whole summer, and in September the tempera­ture on the Kola Meridian reached the normal. On more eastern sections of the Murmansk Current

- 3I- Hydrography

?o'ooN 70.30 7o'oo

35'30£ 33.30 33'30

71.30

33'30

72.00 72.30N 70.00N 70.30 7l00 71.30

33.30 33.30£ 33'30E 33'50 33'30 33'30

72,00 72.30N

33.30 33.30E

0 20

50 75

lOO

iSO

200

250

2:.--_

A. 29/8,1967 .B. 27/8, 1967

300~------------------------~ ~------------------------~

Figure 3r. The vertical distribution of water temperature in the Kola Meridian. A) in rg66 B) in 1967

the negative temperature anomaly decreased from I

0 in April to 0.3° in September. Especially, the heat content increased in the coastal branch of the Murmansk Current. In March the temperature anomaly was - !.3°, in July temperatures were normal and in September the temperature was 0-4° above normal. The temperature distribution on the section along the Kola Meridian at the end of August rg67 and at the end of August rg66 is shown in Figure 31.

In October--November south-western winds dominated, and in December north-eastern ones. In accordance with this, the air temperature in the first case was 2° higher but in December 2 to 4 ° lower than normal. The rate of cooling and convec­tive mixing of the water masses was therefore slow in October-November and increased sharply in December. Usually the temperature of the o-50 m on the Kola Meridian decreases by o.6° from November to December, but in rg67 it decreased by r.8°.

The heat content of the water masses of the 0-200 m layer in the North Cape Current was near the normal during the last three months of this year. In the main branch of the Murmansk Current positive anomalies in October-November (0.3° to 0-4°) turned into a small negative anomaly of o.2° in December. Simultaneously, on more eastern sections crossing the Murmansk Current, and also in the coastal branch of this current, positive anomalies up to the end of the year were nearly 0.3°.

In the near bottom layer of rso-2oo m along the Kola Meridian the water temperature did not reach the normal up to the end of the year, but it was approximately I

0 higher than the tempera­ture of the cold rg66. The distribution of the No­vember temperature near the bottom in rg67 compared with the long-term mean, is shown in Figure 32.

The actual value of the temperature of the o-200 m layer at the rsth of every month in some sections of the Barents Sea is shown in Table 5·

Table S· Average monthly water temperature on standard sections of the Barents Sea, 1967

Month I II III IV v VI VII VIII IX X XI XII Annual Section mean

North Cape-Bear Island (the North Cape Current) 4-2 4·0 4·0 4·2 4·3 4-7 5.1 5·7 6.2 6.1 5·8 5·5 5.0

The Kola Meridian (the main branch of the Murmansk Current) ................. 2.8 2-4 2-4 2.6 3·0 3-4 4·2 4·8 5·3 5·5 5·2 4-4 3·8

From the Kharlov I~land to NNE (the coastal branch of the Murmansk Current) ... r.8 l.O o.6 o.8 r.6 2.7 3·7 4-6 5·5 5·7 5·4 4-4 3·2

-32-

74.

n·

70.

as· • 20 so· 40° 20" so" 40°

Figure 3I. The distribution of water temperature near bottom in November A) in 1967 B) long-term mean

To sum up, the heat content of the water masses of the southern Barents Sea was in the beginning of rg67 on the level of very cold years.

During the period of the spring-summer heating and until the end of the year, water temperatures were near to or a little higher than the normal ones.

As a whole rg67 may be reckoned among the moderately cold years.

A. I. Mukhin The Polar Research Institute of Marine Fisheries and Oceanography (PINRO), 6 Knipovich Street, Murmansk,

USSR.

Surface temperature and salinity observations at English sampling stations during 1967

(Figures 33-64; Tables 6-7)

Surface temperature and salinity sampling by merchant ships and lightvessels on behalf of the Fisheries Laboratory, Lowestoft, con­tinued during rg67. Some of the results are pre­sented here in tabular form and as diagrams of the monthly mean anomalies of temperature and salinity at the observing positions. A number of relevant meteorological parameters are also shown in diagrammatic form to aid interpretation of the anomaly patterns.

Within the area covered by our anomaly dia­grams six lightvessels observed and seven merchant ship routes were operated, positions of the standard observing positions being shown in Figure 33· One route was a new one, Scilly-Shamrock Knoll, running across the western entrance to the English Channel and was intended to supplement data from the Bristol-Finisterre route, raising the frequency of sampling in this area to between

three and five times per month. Sampling was gene­rally at weekly intervals on other routes, and at intervals of four days at the lightvessels. At the Lynn Well and Mid-Barrow lightvessels observa­tions were taken at both high and low water on sampling days, as tidal changes are large at these stations. Observations were not available from the

5' 10'

9·

\,ei\\1 - to~e\\1\n\lel\ 7· Q·

2• 3·

4• 5· 6· 9·

Q.

7·

2· leith 3· i;

~ ...... ~ 6· ~.,<:;~ 5· 5· Bre

/ 4·

~""~ 3·

6· fllen 7·

2· 8·

1·

SevenStone~· . :·.·. . . L.V. .· .: ·· ·::;: .. ·...: · • · .. : · .. · · -Varne>"' Stilly - .·:· .. ····· .·· '0 1·. LV. ·

50' !Shamrock ·1 \ ,1 .. ·::·. · ·· Newhoven 23.. ;····

Knoll 2· '·2 ~-.O.ie.ppe .·· \·6 . ·· t ~4 & •. • : .: .... ·

s· ~G Bristol- ., ·:: . .· ·· · 6' 7· Finisterre ~8 g."8 ' ...• · ... ·. . :· .

48'Lli! o'

48'

Figures 33· Positions of routes and stations mentioned in the text.

-33-- Hydrography

,J,F M A M,J,J AS O,N,O, J F M AM J J AS 0 N 0.

·2 ·2 ~1952-1955 l' \ +2

+ 1 ·1 ',~,A, --o' ''0...,

·1 1905-!954

,_, ol/ '~= ~~

<l

-1

-2

.. ,] ~.

·~~ ~ 0 - --..--~

<l

- 0·5

......._. SEVEN STONES l. V. ~-~-« BAROSEY L.H.

-1

-2

·0-5

-0·5

'", ;,

VARNE L.V.

I I

! 1952-1966

-H J

-2

-0·5

GALLOPER L.V.

"

JFMAMJJASONO JFMAMJJASOND J,F,M,A,M,J,J A,S,O,N,O,

·2 ·2

·1 .1

:;-' 0+-~~--~----------~-------=:; _,

-1

-2 -2

+ 0·51

~o.:~r----;~=~~~~-

• 0·5

-0·5' ,/

MID BARROW L.V. SMITHS KNOLL L.V.

·2

·1

-1

-2

+ 0·5

-0·5

' ' ' \ ~\

'· ~ /,,.~~

' ' \ .tl \,/

~

/\ ' ' / \

.........,_. MORECAMBE BAY L.V. o--~--<o LIVERPOOL BAY l.V.

' ~-J.-6

Figure 34· Monthly mean sea surface temperature and salinity anomalies at lightvessel stations.

Newhaven-Dieppe route in February and March and the Cork-Fishguard route in January to March, as both ships were temporarily withdrawn from service.

Lightvessel observations

Table 6 presents the monthly mean tempera­tures and salinities at the lightvessel stations and their anomalies from long-term means. In addition to the six lightvessels shown in Figure 33

values are tabulated for three stations in the Irish Sea, Liverpool Bay and Morecambe Bay lightvessels and Bardsey lighthouse. For these stations ano­malies have been obtained from the 1935-61 means of HuGHES (rg66). With the exception of the Lynn Well lightvessel, which is situated in an area in which past data are scanty, anomalies for the remaining lightvessels have been obtained from the ICES Atlas (ICES, rg6z). Anomalies for the Galloper, Varne and Smiths Knoll lightvessels have also been computed from monthly means for the period

-34-

Table 6. Monthly mean temperatures and salinities at English and Welsh lightvessels in 1967 and their anomalies from long-term means

Temperature °C .... Anomaly (1905-54) · Salinity 0 / 00 .•......

Anomaly (1905-54) .

Temperature °C .... Anomaly (1905-54) . Anomaly (1952-66) . Salinity 0/00 ....•...

Anomaly (1905-54) Anomaly (1952-66) .

Temperature °C .... Anomaly (1905-54) . Anomaly (1952-66) . Salinity 0 / 00 ....... .

Anomaly (1905-54) Anomaly (1952-66) .

Temperature °C .... Anomaly (1905-54) · Salinity Ofoo ....... . Anomaly (1905-54)

Temperature °C .... Anomaly (1905-54) . Anomaly (1952-66) . Salinity Ofoo ....... . Anomaly (1905-54) Anomaly (1952-66) .

Temperature °C ... . Salinity Ofoo ....... .

Temperature °C .... Anomaly (1935-61) . Salinity Ofoo ....... . Anomaly (1935-61)

Temperature °C .... Anomaly (1935-61) . Salinity Ofoo ....... . Anomaly (1935-61) .

Temperature °C .... Anomaly (1935-61) . Salinity 0 ( 00 ....... . Anomaly (1935-61) .

Jan. Feb. March Apr. May June July Aug. Sept.

Seven Stones lightvessel

10.6 10.1 10.0 +o.6 35-29

+o.o3

10.1 1I.5 13.6 15.7 16.0 +o.1 35.14 -0.04

14-9 -0.1 +o.5 +o.5

35-30 35-30 +o.o5 +o.o4

+o.3 +o.5 +o.4 +o.6 35-29 35-31 35-29 35-23

+o.o3 +o.o7 +o.o5 +o.o1 35-09 ·-0.09

8.o -0.1 -0.5 34·77 -0.25 -0.24

7-0 0.0

-I.1 34-56 - 0 -33 -0-45

4·8 -r.8 33-93 -0.64

5-7 -0.3 -0.7 33-92 -o.5o -0.43

4·1 32-57

5-5 -0-4 32.10 -0.13

6.0 +o-4 3I.60 -0.19

8.1 -0.3 34-31

+o.o5

V arne lightvessel

8.6 9.2 9-3 +r.4 +r.3

34-60 -0.34

10.8 +r.o +o.8

34-94 -0.04

13.2 16.0 17.2 +r.1 +o.7

35-08 +o.r4 +o.19

+r.3 +2.1 +r.6 +2-4 34.87 35.01 -o.11 +o.o2

+o.9 +r.5 +o.7 +r.1

34·96 35.10 o.oo +0.11

+o.o5 +o.17 -o.o6 +0.12 -0.32 -0.01

8.1 +2.2 +r.6 34-86

+o-14 -0.07

6.2 +o.2

34-16 -0-40

5.1 +o.2

0.0 33-98 -0.31 -0.28

4·9 32-91

5-7 +o-7 3L72 -0.36

6-4 +r.4 32-36

+o.6z

Galloper lightvessel

8.3 +2.2 +2.1 34-91

+0.22 +0.13

8.7 10-4 12.8 16.2 17·4 +o.3 +o.7 34-95

+o.o7 +o.15

+r.1 +o.3 -0.4 +o.3 + r.2 +o-4 o.o +o.7 34·68 34-75 35-03 34·78

+0.03 +o.16 +o-48 -0.03 -o.o6 +o.o3 +0.35 +o.o6

7·6 +r.5 34-17 -0.25

Jvl id-Barrow lightvessel

7·7 1I.2 13.9 +o.1 +r.1 +o.5

34-17 34-25 34-51 -0.24 -0.21 +o.o5

Smith's ]{noll lightvessel

5-7 +o.6 +o.6 33-97 -0.19 -0.28

6.1 33-13

6.8 8.9 12.1 +o-4 +o.8 33-96 -0.20 -0.25

+o.1 0.0

33-89 -0.25

-0.25

+o-3 +o.1 34-26

+o.o8 +0.17

Lynn Weli lightvessel

7-3 10.6 13-5 33-22 32-94 32.83

J1lorecambe Bay lightvessel

6.2 6.9 9.0 13.7 +o.7 -o.8 ~.6 o.o 31.83 32-47 32.31 31.98 -0.26 +o.15 -0.35 -o.81

6.9 +r.3 33-04

+r.52

Liverpool Bar lightvessel

7·4 9-4 14.8 -o.6 -r.7 +o.5 32.01 32.00 3L53

+o-45 +o.18 -0.59

Bardsey lighthouse

17-7 +r.9

34-65 +o.o2

18.2 +r.3

34-75 +o.o6

14·7 16.9 +o.r +o.7

o.o +o.s 34.09 34.10 -0.04 -0.02 -0.02 +0.01

16.7 33-30

15.6 -0.3 32-38 -0.47

15-9 -o.5 3I.82 -0-40

17.0 33-72

16.o -0.7 32.18 -o.66

16.5 -o.5 32.13 -o.o8

17.1 +o-9 +o-3

35-05 +o.ro +o.13

16.9 +o.4 +o.1 34-98

+o.o7 +o.15

16.6 +o-3

34-89 +o.o8

16.8 +r.o +o.5 34-26 -0.02

+o.o5

14-9 33-91

15-5 -0.1 32.12 -0.66

15.2 -0.4 32.22 -0.01

7-9 +o.2 34-26 -0.01

8.2 +o-4 34-40

+o.rr

8.7 9.8 11.9 14·8 +o.6 34-34 0.00

15.1 14-5 -0.2 -o.6 -o.5 34-34 34-18 34-33

+o.o4 -0.14 +o.o2

-0.1 -0.7 34-38 34-42

+o.o3 +o.o1

Oct.

13-5 -0.1 35-07 -0.14

15-4 +o.6 -0.1 35-06

+o.o8 +0.11

15.6 +r.4 +o.3 35-03

+o-14 +o.14

13.6 -0.3 34-80

+0.01

14-9 +r.o +o.4 34-45

+o.o7 +o.13

12.2

33-96

13.1 0.0

32.21 -0.51

13.0 +o.2 32-72

+o.51

13.0 -o.8 34-38

+o.o1

Nov.

1I.3 -0.9 35-07 -0.19

12.0

-0.2 -0.9 34-99 -0.03

+o.o3

12.9 +r.8 +o.z 35.01

0.00 +o.o5

10.3 -0.7 34-80 -0.03

11.2

+o-5 -o.5 34-48

Dec.

10.6 -o.5 34·74 -0.52

9-1 -O.j

-L4 34-92 -0.10 --o.o8

9·8 +r.4 -0.2

34-94 -0.03

0.00

6.1 -2.3 34-48 -0.20

7-7 -0-4 -I.2 34-67

o.oo +o.zo +o.o3 +o.27

8.9 33-65

9-6 -0.5 3L83 -0.75

9-3 -0.2 31.72 -0.30

11.4 -0.3 34-56

-1-0.27

6.0 33-40

7-7 +o.2 32.22

0.00

7-0 -0.2

3L59 -0.30

9-4 -0.5 34-44

+o.15

-35- Hydrography

1 1,F M,A,M,J,J,A,S,O,N,O, ,J,F,M,A,M,J,J,A,S,O,N D, .J.F.M.A,M,J,J,A,S,O,N,O,

•2lA JA ·2

•1 . ·1

:.'

~"" <l

-11 v v ------ v -1 j -1

-2 -2 -2

} A J

~ ~ L\ f\/\ !" ~ ~

~ 1

1

::J\/ \I l I :::\7\ 1\f ~

200J v 200J • 200

S.W. ENGLAND AND S.WALES S.E. ENGLAND E.ENGLAND

JFMAMJJASOND

•2

·1

:.'

!;;;

-1

-2

~

~

;1 ~ 1001-f-----'r;-t'----\:-----1~---'~-.,or--.f---

200

H.E. ENGLAND

•2

•1

-1

-2

0

50

JFMAMJJASDND

100-¥--\-+--1--------f--

200

N.W. ENGLAND AND N.WALES

Figure 35· :Monthly mean air temperature anomalies and percentage of normal rainfall for a number of districts of England and Wales during rg67.

1952-66 (ELLETT, rg67), as some doubts were expressed when discussing rg66 data from the Galloper (ELLETT, JONES and READ, rg68) as to the suitability of the ICES regional means for comparison with these data. The monthly mean temperature and salinity anomalies for all light­vessels are shown diagrammatically in Figure 34·

Air temperature anomalies, rainfall and winds

Figure 35 shows the air temperature ano­malies and percentages of normal rainfall for

land areas adjacent to the coasts of England and Wales. The values are those published by the British Meteorological Office (rg67-rg68). Rainfall has been plotted on an inverse scale for easier comparison with the salinity anomalies of Figure 34· Immediately noticeable in Figure 35 are the warm months 0f January-March, July and Oc­tober in all districts, although the two latter months were more markedly warm in east and south-east England than in northern and western districts. A cold May and November were experienced in all districts, and in the east and south-east

-36-

TYNEMOUTH

/ "'··· ,/---.MAR.-· \/" ..... • .. / ':··

\ / _ .. ----·'.--·--··- ·-- ..

. .•.. / DE C. . ..• ..• -··

OCT.

' '·JAN. r ···• ..........__ _ __........

... ·~·< .. .. Lr:U LV

' ..-··-... .. '·/ -~ic·.··'

scale for 10-day mean winds

0 30 kt.

OCT. , ........ . / ,/ .. ..

',(· •.• J

.. I I I I I I I

GORLESTON

~~)~~/~ULY ,; 1

0 CT. ~\-· • ._/DEC .

.·•·· ........... " '· .. · / '...........-·-/ THORNEY ISLAND

,·:._ , .. ·

JAN.r'· ' ,___...,/• /-i MAR. / :· JULY

)./-·-(/ '...... :; ;···· .. '·· " 'J JAN.

' .· .•. ·OCT

'~./J . .----·-·""' /""

,; MAR. "··~:;;'))·JUL.

'· __ .( / ... '-....- ······ .....• • . DEC.

RONALDSWAY

, 0 CT . ·• ..... .........

' _.) -!. DEC MAR. \ ;··· ....... j

.. · ,.

/

·- I .-·-. ' .-... , .....• .• . /

• / \A ).,Yj JULV

JANJ···

/v·

' . / ~

I -1 JAN

ROCHES POINT

\ OCT MAR. ~ \--·--. / \ \.·

·•······· ~----.

.· 1 >··· ··-· ..... / '. . '\ .-· ./·· ~/\._-"t_..-·-JULY

'./ JAN. /

·-.....,/ ~ 0 EC. \

···· ......... SCILLY

N

t

Figure 36. Hodographs of ro-day mean winds for six coastal meteorological stations during 1967.

37- Hydrography

5' O' ~' 1n' 5' 10' ---.,---,

0·6 0·3

0·~ 0·1 -o.z

0·9 0·~

01

-0 12 -0·01 -0·76

-0·02 -0·02 -0·09 .

0·01 0·09 -MO

0·6 -0-24

-0·1 0·17 -0-11 0·3

0·2 -0·2 0·11 -0-o/ -0·05

-0·5 -0·03 -0·1 0·3

0·~ 0·0~ -0·11

-0·12 -0-7 -0·1 -0·07 -0·!,1

-o.z -0-12 -0·3 -0·08

53'

"s'' "s' 48' "8'

Figure 37· Monthly mean temperature anomalies, January 1967.

temperature anomalies in June and April were comparable to those of May. May was also a very wet month, as was October in all regions except north-east England. The general trends of the district air temperature anomalies are reflected to some degree by the sea temperature anomalies at the lightvessels, but good correlation between high rainfall and low salinity is found only in the case of the Morecambe Bay lightvessel, situated near the estuaries of rivers which drain the fells of Westmoreland and the western Pennines, the regions in which the greatest amount of British rainfall occurs.

Winds at six coastal meteorological stations are shown in Figure 36 as hodographs of ro-day mean winds. Vectors for these periods were obtained from the daily observations at the four main synoptic hours published in the Daily Weather Reports (METEOROLOGICAL OFFICE, rg67). The dia­gram shows a rather normal sequence of south to west winds, apart from a month of northerly winds in April which was followed at most stations by two months of light, variable winds. March and October were generally the windiest months, as may be seen from Table 7, which summarizes the month-

Figure 38. Monthly mean salinity anomalies, January !967.

ly mean wind vectors. It is of interest to note that oil patches from the wrecked tanker "Torrey Canyon" travelled from the Seven Stones rocks to the French coast during the April period of north-westerly and northerly winds at a speed of about 3-5 per cent of the wind speed and apparent­ly in the direction of the wind vectors. (SMITH, rg68).

Monthly mean sea-surface temperature and salinity anomalies on the merchant ship routes

Figures 37 to 6z show the anomalies of the mean temperatures and salinities at merchant ship and lightvessel stations from the appropriate 1905-54 regional mean values of the ICES Atlas. These can only be an approximate guide to con­ditions at the stations during each month, as there is some bias within certain of the regional means produced by non-homogeneous data, but they represent a relatively compact method of displaying the 250 or more observations made monthly in terms generally valid to the biologist.

Figures 47 and 52 allow comparison to be made between the monthly mean anomalies for the period May to July in the English Channel and Celtic Sea

- 38--

5'

0·9 0·9 0·4

0-7 0·8 0·9

0·2 1·2

0·5

O.Y 0·6

0·5 0·8 0·8 55'

0·5 1-0 0·6

0-7 0·5 0·8

0·2

f~~~ 53'

10'

-l50'

53'

• 0·0 5

0·12: 012

0·05 -0·32

0·05 -0-11

-0·04 -0·16

-0·09

5' 10'

I 0·18

0·46

006 -0·09 0·10

0·33

0·01

-0·03

0·05 0·12

0·11 -0·14 -0-32

-1-04

48' 43' 48' 48'

Figure 39· Monthly mean temperature anomalies, February 1967.

and two quasi-synoptic surveys carried out by R. V. "Ernest Holt". The mean values used to construct these two figures were obtained by interpolating at the date of each observation from the relevant ICES regional means. The anomaly distributions thus obtained are much more complex than could be inferred from the monthly mean anomalies. Study of the May and June monthly mean temperature anomaly diagrams would have led us to underestimate the quantity of water with a

Figure 40. Monthly mean salinity anomalies, February 1967.

negative anomaly in the western Channel at the end of May as compared with the amount found during the "Ernest Holt" survey at that time, and similarly we might have overestimated the amount of warmer water present in the eastern Channel. In salinity, too, we would have underestimated the size of western Channel negative anomalies and would have remained unaware of a tongue of relatively saline water present between the Baie de la Seine and the Isle of Wight. Conditions

Table 7· Monthly mean wind components at six coastal meteorological stations during 1967

Knots Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec.

Tynemouth ......... N. comp. -2.12 -5.66 - r-42 5·71 -0-49 -0.84 -2.20 -I.69 -2-41 - 4-40 0.00 3·67 (55oor'N OI

0 25'W) .... E. comp. -6.74 -6.59 -15.24 -3.22 -o.2o -4.01 -4.II -2.81 -3.50 - 8.59 -6.39 -rr.o4 Gorleston ........... N. comp. -4.51 -6.JI - 4-93 4·92 -8.28 r.87 -3.07 -3.59 -3.56 - 9.91 -3.62 !.02

(52°35'N OI0 43'E) .... E. camp. -3.97 -3.53 - 9.07 -o.83 -0.74 -r.84 -o.28 -r.s8 -2.29 - 6.76 -3. 42 - 7.7o

Thomey Island ...... N. comp. -3.02 -3·42 - I.67 -4.13 -6.89 -0.99 ·-3.19 -3-51 -2.59 - 6.12 o.89 2.25 (5oo 49'N ooo 56'W) .... E. comp. -2.83 -4-47 - 8.60 -o.98 -4.54 -3.15 -4.57 -5.16 -5-42 -Il.OO -2.83 - 5.11

Scilly . . . . . . . . . . . . . . N. comp. -3.09 -4-42 - 2.04 6.79 -r.72 -o.8s -2.31 -1.13 -o.8o - 4.87 3-44 5·33 (49°56'N 06°18'W) ... E. camp. -2.52 -5.37 - 8.83 1.29 -5-99 -2.62 -4-46 -+98 -6.87 -1r.68 -3.36 - 4-02 Roches point ........ N. comp. -4-89 -6.31 - 3.II 5-44 -0.77 -0.51 -+97 -2.25 -3-92 - 5-72 2.13 2.72

{51°48'N o8°15'W) .... E. camp. -2.oo -3.79 -10.73 -2.76 -4.95 -2.64 -4.31 -3.23 -5.66 -1o.o6 -5.32 - 6.27 Ronaldsway ........ N. CG!Lp. -4.28 -6.73 - s.<;6 5.32 -2.03 -0.59 -4-49 -1.45 -4-01 - 7.10 0.25 I.j6 (54 oos'N 04 °38'W) .... E. comp. -2.14 -3.18 -13.27 -2.22 -0.63 -3.11 -2.62 -3.20 -2.85 - 9·95 -4·91 - 7·58

-39- Hydrography

5' 10'

0·~ 2·0

1·0 0·6 1-2

1-0 0·3

0·6 H

1·0

0·5 1·5 0·6

1-0 1·5 /I.· l5 _j,,, 1·6 0·8

0·8 1-3 1·9

0·1 0·2

53' 1- ;M_ -~~ 0 :_::' .. : ·· ...... ~t,

4 8' 48'

55'

53'

Figure 4I. Monthly mean temperature anomalies, March rg67.

5'

-0·9 }1

-0·8

-0·3 -0·5 -0·4 -0-9

0·3

0·6

0·8 0·3

0-7 1·0 0·8

0·6 1·0 0·8

0·~ 1-4 -0-1

-0·1

10'

55'

53'

5' 10'

0·23 0 03 0·03 -0-13 -0·80

2·25

0·13 0·19

-0·05

0·26 0·16

0·11 0·25

-0·12 -0-10

-O·OB

0·24 0·20 -0-0B -0·20

-0·88

S '/,Anomaly March 1957

4 8' ' 48' s o'

55'

53'

Figure 42. Monthly mean salinity anomalies, March rg67.

,.----, 5' 1 0'

-0·5 -0-54 -3-37

-0-22 -0·06 -0·70 8

0·19

0·12 0•10

0·00 -o-75

-O·OB

-o·OB

-0·22

0·23

0·22 0·20 08

0·29 -O· -0-47 - 0·88

48', 48' 48' 48'

Figure 43· Monthly mean temperature anomalies, April rg67.

Figure 44· Monthly mean salinity anomalies, April I967.

-0·1 0·0 0·0

0·3

-02 0·4 0·3

0·1 -0-1 0·2

0·0 -0·5

-OB

53'

5'

0·3 0·2

0·1

-0·!,

0·6

H

/(::

0·0 1-3

,~~

T'C Anomaly May 1 9 6 7

40

10'

_j~~' 55'

~I 53'

u 5' 10'

0·65 -0·02 1·00

-0·05 -0·08 -0-16 0·05

-0-25 -OB6

-0·06 0·26

0·14

\

-0·02

-o/J-02

. . -0-16

0·19 o·Jo

0·41 -O·OJ -0·02

0·23

-1-51 v

~8' ~8' ~8' ~B' s' o' Figure 45· Monthly mean temperature anomalies, Figure 46. Monthly mean salinity anomalies, May 1967.

May 1967.

~ 8' L..!.L 50

I .... 'jU~ S'/ ~8' 1 .... , c.:···-.} .. -f;;~ l .·· oo Anomaly 50 I I

Figure 47· Temperature and salinity anomalies, 26. May to 8. June 1967, chiefly from observations made by

R. V. "Ernest Holt".

53'

0·9 0·9 0·4

-1-1 -0·6

-02 -09

-1·9 -1-6

-7-0

5'

0·6 0·9

0·9

-1·2

-2-D

-1-1

-1-5

-0·6 -0·3

-0·2

"Ci ~06 .. 0·3 l1 .• 04

0·2. ·1·2

2·2

~i::::::·

10'

~ 8' ~8' s' o'

Figure 48. Monthly mean temperature anomalies, June 1967.

50'

0'

-0·7 - 0·2 1·1

-02 -O.J

1·0 1·5

1·7

0·9 H

-0·3

12 1·1

1-4 1·2

Hydrography

~ 1r

-OS - 0·3 0·2

1-1

1-0

1-2

1·5

0·2

T'C Anomaly July 19 6 7

~8' ~8' ~8' _, ~8'

53'

Figure 49· Monthly mean salinity anomalies, June I967.

-0·03. -0·04· -o-os·

5' 10'

- -0-73 -0·09 -027 -0-30 0-43

-0·77 -0-25

-0-08 -0 70

0·02

D-24

0·27

0·21 0·33

0·30 -0· 77 -0-37 . -0·87

-0·48

. ~2.on-<• o-01, •. q o·oz-. o-1J

. ·004 -008~ ·0:060·07 < ~ ..

·~~00~~ 7 ~ > S'/oo Anomaly --... 0·0 8 · · .. · J u I Y 1 9 6 7

~ 8' ~8'

Figure sr. Monthly mean salinity anomalies, July rg67.

50'~1

Figure so. Monthly mean temperature anomalies, July r967.

.,u .· 5'/oo Anomaly

0~--·· ~-··_·.···· ·•• ·_· ... · .. ·-·• 17-26 July 1967 1 ... I~ . . I I I I 480~1 I .J I _n

Figure 52. Temperature and salinity anomalies, r7-26. July I967, chiefly from observations made by

R. V. "Ernest Holt".

57' 0·8

0·9

0·8 0·4

55°

0·8

1-1 0·9

lO

1·5

1·3

- 42

s' 10'

0·6 0·8

0·5

1-4

ll

1·0

1-1

1 .. · ··· ... ;pv .o3

stwr;_-,1. "Lriil4ip:v __ ··_·_ ....• _·· __ .. ·_····'C·.··-~---__ .. ··_···_ .. _··_-_"·\~_-._. , ~" , ~ . . :· r -oJo1 -o8 . .. . ·. 'CJ .... ·. D·. 3. •.· ~ .. 8 o 10. . . .•...•• ~50' ,."~l:, ·'· . ,,,J;'))/ I

4 8'

11L~· .:i\13. ···. · .. ""· -~, .. \] <.'· c ~,:","~;','' I . 1·2• .:..1909 ... ~--···.·.···· I 48 1-2-· ·0·9 c.· . .. I I

ll• •- 1-0 ~·. ·. ·.1.. I [10 -· I ' 1-2. I

Figure 53· Monthly mean temperature anomalies,

0-7

0·6

0·6

I ···~ 53'

August 1967.

5'

0·9 1·5 0·8

0·6

l6 0·5 1·0

0·8 1·3

0·9 0·4

1·1 1·3

ll

1-2

1-4

1-3 1-6

. 09 -oB";--__07 l · -o5 ·--o4l

~~-70·~~14

.

. . . . ;p/nf~~lf

... ;: .... · ...

10'

48' --u·J 48' o'

Figure 55· :VIonthly mean temperature anomalies, September 1967.

5' 10'

-0·97 1·01

0·32

0·20 0·43 0·69 0·28 -0-1[3

0·01 -0-06

-0·01

0·37

0·29 .·

0·09 0·04

-0·05 -O-D7 -0·14 ~:~ -0·02

k \... 1530

004

-oo4oo6/._. -~-... _.. ~-·0·.· ·• .014

-0-14: > !C\J - ooF 7

0 ( -011- -"o-oo3 -ma:qo4 ~ ~005· ::-000·05~--.. -037~000 4ft :}l:""' - 0 '!'... __ , ... _ ce·l '';"!'oo6 -ool" / ' · ·, ,·· ' · · ' s "' A ' ' (• ;?,- , 'i i A:;

0

1°1~\ly I I I

o'

Figure 54· Monthly mean salinity anomalies, August 1967.

52'

50'

48'

5' 10'

2·16 0·71

1-30 1·90

0·14 0·38

0·30 0·11

0·05

0·13 -0-06 -0·23 -0·05

-0·09 0·04 -0·15 -0·18

-0·22 -0-14 -0-10

-0·11

-o-•l. ·_8_ .• ----.~-v .• ·. _' -~57

, ·.:-.. ·::.·.· . .

.. ·. :

!:~ ~

.

)) I ~- .

53' 53'

-~50'

•U"U::J -" 480

Figure 56. Monthly mean salinity anomalies, September 1967.

-- 43

5' ---,-----,

0·2 0·8

1·2

-0-3 0·1 0·4

0·9 0·5 1·8

1-7

-0·8 0·1 -1·3

-1-4 -0-3 -0-8

-1'1 0·8 1-3

-1·5 0·8 -1-8

-1-3

53'

L, 8' 48'

53'

Figure 57· Monthly mean temperature anomalies, October 1967.

5'

2·3 1-2

2-4

0·9 0·9 0·5 1·5

H

18

0·0 0·4 -0·3 -0·1

-0·8 -1-2 0·2

0·4 -0-8 1-7

0·5 0·2

10'

L, 8' 48' 5' o'

Figure 59· Monthly mean temperature anomalies, November 1967

55'

53'

Hydrography

~ 1r

0·17 0·09 0·24 0·33

0·98 -0-57 0·3 8

0·59 0·64

_,, - ""5_,_, ~ 0·18 ~"'' 4

55'

57'

0·23 -0·11

-0·12 -0-11

-0-13

0·11 0·02

-0·11 0·33 -O·OJ

0·0 2

53°

>-'--, ~ .'Ol08 ·-024

00 5 •• 004 . 0~d1JE$.4 -i50'

~·t;;,';;;;'~ ~:~ .. :·. I -·,.::: ..... , I I I I 48'

5' 0' Figure 58. Monthly mean salinity anomalie,;,

October 1967.

0' 5' 10' r-r--r ~

0·17 0·16

0·28

0·20 0·12

0·19 0·11

0·04 -0-12

0·19

0·28 0·50 0·55 0·19

-0·14

0·05

-0·02 0·05

-007 -0-22 -0·29

0·18

0·19

0·93

4 8' 48' 5' o'

Figure 6o. Monthly mean salinity November 1967.

anomalies,

-44

5' --,--,-

H 0·8

0·7 1-0 0·4 H

1-0 1·1 0·3

0·7 1·3

0·8 0·6 0·9

0-7 0·0 55'~ \ -0·3

-0·4 0·3 1-1

-0·5 2-8 0·0

0·3

53'

.- 0·4 -o-5. ·-0-7 -02 .• 00

-02:

~;',i"c".~,"i' 4 8' 48'

5' o· Figure 6r. Monthly mean temperature anomalies,

December 1967

in the Celtic Sea were, however, much as we might have expected them to be from the monthly charts. We would, perhaps, have been more accurate in estimating the anomalies which existed towards the end of July from the July and August monthly mean anomalies, except in so far as higher salinities occurred in the eastern English Channel than either of the sets of monthly means would have led us to expect at the time of the second survey of the "Ernest Holt".

The chief features of the year

The monthly mean anomaly diagrams show that the North Sea was generally warm during 1967. March and July to September were the months of greatest positive temperature anomaly, and only in June were negative anomalies found over most of the area. In October temperatures were low off the River Humber and on the Dogger Bank and negative temperature anomalies persisted until December on the central Dogger Bank, although they decreased in magnitude. Apart from this, positive anomalies were widely found and were especially marked in the German Bight and off the Danish coast from July to December. Monthly

5' 10'

0·35 0.27

o·o6 0·91

0·34 0·23 0·11

-0·05

-0-13 013 0·29 0·03

0·14 0·18 -0·78

-0·21 0·13 0·11

0·10 0·15

53' 53'

=-076-024/ .· ...

52'~~---~\~p····;d·>. ·. ---- •. ·_ _ ... · COJk ·•· \ 024-029 .. -OJB -02 . . · ··· ... -·• .·.

-o79-027D-07

~-____ .· .... ·'0-0B2·.~o-·2_._a ___ -.. ,

52'

4 8'

· -OJ 0 ·-039 · . -150 -o52. ----~ -~-----• oo5··-024

08 ·-0-20 "'· •: ·. · ... · . S •

1 Anomaly -0· . "' . "

·-008 .· -. :_·- Dec.1967 -ooa_._o-oa .·. . - 007: 0·02 .... 0·05· ~-

5' o· Figure 6z. Monthly mean salinity anomalies,

December 1967

48'

mean salinities were somewhat low off the river Humber from January until June, as they were off the East Friesian Islands from January to April and from June to September. From August to December high salinity anomalies were found on the Leith-Copenhagen route and at some adja­cent stations.

On the Newhaven-Dieppe route in the eastern English Channel temperatures were at, or above, normal during the first eight months of the year, but below normal from September to December. The nearby Varne lightvessel also recorded high temperatures during spring and summer and low ones at the end of the year. Salinity anomalies were negative in January, April, November and De­cember and positive in July and October on the Newhaven-Dieppe route, and at the Varne light­vessel salinity anomalies followed much the same pattern.

The western entrance to the English Channel was occupied by fairly warm surface water from January to April. In May temperatures were a little below normal, but rose to high values in June and again in August: From September until December temperatures were close to the mean

-45- Hydrography

5' 10' 5' 10' ~---,----.,

~ 4·8 16·8 4/3 ~ 6·3 5·7 10/2 16·2 16·2

2217 12/8: . 5·9 2712 18/3

4-Z 16·0 27/8 13/8

17·2 18/2 27/8 2217

5·0 18/2 17'0 12/8

5·3 6·6

~ 1 ~' 1 26/8

5/3 6·2 5·5 '

16·9 12/8 18/2 5·5 19/2 # 55' 55' 28/7 17·1 4/8 .

4·9"'J·4 5·1 ,ct 17'3 1218 /17 412/8

5·0 4 17· 6 26/8

5·1 I 29/1 18/2 16·7 6/8 18·4 13/8 5·6 -19/2

17/2 --· ~ 15·9 23/7 5·914/1

·~ 15·9 17/9 19/3

53'~ \ ,;I:]~ £ ( ~S3' 53'

I I ,~ >I ?J v·4 '~r~ I !12 }, I

52' 52'['~ I; l ~15]31A1 .')' ~52'

50'

48' 48' 48' 48'

Figure 63. Minimum temperatures observed during 1967. (Earliest date given where a value was observed on more

than one occasion.)

values. Salinity anomalies were small from January to April in this area, but rose somewhat during the period May to July. InAugustmonthlymeansalinity anomalies were negative on the Scilly-Shamrock Knoll route and at the southern end of the Bristol­Finisterre route, and were in general negative across the Channel entrance for the remainder of the year.

The Cork-Fishguard route, which operated from April to December, recorded low temperatures off the Eire coast from May to December; salinity anomalies were also negative in this area, except during July, and were greatest from September to November. Warm August temperatures were ob­served where the route crosses St. George's Channel, but otherwise temperatures were near normal during the year over this section of the route. Salinity anomalies were chiefly negative in St. George's Channel, but positive values were found in the vicinity of Carnsore Point during the period April to September.

Maximal and minimal temperatures

Figures 63 and 64 show the lowest and highest temperatures recorded at each of the stations.

Figure 64. Maximum temperatures observed during 1967. (Earliest date given where a value was observed on more

than one occasion.)

The Cork-Fishguard stations have been omitted from Figure 63 as observations were not made until April, and it should be borne in mind that no observations were taken on the Newhaven­Dieppe route during February and March. Both minima and maxima in the North Sea were I-2° C higher in rg67 than in rg66, although in the eastern English Channel minima were comparable in the two years. Maxima on the stations of the New­haven-Dieppe route were also r--2° C higher than in rg66. It is not possible to compare minima in the western Channel and Celtic Sea, but maxima had very similar values in both rg66 and rg67.

D. J. ELLETT, S. R. JoNES, GLYNIS READ

Fisheries Laboratory, Lowestoft, Suffolk, England.

References

ELLETT, D. J., 1967. "Mean surface temperatures and salinities at English lightvessels". ICES CM 1967, (C: z8) 10 pp. (mimeo).

ELLETT, D. J., JoNES, S. R. and READ, G., 1968. "Surface temperature and salinity observations at English sampling stations during 1966". Annls biol., Copenh., 23: 33-49·

-46-

HuGHES, P., 1966. "The temperature and salinity of the surface waters of the Irish Sea for the period 1947-6I". Geophys. J. R. astr. Soc., 10: 421-35.

ICES, 1962. "Mean monthly temperature and salinity of the surface layer of the North Sea and adjacent waters from 1905 to 1954". ICES, SERVICE HYDRO­GRAPHIQUE, Char!ottenlund Slot.

METEOROLOGICAL OFFICE, I967. "Daily ·weather Reports, I }anuary-31 December t967''.

METEOROLOGICAL OFFICE, I967-68. "Monthly ·weather Report, I967''. 84: 222 pp.

SMITH, J. E., (Ed.), 1968. "Torrey Canyon" pollution and marine life". Cambridge University Press, I96 pp.

Temperature observations at English and Welsh coastal stations during 1967

(Figure 65; Tables 8-9)

During 1965 and r966 a number of temperature observing stations were set up around the English and Welsh coasts by the Fisheries Laboratory, Lowestoft, at the locations shown in Figure 65. The local observers use simplified reversing ther­mometers and record the temperature in the sea surface layer twice weekly at high tide. The observation site at each station has been chosen

Table 8. Monthly mean temperatures at English and Welsh coastal stations in 1967

Station

Redcar ....... . Whitby ...... . Bridlington ... . Spurn Point .. . Skegness ..... . Brancaster .... . Blakeney ..... . Cromer ....... . Lowestoft .... . Southwold .... . Harwich ...... . Leigh-on-Sea .. . Shoreham .... . Swanage ...... . Weymouth ... . Fowey ....... . Mousehole .... . Moelfre ....... . Millom ....... . Whitehaven ... .

Station

Redcar ....... . Whitby ...... . Bridlington ... . Spurn Point .. . Skegness ..... . Brancaster .... . Blakeney ..... . Cromer ....... . Lowestoft .... . Southwold .... . Harwich ...... . Leigh-on-Sea .. . Shoreham .... . Swanage ...... . Weymouth ... . Fowey ....... . Mousehole .... . Moelfre ....... . Millom ....... . Whitehaven ... .

January February March April May

Temp. No. of Temp. No. of Temp. No. of Temp. No. of Temp. No. of (

0 C) obs. (0 C) obs. (0 C) obs. (0 C) obs. (0 C) obs.

5-5 6.0 4·7 3-9 4-0 3-7

4-7 4·0 3·6 3-0 3-9 5-9 6.9 8.I 9-I 9-4 6.2 5-9 s.8

8 5 8 9

II 9

6 I6

9 9 6 9

I2 9 9 9 9 9 9

July

Temp. No. of (

0 C) obs.

I2.8 13.6 IS-7 !6.4 I8.4 I8.9 I6.I I7.3 I7.8 I7-7 I8.s

19-4 I8.7 17-7 r6.o I5.2 rs.r I4-4 I6.2 IS-9

8 9 8 8

II 8 8 9

I8 9 9 8

IO 14

8 9 9 8 7 7

5·7 s.8 5-4 5·4 5-0 s.o

5·3 4·7 5-2 7·2 s.6 7-3 7·5 6.6 8.7 9-2 6.3 5-2 5·7

8 8 8 8 9 8

8 12

8 8 7

IO 9 8 8 7 8

7 7

August

Temp. No. of (

0 C) obs.

13.0 12.9 15-4 15-9 I7-3 17-9 I7-9 I8.2 I8.4 I8.2 19.I I9-3 I8.6 I8.o I7.2 I 5-7 IS-9 IS.O I6.I I6.I

7 8 8 9

IO 9 7

IO II

9 8 8 9

II

9 8 9 9 6 8

5-9 6.0 6.8 6.3 6.6 6-4

6.4 6.3 6.6 8.6 7-I 8.3 8.3 7-9 9-4 9-7 7-2 6.6 6.3

7 9 8 9

II 9

IO IS

8 9 9

II II IO

9 8 9 7 8

September

Temp. No. of (

0 C) obs.

12.5 12.9 14-4 14-4 15-3 I5.2 I5.6 I5.6 I6.I I6.4 I6.5 IS-4 I6.9 !6.3 I6.7 14·8 q.8 14·7 14-9 I 5-5

7 9 7 9

IO 8 9 9

I3 9 9 8 9 9 9 9 8 9 9 7

6.8 6.5 7·3 7-I 7·8 7·2

7·4 7·7 7·6 9-6 8.9 9-7 8.4 9-8 9-7

I0.2 7·6 7-5 7-I

7 8 8 8 9 8

8 I6

8 8

7 9 9 7 8 9 8 8 8

October

Temp. No. of (

0 C) obs.

II.6 II.S

8.3 rr.s II.9 II.8 I2.I

I2.3 I3-9 I3-7 IZ.3 12.2

J4.2 14·5 14·7 I3-4 I3.6 IZ.8

IZ.O

!2.2

6 9 9 9

IO 9 9 8

I3 9 9 7 8 5 9 9 9 9 8

7

9-0 8.o 9-8

IO.O II.6 II. I I0.6 II.O II.6 II.6 II. I I3.0 IZ.6 II.3 II.O II.2

II.7 9-0

Io.5 IO.I

7 9 8 9

IO 9 9 9

l4 9 9 6 9

IO 9 9 9 9 8 7

November

Temp. No. of (

0 C) obs.

8.7 !0.2

7-5 7·8 7·8 7·4 7-6 7·7

8.9 8.8 8.8 9-9

I0.3 12.0

II.4 1!.2

IO.O 8.2 9-0

5 9 8 8

IO 9 8 9

8 8 7 9

IO 9 8 9 8 7 8

June

Temp. No. of (

0 C) obs.

II.5 I0.9 I3-4 I3.8 IS.Z IS.O I3.6 q.6 q.6 I4-5 IS.Z IS-9 IS-7 IS-3 I2.3 I3. I I3-4 I3-3 13.6 q.I

7 9 8 8

IO 9 9 8

I8 8 9 7 9

I8 9 9 8 9 6 8

December

Temp. No. of (

0 C) obs.

7·0 7·3 6.0 4·8 4-8 4-2 4-6 4·9

5·5 5·7 6.2 6.9 7·6 7·0

IO.O 9-7 7-3 6.7 6.5

5 9 8 9

IO 8 9 9

9 8 6 9

IS 8 8 8 9 7 5

-47- Hydrography

55° I

54°

53°

52"

. 51°

{)

~\.~ ~~'0\.~

~\\.'-~~ ~~\,'lr-~ '\\'V>*-~ ~~\

~'X.~~\ ~'X_'\)~

~"''Ir-s\\.~ 'V>~~ ~ ~\,~~~~

~\.~\_\.~

~~~~'\)\~ ~

s~'lr-~~\:,\.

50°

60 t Figure 65. Locations of English and Welsh coastal temperature stations

to allow the best exposure to offshore temperature conditions, and the readings are taken from piers, outer harbour walls and similar places where a maximal depth of water is available at the time of observation.

The monthly mean temperatures are set out in Table 8, and the values and dates of the ob­served maxima and minima are given in Table g. The greatest annual range of temperature will be seen to have occurred along the east coast of

-48-

Table 9· Minimal and maximal observed temperatures and annual range at English and Welsh coastal stations in 1967

Observed minimum Date Station (OC)

Redcar ........ 4·7 28 February Whitby ....... 5.I 7 January Bridlington .... 3·9 I7 January Spurn Point ... 3-I 8 December Skegness ...... 3·0 9 January Brancaster ..... 2-4 9 January Blakeney ...... 2.2 22 December Cromer ........ 3·4 19 December Lowestoft ..... 3.2 w January Southwold ..... I.5 4 January Harwich ....... 2.2 13 January Leigh-on-Sea ... I.O 8 January Shoreham ..... 4-4 5 January S\vanage ....... 4·5 9 January Weymouth .... 6.0 18 February Fowey ........ 7·6 I7 February Mousehole ..... 8.4 I5 February Moelfre ........ 5·0 I3 January Millom ........ 3·8 I7 February Whitehaven .... 5·2 26 February

England between Skegness and Leigh-on-Sea, where large areas of sand and mudflats facilitate the exchange of heat between the air and the sea. In contrast, the stations of Fowey and Mousehole in the Cornish peninsula and Redcar and Whitby on the north-east coast of England have the smallest annual range, due to steeply shelving coasts and the influence of adjacent Atlantic water, originating from the western approaches to the English Channel in the first case and from the northern North Sea in the second.

T. c. DODDINGTON, S. R. JONES

Fisheries Laboratory, Lowestoft, Suffolk, England.

Polish hydrographical observations off South Ireland and in the central part of the North Sea

in 1967 (Figures 66-81)

In rg67 two cruises were made on board R. V. "Birkut", the research vessel of the Sea Fisheries Institute at Gdynia, in the periods June-July and September-October.

During the first cruise, additional observations covered the area off South Ireland.

The total number of stations was ror. Their locations are given in Figures 66 and 67.

The waters off South Ireland in June 1967

In this area, the surface temperatures ranged between II 0 and r6oC. The warm waters with temperatures of I4° to r6°C covered the area from

Observed maximum Date Annual range (OC) (OC)

14·5 14·5 16. I 17.8 I9.8 20.2

r8.5 20.0

20.0

19.6 20.7 2r.6 20.0

19·5 17.6 I6-4 I7·5 I5.8 IS.o I6.6

29 June 3I July

7 July IS July 3I July I7 July 25 August 26 August

I August IS July 3I July 26 July I9 July I2 July

2 September 24 July 27 A11gust 28 August 22 August 28 July

9·8 9-I

12.2

I4·7 I6.8 17.8 r6.3 16.6 !6.8 rS.r r8.5 20.6 I5.6 I5.0 II.6 8.8 9-I

Io.S 14·2 II.4

52°N and 7oW in north to the English coast m south-east. North of szoN colder waters were observed. The lowest temperatures were found at stations in the Irish Sea.

w so 70 50 so r-~----~----r----.

797 0

796 0

795o SZO I I r " I . - ·_v_;.- 71 52°

o783 790o 0782 7890

0 792

7810 t788

51 01---+----o780 7850 o787 o784 I o779 1786 o

7780

w 8° 70

777o 7760

60

51°

so

Figure 66. Hydrographical stations off South Ireland, June I967

- 49 -- Hydrography

go ao 70 60 so

Figure 67. Surface temperature off South Ireland, June 1967.

m 783 782 781 780

.:1 PT.±,·f.. 50

75

100

go ao 70 60 so 40 30 .----.----.----..----.~~----~53°

I lrL~ I ..-r= I ls2o

~ 50°

L_ __ _L ____ L_ __ _L ____ ~--~--~49°

Figure 68. Bottom temperature off South Ireland, June 1967.

Figure 69. Temperature section through stations 776 to 783, off South Ireland, June 1967.

m 0

25

50

75

100

sw NE 796

Figure 70. Temperature section through stations 784 to 796 off South Ireland, June 1967.

Figure 71. Temperature section through stations 795 to 797, Irish Sea, June 1967.

m 797 0

25

50

75

100

796 795

I --,

>110

-so-

zo 10 oo 10 zo 30 40 so 60

I IV::: .. ~ ~~:t 829o oTr I 8~4 828 113 7 836 835

r r 0

r

sgo

826 827 838 839 840 --------() -----o --o-o--- 58°

) 8~} 82sl I I I 0

850 849 848 8~ 8~2 8~1 0 0 0

8~8 8iF [ 082~ 847

I I 8b8 817 816 1815 861 844 845 846

~~68"859~~ I o823 o-o-o---

08700871 08600&55 811 1812 8131814 852 0822

0865[866 °861'j'854 I

0864"86308620853 °821

810 869 ao8 867 ~~-o--o

oszo

57°

56°

\ I 08(9

\ Joz ~j 8g1 ~72

0 0873p803 99§06° o875 804

(b~8o go's 0876

4

55°

54°

Figure 72. Hydrographical stations in the North Sea, July and September-October 1967.

20 10 oo 10 20

~--+-~~---+---4----r---+---~--~560

~~+---*---+---~---+---+---4--~55°

·- 40

Figure 73· Bottom temperature in the North Sea, July 1967.

20 10 oo 10 20 30 40 so

\ ,JU

>35 ~~ v

) 3~\ / v-.. u /

3~.6 /

... / /""""'... ...

~~ ) ....___ ... v f.-1

34.8 _.,.. lJ

< 35 r--.. '~

1\ ~ 34.8

\ 31\_ 1\ ( ~ 34.2 -- _L.,_

Figure 74· Bottom salinity in the North Sea, July 1967

sgo

58°

57°

56°

55°

54°

The lowest bottom temperatures ranged from 8.5° to ro°C and were found in an area between 5I 0 3o'N and 5Z 0 N and limited by 6°W in the east. From this area the temperature gradually increased in the northern direction until a fully homo­thermic condition was observed in tl::.e Irish Sea at a temperature of II°C (Figures 68 and 71).

At that time the thermic discontinuity layer in the open sea was very distinctly marked and was found between 15 and 30m depth (Figures 69 and 72).

The salinity, both of surface and bottom waters, ranged from 350foo in the south to 34.200fo0 in the Irish Sea.

The 35°i00 isohaline was running almost along the parallel of 5I 0 N, both at the surface and at the bottom.

The North Sea in July and September-October 1967

In the North Sea detailed observations were made in three areas: Flam borough Head, Berwick Bank and the Norwegian Channel.

- 5I- Hydrography

SW m

0

25

819

c-17 r--:..-13°

820 821 822 823 824 825

NE 826

'14°~ 13c>3:-12_0_=2j _____ ,

:::!:::::::-: .11°-10°

50 ---r-::=: 7 0 .go

75 ~

100

Figure 75· Temperature section through stations 819 to 826, North Sea, July 1967.

w E m 0 828 837 836 835

50

100

150

200

250

Figure 76. Temperature section through stations 8z8 to 835, July 1967.

zo 10 oo 10 20 30 40

12° 11°110°

'I II f fl I , Ti I I , 11.2o I 157

~-r-+~-+~----r----+----~----+-~56°

~~~~~~~t----r--~----j-155°

L__1_2l_ _ _j__ _ _L__!_____!.___,s4o

N s 842

11° so

100

150

200

250

Figure 77· Temperature section through stations 832 to 845, July 1967.

20 10 oo 10 20 30 40

I I I! \ I I\ I \J • I l57o

1 I '- I'" -J ,.,1 I I 156°

r--4-+----~---1~---+----~----+-~55°

L_ __ _L __ ~~--~----~--~----~~54°

Figure 79· Bottom salinity in the North Sea, September­October 1967.

Figure 78. Bottom temperature in the North Sea, Septem­ber-October 1967.

-52-

m 0

25

50

75

100

848 847

Figures So. Temperature section through stations SsS to S47, North Sea, September-October rg67.

The distribution of isotherms and isohalines is presented in Figures 73 to 8r.

The collected material permits the following statements: r. For the whole investigation period, the tempera­

tures at the surface were generally in accordance with the long-term means, except for the east coast of England where small deviations occurred.

2. The bottom temperatures in the summer period did not deviate from the long-term means. More conspicuous differences, however, occurred in autumn, when the g-I2° isotherms indicated that the warm waters (compared with rg66) occupied a considerably larger area towards the east, and when at the same time the bottom temperature in the central part of the sea was higher than in the previous year.

3· The surface salinity in the central part of the investigated area remained at the level of the long-terms means.

4· At the bottom, the area occupied by Atlantic waters was much larger than in rg66.

J. FILARSKI

Sea Fisheries Institute, Dept. of Oceanography, Aleja Zjednoczenia I, Gdynia, Poland.

Hydrographic and chemical observations in the Southern Bight, August and November

1967 (Figures S2-93)

In rg66 a detailed survey of the Southern Bight was started at more .than a hundred stations and three depths. The object was to obtain deeper insight into the hydrographical and chemical interrelationships and seasonal fluctuations in this area, with emphasis on the dominant influence of fresh water inflow from the river Rhine and to a lesser extent from the Meuse and Scheidt rivers.

m 0

25

50

75

100

Figure Sr. Temperature section through stations S6g to Ssr, North Sea, September-October, rg67.

54°

53°

20 30

S 0 /oo, surface

7- 19 aug. 1967

40

/ /

I I

I

50

I '346 ....... ,,/ .,.,.. '

,."' ,. .... 34,2 ,... .... ;.............. _ ..... / 1/ _,./</_,./,----

// /,//// _,.,. / / /" //

",.,./",,."'/,/' //

.,/' // / //

..,. .. ;"' // /// //

// / /

34;4/ ,' I I

I I I I I ,..._..'/

34;8' ............ - ............. ..,..,.:, ,."'" , ... -:: .... /I

;/ I ,' ,. .... "

,' ,. .... ~,./.,.,."'" I I' , "'

I I ' 1 t/ I /1

I I J ,,

I J/ I It

I J / Jl

349 1,' !/ I A ,,

34:4~: 20 30 40

Figure S2.

50

54°

53°

52°

After a preliminary survey in September rg66 two cruises followed in August and November rg67. Part of the observations are presented here.

Salinity (Figures 82 and 83). In August as well as in November salinities were

clearly higher than normal (Ref. r.).

Temperature (Figures 84 and 85). Temperatures in August were o.5-r°C higher

than the mean values. Temperature distribution in November was characterized by higher gradients in W-E sections than normal (Ref. r.).

---------- -··-----·---------------------------------------------

54°

53°

54<?i

20 30

S 0 /oo, surface. 13 nov. -1 dec. 1967

/;.· ;' ,, / // / " /

.... ~/ // /1 / I /

I I I I

I I I I

/ I I I

3' 4,8.

20

20

t oc surface

30

Figure 83.

30

13 nov. -1 dec. 1967

20 30

Figure 85.

40

40

40

40

-53-

50

54°

53° 53°

52°

50

50

/154' 54°

53° 53°

20

t oc surface

30

7-19 aug.1967

20

20

_/ 16,5

30

Figure 84.

30

Hydrography

40 50

16/ 54°

..... ~

53°

52°

40 50

40 ~?

Secchi disc visibility, m.

7-19 aug. 1967 ~540

___.-5

52° 52o/ "If ./1 / /I l-52°

50 20 30 40 50

Figure 86.

54°

53°

2" 30 40

Secchi disc visibility, m.

13 nov.- 1 dec. 1967

20 30

Figure 87.

dissolved oxygen, %saturation

surface 13nov-1 dec.1967

< 95°/o 95-100% 100-105% > 105%

Figure 89.

10~/ 5

40

40

50

50

50

-54-

54°

53°

52°

54°

53°

surface 7-19 aug.1967

< 95 "lo 95-100% 100-105%

20

Figure 88. 30 40

dissolved P04 -P, pg-at/ I.

G surface 7-19 aug. 1967

Q"2

20 30 40

Figure go.

50

50

54°

53°

52°

50

-55- Hydrography

S4°

S3°

20 30 40

dissolved P04-P,_,ug-at/l. surface 13nov.-1dec.1967

30

Figure gr.

40

Secchi disc visibility (Figures 86 and 87).

so

,5

54°

53°

52°

50

The light attenuation differences in August were greater than in November. The Channel water tongue roughly coincided with maximum Secchi disc readings but large deviations from this pic­ture occurred.

Dissolved oxygen (Figures 88 and 8g). The extremely low oxygen values of the heavily

polluted Rhine water caused the low saturation values in the vicinity of Rotterdam Waterway and Haringvliet. In November this area had enlarged, possibly as a result of decreasing photo­synthetic oxygen production. The mean August values are certainly higher than in November. Rather well defined areas with appreciable super­saturation occur close to the Netherlands coast, especially in summer.

Dissolved phosphate-P (Figures go and gr). Comparison of our August distribution with

the July-August picture given by JoHNSTON and JONES shows our values to be much higher (Ref. 2.). Values significantly below o.r [.Lg-at./1 did not even occur. Also in autumn our figures were higher, particularly at high salinities.

54°

20 30

ldissolved organic surface 7-19 aug. 1967

40 50

P. _,.ug-at/1.

~ 0 d

53° 0 ~

20 30 40 so

Figure 92.

20 30 40 50

dissolved organic P, _,.ug-at/1. surface

54"1 13 nov. -1 dec.1967 ./

54°

53°

52°

~540

5?[\ ~ \ "-!/ / f-S3°

J,~~t f-s2° <0,05 ~

~ ~~~

20 30 40 so

Figure 93·

Dissolved organic-P (Figures 92 and 93). Existing information on dissolved organic-P

is meagre. In both periods values ranged from zero up to 0-4 [Lg-at·/1 (o.os [Lg-at.jl being probably not significantly different from zero). The only comparable values given by JOHNSTON and JoNES are o.r and 0.4 [Lg-at.jl at two stations in this area sampled in November.

S. B. TIJSSEN Netherlands Institute for Sea Research, Den Helder,

The Netherlands.

References:

I. 1962. "Mean monthly temperature and salinity of the surface layer of the North Sea and adjacent waters from 1905-1954". Cons. perm. int. Explor. Mer, Ser­vice Hydrographique.

2. JoHNSTON, R. & JoNEs, P. G. W. 1965. "Inorganic nutrients in the North Sea". In Serial Atlas of the l'vl arin& Environment. Folio II, American Geographical Society.

56-

Hydrography of the south-eastern North Sea 1967, Danish observations

(Table 10)

At the lightvessel "Vyl" low salinities were predominant during the first 9 months of the year with unusually low salinities in February and May, and at the surface also in April and June.

Temperatures did not deviate much from normal conditions with the exception of March when the temperature was about 2° above normal.

HELGE THOMSEN Meteorologisk Institut, Gamlehave alle, Charlottenlnnd,

Denmark.

Hydrography of the Skagerak and Kattegat areas, Swedish observations 1967

(Figure 94; Table II)

Table II presents monthly mean values of tem­perature and salinity at the lightship "Fladen".

Table 10. Monthly means of salinity and temperature at surface and bottom a( the lightvessel "Vyl" (55°24'·4 N, 7°33'·5 E) for a longer series of years, and deviations from these means

(From the Danish Meteorological Institute, Nautical Department)

Month Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec.

Salinity Surface

Mean 1931-39, 1946-6o 33·0 33·1 32.8 32·5 32.6 32·7 32-5 32.6 32.6 32-7 32-9 33·0 Deviation 1967 ....... -0.9 -2.5 -0.8 -I.8 -I.6 -1.4 -0.6 -0.7 -0.7 0.5 0.8 0.3

Bottom (20m)

Mean 1931-39, 1946-6o 33-4 33·4 33-2 33·0 33·1 33.1 32.8 32·9 32.8 32-9 33-2 33·3 Deviation 1967 ....... -0.8 -1.7 -0.5 -1.1 -I.8 -0.8 -0.6 -0.3 -0.1 0.6 o.8 0.3

Temperature Surface

Mean 1931-39, 1946-60 4·3 2.9 2.8 5-0 9-0 12.9 15.6 16.8 16.0 13.1 9-7 6.7 Deviation 1967 ....... -o.5 0.7 2.0 I.1 -0.1 -0-4 0.3 0.5 -0.1 0.8 0.4 -0.2

Bottom (20m)

Mean 1931-39, 1946-60 4·7 3-2 3·0 4·7 7·5 10.6 J4.1 16.o 16.o 13-5 10.2 7·1 Deviation 1967 ....... -0.6 0.9 I.9 1.3 I.2 0.2 0.6 0.9 ·-0.1 0-4 0.0 ·-0.4

Table II. Monthly means of salinity and temperature in 1967 at surface and bottom at the lightship "Fladen" with deviations from means 1923-52

Month Jan. Feb. March April

Salinity 24·7 24.1 27.2 18.6

Deviation .... +o.6 +o.6 +5-7 -2.3

33·3 34·0 32.6 33.1 Deviation .... -0.1 +o.6 -1.3 -I.O

Temperature

1.9 1.3 3.6 5.1 Deviation .... -o.6 -0.3 +1.7 +o.1

6.6 5.6 4·3 4.8 Deviation .... +o.2 +o.6 -0.7 -0.2

May

17-3 -1.3

33·9 -0.2

9·7 -0.3

5·8 +o.5

June July

Surface

17-4 19.2 -2.2 -1.4

Bottom 40 m

33-4 32-9 -0.6 -0.6

Surface

14.1 16.8 +o.1 -0.4

Bottom 40 m 6.8 7·7

+o.5 -0.2

Aug. Sept. Oct. Nov. Dec. Year

19.4 19·4 25.0 (25.1) 23.8 21.8 -0.7 -2.0 +I.5 +I.8 ±o +o.1

32-7 33·0 33.1 (32·5) 33-2 33·1 -0.5 -0-4 -0.2 -I.O -0.3 -0.4

17.6 15-7 13.0 (8.8) 4·4 9·3 -0.1 +o.4 +I.8 +I.3 -0.1 +o.3

9·8 12.0 13-5 (II.9) 9-3 8.2 -0.1 +o.1 +I.4 +I.6 +I.o +o-4

-57 Hydrography

Figure 94 shows the temperature at some stations at the deepest part of the Skagerak. The figure is similar to the one presented last year in this publication but completed with the latest measure­ments showing that the slow but continuous increase of temperature which started right after the strong sudden cooling in March rg66, is still gomg on.

A. SVANSSON

Kungliga Fiskeristyrelsen, Hydrografiska Avd. Box 4038, Goteborg 4, Sweden

Hydrography of the Kattegat area 1967, Danish observations

(Table 12)

At the lightvessel "Anholt Nord" surface temperatures and salinities were high in March and November. During the summer low salinities and nearly normal temperatures prevailed at the surface. Near the bottom the salinity was below normal through the greater part of the year.

HELGE THOMSEN

Meteorologisk Institut, Gamlehave alle, Charlottenlund, Denmark.

Danish observations in the Great Belt and the Baltic, 1967 (Tables 13-15)

The most conspicuous feature of the variation of temperature and salinity at the lightvessels "Hals­skov Rev" and "Gedser Rev" are the high salinities recorded in March. The mean salinity at the surface amounted to zr.s%o and 13.7%0 resp. which is exceptionally high for March. In the same month also the temperatures were well above normal.

HELGE THOMSEN

Meteorologisk Institut, Gamlehave alle, Charlottenlund, Denmark.

r·c B

7 f . :· .. 6

5

7!--•"" ..

:f I

1962

7

f· 0 .· 6

5

I 4

7

6

5

4

3

. I

63

·.

64

+ M6, N 58.10' E09.30'

o N 59• oo· E os· 11'

x Other positions

200 m ·:

., .. ~ ...... r!f+

300 m

~ '3: x b 0 o +

• r ·: •• 1 ~ . .

65 66

400 m

~" .,o - "! '•., 7oo.,

..

600m

... ao.,.o.,

:'

67 68

_,.__

Figure 94·

Table 12. Monthly means of salinity and temperature at surface and bottom at the lightvessel "Anholt Nord'' (56°51'2N II

0 48'1E) for a longer series of years, and deviations from these means

(From the Danish Meteorological Institute, Nautical Department)

Month Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec.

Salinity Surface Mean 1931-60 ........ 23·7 23.6 21.3 20.4 18.2 18.6 19.6 19.9 20.5 21.8 22.1 23.3 Deviation 1967 ....... I.Z -I.O 3·2 r.6 -1.3 -2.1 -1.1 -1.9 -1.8 -0.2 2.2 o._

;)

Bottom (30 m) Mean 1931-60 ........ 33·0 33·0 33·2 33·6 33·6 33·5 32.9 32.6 32.6 32·7 33·1 33·0 Deviation 1967 ....... -0.2 -0.2 -1.7 -1.3 -o.8 -0.8 -1.1 -0.6 0.1 -0.1 -1.5 -1.3

Temperature Surface Mean 1931-60 ........ 2.4 !.2 1.7 4·7 9·9 14·5 17·5 17.8 15·4 11.6 7·8 4-9 Deviation 1967 ....... -0.1 0.4 1.5 0.6 -0.2 -0.4 -o.8 0.2 0-4 1.1 1.4 0.0

Bottom (30 m) Mean 1931-60 ........ 6.7 5·2 4·6 4·7 4·9 6.5 9·6 12.5 13-4 12.9 11.0 8.7 Deviation 1967 ....... 0.2 -0.2 -o.5 -0.3 o.8 I. I -O.I 0.6 0.6 I.O I.O 0.9

- ss-

Table I3. Monthly means of salinity and temperature at surface and bottom at the lightvessel "Halsskov Rev" (55°20.2N, II

0 02.7E) for a longer series of years, and deviations from these means

(From the Danish Meteorological Institute, Nautical Department)

Month Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec.

Salinity Surface

Mean I93I-6o ........ I7·5 r6.7 I4·5 q.6 I2.4 I3-7 q.o q.o I5·4 r6.7 rs.8 I7.4 Deviation I967 ....... -0.3 -2.0 7·0 -2.2 -I.4 -2.0 -o.8 -o.8 -2.9 3·4 0-4 --0-4

Bottom (rs m) Mean I93I-6o ........ 20.6 20.3 I9.4 2r.6 22.7 26.9 25·7 24.0 22.3 ZI.I I9.7 20.8 Deviation I967 ....... -r.8 -r.8 4·2 -6.7 -4·4 -3.I -I.9 2.8 o.8 3-3 -r.8 -2.4

Temperature Surface

Mean I93I-6o ........ 2.3 L4 I.9 4·8 9-3 I3.8 r6.9 I7-3 IS-3 II.6 7·8 4·6 Deviation I967 ....... 0.3 o.8 2.2 0.7 0.6 -0.2 0.3 o.s 0.3 o.8 o.6 -O.I

Bottom (rs m) Mean I93I-6o ........ 3·3 2.3 2-4 4·5 6.9 8.7 II.4 I3.6 I4.I II.9 8.7 s.6 Deviation I967 ....... -0.7 0.0 I.3 o.8 0.6 0.2 O.I -I.? -o.s 0-4 0.0 -0.7

Table q. Monthly means of salinity and temperature at surface and bottom at the lightvessel "Gedser Rev" (54°27.2N, I2°I0.8E) for a longer series of years, and deviations from these means

(From the Danish Meteorological Institute, Nautical Department)

Month Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec.

Salinity Surface

Mean I93I-6o ........ IZ.O II.5 !0.2 9·8 8.9 9·2 9-5 9-6 ro.s II.6 II.3 !2.2

Deviation I967 ....... -0.7 0.2 3·5 O.I -O.I -0.2 0.2 -0.2 -I.3 2.6 0.2 0.0

Bottom (rs m) Mean I93I-6o ........ I4.I I4-I I3.9 I4·5 I4·4 I4·7 q.8 rs.s r6.o IS-7 I3.8 I4·4 Deviation r967 ....... -!.2 -0.6 3-I -o.8 -2.6 -0.2 O.I 0.7 -z.s -O.I -I.4 -0.6

Temperature Surface

Mean I93I-6o ........ 2-4 I.4 I.7 4·I 8.o rz.9 r6.3 r6.7 rs.r II.8 8.2 4·9 Deviation I967 ....... 0.3 0.7 I.? 0.9 0.4 -0-4 o.s I.3 0.0 o.8 0-4 0.0

Bottom (rs m) Mean I93I-6o ........ 3·0 I.? r.8 3·5 6.I IO.I I3.2 q.6 I4-4 IZ.3 8.9 5·5 Deviation r967 ....... -0.2 0.6 r.s I. I o.8 -0-9 -0.9 -I.4 -0.3 0.3 -O.I -0.2

Table IS. Monthly means of salinity and temperature at Christianso (55°Ig'N, I5°IZ'E) for a longer series of years, and deviations from these means

(From the Danish Meteorological Institute, Nautical Department)

Month Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec.

Salinity

Mean r898-r930 ...... 7·0 7-0 7-0 7·0 7·0 7·2 7·4 7·2 7·0 7·0 7·I 7·0 Deviation I967 ....... o.s o.s 0.7 0.9 0.6 0.3 o.s 0.6 0.7 o.s 0.7 o.8

Temperature

Mean r898-r930 ...... 3·3 2.I r.S 3·0 6.I II.O IS.2 r6.o I4.I II. I 8.r 5·5 Deviation I967 ....... -0.6 -0-4 0.6 o.s 0.6 0.2 I.O 2.I I.8 o.s I.O 0.0

-59- Hydrography

Year 1967

Month Dec.

Date

,: ~lTI • I I \ \ s.s I p_•" I ~~ t;\ \4.;' 4 ~A· R ~~~? I I I I ~~~l!P8.2 1.6

2 2 3

Dopth

20 t\ \ 1~ m 30 4

'\ 40 r\ 5

6 \ e3.0 50~

Temperature oc

0

10 f

7.51

7.S<S<8

20 Depth

m 30

40

so Salinity %o

Figure 95- Arkona Sea, Station A 1 : 55°02'N 14 °0I'E, depth about so m. Temperature and salinity in 1967.

Polish hydrographical observations in the southern Baltic in 1967 (Figures 95-98; Table r 6)

The investigations covered the area from the Arkona Sea in the west to the Gdansk Deep in the east.

The surface temperature, about 6° C in December rg66, declined in January rg67 by nearly I 0

•

In February the cooling of the water lead to a temperature minimum of 0.5° C (Gulf of Gdarisk). During the subsequent three months a warming-up by IO-I3° occurred, and in August the maximum of ZZ° C reflected the very hot summer this year. The subsequent gradual cooling at the surface and in the sub-surface layer resulted in temperatures of 7° to 4° C about mid-December.

The Arkona Sea (StationAl at 55°0Z'N I4°0I'E, depth about so m,

Figure 95) In December rg66 and in January rg67 the

convection embraced the waters from the surface

to about 30 m depth and the temperature fell from about 7° C to about 3° C. In the third decade of February I.6° C was measured from the surface to zo m depth. On 6. May the temperature in the same water layer was about 5.5° C, but in the last decade of May the existence of a thermocline was already quite conspicuous; in the layer from zo to 30 m the temperature decreased by nearly 3° (from soC to 5° C). The most distinct thermo­cline was observed in August when the temperature fell by 10.5° within a layer of 5 m thickness.

The vertical mixing of the upper waters in October reached down to 30m depth, the tempera­ture was at this time II.Z° C to rr.6o C. In No­vember temperatures of II° C to so C probably reached to the bottom. In December the typical temperature inversion was conspicuous.

Bottom temperatures in the Arkona Sea were near to 3° Cat 40 m and 44 m depth on zz. February. In June the isotherm pattern was more complicated from about 25 m to the bottom, and in July the measurements revealed an inflow of warm waters

- 6o-

Table 16. Oxygen content (ml/l) in the water layer below 50 m depth at three stations representing the Bornholm Deep (B1), the western part of the Slupsk Furrow (B2) and the Deep of Gdansk (G2) in 1967

Station B 1

m S· May rS. May 20. July ro. August rS. August 2S. October ro. Dec.

so ........... 7-19 6.ss 7·79 7·79 7-sS 6.79 7-S2 6o ........... s.22 6.22 6.00 4.S6 3-SI 3.2S 70 ........... 6.13 6.19 6.96 4·36 4·39 2.3S r.SS So ........... s.62 3-40 4.22 2.ss 2.20 I.I3 1.40

290 ........... 4-0S 4·7S 2.so 1.47 1.47 I.I3 I. IS

Station B 2

m ro. February 12. May 17. May 12. August r6. August 2S. October 9. Dec.

so ........... S.72 s.ss s.ss 7·30 7·14 6.99 7·7° 6o ........... S.37 6.S2 S-72 5·53 S·3S S·3S 7·03 70 ........... 6.r6 2.57 3·S9 S-09 4.82 2.31 7·72 So ........... 4·92 3-IS 3-52 3·38 2-94 7.62

290 ........... 4·3S - 2.65 - 3-IS 2.80

Station G2

m 20. January 3· February 31. May S· August 12. August 27. October 13. Dec.

6o ........... S.6s S.9S 8.r6 70 ........... 2.65 6.6r 3·83 So ........... 2.36 I.S3 3-41 90 ........... 2.08 2.82 +IS

roo ........... r.S4 2.96 3·S7 IOS ...........

2I07 ........... 2.sr 2.S2 2.59

of II° C, as compared with 5o C in June. In August a temperature of rr.6° C was observed. After some decline at the end of August, a new temperature increase to I2° C and more was observed at the end of October. In the last decade of November a temperature of 9.3° C indicated that the warm water mass had passed by.

As usual, there was considerable variation in salinity in the Arkona Sea. The surface salinity ranged between 7·390foo in May-June and August, and 8.38%0 in October. In December a slight de­crease was observed. The bottom salinity, which was about r60fo0 in December 1966, increased to 22.rr0j 00 in the third decade of February. Towards the end of May over r8°/00 was still found. How­ever, after 20 more days, values less than 9°/00 proved that the highly saline waters had dis­appeared from the Arkona Sea. After a short time, somewhat more saline waters (of about I50foo) appeared again. In the last days of November only 9-ro%0 salinity was observed at 46 m depth.

The observations mentioned above indicate a marked influx of very saline bottom water in February. A lesser influx took place in July and a third one near the end of October. The last influx was characterized by a low salinity with marked

6.12 7.06 6.89 3.01 3·70 S-73 s.os 2.67 1.94 I.98 1.43 2.34 2.52 r.28 I.I4 - r.88 I.OI - r.6r o.S3

I.70

increase in the oxygen content, as compared with August, when the low oxygen content seemed to indicate only a local deplacement of bottom waters (Table r6).

Bornholm Deep .

(Stations Blat 55°20'N I5°45'E and Ps at 55°I8'N I5°58'E, depths 98 m and 90 m, respectively,

Figure 96)

The lowest surface temperature (about r.8° C) was found in February, when this temperature reached a depth of at least 40 m. Until May the warming-up process at the surface was slow, and on 5- May only about 5° C was observed. Afterwards a quick warming of the surface waters took place so that about mid-August a maximum of r8.6° C was attained. At the end of October the cooling resulted in temperatures of about II° C and on ro. December in 6.7°C.

The thermocline began to form in May, and was most pronounced in August, when in the layer between 20 and 40 m depth the temperature fell frorri nearly r8° C to nearly 5° C. Later on the convection involved deeper and deeper waters so that in December the homogeneity reached

Month

Date

10

20

30

40 Depth

m 50

60

70

60

90

100

0

10

20

30

40 Depth

m 50

60

70

80

90

- 6r-

rc;u \ ~.5 ·4.45 5.1· .. 5.36

7.44 7.47 : 7.59

/ /

/ ________ 7.5"'

I /

/

I I I

I

16 16

\ \

\ -\ .,.. ..... \ I ',

' I ' '-" '

• 16.22

' ..... --

Hydrography

Dec.

.75

7 6

5.~9 i9

Temperature °C

7.42

I I

/ /

15.91 •

1 I I I

7.5 I I I

I I

1.16

15.66 • 100 I

Salinity %o

Figure g6. Bornholm Deep, Station B2: 55°20N', I5°45'E, depth about gS m. and station Ps: 55°I8'N, Ij 0 j8'E, depth about go m. Temperature and salinity in 1967.

-62-

to about 45 m depth. Beneath the thermocline was found the winter water, characterized by temperatures lower than 4° C and, from July, by temperatures of 4 to 5° C, which lasted till as late as September-October at depths from 40 to 70 m.

Beneath a depth of 5o-6o m, high temperature values (9-10° C) were found at the end of the preceeding year, and they endured at 70 m depth till February 1967. The subsequent decrease in temperature took place till at least May when a value of 4-45° C at the bottom was a sign of a winterly influx into the Bornholm Deep. As early as in the second half of May, however, a temperature of 5·95° Cat So m depth indicated a coming change. In July and August a temperature increase by about r to L5° near the bottom started a period of rather monotonous thermic conditions lasting till the end of 1967.

The surface salinity ranged between 7.36°/00

and 7·590fo0, values higher than 7·50foo prevailing in early summer as well as at the end of the year. The SOfo0 isohaline oscillated between 43 and 56 m. These figures give at the same time the thickness of the isohaline upper layer. The halocline was found in depths from about 43 to about S7 m. The mean salinity gradient within the halocline was 0.2S0j00 per metre with variations from 0.21 to 0.390foo·

The bottom salinity exceeded r60fo0 in December 1966; in February 1967, however, it was probably less than r60fo0 . From May values higher than r60fo0 lasted until at least August. Towards the end of the year a declining tendency was observed. The maximum bottom salinity was r6.940fo0 on ro. August, the corresponding tem­perature being 5.J4°.

The highly saline and cold bottom waters which had been present in the Arkona Sea in February did not enter the Bornholm Deep until they had undergone thorough mixing with the surrounding diluted waters and lost their charac­teristics. The waters of lower salinity, however, passed eastwards resulting in the salinity increase observed in May. The waters which disappeared from the Arkona Sea in June, passed into the Bornholm Deep and caused the further increase in salinity observed there in August, after a supposed slight heating of the corresponding water. As to the oxygen content in the bottom waters of the Born­holm Deep, a comparatively high content was observed in May at 93 m depth (4.75 mljl); after­wards, however, a continuous decline took place.

The western part of the Slupsk Furrow (Stations B2 at 55°14'N I7°0o'E, depth about 95 m and P 3 at 55°I3·5'NI7°0o'E, depth9om,Figure97)

From the beginning of December 1966 to ro. Feb­ruary 1967 the surface temperature fell from 5.S° C to 2.1° C. A temperature near to 2° C occurred in the water layer to about 55 m depth. As in the Bornholm area and elsewhere the thermocline started to form in May. The heating of the surface waters during spring and summer resulted in a maximum of rS.5° C observed in August. The winter water occupying the depths beneath the thermocline gradually warmed up; nevertheless temperatures less than 4° C existed till August at 50-65 m depth. The cooling of surface and sub­surface waters resulted in convection processes that brought with them the mixing and homo­genizing of waters to more than So m depth in December, when the temperature was 7-S 0 C. Within the bottom layer (70-95 m depth) the temperature fell from 7.5° C in December 1966 to 5.6° C in December 1967.

The surface salinity oscillated around 7 .50foo as in the Bornholm area, but the periods of low salinity were not quite the same in the two areas. The water layer with a salinity less than SOfo0 was of a thickness which ranged between 36m (Decem­ber 1966) and So m (December 1967).

While the temperature of the bottom waters gradually decreased, the salinity in the bottom layer oscillated within the limits of 14.33%0 in May and rr.Sr0fo0 in December. After a period of comparatively low salinity observed at the beginning of 1967, a new increase in salinity started in May. During the second half of the year however a decrease in salinity took place. In De­cember an unusual extension of the isohaline top water layer was observed down to about So m depth, as was already mentioned under the tempera­ture conditions.

It should be emphasized that the rise in bottom salinity in May was accompanied by a decrease in the oxygen content which at this time was probably the lowest during the year (Table r6).

Gdansk Deep (Station G2 at 54o5o'N I9°20'E, depth no m,

Figure 98)

The lowest winter temperature which, however, did not descend below I° C was observed in Feb­ruary. The same temperature was then found in water layers to about 6o m. Values lower than

-63- Hydrography

Year 1967

Month I Jan. Dec.

Date

0

I I I 2.1 2.0

10

20. 4 3 I

4 3 2 30

40 Depth

m 50

50

70

80

90

Temperature ° C

0 . I

10 r?.5

20

30

40 Depth

-- - . \7.47 •7.39 7.32 7.18 t,v':# : l61

\ I I I

7.5 1 I I I

I I I 7.5 I .... ---, ,' I _,. ' / \ .......... ' / '--~....., ......... ..__-- __ ..,.,

7.63 7.54

m 50

50

70

80 • 12.65 90 ~2.45

Salinity %o

Figure 97· Western part of the Slupsk Furrow, Station B 2 : 55°q'N I7°oo'E, depth about 95 m. Temperature and salinity in 1967.

-64-

Year 1967

Month I Jan. I Dec.

Dote

0

10

20 ~~ 4

30 I-I I ~ I t < 2 2

40 Depth 6

m 50 3<t<4

50

70

80 5 5~ 4

90 5

•5.2 100

110 5.5. 5.8·•5.8 5.7 •

5.6 • 5.8• 5.4 • .S.5

Temperature °C

0 1 7.54

I 7.541 7.30 7.437.03\... 6i87

7 7.36 7.38 7.32 7.27 7.48 1

I I I I I I I

10

20

30

40 Depth

m 50

60

70

80

90

100

110

1 I I 7 < s < 7. 5 I I ------\ ___ :-- -,\ '75------- \

. ' ' 7.5

12 12.89 12.70 12.83 12.7CI l2·68

• ··12.92 • ~

--~

12\

12 .16. .12.09

I I I I I

I ~/

11.58 •

Salinity %o

Figure gS. Southern part of the Gdansk Deep, Station G2 : 54°5o'N I9°2o'E, depth about IIO m. Temperature and salinity in 1967.

-65- Hydrography

3° C of the winter water did not last long, and in May the minimum winter water temperature amounted to 3.24 ° C.

The maximum surface temperature (20.8° C) was measured in August. About mid-December the surface temperature (6.8° C) was somewhat higher than at the same time the year before. At the end of the year a thermic homogenization took place in the top water layer to a depth of about 6o m. The forming of a thermocline started in May, and it was most pronounced in August, as was also the case in other areas. Below the thermocline a winter temperature of 3° C ended before May and temperatures less than 4° C disappeared in August-September. Below 8o m a temperature oscillation around 5° C was observed. In the lower part of this bottom layer the temperature remained above 5c C during the whole year. For nearly a month the bottom temperature even exceeded 6° C, the maximum was observed on 3· February at room depth.

In January the surface salinity was higher than 7 .50foo but it declined shortly afterwards, with the minimum salinity occurring in May (less than 70foo). Till the year's end the surface salinity remained below 7·5°/00 .

The depth of the 80fo0 isohaline ranged between 59 and 73 m indicating the thickness of the isohaline top water layer. In the bottom water layer the salinity oscillated around I20fo0 . In January it was less than I2°/00 , in February I2.2°/00 was observed in a layer more than ro m thick near the bottom, but only for a short time. At the end of February values less than I2°/00 reappeared, and this time for a longer period. The I20fo0 isohaline did not disappear before November. The maxi­mum salinity was rg.g0/ 00 on 3r. May at rog m depth. In December rr.g0fo0 salinity was found at g6 m depth.

The oxygen content at the bottom ranged from 3·7 mljl in May to 0.74 ml/1 in November. Those changes in the oxygen content (Table r6) seemed to indicate that there had been a rather marked renewal of bottom waters in May with succeeding stagnation during the second part of the year.

A. GLOWINSKA

Sea Fisheries Institute, Aleja Zjednoczenia r, Gdynia, Poland.

Observations at Swedish lightships and in the central Baltic 1967

(Tables r7-r8)

There are only four swedish lightships left in the Baltic carrying out hydrographic measure­ments. The others have been replaced by un­manned lighthouses built on caissons. The re­placement of the oldfashioned manual observations carried out on the lightvessels by the crewmembers, by recording telemetering buoys becomes more and more urgent. The high costs and the fast development in this field make it difficult to find a suitable and reliable system for replacement of the lightship measurements.

Compared with the long-time means (KoczY, I954) all the lightship observations show positive salinity anomalies almost through the whole year, except for the deep observations at "Finn­grundet". Especially during the autumn the in­crease has been considerable, around 0-4-0.5 °/00 .

The temperature has also increased at all four stations, compared with the long-time means.

During rg67 only three expeditions with the "Skagerak" could be carried out. The September expedition had to be cancelled due to unexpected reparation works on board.

The stagnant conditions in the Baltic deep basins grew worse during the winther months of rg67. In the Arkona Basin, however, the condi­tions in the bottom water were better than in November rg66, indicating the beginning of a new inflow of salt water. At 45 m 5·93 ml oxygenjl was recorded in February. In May the salinity at 45 m was as high as r8.or0fo0. In December the salinity was down at I4.760fo0 at 45 m, indicating that the inflow was over.

In the Bornholm Basin the conditions were stagnant in February and only 0-42 ml oxygenjl was found at 85 m. In May the oxygen value had changed to 3.20 mljl at 85 m and the salinity at the same depth was r7.0I 0/ 00 . In December the con­ditions were again stagnant, showing only o.g2 mljl oxygen at 87 m.

In the Gotland Basin the stagnation was com­plete in February and 2.35 y.g-at. H 2Sjl was found at r5o m. At 240 m r8.55 r1g-at. H 2Sjl was ob­served. In June new water had penetrated to the bottom of the Gotland Deep, showing r.72 ml 0 2/l at 240 m and above this water r4.24 y.g-at. H 2Sjl was found at 200 m. This development in the Gotland Basin has been described by the author earlier (FoNSELIUS, rg67). In December

-66-

Table 17. Monthly means of salinity and temperature in 1967 at surface and bottom at Swedish lightships with deviations from the 30-year means, at "Havringe" from ro-year means

Month

'' F inngrundet''

Salinity ..... . Deviation .... .

Salinity ..... . Deviation .... .

Temperature .. Deviation .....

Temperature .. Deviation .....

"Svenska Bjorn"

Salinity ..... . Deviation .... .

Salinity ..... . Deviation .... .

Temperature .. Deviation .....

Temperature .. Deviation .....

"Hdvringe"

Salinity ..... . Deviation .... .

Salinity ..... . Deviation .... .

Temperature .. Deviation .....

Temperature .. Deviation .....

"F alsterborev"

Salinity ..... . Deviation .... .

Salinity ..... . Deviation .... .

Temperature .. Deviation .....

Temperature .. Deviation .....

Jan.

(5-9) +o.5

(5-9) +o.1

(o.7) -o.g

(o.8) -o.8

6.7 +o.5

6.8 +o.5

r.6 -o.8

2.3 -0.4

6.7 - 0.3

6.8 -o.5

2.0 -0.2

2.3 -0.7

8.2 ±o

8.3 -0.2

2.4 -o.5

2.5 -0.4

Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Year

(5-7) +o.2

5·7 +o.3

Surface

5.6 +o.1

5-4 ±o

Bottom 30m

5-2 -0.1

5-4 +o.z

5·6 +o.3

(5-7) 5·7 5-7 5·7 5.6 -0.1

5.6 -0.2

5.6 -0.1 ±o ±o ±o -0.1

7-8 -0-3

(6.3) +o.1

(6.6) -t-o.z

(o.8) -0.3

(1.3) +o.1

(1.4) +o.1

(r.2) +o.r

6-4 -to.3

6.7 -to.4

2.7 +r.o

1.9 +o.5

(6.7) 7·0 -o.2 +o.1

(7.6) 7·1 +o.1 -0.1

(r.6) 2.7 +o-4 +o.8

(2.4) +o-4

8.4 +o.6

2.4 -to.7

8.2 +o.7

7.8 9.1 8.3 +o-7 -0.5 +r.3

1.7 2.7 -0.1 +o.7

L7 -0.1

2.6 +o.6

4-6 +o.g

4-5 +o.g

2.7 -o.5

Surface

7·3 ±o

14·4 +o.6

Bottom 30m

q.6 13.9 -r.o + r.8

9-4 +r.4

2.3 -o-5

3·9 -0.6

4·4 6.1 6.8 7-4 -o.8 +o.8 + r.o +o.g

6.2 +o.3

6.6 +o.3

4-7 +o.s

3·0 +o.3

Surface

5.8 5-7 +o.1 -to.2

Bottom 30m 6.8 7-0

+o.6 +o.8

Surface

8.3 15.8 -o.6 +r.1

Bottom 30m

4-6 6.7 +o.1 +o.7

Surface

6.7 6.5 6.6 +o.1 ±o +o.z

Bottom 40 m

7·0 6.g 7-5 ±o -0.3 +o.3

Surface

6.0 -to.5

7·0 +o.8

13-9 -1.9

7·6 +o-4

6.8 +o-4

7-3 -to.1

4-9 -0-4

10.5 -0.5

15.1 16.3 -0.4 -to-4

3·8 +o.g

7-8 +o.4

Bottom 40 m

4·5 +o·7

3-4 - o.g

Surface

7·7 +o.z

7-8 --0.1

Bottom IO m

7-9 7·7 7-8 -0.3 +o-4 -to.1

8.2 +o.4

8.1 -to.6

Surface

12.7 +o.3

16.2 -to.4

Bottom IO m 12.6 15.8

+o.8 +r.2

4·2 -0-4

8.3 -to.4

8.4 +o.z

17.2 +o.7

16.2 -to.5

6.2 +o.6

6.g +o.6

13.6 -to.5

7-9 -I.O

6.5 ±o

7-0 -0.3

q.6 +r.5

8.g +3-7

7-9 -0.1

8.o -0.2

15.1 +o-4

14.8 +o.2

6.5 --jo.6

6.8 +o-4

10.2 +r.2

8.8 +o.8

6.g -to.z

7·8 +o-5

10.3 +o.7

4·2 -r.8

9-1 +o-7

9-1 +o-4

12.5 -to.8

12.6 +o.g

5.6 +o.2

5·7 +o.4

5.6 +o.2

5-6 5-7 5·7 -0.1 ±o ±o.z

6.2 +r.1

6.3 +r.z

6.5 +o.4

6.7 -to.4

7-4 +o.8

7·7 +r.3

7·1 +o.3

7·5 +o.z

6.7 -0.1

5·4 -0.1

2.7 -0.3

2.8 -0.1

6.7 +o.6

6.8 ±o-5

4·3 ±o

5·2 +o-7

9-9 9·5 +r.6 +r.2

IO.I

-tr.8

8.8 +o-4

g.o -to.6

9-9 +r.4

5.1 ±o

5·3 +o.2

6.2 -to.z

3·6 +o.r

6.3 +o.4

6.8 -to.5

7-0 +o.r

4-9 +o-3

6.8 +o.r

7·3 ±o

7·5 +o.2

4·0 +o.2

8.4 +o.5

8.5 +o-4

8.g -to.3

8.8 -to.5

-67- Hydrography

the stagnant conditions had returned and H 2S was again found at 240 m.

The Landsort Deep could not be worked during the February expedition due to bad weather conditions. In June the inflow had, however, not reached the Landsort Deep. Only o.II ml 0 2/l were found at 440 m. In December traces of the

inflow could be observed. The oxygen value at 440 m was o.zr mljl, but at zoo m it was o.r6 m and at rso m as low as o.r3 mljl.

000 010 030 045

000 010 030 045

000 010 030 045

000 010 030 050 070 o85

000 010 030 oso 070 087

000 010 030 050 070 087

Depth

m

Depth

m

Temp. oc

2.14 2.13 2.33 4.62

9-54 9-31 5-59 4·24

7-39 7·3° 7·38

10.23

Temp. oc

2.13 2.16 2.13 7-99 9-47 8.97

8.94 8.95 5-21 3-64 5-90 4·97

6.92 6.95 6.96 6.34 s-89 5·84

Evidently the bad oxygen conditions will continue in the deep basins during the first part of rg68. If there will not be any improvement in the oxygen conditions in a near future, hydrogen

Table r8.

Arkona Deep

55ooo'N 14oos'E

s 02 pH P04-P A1kal.

Ofoo m1/1 [Lg-at./1 mva1j1

9· February

7·92 9-09 7.82 0.39 7-91 9-09 8.01 0-37 7.85 8.98 8.20 0.33

15.74 5·93 7-89 0.97

30. May

7·69 8.07 7·85 o.os I.61 7.68 8.17 8.17 0.20 I. 56 7.81 8.07 8.IO 0.13 I. 54

18.01 3-44 7-55 o.51 I.93

7· December

8.25 7.51 7-96 o.q !.49 8.18 7-75 8.14 o.o8 1.54 8.18 7.68 8.13 0.19 I. 53

14·76 4·44 7.81 1.31

Bornho1m Deep

55°15'N 15°59'E

s 02 pH P04-P Alkal.

Ofoo m1/1 [Lg-at./1 mva1/1

I. February

7-52 8. 56 7·78 0.39 I. 53 7-51 8.78 7-95 0-48 I. 53 7-51 8.63 7-99 0-43 I. 53

13.27 4·47 7-58 1.43 I.75 15.20 I.73 7-31 1.92 I.81 16.10 0.42 7-25 2.51 r.86

30. May

7-43 8.78 8.13 0.12 I.6I

7-37 8.88 8.26 O.IO 7.61 8.66 8.rs 0.18 I.65 9-97 6.16 7-67 0.63 I.64

q.81 4.11 7-49 0.92 r.81 17.01 3.20 7·44 1.12 r.88.

7· December

7-85 8.16 7·78 0.20 I. 52 7·83 7-83 7.88 0.21 I. 52 7-83 7-73 7-91 0.19 !.52

9-54 4.02 7-33 0.94 r.s8 15-53 I.03 7.18 I.77 !.78 15.80 0.92 7.12 I.70 !.78

-68-

Table 18 (continued).

Gotland Deep

57ozo'K zo0 o3'E

Depth Temp. s 0~ pH P04-P Alkal. H 2S

m oc 0 foo ml/1 [Lg-at.jl mval/1 [Lg-at./1

3· February

000 ........... I.6g 7·63 8.82 7.61 0.30 070 ........... 4.1 I IO.I I I.SI 7-43 I.62 roo ........... 4.88 I I.S4 I.03 7.15 I.74 ISO ........... 5.6r 12.41 7.01 3.18 - 2.35 200 ........... S·75 12.70 - 7.13 4·97 - 12.60 240 ........... 5.8o 12.99 - 7-22 6.37 - r8.55

r. June

000 ........... g.r6 7-44 9·57 8.17 0.06 I.S5 070 ........... 4.26 10.27 I.28 7-21 I.73 I.67 roo ........... 5·0S II.37 o.g6 7.13 I.79 I.7I ISO ........... s.63 12.36 I.37 7.12 2.60 I.76 200 ........... s.6o !2.70 - 7.18 5.65 r.82 14·24 240 ........... 5·94 13.00 I.72 7·23 3.17 I.77

12. December

000 ........... 6.33 7.18 7·98 - 0.30 I.47 070 ........... 4-02 g.83 !.25 z.rs -roo ........... 4-73 ro.g2 0-43 - 2.31 r.6s ISO ........... 5·54 12.27 o.r8 - 3·30 I.70 200 ........... 5·7S 12.65 s.63 r.68 4·85 240 ........... s.84 12.82 - - g.oo r.88 9·25

Landsort Deep

58°3s'N r8°14'E

Depth Temp. s Oz pH P04-P Alkal.

m oc 0/oo ml/1 [Lg-at.(l mval(l

6. June

000 ........... 8.7I 6.76 8.7s 8.32 o.r8 I.47 070 ........... 3·SO 8.g8 3-41 7·37 I.64 I.64 roo ........... 4-46 10-44 0.38 7·09 3·14 !.70

ISO ........... 4·58 10.79 0.28 7-12 2.92 I.72 200 ........... 4·74 ro.go o.zs 7-12 3.10 I.70 440 ........... 4·74 II.OO O.I I 7.13 3.16 I.7I

g. December

000 ........... 6.37 7.12 8.oo 0.28 I.46 070 ........... 4-76 8.s2 4·33 - I.IZ I.S7 roo ........... 4-42 IO.{O o.58 2.42 I.63 ISO ........... 4·72 I I.OI 0.13 - 2.6I zoo ........... 4·79 II.09 O.I6 2-49 I.67 44° ........... 4·89 I I.I6 0.21 - 2.74 r.66

sulfide will be formed in the deep water north of Gotland, creating a large stagnant H 2S-con­taining water mass.

References FOJS"SELIUS, S. H., 1967. "A new short stagnation period in

the central Baltic". ICES CM 1967 (C:32) (mimeo).

Koczv. F. F., I9S4· "Monthly average values of hydro­graphical observations at Swedish lightships 1923-1952". (in Swedish). Fishery Board of Sweden, Ser. Hydrogr., (5).

S. H. FONSELIUS

Kungliga Fiskeristyrelsen, Hydrografiska Avd., Box 4038, · Gi:iteborg 4, Sweden.

-JO-

.10 .zo .30 .40 .so .60 .70 .50

80o\ A c m-1

blue

70'\_ 60

ao7()-.......,. 60~t7o depth {ml 60~()+"-.. ¥

+~ 50

.10 Station A 14.July 1967 beam attenuance

50"-x~ 40 40

3~~~.13~ .20 + 09.30 local

0 12.00 X 15.30

time

.30

20~~'\

~2~0 "1 .I +'9-10 8 1

.40

.50

A c m-1 red

.60

Figure 99·

Some optical measurements at Ocean Weather Station A

(Figures 99-100)

During July 1967 opti-cal oceanographic mea­surements were made at ocean weather station A (62°N 33°W). Some relevant data will be given here.

Observations of Secchi disc visibility ( 0 = r foot) on several days at local noon gave a visibility depth of about ro metres; the colour of the surface water corresponded to about ro% yellow according to FoREL's scale.

By means of a 2-metre-path-length beam attenuance meter records down to a depth of So metres were made in red and blue light (2 mm RG r and 2 mm BG 12, respectively), which sometimes gave large variations over a rather short time. An example of this "optical variability" is given in Figure 99 (zero point arbitrary).

Some curves of measured daylight attenuation are given in Figure roo. Daylight was measured by using a Photronic cell 856 RR with a cosine collector and filters Wratten nr. 29 (red), 6o (green) and 45 (blue). Measured values of the vertical attenuation coefficient K (based on natural logarithms) are, red: 0.25-0.50; green: o.o7-o.ro5 and blue:

o.o5-o.r25 m-1, with the sun's zenith distance 40-50°. It may be concluded that ocean water of type 2 to type 3 was present, according to JERLov's classification.

Comparison of beam attenuance and vertical attenuance shows that a strong vertical gradient of the scattering coefficient existed, but no mea­surements of the latter have been made.

No strong thermocline was found, temperatures being about 7·5 to 9.0°C at the surface and 6.5 oc at room depth. Salinity was constant from surface to that depth (35.2 Ofo0). Neither temperature nor salinity showed a daily variation worth mentioning.

Reference

N. G. }ERLov, I95I. "Reports of the Swedish deep-sea expedition"., 3 (r).

M.P. VISSER

K. N. M. I., De Bilt, The Netherlands.

Beam transmittance measurements in Ice­landic waters in May and June 1967

(Figures IOI-II2; Table 19)

Beam transmittance measurements were carried out in the waters west, north and north-east of Iceland from 30. April to 5· May and from 29. May to 5· June in connection with hydrobiological work

-71- Plankton

0.1 0.2 0.5 1 2 5 10 20 100 ---~-~-*.~?1 0

•/ /x-::;.+

/•+'"' ,?/;/

..//~ r/

/////

/.:· /

/ /

+'

/ /

/

X /+"' /

/ ,r

/

/

/+ ///

Station A July 1967

downward irradiance Ed

o red x green + blue

so

m

'100

Figure roo.

(MALMBERG, this volume, pp. rz-rg: "Hydrographic conditions in Icelandic waters in June rg67''). The measurements were recorded continuously at two spectral ranges of the light spectrum (red - 655 m[l. and blue - 450 mtL) down to 170 m depth. Only the measurements made at 655 mlL- the wavelength reproducing the content of suspended substances in sea water - will be dealt with here.

Figures ror-roz show the location of the stations. Figures 103-105 show the vertical distribution of the attenuatinon coefficient at 655 mi.t. (-a (R)) in the sections off Kogur, Siglunes and Langanes-NE worked in April-May and Figures ro6-rro show the distribution in the sections off Smefellsnes, La­trabjarg, Siglunes, Langanes-NE and Langanes-E worked in May- June. Figure III shows the

relationship between Secchi disc readings and the respective attenuation coefficients at 655 mlL at all stations. Table rg and Figure rrz illustrate the correlation between the vertical distribution of attenuation and that of plankton at two stations off Langanes, i. e. stations 36 and 49 from June.

The beam transmittance measurements in May and June in Icelandic waters revealed the following:

Off Smefellsnes, Latrabjarg and Kogur (Figu­res ro6, 107, 103) the highest attenuation was found in the surface layers over the shelf edge, with values

decreasing towards the coast and also towards deeper waters.

Off Siglunes (Figures 104, ro8) the vertical atten­uation distribution was rather complex, but on the whole a decrease with depth was observed. The surfac maximum of attenuation observed in May was in June found at ca 20-30 m depth, probably due to a growing thermocline from May to June and also due to the sinking of suspended substances. Besides, an intermediate maximum found at approximately 50 m in May was stronger in June than in May.

Off Langanes-NE and Langanes-E (Figures ro5, rog, rro) the maximum attenuation was found in the near surface layers at a distance ofso-6o n. m. from the coast in the core of the cold tongue north-east of

Table I9. Quantity of zooplankton according to sampling and of phytoplankton according to primary production

measurements at stations 36 and 49 from June I967

Depth Station 36 Station 49 m zoopl. phytopl. zoopl. phytopl.

ml mg Cfm3h ml mg Cjm3h

0 ......... - 0.2 - o.s 5 ......... 0 - 3

IO ......... - 0.2 - o.s 20 ......... -- 3·6 - I.O

30 ......... 0 0.8 77 !.7

f "~ 66t

I

,J ~

64+

30/4-7/5,1967

··.·:=::-:-:; .• , ...

ci •"?,

oO

""'

-72-

"---,----'."' ~ ""~--, <0" ~---~l·

ICE LIMIT

•

BEAM TRANSMITTANCE

MEASUREMENTS.

•

Figure 1or. Location of stations of beam transmittance measurements in Icelandic waters in April and May 1967.

20" --,-

29/5-5/6,1967 68r

J ~~ l ;~~:.:-:::-::.:::":".'::,·-:·:·:.:::.:·:·:·:.:-:.:·::.:..-.::::::.:;:::-.: .. :.:·.:~:.·.:-:-:: . .:::-:· ................

~ . Q r0'\

• •

. .

15"

• •

10°

•

•

•

BEAM TRANSMITTANCE

MEASUREMENTS.

5"

• •

Figure 102. Location of stations of beam transmittance measurements in Icelandic waters in May and June 1967.

S11

0~------J_-.-.--r-------------~--, m

2 3 4

On.m.

10------

'-- =----.::::::::: 09 -----~ oa_

:;~ ~

os ___ _

50

Figure 103. Section north-west of Kogur- 6 a (H.)

51:44 42 41 40

-73-

ST. 8 9 10 II

0.-~--e---~------L-, m

100

<

\_

::

150 l~

~!\\ C\J :~

200 ,.,

0 n.m.

10~ -o?s_

~

06 06

40

Figure 104. Section north of Siglunes

39 38 37

Plankton

6 a (R)

o,-L------L----r-~---,,--,--L---------------L------------~------------L-, m

50

<f) LI.J ~· ·' z <!

"' z <!

100' _J

150

"' "' -O> a:­-.0 0 ....

<>"'

"' 2 ·:.1

On.m.

0.8~

~08

~ I

O.T

I 50 100 150 170

Figure ros. Section east of Langanes - 6 a (R)

Iceland. The maximum was intensified from May to June in these sections as in the section off Siglunes.

The close relationship between Secchi disc readings and attenuation in Icelandic waters in May and June I967 shown in Figure III proves the usefulness of the Secchi disc. Beam transmittance measurements have been used as a measure of horizontal distribution of phytoplankton (BERGE,

I963), but they may also bee a helpful tool in studying the vertical distribution of plankton. For example, an attenuation maximum on the left in Figure I IZ corresponds to a maximum of zooplankton according to samplings (Table I g) and the attenua­tion maximum on the right in the same figure corresponds to a maxumum of primary product­ion (Table Ig).

-74-

501

100

150

STB

<OJ -06

~ z

~ G

--------

06

\ ~07 ;.

<06 ~0.7-----\ <06. ·· ... ·,'1

I <07 \ m

~

!>o(R) 29-3015,1961 ~~ 200 I :.=

!OOn.m. 50 0

Figure ro6. Section west of Sn<efellsnes - f'la (R)

S1 9 II

0 m

I

501- ~

100

150 o.-0

200 , .••. 90n.m. 50

13 14

Figure 107. Section west of Latrabjarg - L'la (R) sT. 24 25 26 2 r

lsor

I

!_,.

~~.·.·.! ! -, ' 200~ i On.m. 40

Figure ro8. Section north of Siglunes L'la (R)

ST33 35 36 37 38 39

~ <O~~,n~' ~0 /~---- 1.0 1.5 / ...._____ !2'5---......._ '

0.75 w.....__ \

"' w z "' "' z "' __J

1501

I 6 o(R)

200

I 2-3/6,1961

On.m.

G ~

50 100

Figure rog. Section north-east of Langanes -- L'la (R)

0.75....__ ~

I j

l I

150

0

-75-- Plankton

ST50

U>

"' z "' "' z

"' 100! _J

150

"' -"' "'"' -;~ <l"' .;.

49 48 47

06

200~--~L_~---L--~----~ On.m. ~

46 45 44 43

06·--------------------

[

tOO 150 200

Figure r ro. Section east of Langanes-- 6 a (R)

40.--------,--------.--------,-------.--------.----,

E 0

30

A-1 1967

A-ll 1967

20

10

0 2 ~a(R)

Figure I I r. Relationship between Secchi disc readings (D(m)) and respective beam attenuation coefficients at 655 m[J- ( 6a (R)) at all stations shown in Figures IOI--IOZ.

0 v 2 1::. o(R)

50

t'C !::. o(R} t'C 6 o{R)

All-67-49 A\l-67-36

tOOL..!.__ oo t"C I" 2" .,. 0" I"

Figure rrz. Vertical distribution of beam attenuation coefficients at 655 m[J- ( 6 a (R)) at stations 36 and 49 from

June.

From beam transmittance measurements m Icelandic waters in May and June rg67, it can be concluded that the maximum attenuation due to suspended matter was in general found in the surface layers above the shelf edge and over the continental slope. A sinking of the maximum was observed from May to June.

Sv. -AA. MALMBERG

Hafranns6knastofnunin, Skulagata 4, Reykjavik, Iceland.

Reference BERGE, G., I963. "A recording transparancy meter for

oceanic plankton estimation". N orw. Fishery and Marine Invest., 13 (6).

-76-

The Continuous Plankton Recorder Survey: plankton in the Irminger Sea region during

I967 (Figure 113)

The survey by the Continuous Plankton Re­corder in the Irminger Sea was continued in rg67 as in previous years. Two statistical areas, B6 and B7, have been sampled, at monthly intervals when possible, since 1957, the samples being collected at the standard depth of ro metres on the routes shown by GLOVER and RoBINSON in Annls. biol., Copenh., 22:59-60.

The survey is supported by the British Treasury and by contracts N6z 558-3 6rz and F6r o5z-67C-oogr between the Office of Naval Research, Department of the United States Navy and the Scottish Marine Biological Association.

The positions of the two areas are shown in Figure II3. The methods of presentation of results are given by GLovER and RoBINSON in this volume (p. 8rff.). The histograms show the fluctua­tions in abundance of a few selected species, or groups of species, in the two areas in rg67. The line graph:: give the average monthly abundance of these organisms in each area during the nine years 1957-1965. The results are presented in this way so that the results in rg67 may be com­pared with the average seasonal cycle.

The estimate of phytoplankton is obtained from a visual estimate of the green coloration of the filtering silk. The spring outbreak was exceptionally rich in both areas but, whereas it was late and short-lived in B6, it was early in B7. Chaetoceros spp., Nitzschia seriata and Thalassiothrix longissima were extremely abundant in both areas in June. As in rg66, Thalassiothrix longissima with Thalassionema nitzschioides were common in October in B6, as they were also in the neighbouring areas to the east, B5 and B4 (see GLovER and RoBINSON, this volume p. oo-oo).

Like the phytoplankton, the initial peak of copepods was early in B7 with above-average numbers in May and June. Copepods were less numerous than usual for most of the year in B6, and in September and October in B7. These results reflect the numbers of the dominant cope­pod in this region, Calanus finmarchicus (shown in two parts, (a) as copepodite stages I-IV and (b) as stages V and VI). The numbers of young stages were below average in B6, but were early and abundant in May and June in B7. The over­wintering adult stages were more abundant than usual during the first half of the season in B7 but be­low average in the second half; this situation was re-

40 30

65

60 ~.::::·l:!'~l:='!i!ili!!i.:~:~::II:!:.JII B 5

C8 C7 C6 C5

87 86 JFMAMJJASOND JFMAMJJASOND [3 ~4·7

r: L"n'"'""" ~

150

t:: ~:;:~~:M ._

t" ~"'"'''' I : ~'""'''" A""

~: 11_ YOUNG STAGES

OF SESASTES

~ JFMAMJJASOND JFMAMJJASOND

Figure rr3. Histograms showing average numbers, per Recorder sample, of selected organisms in areas B6 and B7 in 1967. The numbers of Thalassiothrix longissima are given in thousands per sample. The line graphs show the mean values for the period 1958 to 1965. For further

details see text.

-n- Plankton

versed in B6 where numbers tended to be low at first and high, or average, from July to October.

The numbers of E~tchaeta norvegica were cal­culated from samples taken at night only (because this species makes vigorous diurnal migrations). Gaps in the baseline in June and September in B6 indicate that there was no night sampling in this area in 1967. Numbers were extremely high in July in B6 and in August in B7.

The young stages of Sebastes were present in average numbers in B6, but were exceptionally abundant in B7, in May and July. A more detailed account is given by HENDERSON (see below).

R. S. GLOVER, G. A. ROBINSON Scottish Yiarine Biological Association, Oceanographic Laboratory, 78 Craighall Road, Edinburgh, 6, Scotland.

Sebastes in continuous plankton records in 1967

Regular sampling with the Hardy Continuous Plankton Recorder in the North Sea and North Atlantic was continued at the standard depth of 10 metres throughout rg67. The work was supported by a grant from H. M. Treasury through the Natural Environment Research Council and by Contracts N62558-36rz and F6ro52-67C-oogr between the Office of Naval Research, Depart­ment of the United States Navy, and the Scottish Marine Biological Association. The routes currently traversed by the Recorder survey were shown by GLOVER and RoBINSON (Annls biol. Copenh., 22: Figure 82).

Sampling was fairly satisfactory during the months April to September, the period of occurrence of young Sebastes, apart from a small gap in May at the northern end of the Reykjanes Ridge. Sampling over the Nova Scotian Shelf and in the Gulf of Maine was, however, much less complete; there were no records in these areas in May, July or September, due to changes and variations in shipping schedules.

The distributions of the young stages of Sebastes in rg67 were similar to those illustrated in earlier volumes of the Annales biologiques. The small patch of young in the Flemish Cap area off the Newfoundland Bank, apparantly similar to, but isolated from, the main oceanic stock. (see Annls biol. Copenh., 23: 85) was rather more abundantly represented in rg67, with fairly large numbers in May. The size compositions of young Sebastes taken in the individual months in 1967 fall wholly within the ranges found in previous years, an example of which has been illustrated for 1964 (Annls biol. Copenh., 21: Figure 6g).

The non-pigmented (oceanic) young stages In April relatively small numbers of young

were found over the western slopes of the Reykjanes and mid-Atlantic Ridges, as in many of the pre­vious years. They were, however, disposed in two apparently separated areas, between 6o 0 and 62° N. lat and between 55° and 58° N. lat. The majority were caught in the last few days of April, suggesting the possibility that the main 'spawning' or 'hatching' may have started a little later than usual. The distribution in May was, as usual, more widespread than in April but still with a suggestion of two separate areas of abundance, although the short gap in the continuity of sampling along the line of the Ridge does not allow any certainty in this respect. The numbers taken in May were very much greater than in April, and the overall abundance in the Irminger Sea area compares with the best of the previous years. About 85% were, however, within the smal­lest size ranges of 6 and 7 mm, confirming the im­pression that the main 'spawning' started late. In June and July, young Sebastes were more widely distributed over the areas of the Irminger Sea and south east from Cape Farewell, Greenland, but there appeared to be fewer than usual south from Cape Farewell. The numbers in June were about a third of those in May, as would be expected, but remained fairly high in July, at about 8o% of the June figure. A few specimens within the size range of 30 to 46 mm in length were taken in August, in the sector from south to east of Cape Farewell, where these larger sizes have occurred previously.

The pigmented (shelf and slope) young stages The population north of the Grand Bank of

Newfoundland, which has been observed in the years since rg63, was absent from the samples in May, and in June and July was well below average, being even less abundant than in rg66. None were caught here in August or September, as in some years. Because of the deficiencies in the sampling over the Nova Scotian Shelf and in the Gulf of Maine, no useful information can be derived from these areas.

G. T. D. HENDERSON Scottish Marine Biological Association, Oceanographic Laboratory, 78 Craighall Road, Edinburgh, 6, Scotland.

Plankton distribution in the Norwegian Sea in the spring-summer of 1967

(Figure I I4)

In rg67 the observations on plankton development were continued in the Norwegian Sea. The most

zoo 10°

£Z] 50-100 mg/m3

~100-200

WJJ 200-500

~ 500-1000

11111000-2000

7 4 0 ~ - > 2000 i

70° r- <

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6 z 0 t-- I DJE---"

14° 10° 60

-78-

zoo

74°

70°

66°

62°

oo 40 ao Figure rq. Distribution of the biomass of plankton (mgfm3) in the 0-50 metre layer in the Norwegian Sea

in June, I967.

-79- Plankton

complete investigations were carried out in March­April in the spawning areas of the Atlanto-Scandian herring, and in June over the whole area of the Norwegian Sea. Plankton was sampled with the Juday net (No. 38, 37 em in diameter) at depths of soo-zoo, zoo-roo, roo-so and so-om. In June, plankton was also collected on all sections with the Hensen net (No. 23, 73 em in diameter) in the o-so m layer. The water displacement method was applied for measurements of plankton volume.

Visual and quantitative analyses of the collected samples allowed us to give a short analysis of the plankton development in the Norwegian Sea.

In March observations were made in the Norwe­gian Shallow area and on the section along 67°3o'N. Over the whole investigated area the plankton biomass was not higher than roo-zoo mgjm3 and only at some stations off the Lofoten Islands about 6oo mgjm3.

Plankton was chiefly represented by Calanus finmarchic~ts, Metridia lucens, Pseudocalanus elong­atus and other small species of Copepoda. At the end of March the reproduction of C. finmarchicus was observed off the south-western Norwegian coast.

In April the investigations were carried out in the coastal waters off West Norway, near the Faroe Islands and on the sections at 67o3o'N, 6S 0 4S'N and 63°0o'N. In the Faroes area the distribution features of the plankton biomass were the same as in previous years (except rg66). The coastal waters were poorest in plankton (roo-zoo mgjm3) ,perhaps due to the predominance of small copepods there; moving offshore the plankton biomass increased a little. In the beginning of April, the arrival of a biological spring was observed south-east of the Faroes, with the occur­rence of great quantity of echinoderm and poly­chaete larvae together with nauplii of Cirripedia, and eggs, nauplii and young copepodites of C. finmarchicus. To the north of the Faroe Islands, the state of the plankton corresponded to the biological winter season. Pre-spawning specimens of the overwintering generation prevailed.

Plankton biomass fluctuations were observed from so to 6oo mgjm3 in the Norwegian Shallow area. The greatest quantities were registered in the southern part of this area, due to a mass develop­ment of phytoplankton (mainly Skeletonema costa­tum, Thalassiosira sp. and Coscinodiscus sp.) and of zooplankton (mainly C. finmarchicus). Euphausiacea constituted also a considerable part of the biomass.

In April plankton quantity in the Lofoten area was rather less than in March, which may be

related to the intensive grazing by herring. The plankton now mainly consisted of young copepodites of C. finmarchicus and different kinds of small Copepoda (P. elongatus, M. pusillus, 0. similis). In the central Norwegian Sea the plankton biomass fluctuated over a wide range from zoo to rooo mgjm3,

maximum quantities were recorded in the Atlantic waters of the Norwegian Current.

In June the oceanographic survey of the Nor­wegian and Greenland Seas was carried out in collaboration with Norwegian and Icelandic scien­tists.

An analysis of the age composition of the C. finmarchicus population showed that the western Norwegian Sea was characterized by later arrival of the biological spring, whereas in the eastern branch of the Atlantic Current it was a little earlier compared with rg66. The plankton biomass distribution was irregular. As in last year the lowest biomasses were found in the waters north­east of Iceland (Figure rr4). Areas with high bio­masses observed in the eastern and central parts of the Norwegian Sea were due to development of C. finmarchicus. In general, over the whole area the plankton biomass was lower than in rg66 and rg6s.

In July observations were made in the Jan Mayen-Mohn's Ridge area. In both areas high plankton biomasses were registered, up to r,ooo-z,ooo mgjm3, due to different kinds of copepods. Great concentrations of food organisms favoured good fattening of herring during this period.

A. F. TIMOKHINA

The Polar Research Institute of Marine Fisheries and Oceanography (PINRO), 6 Knipovich Street, Murmansk,

USSR.

Phytoplankton investigations from Aberdeen in r967

In rg67, because of other commitments, phyto­plankton sampling in the near northern seas area was very much reduced. It was restricted during the winter months to the west coast of Scotland, where although numbers were low the variety of species was unusually marked. The spring increase in the central North Sea was evident early in March with high numbers of chaetocerids and patches of Rhizosolenia hebetata forma semispina associated, on occasions, with much higher numbers of Thalassiothrix longissima than have occurred in recent years. In May phytoplankton growth was well established, Skeletonema costat~tm was abundant in the central North Sea and large patches Thalassio­sira gravida appeared in the outer Moray Firth.

- 8o

Off the west coast of Scotland, during the period April-May-June, the diatoms which were abund­ant over a wide area of the north-eastern Atlantic­and in the earlier part of this period also over Rockall Bank - continued to flourish over the deep water but during May and June, in the Calanus rich water on Rockall Bank, the diatom population was much reduced. Rhizosolenia alata forma indica and Rhizosolenia bergoni were present on the west side of Rockall Bank in June. In the central North Sea in June a tongue of Rhizosolenia styliformis var. oceanica extended south between Shetland and Norway while dinoflagellates, especial­ly Ceratium fusus, and Ceratium lineatum showed a marked increase except in neritic waters where Thalassiosira gravida and Chaetoceros didymum were still abundant.

In the latter part of the year the only area investigated at a reasonable sampling density was around Orkney and Fair Isle. Rhizosolenia alata forma gracillima was abundant west and east of Orkney but diatom numbers were generally low in September to the south west of Shetland and near Fair Isle where oceanic water with abundant Salpa fusiformis had penetrated.

Sampling in the distant northern seas area was restricted to a few samples taken in the coastal waters at Faroe during October. Dinoflagellates especially Ceratium jz£sus and Ceratium macroceros were moderately abundant and chaetocerid numbers remained high. Rhizosolenia alata forma curvirostris was taken at 62°46'N o6°z8'W.

D. D. SEATON

Nephrops larvae were found in May and June in the Moray Firth and north-western North Sea and in July to the north-west of Cape Wrath. Pleurobrachia is often at its greatest abundance late in the year but the rg67 sampling was then inad­equate in the North Sea to make comparisons. A small summer peak occurred but numbers rarely reached roo in the r metre nets (North Minch, Orkney and off the Aberdeenshire coast) and one station only in the Moray Firth gave over 3,000,

mostly small (z-5 mm). Only about zo% of the Pleurobrachia contained food, again mostly crusta­ceous, and parasites were not present in spring and early summer.

There was considerable oceanic plankton in the northern North Sea in rg67. In the early months of the year this was due to persistence of species brought in the previous autumn, and Sagitta serratodentata persisted until April and May. The rg67 inflow of outside species was first seen off the north coast of Scotland in June and July carrying the medusa Cosmetira to the Moray Firth. At this time indigenous North Sea species occupied the bulk of the northern North Sea; Sagitta setosa and Tima bairdii reached to about 6o 0 N off the Nor­wegian coast in June.

The inflow of strictly oceanic species was plainly evident in September especially in the Fair Isle region and east of Orkney. These included Sagitta lyra, Salpa fusiformis, the siphonophores Muggiaea atlantica, Sphaeronectes gracilis and Agalma elegans, and the copepods Rhincalanus nasutus and Eucala­nus elongatus.

:\'Iarine Laboratory, Victoria Road, Torry, Aberdeen, West coast of Scotland Scotland.

Zooplankton investigations from Aberdeen in 1967

Northern North Sea

Sampling from Aberdeen was not extensive in the northern North Sea, rg67. Calanus was abundant in spring and early summer over the Norwegian Deeps and only moderately abundant in the Fair Isle and central parts of the northern North Sea. Numbers were low on the western side generally and especially so in the Moray Firth. Small copepods, especially Acartia, were common east of the Moray Firth and off the Buchan coast with Thysa­noessa inermis, and with Spiratella and Oikopleura in the central northern North Sea. By late summer the numbers of Calanus had increased in the Fladen area.

Special investigations were made in the region of Rockall in 1967 concerning the abundance and distribution of adults and larvae of Micromesistius (Gadus) pMttassou and their biological environment - (see separate contribution by D. D. SEATON).

During May Calanus was abundant over the relatively shallow waters of Rockall Bank although accompanied by small numbers of a great variety of oceanic species, such as Sagitta maxima, S. serratodentata, Eukrohnia maxima, Physophora, Lensia conoidea, Clio pyramidata, Rhincalanus nasutus and Eucalanus elongatus. Off the bank, however, the numbers of Calanus were much redu­ced while Acartia and many oceanic species increased in abundance. Other more exotic oceanic species only occurred over deep water on either side of the bank, and these included the medusae Crossota and Halicreas, the siphonophores Vogtia spinosa, Hippopodius, Rosacea, Lensia fowleri,

- 8r

L. multicristata, the pteropods Clio cuspidata, Diacria trispinosa, Pneumodermopsis ciliata, the amphipod Phronima sedentaria and the cephalopod Desmoteuthis. This fauna extended in deep water north-west of Rockall and towards the Faroe­Shetland Channel.

In September there was no planktonic evidence of a selfcontained community over Rockall and the oceanic species were as abundant over the bank as over the deep water on either side. The species now included Sagitta lyra, Eukrohnia jowleri, the medusae Pantachogon haeckeli, Periphylla, Rho­palonema funarium, Bythotiara murrayi, Solmaris corona, Solmundella bitentaculata, the siphonophore Muggiaea atlantica, Arachnactes larvae, Calanus gracilis, Euprimno macropus, Euphausia krohni, Stylocheiron longicorne, N ematoscelis megalops and the zoea larva Problemacaris.

J. H. FRASER Marine Laboratory, Victoria Road, Torry, Aberdeen,

Scotland.

Chlorophyll a and zooplankton standing crop in the central and northern North Sea 1967

(Figures II5-II7)

The assessment of the phytoplankton and zoo­plankton standing crops in the northern North Sea was continued in r967. The areas surveyed and the results available for March-April and June are shown in Figures rrs and II6 respectively. No autumn or winter surveys were carried out. The methods used have been described by ADAMS (Annls biol., Copenh., r8: 69) and ADAMS and BAIRD (Annls biol., Copenh., rg: 63-5; ZI: 63-5; 22: 65-6). The chlorophyll a values given in this report were obtained with a spectrophotometer.

The restricted sampling in March-April gave chlorophyll a and dry weight values similar to previous surveys about the same dates. The chlorophyll a values in June are about average for that month; the zooplankton dry weight values for the same survey are of interest in that they show the area of greater than 3 g dry weight/roo m3 to be less extensive than in June r965 and July r966 and furthermore, the complete absence of areas with greater than ro g dry weight/roo m3.

Some data were obtained from the central North Sea during the international survey for adolescent herring in March. The standing crop of zooplankton during that survey is shown in Figure II7.

J. A. ADAMS, I. E. BAIRD Marine Laboratory, Victoria Road, Torry, Aberdeen,

Scotland.

Plankton

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31 MARCH-II APRIL 1967

1'

Figure r 15. Chlorophyll a (mg/m3) and standing crop of zooplankton (g dry weight/roo m 3), 31. March- II. April,

I967.

The Continuous Plankton Recorder Survey. Plankton around the British Isles during 1967

(Figures I IS-128)

The Survey with Continuous Plankton Re­corders was continued in r967 on the same basis as in other years. It was financed by the British Treasury through a grant from theN atural En­vironment Research Council and by Contracts N6z558-36rz and F6rosz-67C-oo9r between the Office of Naval Research, Department of the United States Navy and the Scottish Marine Biological Association. This report is restricted to the results from the area round the British Isles, shown stippled in Figure n8. Other reports on results from the Recorder survey are given elsewhere in this volume by HENDERSON (p. 77) and by GLOVER and ROBINSON (pp. 76-7).

The methods of presentation of the results are the same as those used by GLOVER, CoLE­BROOK and ROBINSON (Annls biol., Copenh., r8: 69-74). Recorders are towed at a depth of ten metres, at monthly intervals whenever possible, along standard routes; see GLOVER and ROBIN­SON, Annls biol., Copenh., 22: 67 (r967). For each month, in each of the sub-areas shown in Figure rr8, the mean number per Recorder sample (of 3 m3) has been calculated for the common species of plankton. The results of a selected few of these are shown in Figures n9-rz8 in which the data for r967 are presented as histograms (gaps

-82-

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Figure II6. Chlorophyll a (mgfm3) and standing crop of zooplankton (g dry weightfwo m 3), 6.-zo. June, 1967.

jo 0o -p f' 4° 5° •" 7" · ----,-------, I I I l 0·2

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Figure II7. Standing crop of zooplankton (g dry weight/ roo m 3), 9.-26. March, 1967,

in the baseline indicate that there was no sampling). A measure of the "normal" seasonal cycle is provided by line graphs of the average numbers per sample during the eighteen years rg48-rg65. Both the monthly means for rg67 and the long­term means were calculated from logarithmic transformations of the original counts. Inform­ation from other areas and for species not illustrated here will be supplied on application to the Director, Oceanographic Laboratory, Craig­hall Road, Edinburgh 6, Scotland.

The results are arranged in two groups in each Figure; above the heavy line are the graphs and histograms representing sampling over deep oceanic waters from the most southerly (DS )to the most northerly (Al); below the line are the results from the Atlantic shelf and the North Sea arranged in a sequence clockwise around the British Isles from C4 to Dr.

Phytoplankton (Figure rrg) was estimated by a visual assessment of the green coloration of the filtering silks. The spring outbreak was low and late everywhere except in the west-central and southern North Sea (sub-areas Cz, Dr and Dz). The late start of the season was most evident in the Norwegian Sea (Ar and Br) and in the northern Atlantic areas B4 and Bs. Chaetoceros spp. and Thalassiosira spp. were scarcer than usual every­where in the spring except in the north-west and southern North Sea (Bz, Dr and Dz). How­ever, there was a recovery in the second half of the season and the phytoplankton was more abundant than usual from July onwards in all areas except B5 and Ar. Rhizosolenia stylijormis was abundant in B4 in July, and Ceratium fusus and Ceratium furca in all oceanic areas from July to September. Thalassiothrix longissima, as in rg66, was common in areas B4 and B5 in October. Ceratium fusus was abundant in all North Sea areas from August to October and Ceratium lineatum in all western North Sea areas (Bz, Cz and Dz), especially in September.

Copepods (Figure rzo) attained their spring maxima later than usual in all oceanic, coastal Atlantic and northern North Sea areas (D5, C5, Bs, B4, Ar, C4, Bz and Br), but numbers were generally close to the long-term mean from May to September. In the central and southern North Sea, the numbers and timing were close to the average in spring (Cr, Cz, Dr and Dz). In all parts of the Atlantic and North Sea, numbers were below average, and in many areas very much below, from October to the end of the year.

The spring increase of stages V and VI of Calanus finmarchicus (Figure rzr) was later than usual

-83- Plankton

zo· ".

Figure I IS. A chart showing the area sampled by the Con­tinuous Plankton Recorders during I967. The area has been divided into sub-areas (see text). The stippled sub­areas have been sampled regularly since I948 and are

the basis of the results presented in Figures IIg-!28.

in all the oceanic areas except D5 but the numbers were above average in the early or mid-summer months (D5, B5, B4, Ar). In contrast, in all shallow-water areas except Cr, C. finmarchicus was less common than usual; this was particularly noticeable in areas C4, Bz and Cz througout the year.

The distribution of Calamts helgolandicus (most abundant in areas affected by warm water currents) is complementary to that of C. finmarchicus (found most abundantly in the colder northern areas). C. helgolandicus (Figure rzz) was above average in the southern oceanic area D5 in April, May and June, when C. finmarchicus, also, was abundant in this area. It was more numerous than usual in almost all areas in September, and in the extreme southern North Sea in November (Dr) and December (Dz).

As in every year since rg6z, the numbers of the combined genera Pseudocalanus and Paracalanus (Figure 123) continued to be well below average in most months in all areas. They were scarce in spring in all oceanic areas except for the most southerly region (D5) in June and were exceptional­ly scarce in the northern oceanic Atlantic and the

JFMAMJJASOND

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JFMAMJJASOND JFMAMJJASOND

Figure IIg. (left) -Phytoplankton

Figure Izo. (right) -Total copepods For details, see text, p. &z and Figure n8.

JFMAMJJASOND

D5

85

84

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-84-

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JFMAMJJASOND JFMAMJJASOND

Figure 121. (left)- Calanusfinmarchicus, stages V and VI.

Figure 122. (right)- Calanus helgolandicus, stages V and VI. For further details, see text p. 83 and Figure u8.

Norwegian Sea (B4, B5 and Ar). In the shallow water regions, numbers were generally low except for Cr in April and May and C4 in May and June, Br in July and Bz in September when numbers were higher than usual.

Acartia clausi (Figure 124) was abundant almost everywhere, although not reaching the high numbers found in Atlantic oceanic waters from rg6r to 1963. The exceptions were in the northern oceanic areas B4, B5 and Ar where it was much below average.

~C1~

J FMAMJ J ASOND JFMAMJJASOND

Figure 123. (left)- Pseudocalanus elongatus and Paracalan~ts spp. (combined).

Figure 124- (right)- Acartia clausi For details, see text p. 83 and Figure rr8.

JFMAMJJASOND

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84

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Figure 125. (left) Clione limacina. Crosses indicate the occurrence of Clione in small numbers during the pe~iod

rg48-r965. Figure rz6. (right) - Spiratella retroversa

For details, see text and Figure II8.

Clione limacina (Figure 125) and Spiratella retro­versa (Figure 126) were both much below average over most of the area; Clione, especially, was extremely scarce throughout the North Sea. In a few areas one or both species showed momen­tary peaks close to the long-term average. The only above-average numbers were in the extreme west of the area; in Ds, where both species were abundant in June and B5 where Clione were numerous in July and August.

Two other species found in below average numbers almost everywhere were Salpa fusiformis (Figure 124) and Dolioletta gegenba~tri (Figure 128). Like Clione and Spiratella, Salpa showed brief

Plankton

JFMAMJJASOND J FMAMJ J A SOND

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JFMAMJJASOND JFMAMJJASOND Figure 127. (left)- Salpa fusiformis

Figure rzS. (right) - Dolioletta gegenbauri For details, see text and Figure II8.

peaks of abundance in a few areas, notably in the coastal Atlantic (C4) in July and October, and the north-western North Sea in October. Dolio­letta, however, was found in only one area (C5 in September). This species had been abundant in the oceanic areas D5 and C5, from 1954 to 1960 (except 1958), but its numbers have been low from 1961 onwards.

-86-

To summarize, the spring outbreak of phyto­plankton was low and late in all oceanic and nor­thern North Sea areas. This was followed by the late production of copepods in spring in these areas. For the rest of the year phytoplankton was above average, and copepods were generally abundant in summer, but scarce again from October onwards.

In April and May in the Atlantic, to the west of Ireland (D5) the following species typical of warm water oceanic conditions were found: Pleuromamma gracilis, P. borealis, Rhincalanus nasutus, N annocalanus minor, Clausocalanus spp., Euchaeta acuta, Scolecithricella spp., Ceratium hexacanthum and Rhizosolenia bergonii. In the autumn these species were more widely distributed to the west of the British Isles, together with P. abdominalis, P. xiphias, E~tclio spp., Calamts tenuicornis, Eucalanus elongatus, and E'Vtchaeta hebes. From August to Ocotober Salpa fusiformis was found in the north-western North Sea (Bz) and in October, in small numbers, in the Nor­wegian Sea (Ar). In October, also, Eucalan'ns craSS'US appeared in the North Sea (Bz).

Atlanta peroni, a heteropod, which has not been recorded in the North Sea previously, was found at oro 40' W, 56° oo' N in June.

R. S. GLOVER, G. A. ROBINSON Scottish Marine Biological Association, Oceanographic Laboratory, 78 Craighall Road, Edinburgh 6, Scotland.

Zooplankton investigations on Rockall Bank, May, June and September 1967

(Figures 129-131)

The Rockall Bank area was surveyed in May, June and September. The main objectives were to locate any concentrationss of M icromesistius (Gadus) poutassou larvae and, as "Explorer's" hydrographic capability had been temporarily reduced in order to facilitate gear investigations, to obtain- from the plankton samples- inform­ation about the environmental conditions in this area. The principal sampling apparatus used was the International W. P. 3 net fitted with a T. S. K. flowmeter.

Observations from earlier years indicate that there is a strong possibility that a gyre system exists in this area, FRASER (rg58), but as these observations are few and scattered, little can be deduced about the duration, timing or stability of this system. The material obtained in rg67 and the work of HENDERSON (rg6r) has shown that Rockall Bank is a principal centre of spawning for M. poutassou and the results lend considerable

support to the gyre theory. It may be that the physical conformation of Rockall Bank is the main factor in the formation of the gyre. The resistance offered by the bank to the predominantly north flowing current may tend to entrap water along its south/north axis, while the steep eastern edge permits a relatively faster transport along its eastern margins. In such a situation the entrapped water on top of the bank may provide a more suitable environment for an earlier growth of phytoplankton than does the water surrounding the bank. The bank area would then, in turn, support a flourishing Calanus crustacean com­munity such as was found during the May survey.

In May, on the bank, within an area roughly delimited by the zoo fm contour Calanus was extremely abundant, Figure rzg, and associated with high numbers of euphausids (mainly Thysanoessa longicaudata) and various decapod larvae (mainly eupagurid sp.). Coelenterates were generally sparse and other carnivorous zooplankton species, viz. Tomopteris and Sagitta, were present in very small numbers. Over the deeper water surrounding the bank the position was reversed. Calanus was poorly represented while coelenterates and other carni­vorous zooplankters were very much more abundant than on the bank. Salpa fusijormis was not present on the bank but was taken in small numbers on both sides of the bank and penetrating much further north on the eastern side than the western side. Lusitanian forms did not appear further north than the extreme southern extension of the bank except in the deep channel east of the bank. The main centre of abundance of M. poutassou larvae was located on the shallower, northern part of the bank in an area of abundant Calanus.

In June, conditions in the area were very similar to those in May. Calanus and other crustaceans were again very abundant on the bank. Coelentera­tes, though a little more numerous, did not occur in really significant numbers. Over the deeper water on all sides of the bank Calanus was sparse while coelenterates and other carnivorous zoo­plankters continued to dominate the collections. Salpa Jusijormis was present to the west and east of the bank and, as in May, it was taken much further north on the eastern side. A few salps were present over the southern extension of the bank and also on its southern margins. This feature when combined with the slightly changed Calanus distribution on the bank, Figure 130, might be interpreted as indicating some measure of oceanic inflow on to the bank and a consequent northerly displacement of the main body of "bank" water with some peripheral spill out from the central

<1<1<J •

0~

<I . <l <I

•

"~ ~

~" • '\ '

~

"~~ ~ '\ '•

~L------------~ •,

0~

5

/.X~ /~/

16°

-88-

14°

/./::( ////

.b.

.6

. D. ~L

-~v/ .l:::J. / ~

/··-.....

( ."- _/

/// ///~~

\

"·~ \)~ I / j I

/ . (- \ /.£'/ -/ /7/ J

/

'';·~~~-// /////

/ l ~-" "

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'/ / I .. , • • A / I v

- 'J •• (>

•· oA

;K/ ~TY

560 . A :;&:; ~/ /// /

~& /// l /

Figure I30. Rockall Bank June I967

• Calanus

. / /til ~ J./ // /

6 Coelenterates and Salps (excluding Aglantha) 2. Salpa fusiformis

12°

16°

58 ,

8g-

14°

/·-........

( \ ·.'-._ __ /

// /J //, / ?¥/ / /

/: v /fl} :p; //If; /

/.M //4 //7/ /- "/•77

: '·..._

/r/1·--71 ;' /~-·-: I

/ /' !

I I

D ( / /

~/(!;0.' . /1;:; / /-7-7. /1 / ~ty I ,. // /

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57

56°

I (.-- ·-·~ "'-

A i ,...;;;;'~_/~· // •u . / . / ~!\/ /' y // / / /};7/ .

/1% / / /. /. ./ _Af5// / //7/

( - __ ./ \ ~-

.. __ _)

Figure 13L Rockall Bank September 1967

• Calanus !':, Coelenterates and Salps (excluding Aglantha) 2= Salpa fusiformis

Plankton

120.

-go-

area. The northern limits of Lusitanian species were almost identical with those in May.

M. poutassou larvae were taken in very small numbers in June, probably due to a combination of several factors, e. g.

(a) Increased ability to avoid the net (b) Migration into deeper water (c) Displacement of the water mass (d) A high mortality. In September, conditions were very different

from those in May and June. The plankton com­munities both on and off the bank were virtually identical, Figure I3I. Calamts numbers were almost uniformly low and coelenterates high, while Salpa jusijormis was now widely distributed over the whole area although particularly abundant on the northerly shallow part of the bank. The salps to the north and east of the bank towards the Butt of Lewis were in poor condition - presumably as they were part of a population brought into this area in May and June. On the bank the salps were in good condition and were reproducing. No M. poutassou larvae were taken in any of the Sep­tember plankton hauls.

Whereas in May and June Lusitanian forms did not extend further north than the southern extremity of the bank, in September such species as Nematoscelis megalops, Stylocheiron spp., Vogtia sp., Hippopodius hippopus and Sagitta lyra were present in small numbers, on the bank as well as east towards the shelf area off the Northern Hebrides, the presence of these organisms indicating a weak but widespread Lusitanian influence permeating the whole of the area.

As very few hydrographic observations were made during these three surveys, any definite conclusions about the timing, duration and stability of the possible gyre system will have to await the results of further investigations planned for rg68. It does, however, seem that there are at least two possible interpretations of the planktonic evidence obtained in rg67.

I. The gyre system is not a permanent feature of the area but in rg67 it was established early in the year, enabling a rich Calanusjcrustaceous com­munity to develop over the bank and creating conditions which were very suitable for the spawning of M. poutassou and the subsequent early develop­ment and retention of their larvae, the system remaining stable until the latter half of June. Because of an increase in the flow of oceanic water on to the bank, the equilibrium of the system would then be gradually destroyed, allowing the whole

area to be swept by oceanic water which displaced and dispersed the Calanus community and the developing poutassou larvae. By early September conditions both on and off the bank were thus identical.

II. The gyre system is a more or less permanent feature of the area and the apparent breakdown is really a reflection of the seasonal succession of species and a slow change over several months­in the character of the zooplankton community on the bank, this change being brought about by a combination of several factors - listed below -which tip the balance against the Calamts com­munity which successfully dominates the bank in the early part of the year.

(i) The gyre system can never be completely self-contained and must, in the long term, be subject to considerable variations in peripheral increments of oceanic water and losses in 'bank' water. Therefore the number of oceanic forms and of zooplankton preda­tors must build up.

(ii) The Calanus community on the bank will suffer heavy predation from the large populations of bathy pelagicfishes - myc­tophids, Benthosema sp., M aurolictts sp., etc. which are known to occur in this area -and from the high numbers of fish larvae (especially M. poutassou, Gadiculus argen­teus thori and Argentina sp.).

(iii) By September the Calanus population on the bank will have completed three breeding cycles and the survivors will form the overwintering stocks whose normal pattern of behaviour is to migrate into deeper water, thus moving off the bank.

The end result will be that the dominant positions in the bank community will be occupied by the coelenterates and by the salps which are often widespread in the North Atlantic at this time. The greater stability of the water mass in spring will, as mentioned before, enable an early develop­ment of phytoplankton and so start the cycle again.

D. D. SEATON Niarine Laboratory, Victoria Rd., Torry, Aberdeen, Scotland.

References

FRASER, J. H., 1958. "The drift of the planktonic stages of fish in the north-east Atlantic and its possible significance to the stocks of commercial fish". Spec. Publs int. Commn NW Atlant. Fish., (r) z8g-3ro.

HENDERSON, G. T. D., rg6r. "Continuous plankton records: contributions towards a Plankton Atlas of the North-Eastern Atlantic and the North Sea". Bull. mar. Ecol., 5: (42) (5) 65-rr r.

-92-

Gadoid Fish COD

Introduction

The contributions on cod give a rather scarce picture of the distribution, abundance and age- and length-composition of the catches taken from the major cod stocks in the north-east Atlantic. How­ever, this report is based on the contributions, on some data from papers presented to the ICES meeting in rg67, some umpublished Norwegian data, and British data given in "Fish stocks Re­cord rg67''.

Soviet data on catch per unit effort for a Murman side steam trawler fishing in the Barents Sea and the Bear Island Area showed higher yield per hour trawling in both areas in rg67 than for the period rg58-67. Average catch-rates for British trawlers have also increased and returned to the early rg6os, o.s tons(hour in the Barents Sea and o.6 tons(hour at Bear Island. The Norwegian spring cod fishery, which takes place along the Finnmark coast and in the Barents Sea in April-June, have given in­creasing yields since rg64. These improvements in the fisheries are caused by improved stock abund­ance, firstly because the amount of international fishing has remained low, and secondly because the rg63 year-class is good. However, high availability of fish in coastal areas in recent years have also been favourable for the Norwegian fishery with gillnet, long- and handline.

Nearly half of the catches taken by U.S.S.R. in the southern Barents Sea consisted of the rg63 year class, while the same year class amounted to about 70 per cent in the catches from the Bear Island area. The rg64 year class amounted to z6 and r6 per cent respectively in the two areas. Norwegian long- and handline landings of immature Arctic cod (spring cod) were in rg67 dominated by the year classes rg6o-rg63. However, the landings of coastal cod which made up about rg per cent in number of the total landings, were dominated by the year classes rg6z and rg63:

Age-groups Arctic cod Coastal cod

3 ........ 17 62 4 ........ 384 540 5 ........ 203 284 6 ........ 132 57 7 ........ 169 57 8 ........ 85 9 ........ 9

10 ........

Norwegian catches of spawning cod were in rg67 of the same magnitude as in rg66, but a greater part of the Norwegian catches were taken inside the Vestfjord. At the same time the English catches of spawning cod continued to decline. Since there is no indication that the stock of spawning fish has suddenly increased, the heavy Norwegian fishery is a result of a change in the distribution of the stock. This have made the spawning cod congregate more densely within the Vestfjord, leaving rela­tively few on the outer spawning grounds.

The spawning stock of Arctic cod was in rg67 dominated by the year-classes rg58-rg6o. How­ever, the stock of coastal cod in Lofoten, which is both mature and immature fish, was dominated by the year classes rg6o-rg6z:

Ags-groups

3 4 5 6 7 8 9

10 II

12 13 14 rs+ ...

Arctic cod

12 195 450 240

55 24 10

9 3 4

Coastal cod

4 6o

261 220

258 107

45 26 15

4 8

The spawning stock of Arctic cod wa5 in rg67 to a great extent dominated by first time spawners, while the first time spawners of coastal cod made up 65 per cent:

Spawning class Arctic cod Coastal cod

. . . . . . . . . 88o 651 2 ......... 88 220

3 . . . . . . . . . 12 42 4 ......... 10 47 5 ......... 5 19 6 ......... 2 II

7 8 . ..... 9 .........

Soviet young fish surveys and international 0-group fish surveys in the Barents Sea and in the Bear Island area have shown that the year classes rg65-rg66 are very poor. International surveys

-93- Gadoid Fish Cod

in I967 have shown, that the I967 year class of cod is bad too. This means that the prospect for the abundance of the stock is bad.

The English cod fishery at Iceland, mostly based on immature fish, was relatively good in I967 although the amount of fishing decreased. Catch­rates regained the Ig6o level of 0.3 tons/hour, but the total landings remained at the level of the more recent years. Higher catch per unit effort was caused by better catches of the I962 year class, which is not outstanding, but better than its im­mediate predecessors.

Catches of spawning Icelandic cod were still in I967 dominated by the I95S year class, but the Ig6o, Ig6I, and Ig62 year classes made up a greater part of the catches. The abundance of the first-time spawners decreased from Ss percent in Ig66 to So per cent in I967.

Total mortality rate of Icelandic cod was in I965 estimated by the North-Western Working Group (Coop Res. Rep. Ser. B., Ig66) to 6o per cent for immature cod and 70 per cent for mature cod. A study made by this working group in I967 has shown that for a stock which experiences a 6o per cent annual mortality rate the ratio of 3-6 year old (immature) and 7 year and older (mostly ma­ture) caught should be I : 0.076. However, the observed ratio for recent years is I : 0.5, which indicate a much larger number of mature cod than expected with a constant mortality ra~e of 6o per cent. In order to explain this difference comprehen­sive research programmes have been made.

Age compositions of the cod stock exploited in I967 by British trawlers and seiners in the northern North Sea have showed that the effect of the strong Ig6I year class has been greatly reduced since Ig66. The I965 year class which have shown to be well above average abundance, and the good I964 year­class have kept the landings per unit effort high. The Ig66 year class promise to be of about average strength.

British landings of cod in I967 from the area south of Doggerbank have depended largely on cod spawned in I963, but no new strong year classes have entered the more southern fisheries. The Ig66 year class is very abundant inshore off Lowestoft, but it has not yet started to enter the offshore

fisheries. Colding born in I967 are conspicuously absent in the same area.

Some data on the cod stock on the west and north coast of British Islands have been reported. Increasing landings of cod have been observed in the period I964-I967 from the Firth of Clyde as a bycatch in the trawl fishery for Nephrops. This has not been reflected in reduced landings by seiners, so higher total landings were recorded from the area in I967 than in previous years. Scottish age compositions have shown that the I964 year class dominated the landings from the western area, while English landings from this area have depended mainly upon the excellent I963 year class. Landings from the northern area have been domi­nated by the I964 and I965 year classes.

The German cod fishery in the western Baltic yielded about 20 per cent more in I967 than in Ig66. This was made possible by a fairly good recruit­ment of the Ig66 year-class. In I967 this year class made up more than So per cent of the total catch in number. However, fish older than 2 years were rare, and 5 years and older were practically not present in the catches. This has, according to Ger­man investigations, partly been caused by the fishery itself.

The Polish fishery for cod in the southern Baltic yielded about the same quantity in I967 as in Ig66, which was about 26 per cent higher than in I965. The catches in I967 were dominated by the I964 year class, which is estimated to be exceptionally abundant.

Several papers presented at the I967 ICES meet­ing drew attention to the problems confronting the Baltic cod fishery. Since Ig6o the proportion of cod exeeding so em total length in the Swedish coast fisheries has decreased from about 45 per cent to about 75 per cent. At the same time there has been a substantial increase in the amount of cod con­signed for reduction purposes. There is a need to evaluate these changes with respect to fluctuations in year class strength, the amount of fishing and the regulations at precent agreed between the nations participating in the fishery.

ARVID HYLEN

Fiskeridirektora tets Ha vforskningsinstitutt, Nordnesparken z, Bergen, Norway.

-94-

The spawning stock of Icelandic cod in 1967 (Table 2o)

As in previous years Table 20 is based upon the commercial catches from lorg lines, gill nets, trawls and purse seines from the spawning fishery and weighted in accordance with the actual quantity caught in each gear.

The percentage of first time spawners is some­what lower than in the previous year, but never the less, first time spawners constitute about So% of the total spawning population.

The 1958 year class was still dominating in the catches, but besides that, the fi:;hery was mainly based upon the year classes from rg62, 6r and 6o.

]. JONSSON

Hafranns6knastofnunin, Skulagata 4, Reykjavik, Iceland.

Soviet investigations of the age- and size composition of cod stock in the Barents Sea

in 1967 (Tables 21-27)

In 1967 as in previous years ir~vestigations were continued on the state of the c:od stocks in the southern Barents Sea and the Bear Island-Spits­bergen area. Off the north-wEstern Norwegian coast the observations were made nainly in January to April.

Table 21 shows the mean catch per trawling hour, the number of fishes and the mean weight

per specimen, by a Murman side steam trawler during the last ten years. In 1967 the catch in weight of cod per trawling hour was higher than the mean for rg58-rg67. This was due to in­creased fish abundance, the mean weight per specimen being below the long-term mean.

In Tables 22 to 24 the size composition of the cod catches is given by areas according to the ICES divisions. In rg67 cod measuring 40-45 em were caught in greater numbers in the southern part of the Barents Sea and in the Bear Island­Spitsbergen area as compared with the long-term mean for 1958-rg67. Off the north-western Norwegian coast where samples (750 fishes) were taken in January in the S0r0y and Fugl0y grounds and in January-April (12,427 fishes) in the western regions of the Norway Deep, catches of cod up to 6o em in length were predominant in 1967. The remaining size groups were less abundant when compared with the long-term mean.

Table 25 gives data on the age composition of the cod catches. In the southern part of the Barents Sea nearly half of the catches consisted of 4 year old fishes of the rg63 year class, and in the Bear Island-Spitsbergen area nearly 3/ 4 of the catches were of the same age. Next in abundance were 3 year old fishes of the 1964 year class. Both year classes are very numerous according to previous investigations of the abundance of young ones at an age of 2-3 years (r+2+). The rg63

(cont. p. g6)

Table 20. Icelandic spawning stock of cod, 1967

Age at first spawning Age-groups 3 4 5 6 7 8 9 IO II IZ I3 Total

III ............. 58 - - - - 58 IV .............. 402 - - - - 402 v ............... - 9 IAII - - - - - I,420 VI .............. - 70 I,49I - - - - - I,56I VII ............. - - 5 269 I,499 - - - - - I,773 VIII ............ - - - 25 I82 607 - - - - - 8q IX ............. - - - 40 !02 45I I,888 - - - - 2-48I X . . . . . . . . . . . . . . - - - 8 20 76 q8 320 - - - 572 XI . . . . . . . . . . . . . - - - - II I23 I65 294 269 - - 862 XII ............. - - - - 5 8 - - - - I3 XIII ............ - - - - - 8 3 - 3 - I4 XIV ............ - - - - - 3 3 8 5 3 22

XV ............. - - - - - - - - - - 3 3 XVI ............ XVII ........... XVIII . . . . . . . . . . Total ........... 58 4II 1-486 r,833 I,8q !,262 2,220 62I 277 9 6 9.997

Spawning classes

2 3 4 5 6 7 - Total

Number ......... 7.945 1-429 38I 202 35 3 2 - 9.997

-95- Gadoid Fish Cod

Table 21. 'Neight, number of fishes and the mean weight per specimen of cod in catches per trawling hour by a Murman side steam trawler

Years of fishing Average Indices 1958 1959 rg6o rg6r 1962 1963 1964 1965 rg66 1967 data

The southern Barents Sea Catch (weight in kg

per trawling hour) ..... 340 370 410 370 58o 590 350 380 420 570 438 Number of fishes ....... 190 299 297 284 464 468 314 270 331 48S 339 Mean weight per

specimen (kg) ........ I.8 !.2 1.4 1.3 1.2 1.3 I. I 1.4 1.3 I. I 1.3

Bear Island-Spitsbergen area Catch (weight in kg

per trawling hour) ..... 490 360 240 sso Number of fishes ...... 3S3 309 200 403 Mean weight

per specimen (kg) ..... 1.3 !.2 !.2 1.4

Table 22. Size-frequencies of cod in the southern Barents Sea (Ofo0)

em 1967 rgsS-1967

IS- 20 ............... . + I

20- 25 ............... . 2 6 25- 30 ............... . 21 26 30- 35· .............. . ss 72 35- 40 ............... . 132 200

4°- 45· .............. . rSS 170 45- so ............... . 206 131 so- 55· .............. . 167 140 ss- 6o ............... . 94 99 6o-- 65 ............... . 44 64 65- 7o ............... . 23 44 70- 75 ............... . r6 29 75- So ............... . II 19 So- Ss ............... . 6 12 Ss- go ............... . 3 8 95-100 ............... . 4

>roo ............... . 9

N- 32,3386

Table 23. Size-frequencies of cod in the Bear Island­Spitsbergen area (0 / 00)

em 1967 1958-rg67

IS- 20 ............... . 20- 25 ............... . 25- 30 ............... . 30- 35· .............. . 35- 40 ............... . 40- 45· .............. . 45- so ............... . so- 55· .............. . ss- 6o ............... . 6o- 65 ............... . 6s- 7o ............... . 70- 75· · · · · · · · · · · · · · · · 75- So ............... . So- 85 ............... . ss- go ............... . 90-100 ............... .

>roo ............... .

N = 21,3626

+ 2

17 51 86

217 291 190

59 17 13 r6 r6 12

7 4 2

2

9 21 so g6

157 171 149 II5 Sr 56 3S 25 l4 s 4 6

790 s6o 390 490 190 Sro 490 475 342 235 219 143 6So 339

1.7 I.6 !.7 2.2 1.3 1.2 I.S

Table 24. Size-frequencies of cod off the north-western coast of Norway (0/ 00)

em 1967 1958-rg67

IS- 20 ............... . 20- zs ............... . I

25- 30 ............... . 3 3 30- 35· .............. . r6 7 35- 40 ............... . 48 19 40- 45· .............. . 148 30 45- so ............... . 225 49 so- 55· .............. . r82 6r ss- 6o ............... . 95 72 6o- 65 ............... . 78 Sg 65- 7o ............... . 77 roo

70- 75 · · · · · · · · · · · · · · · · 62 107 75- So ............... . 40 97 So- 85 ............... . 17 ss Ss- go ............... . 6 S3 90- 95· · · · · · · · · · · · · · · ·, 6o 95-100 ............... . 51

>roo ............... . g6

N = 13,177

Table 25. Age composition of cod catches (0/ 00)

Year class Age Southern Bear Island- North-Barents Sea Spitsbergen western

area coast of Norway

1964 ..... 3 263 159 41 1963 ..... 4 498 714 453 1962 ..... 5 164 51 219 rg6r ..... 6 33 15 78 rg6o ..... 7 19 23 104 1959· .... s r6 22 77 1958 ..... 9 5 12 26 1957 ..... IO I 4 2 1956 ..... II + - + 1955 ..... 12 + - + 1954· .... 13 - +

-g6-

Table 26. Mean length of cod, (em)

Age Southern Barents Sea Bear Island-Spitsbergen area

1967 19s8-1967 1967 rgs8-1967

3· .... 39·1 38.2 39·7 39·S 4· .... 48·7 4S·7 49·S 49·0 S· .... S7·3 S2·4 s6.g S4·2 6 ..... 6s.o 61.2 64·3 62.8 7 ..... 71.8 70.8 72·5 71.5 8 ..... 77-7 78·3 79·2 79·7 9· .... 83·7 82.0 83·7 85.8

IO ..... 92-4 91.3 go.6 go.6

Table 27. Mean weight of cod, (g)

Southern Barents Sea Bear Island-Spitsbergen Age area

1967 1958-1967 1967 rgs8-r967

3 ..... 536 562 S96 590 4· .... 1,000 866 1,094 946 S· .... 1,552 1,282 1,625 1,405 6 ..... 2,293 1,969 2,306 2,140 7 ..... 3,192 2,916 3,200 3,170 8 ..... 4,090 4. 037 4.299 4.490 g ..... 5,317 5.373 - 5,728

10 ..... 7,220 6,741 7,055

year class was also found in great quantities m catches taken off the north-western coast of Norway.

In Table z6 are given the mean sizes of cod as observed in rg67, and the long-term mean sizes for rg58-rg67. In the southern Barents Sea the size of cod at an age of 3 to 7 years was in rg67 above the long-term mean, and the size of those at an age of 8 to ro years was below the

mean. In the Bear Island-Spitsbergen area cod at an age of 3 to 4 years was of a size equal to the long-term mean. The size of cod at 5 to 7 years of age was above the long-term mean, while that of 8 to ro years old cod were below the long­term mean.

In Table 27 is shown the mean weight of cod of different age groups in rg67 and rg58-rg67. In rg67, cod of all age groups were heavier than the long-term mean. 3 year old cod in the southern Barents Sea and 8 year old cod in the Bear Island­Spitsbergen area are exceptions.

V.P. PONOMARENKO

The Polar Research Institute of Marine Fisheries and Oceanography, 6 Knipovich Street, Murmansk, USSR.

Scottish investigations of the west coast stock of cod, 1964 to 1967

(Tables 28-32)

Commercial statistics

The landings, fishing effort and landings per unit effort by British vessels fishing on the Scottish north and west coasts and landing their catches in Scotland from rg64 to rg67, are given in Tables z8, zg 30 and 3I. The principal fishing areas for cod were the north coast and North Minch by all methods and to a lesser extent the Firth of Clyde by Danish seine and light trawl. Some fairly high catching rates have been recorded by motor trawlers fishing the Outer Hebrides

Table 28. Cod landings (nominal catches) and fishing effort by British vessels at all Scottish ports in 1964 from the north and west coasts of Scotland

North North Outer South S. of Firth Coast Minch Hebrides Minch Lat. s6°N of Clyde

Landings ('oo tons) Motor trawl ............................ 31.07 rs.sr rs.84 0.76 Steam trawl ........................... 1.55 o.89 0.06 Light trawl ............................. 0.98 s.gr 0.06 0.21 O.OI 0.02 Seine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-43 24.04 O.IO 1.19 0.03 6.43

Fishing Effort ('oo hours) Motor trawl ............................ 448 ISS 243 - 22

Steam trawl ........................... z6 8 4 Light trawl. ............................ 48 378 4 30 I 2 Seine ................................. 394 742 7 379 2 398

Seine (days' absence) ...................... 4.53S 8,449 66 3,326 17 s.sos

Landings per unit effort

Motor trawl (tons/roo hours) ............ 7·0 IO.O 6.s o.s 3·6 Steam trawl (tonsjroo hours) ............ S·9 11.4 r.6 Light trawl (tons/roo hours) ............ 2.1 1.6 r.s 0.7 r.o 1.3 Seine (tonsjroo hours) ............ 2.4 3·3 r.s 0.3 2.0 r.6 Seine (tons/days' absence) ............... 0.2 0.3 0.2 0.2 0.1

-97- Gadoid Fish Cod

Table 29. Cod landings (nominal catches) and fishing effort by British vessels at all Scottish ports in 1965 from the north and west coasts of Scotland

North North Outer South S. of Firth Coast Minch Hebrides Minch Lat. 56°N of Clyde

Landings ('oo tons)

Motor trawl ............................ 25-94 !2.01 15-71 - LSI Steam trawl ........................... 0.7S 0.06 0.94 Light trawl ............................. 2·44 S-17 0.02 0.12 0.20 Seine ................................. 4·S6 13-92 0.04 l-49 O.OI I2.I6

Fishing Effort ('oo hours)

Motor trawl ............................ 4SS 142 I7S 33 Steam trawl ........................... r6 2 II

Light trawl ............................. S3 326 2 13 - 19 Seine ................................. 3S6 644 2 246 I 47S Seine (days' absence) .................... 4,SS7 S,ro9 19 2,3Il 7 s,6S9

Landings per unit effort Motor trawl (tonsjroo hours) ............ 5-4 s.s S.9 - 4·7 Steam trawl (tonsjroo hours) ............ 4·s 2.9 s-4 Light trawl (tonsjroo hours) . . . . . . . . . . . . 3·0 L6 L3 0.9 1.7 LI Seine (tons/roo hours) ............ !.2 2.2 2.S 0.6 r.S 2.6 Seine (tons/days' absence) ............... 0.1 0,2 0.2 O.I 0.2 0.2

Table 30. Cod landings (nominal catches) and fishing effort by British vessels at all Scottish ports in 1966 from the. north and west coasts of Scotland

North Coast

Landings ('oo tons)

Motor trawl ............................ 29-39 Steam trawl ........................... 0.2S Light trawl ............................. LSI Seine ................................. 6.rS

Fishing Effort ('oo hours)

Motor trawl ............................ 6oo Steam trawl ........................... 9 Light trawl ............................. So Seine ................................. 394 Seine (days' absence) .................... 4.937

Landings per unit effort Motor trawl (tonsjroo hours) ............ 4·9 Steam trawl (tonsjroo hours) ............ 3-l Light trawl (tonsjroo hours) ............ L9 Seine (tons/roo hours) ............ L6 Seine (tonsjdays' absence) ............... 0.1

and south· of latitude 56oN but the fishing effort in these areas has fallen considerably in recent years. One of the most striking factors has been the increase in the landings of cod in the Firth of Clyde, as a by-catch in the trawl fishery for Nephrops. This has not been reflected in a reduction of fishing by Danish seiners so that higher total cod landings were recorded from this area in rg67 than in previous years.

Age composition

Although some market sampling had been carried out prior to 1967 at Scottish west coast

North Outer South S. of Firth Minch Hebrides Minch Lat. S6°N of Clyde

9-9I 2.S4 o.rs L79 - 0.06 - -

4-63 0.02 0.11 0.16 o.Ss r6.s3 0.06 LIS 0.03 IL26

rss 33 3 4s I - -

294 3 20 IS 6S 762 4 IS3 9 436

9,097 36 1,793 So S.376

6.4 S.6 s.o 3·7 - 6.0 L6 0.7 0.6 I. I L3 2.2 L5 0.6 0.3 2.6 0.2 0.2 0.1 o.o 0 ·?

ports for length and age data of the West Coast cod stocks exploited by British vessels, this was not comprehensive enough to allow any direct con­clusions to be drawn. In 1967, however, an extended programme of sampling was started at Aberdeen on catches of cod consigned from the west coast ports of Gairloch and Ullapool. The age compositions of the North Minch cod landings by motor trawler from the Butt of Lewis grounds and by light trawler from the northern Inner Hebrides grounds are shown in Table 32 and compared with that from the north coast of Scotland by motor trawlers. The rg64 year class dominated the landings from the North Minch by both fishing methods but

-g8-

Table 31. Cod landings- (nominal catches) and fishing effort by British vessels at all Scottish ports in 1967 from the north and west coasts of Scotland

North North Outer South S. of Firth Coast

Landings ('oo tons) Motor trawl ............................ 27.19 Steam trawl . . . . . . . . . . . . . . . . . . . . . . . . . . . O.Or Light trawl ............................. 0.46 Seine ................................. 5.82

Fishing Effort ('oo hours)

Motor trawl ............................ 433 Steam trawl ........................... I Light trawl ............................. 43 Seine ................................. 276 Seine (days' absence) .................... 3,738

Ladings per unit effort

Motor trawl (tons/roo hours) ............ 6.3 Steam trawl (tons/roo hours) ............ I.O Light trawl (tons/roo hours) . . . . . . . . . . . . r.r Sei:J.e (tonsfroo hours) . . . . . . . . . . . . 2.1

Sei:J.e (tons/days' absence) ............... 0.2

the rg65 year class was of above average strength on the north coast.

Tagging

A total of ro5 cod were tagged on the west coast in rg67. Recapture rates were about 20% which is similar to the results from previous years and is probably associated with the lower fishing effort compared with Scottish east coast inshore grounds.

D. F. S. RAITT, M. GROVES

Minch Hebrides Minch Lat. 56°N of Clyde

8.75 0.20 O.Or r.89 O.Or - -6.82 0.03 0.38 5-27

22.96 o.r6 I.63 o.r5 rl.94

r58 5 3 44 0.3 - - -50r 2 40 0.2 276 694 13 187 ro 557

8,r94 141 r,9I4 97 6,6II

5-5 4·0 0.3 4·3 3-3 1.4 I.5 I.O - I.9 3·3 1.2 0.9 I.5 2.!

0.3 O.r o.r 0.2 0.2

Table 32. Average of cod of each year class landed per 10 hours' fishing by British vessels in Scothnd in 1967

Year class

r966 .... . r965 .... . r964 .... . r963 .... . r962 .... . r96r .... . r96o .... . r959 and

North Minch North Coast Motor trawl Light trawl Motor trawl

Butt of Lewis Inner Hebrides

69.r r23.2 20.2

r6.3 II.9 4·2

1.3 !0.2

32.1 6.7 4-2 2.2

0.7

r6.4 r35·6 r25-5

6.0 9-2 7·9 o.6

Marine Laboratory, Victoria Road, Torry, Aberdeen, over .. 2.4

248.0 0.3

57·6

0.9

302.r Scotland. Total ...

Scottish investigations of the North Sea stock of cod in 1967

(Tables 33-35)

Commercial statistics

The landings, fishing effort and landings per unit effort by British seine net vessels fishing in the North Sea and landing their catches in Scotland are given in Table 33 by quarterly periods for the areas north of latitude 57°30'N, from latitude 55oN to 57o3o'N, the Moray Firth and for all areas combined. Highest catches and catching rates occurred north of 57°30'N and in the Yforay Firth in the first and second quarters of the year. In Table 34 the corresponding data for British Motor Trawlers are given. Highest catches and catching rates were again to the north of 57°30'N but were to be found more during the second and third quarters of the year.

Age composition

The age composition of the North Sea cod stock exploited by British trawlers and seiners in rg67 are given in Table 35· The areas designated are those used in reports to the ICES Statistical News Letters. The effect of the strong rg6r year class was greatly reduced and the numbers caught as six year olds in 1967 were fairly low. However, the rg65 year class has proved to have been well above average strength and this together with the good rg64 year class which was also well represented has kept landings and landings per unit effort figures high with the emphasis on the smaller categories of cod. Prospects for the rg66 year class appear average.

Tagging

A total of 322 cod were tagged in the area in rg67. Of these only 55 had been returned by

-gg- Gadoid Fish Cod

Table 33· Landings of cod by British seine net vessels at all Scottish ports from the North Sea in 1967

a) North of 57°30'N

Quarterly period Wt. landed Effort Wt.landed (roo tons) (roo hours per

fishing) roo hours

Jan.-March .... 35·8 957 3·7 April-June .... 34·6 969 3·6 July-Sept ...... 32.8 950 3·5 Oct.-Dec ....... 31.4 894 3·5 b) 55°N to 57°3oN Jan.-March .... 6.9 r86 3·7 April-June .... 14·7 428 3·4 July-Sept ...... II.7 403 2.9 Oct.-Dec ....... 10.2 353 2.9

c) Moray Firth Jan.-March .... 27·7 593 4·7 April-June .... I 2.1 310 3·9 July-Sept ...... 8.o 315 2.6 Oct.-Dec. .... 13·7 390 3·6 d) All areas Jan.-March .... 42·7 I,I43 3·7 April-June .... 49·3 1,397 3·5 July-Sept ...... 44·5 1,353 3·3 Oct.-Dec ....... 4!.6 1,247 3·3

Table 34· Landings (nominal catches) of cod by British motor trawlers at all Scottish ports from the North Sea in

1967

a) North of Lat. 57°3o'N

Wt. landed Effort Wt. landed Quarterly period (roo tons) (roo hours per

fishing) roo hours

Jan.-March .... 8.4 354 2.4 April-June .... 13.6 r68 8.r July-Sept ...... 22.6 371 6.r Oct.-Dec ....... 25.2 481 5·2

b) Lat. 55°N- 57°3o'N Jan.-March .... 5.6 II5 +9 April-June .... 12.0 191 6.3 July-Sept ...... I2.I 234 5·2 Oct.-Dec ....... II.2 239 4·7 c) All areas Jan.-March .... 14-0 469 3·6 April-June .... 25.6 359 7·2 July-Sept ...... 34·7 6os 5.6 Oct.-Dec ....... 36-4 720 s.o

February rg68 but recent tagging experiments have been confined to offshore areas and to larger cod and the return rates from this type of experi­ment have always been rather lower than from those based on young fish in inshore areas where there is a relatively higher fishing effort.

D. F. S. RAITT, M. GROVES

Marine Laboratory, Victoria Road, Torry, Aberdeen, Scotland.

German investigations on cod in the western Baltic 1967

(Figure 132; Table 36)

The cod stock of the Kiel Bay was surveyed by means of quantitative fishing with a standard trawl on seven places (Fig. 132). Each haul normally lasted r hour. The effort can be seen from Table 36.

The landings of the German cod fishery in the western Baltic amounted to nearly g,200 tons. If the proportion of cod in the by-catch is included, a yield of about g,soo tons was obtained in rg67.

This is about 20% more than the yield in rg66. The increase is at least partly due to improved stock condition. The catch per hour trawling with the standard trawl rose from 172 cod in rg66 to 215 cod as an average for rg67. A fairly good recruitment of the rg66 year class, being slightly better than the rg65 year class, is responsible for this increase.

The length composition of the quantitative catches shows two maxima which represent two subsequent age-groups. The year class rg66 was first recorded in July rg66. It was fully recruited about November rg66. During its second year of life it made up for more than So% of the total catch in number. The rg66 year class was followed by the rg65 year class, which caused the second maximum until May rg67 but was nearly exhausted thereafter. Cod older than 2 years were very rare in the catches and fish of an age of more than 5

Table 35· Numbers of cod of each year class landed per 10 hours fishing by British trawlers and seine ·net vessels in Scotland during 1967

Trawl Seine North Northern East and North Northern East and Moray

Year class Central Orkney Central Orkney Firth

1966 ........................ 2.8 78·4 82.5 43·2 9·4 49·4 3·2 1965 ........................ 396.8 I IO.I 268.9 213.8 !60.9 r8o.8 121.8 1964 ........................ 56·7 88.0 85.7 67.8 67·4 ss.6 107·3 I963 ........................ 28.3 13·4 rs.s 25-4 8.7 s.8 II.8 1962 ........................ 3·5 15·7 8.3 10.3 ro.s 2.9 7·3 1961 ........................ 2.8 6.3 9.2 5·3 3·5 I.7 2.5 1960 ........................ 2.8 1.4 1.9 2.3 0.9 0.6 0.6 1959 and over ................ 2.8 I. I I.5 2.7 1.2 o.s 0.4

Total •••••••••••••••• 0 •••••• 496·4 243·8 473·5 37°·7 262.5 297·3 254·9

-roo-

10m ~----·-15m

!-----20m

100 10°30' 11°

so

_/:}/ 20"

Figure 132: Fishing places of the Kiel Bay, the area 8 is very seldom visited.

Table 36. Length distribution and age composition of catches of cod, number per r hour hauls with the standard

trawl, Kiel Bay, 1967

Length March May July Sept. Nov. em

4- 5 ..... 0.3 1.9 6-10 ..... 27·7 8.3 1-4 8.8 0.3

11-15 ..... 85.8 II9.1 171.8 25.0 3·0 16-20 ..... 36.1 73·7 160.2 75.1 8.9 21-25 ..... 20.8 16.3 26.8 23-3 27-3 26-·30 ..... 25-3 13-5 6.0 4-2 13.0 31-35· .... 7-9 14-3 5-2 1.4 6.2 36-40 ..... 7-1 5·8 4·0 1.2 6-4 41-45· .... 8.3 4.1 2.8 o.8 3·9 46-5o ..... j.2 2.5 1.3 0.4 0.9 51-55····· 3.1 o.8 0.7 0-4 0.3 56-60 ..... 1.5 0.2 0-4 0.1 0.1 61-65 ..... 0.6 0.1 0.1 66-70 ..... 0.1 0.2 71-75· .... - - 0.1 76-8o ..... 81-85 ..... 0.1

years were practically not present. There is evidence that this phenomenon has partly been brought about by the fishery itself. A minimum size of 30 em and a mesh size of 30 mm (between knot

Year class March May July Sept. Nov.

1967 .... 0 .. - 0.6 10.7 2.3 1966 ....... 152-4 217-3 361.9 127.6 52.2 1965 ....... 48.8 31.9 14-4 3·3 12.6 1964 ....... 15.6 6.8 2.8 0.6 2.8 1963 ....... 9·8 2.2 1.1 0.3 0-4 1962 ....... 2.7 o.s 0.2 0.1 0.1 196r. ...... 0.1 0.2 0.1 1960 ....... 0.1

Total ..... 229-5 258.9 381.1 142.6 70-4 Investigated 4,092 4,198 6,301 2,029 1,291

Hours trawling . 18 16 17 14 18

and knot) is introduced by order of the territory of Schleswig-Holstein. But a by-catch of under­sized cod of 1/ 3 of the total catch in weight may be landed. Unfortunately the mesh size in action corresponds to a so% retention length of only about 20 em, so that a considerable number of

-IOI- Gadoid Fish Cod

juvenile cod is wasted. But it is hoped that the discrepancy between minimum size and mesh size will be abandoned in the near future.

F. THUROW

Bundesforschung~anstalt fur Fischerei, Institut fur Kusten- und Binnenfischerei,

Labor Kiel, Kiel-Seefischmarkt, Germany.

Polish cod investigations in the southern Baltic in the years 1966 and 1967

(Tables 37-40)

The results of cod catches were the same in rg66 and rg6J, amounting to s6,ooo tons per year, which means an increase by 25.9% in com­parison with the results in rg65 (41,500 tons). The mean fishing yield per day for various types of vessels, obtained in the above three years, is given in Table 37·

The increase in the yield in the recent years is noticeable, particularly the results obtained by the 24 m cutters.

The length composition of the catches in rg66 and rg67 is given in Table 38. Cod in the length­groups 30-45 em predominated, as was also the case in rg65, but in the eastern region of the Baltic there was in rg67 a considerably greater percentage of fish in the length-groups 33-35 and 36-38 em than in previous years. The pre­dominance of these two groups lead to a decrease in the mean length of the fish caught in 1967.

The age composition of the catches is given in Table 39· Age-group III was predominant in both regions and made up a considerably higher percentage in rg67, especially on the fishing grounds of the eastern region. This shows the occur-

Table 37· Comparative data for mean daily fishing yield in kg per cutter-day

Type of vessel Fishing Yield in g~ar 1965 1966 1967

Cutter 17m bottom trawl 532 916 763 Cutter 24m bottom trawl 986 1213 1385

Table 38. Length composition of cod catches in the southern Baltic in the years 1966 and 1967 (in %)

Length-groups in em

21-23 ............. 24-26 ............. 27-29 ............. 30-32 .............

33-35- ............ 36-38 ............. 39-41 ............. 42-44· ............

45··-47 ..... - ....... 48-so ............. 51-53- ............ 54-56- ............

57-59- ............ 60-62 ............. 63-65 ............. 66-68 .............

69-71. ............ 72-74· ............ 75-77· ............ 78-So .............

Above So . . . . . . . . . Mean length .......

Number of fish .....

Eastern regi0n 1966 1967

0.1 0.5 2.7 I.O

10-4 8.5

14-5 21.3 15-9 23.6 16.1 18.o 13-3 II.8

9-2 6.6 s.s 4·0 3-7 1.9 2.9 0.8

1.7 0.6 !.2 o.s 0.7 0.3 0.5 0.2

0.3 0.1 0.2 0.1 0.1 0.1 0.1 0.1

0.1 o.s 4o.o em 38.8 em

14,158 12,763

Western region 1966 1967

0.2 0.1 3-9 3-0

12-4 11.9

15-9 17-4 16.8 19-3 14-7 16-4 11.8 11.6

8.9 8.4 5-9 4·7 3-5 2.9 2.2 r.S

1.4 1.1 0.8 o.S 0.5 0.5 0.2 0.2

0.2 0.2

0.1 0.2

0.1 0.1 0.1 0.1

0-4 0.3

39-9Cm 39.6 em

25,607 25,235

renee in the catches of an exceptionally abundant year class, born in rg64. The trend in the compo­sition of the catches in rg66 was very similar to that in rg65, except for age-group II, the partici­pation of which was very high in the western region as compared with other years.

Table 39· Age composition of cod catches in the southern Baltic in the years 1966 and 1967 (in %J Age-group

Region Year I II III IV v VI VII VIII IX X

Eastern ...... 1966 0.2 16.3 49-9 20.9 9-3 2-4 0.9 0.1 1967 !2.2 65.s 17.2 3-3 0.7 0.2 0-4 0.1 0.1

Western ...... 1966 0.1 17.2 51.3 20.9 7-9 I.8 0.3 0-4 0.1 1967 15.8 56.6 19-3 6.o I.6 0.5 0.1

Table 40. Percentage of cod in the catches in maturity stage VI and VII in particular months of 1966 and 1967

Month Region Year I II III IV v VI VII VIII IX X XI XII

Eastern ..... 1966 0.3 6.9 18.3 21.6 15.6 2.0 I.O 7-0 1967 3-0 I.5 38.5 28.0 32-7 2.0 - 0.3

Western ..... 1966 2.7 4·0 15-3 18.3 29.0 2.0 - 0.3 - 0.5 1967 11.0 15-7 26.0 18.5 30-5 64·5 -- - 3-5

-102-

The course of spawning is shown in Table 40. The data show that the percentage of spawning fish in the season of rg67 was higher than in rg66. In the eastern region, the climax of the spawning was observed in May, while in the western region it was noted in June in rg66 and in July in rg67.

The climax of the spawning in the eastern region usually takes place in earlier months than in the western region and only sporadically in the same months in both regions.

M. KOSIOR

Sea Fisheries Institute, Aleja Zjednoczenia I, Gdynia, Poland.

HADDOCK

Soviet investigations on young haddock of the 0, I, II and III age-groups in the Barents

Sea (Tables 4I-44)

Determination of the abundance of young haddock in the autumn-winter of rg66jrg67 was carried out during two cruises of the R. V. "Tunets" and in one trip of the scouting trawler "Nikopol". In the north-western areas of the Barents Sea investigations on young haddock were conducted from September to December rg66, in the southern part of the Sea from November rg66 to February rg67. A 25 m bottom trawl was used. A ro mm mesh (knot-to-knot) capron net was inserted into the cod-end.

The southern Barents Sea (Subarea I)

The total abundance of young haddock in rg66 to rg67 was approximately on the level of rg65 to rg66 (Table 41). The rg64 year class was of the greatest importance in the catches (Table 42),

constituting 6g% of the total catch. The average catch of young haddock of this year class per I hour trawling amounted to I5 specimens against r2 in rg65-rg66, but the increase in the average catch of the rg64 year class was observed only in the coastal regions.

Young haddock of the rg63 year class, 36 em in length, occurred in all investigated areas, but the average catch per trawling hour, compared with rg65-rg66, decreased to almost one half. This reduction in the catches of the rg63 year class may be due to the fact that this year class in the period under investigation was more than 35 em in length and therefore was not registered quantita­tively.

Only one fish per trawling hour was found of the rg65 year class, and fingerlings (the rg66 year class) were absent in the catches.

A comparison between the data from rg66-rg67 and those obtained in previous years (Table 43) shows:

Table 41. Average catches (in numbers) of young haddock up to 30 em in length taken per trawling hour in the southern Barents Sea

I96I-I962 I962-I963 I963-I964 I964-I965 I965-I966 I966-I967 Number Number Number Number Number Number of of of of of of of of of of of of

trawl- fish trawl- fish trawl- fish trawl- fish trawl- fish trawl- fish Areas ings ings ings ings ings ings

Central ............ III 102 I 53 IIO I09 I9 Io6 II 93 2 98 3 Western ........... I32 79 70 73 84 95 87 36 63 38 73 I9 Coastal ............ 26 273 26 569 28 249 29 So 23 79 24 II4 Total ............. 269 - 249 221 - 222 - I79 - I95 Averages .......... - I07 - I48 77 30 - 25 - 23 Eastern ........... 42 IS 62 38 33 34 36 I5 29 - 37 North-eastern ...... 42 <I 38 - II - IO I4 - 9 Central Elevation ... 67 5 5 - I4 I 27 <I 34 <I r6

-103- Gadoid Fish Haddock

Table 42. Average catches of young haddock (in numbers) of different year classes taken per trawling hour in the southern Barents Sea in the autumn-winter 1966/1967

Age and year class Number of o + (r)

rg66 I+ (2) 2 + (3) 3 + (4)

1963 Total of

Areas Months trawlings

Central ............ XI-I g8

Western ........... XI-II 73 Coastal ............ XI-II 24 <r

Total ............. 195 Average of the

absolute number .. <I Eastern ........... XI-I 37 North-eastern ...... XI-XII 9 Central Elevation ... X--II I6

Table 43· Average catches of young haddock (in numbers) of different year classes in their 1-4 years of life in western, central and coastal areas of the sea in the autumn-

winter

Mean number Year Years of life of 2-3 year

I 2 3 4 olds

1957 ....... 38 9 I4 2 I2 1958 ....... 2 4 5 2 4 1959· ...... 7 I4 33 2I 25 Ig6o ....... 30 40 72 24 56 rg6r. ...... 32 50 34 6 42 1962 ....... 5 3 4 I 3 I963 ....... I6 9 I2 7 IO I964 ....... II I2 I5 - I4 1965 ....... <I <I rg66 ....... <I

I965 I964

2

<I I2 8I

<r 15

7 32

7

Total the young

3 288

I9 1,393 II4 2,734

4,4I5

23

r. The rg64 year class at the end of its second and third years of life can be estimated as of medium strength.

z. It is confirmed that the rg66 and rg65 year classes are poor ones.

The Bear Island-Spitsbergen area (Subdivision lib) Young haddock were very scarce in the north­

western areas of the Barents Sea. All the twenty­nine specimens caught belonged to the rg64 and rg63 year classes. Haddock of the rg66 and rg65 year classes were not observed in the catches (Table 44).

Z. P. BARANOVA

The Polar Research Institute of Marine Fisheries and Oceanography (PINRO), 6 Knipovich Street, Murmansk,

USSR.

Table 44· Average catches of young haddock (in numbers) of different year classes per trawling hour in the Bear Island­Spitsbergen area in the autumn-winter 1966/1967

Areas

Bear Island Bank Southern slope .... . Eastern slope ..... . Western slope ..... .

Total ............ .

Average .......... .

West Spitsbergen area South Cape Deep .. . Hopen area ....... . Perseus Elevation .. Western Deep ..... . Kopytov area ..... .

Total all over the areas

Average .......... .

Months

X-XII XI X-XII

IX-XI X-XI X-XI X-XII X-XI

XI-II

Number of hauls

19 7

33

59

52 r6 25

7 I6 6

r8r

o + (r) Ig66

Age and year class I+ (2) 2 + (3)

1965 1964

<I

<I

<r

<r

3 + (4) 1963

<r

<r

Total

<I

<I

<I

Total young ones

28

28

I

29

-104-

The length-age composition and growth rate of the Arcto-Norwegian haddock

(Figures 133-134; Tables 45-46)

In 1967 a comparatively great by-catch (by number of specimens) in the southern Barents Sea consisted of fish from the average to abundant 1963 and 1964 year classes of haddock.

However, a considerable portion of the catch included haddock of the 1960-1962 year classes at an age of 5-7 years. Reckoned by weight, these year classes apparently prevailed (Figure 133).

From 1964 to 1967 the peak of the size-frequency curve was gradually displaced to the right. In 1964 the main bulk of the haddock were 30-45 em long whereas in 1967 they were from 35 to 55 em.

Immature haddock usually remain in the southern Barents Sea. After spawning mature fishes move back to the Barents Sea in small numbers only. In April/August 1958 to 1965 haddock returning to the southern Barents Sea after spawning made up on an average 2.8% of all the fish investigated.

Maturation of the Arcto-Norwegian haddock depends upon length and not upon the age. In the fifties and sixties the average length at maturation of fast-ripening specimens was 42.5-47.0 em, usually however, they mature when they are more than 50 em long.

The length-age composition of the stock of haddock in the southern Barents Sea depends greatly upon the growth and maturation rates. The slower the growth and maturation rates, the longer the haddock will remain in the southern Barents Sea, and the greater the number of older fishes in the stock. For instance, low linear growth (and weight growth) rates were observed in haddock of the 1950 year class (Tables 45 and 46); and the bulk of this haddock ripened at an age of 6-9 years and remained until then in the Barents Sea.

In recent years the fastest growth rate was observed in haddock of the 1956 and 1957 year classes. As Tables 45 and 46 show, the average length and weight of haddock of these year classes were considerably greater as compared with haddock of

Table 45· Average length in ern of haddock of some year classes at different age

Year Age classes 3 4 5 6 7 8 9

1956 ... 37.1 42·3 51.0 57·5 6o.o 69-4 76.6 1957 ... 37·8 45·5 5I.O 55·5 64-4 69·5 ]2.2 1960 ... 35·0 38·7 44·0 49.1 56.3 - -1961. .. 34-1 4°·7 45·8 53·8 - - -1950 ... 33·0 40.0 43·0 48.0 52-4 58.8 64·7

!Y,

20

10

%

1964 n- f2'r519

\ 0 11-'·--'-................ ~---196!5

10

2~1 _./ :/'-.:--..........____-=,~-

!0

2~ I .-/' ,-... ___ .......___--==,__-10

0 I , ~- , - -- ..... _ ... _ 3 4 S B 7 8 age

Figure 133. Length and age composition of haddock in the southern Barents Sea in 1964-1967.

the 1950 year class at the same age. Thus, according to average length and weight, 5 year old fishes of the 1956 and 1957 year classes resembled 7 year olds of the 1950 year class. Fishes at an age of 6 years of the 1956 year class resembled 8 year olds by length, and 7 year olds of the 1957 year class corresponded to haddock at an age of 9 years of the 1950 year class. Consequently, fishes of the 1950 year class were charcterized by a slower growth rate than those of the 1956 and 1957 year classes, therefore, they matured later and stayed in the southern Barents Sea for a longer period. Haddock of the 1950 year class were observed in great numbers in the southern Barents Sea even at an age of 9 years, while fishes of the 1956 and 1957 year classes stayed there only until they were 7 years old, i. e. the haddock of the 1950 year class remained in the above mentioned part of the sea on an average two years longer than those of the 1956 and 1957 year classes.

Comparatively low linear and weight growth rates are observed in haddock of the 1960 and 1961 year classes. Average length and weight of fishes of these year classes at different ages are somewhat greater than in specimens of the 1950 year class, but considerably lower than in those from 1956 and 1957. Consequently, haddocks of the 1960 year class matured in great numbers during their sixth

Table 46. Average weight in kg of haddock of some year classes at different age

Year ~t\ge

classes 3 4 5 6 7 8 9

1956 ... o.59 o.8o I.38 I.84 2.09 3.01 4-46 1957 · · · 0.57 !.02 1.34 I.63 2.57 3.66 4-17 1960 ... 0-44 0.56 0.86 I.2I I.87 1961 ... 0 39 0.68 I.OO I.64 1950 ... 0.33 0.62 0.77 I.03 I.32 2.00 2 ·77

-ros- Gadoid Fish

%

20

10

0

10

0 20

10

0 20

iO

0 20 30

1965

1966 n-597

1967 n.-1072

80 sm 3 4 S 5 7 8 9 aie

Figure I34· Length and age composition of haddock off the north-western coast of Norway in the first half of 1964 to

1967.

and seventh years of life and stayed in the Barents Sea for 8 years, i. e. one year longer than fishes of the 1956 and 1957 year classes. The growth rate of haddock of the 1961 year class during its sixth year of life increased sharply. However, at the age of 7 years they will still be present in the catches.

In samples obtained in the first half of the years 1964 to 1967 off the north-western coast of Norway, haddock of zo-8o em in length and at an age of 3-II years were observed. In 1964 the catches mainly consisted of large fish of the 1956 to 1959 year classes and they were at a length of 50-75 em (Figure 134). In 1965 to 1967, however, the peak of the size curve of the haddock was markedly displaced to the left, and fishes of 40-60 em in length dominated in the samples. In age samples taken in 1966 and 1967 the number of 4 year olds increased, while the number of 8 year olds decreased as compared with 1964. According to data collected on board the R. V. "Turrets" in the first half of 1966 near the north-western coast of Norway, great quantities of immature haddock were met with, which evidently migrated to this area due to the strong cooling of the Barents Sea.

M.A. SoNINA

The Polar Research Institute of Marine Fisheries and Oceanography (PINRO), 6 Knipovich Street, Murm,1nsk,

USSR.

Scottish investigations on the Faroe stock of haddock in 1967

(Tables 47-49)

Commercial statistics

Haddock landings in Scotland during each month of 1967 are shown in Table 47· The mean catch per roo hours fishing was 153 cwt, the comparable value for 1966 being 169 cwt. Note that in this volume, statistics have been given for the whole

Haddock

Table 47· Landings (nominal catches) and landings per unit effort of three market size categories of haddock by British motor trawlers at all Scottish port from the

Faroes - 1967

Hours Cwt per roo hours fishing Month fishing Large Medium Small Total

January . . . 2,682 February . . 3,962 March . . . . . 6,993

April . . . . . . 6,699 May ...... 3,525 June . . . . . . 5,139

July ...... 6,198 August . . . . 6,786 September . 3,519

October . . . 3.465 November. . 2,613 December . 1,302

Total Mean 52,883

Annual

40.6 35-4 37·7 26.8 24-6 20.9

17-4 46.6 33·3 26.1 19·3 31.1

30-4

47·6 47·0 59-3

56.8 43·1 83.0

75·3 121-4

72.1

29-4 22.8 26.r

64.8

62.3 41.8 44·5 84-2 56.8 42·3

42·9 79.6 6r.8

58-4 48.o 65·7

57·9

150.5 124.2

141.5 167.8 124·5 146.2

135·6 247·6 167.2

113·9 go.1

122.9

153·1

Landings (cwt) .... 16,092 34,273 30,625 80,990

of Scotland instead of only for Aberdeen. For comparison the 1966 and 1967 catches per roo hours fishing by Aberdeen trawlers were 159 and 144 cwt respectively.

Age composition

The age composition of the haddock sampled on Aberdeen market, are given in Table 48. These are expressed as landings per ro hours fishing by all British trawlers landing in Scotland.

Length composition

The mean lengths of the haddock sampled are shown in Table 49·

Tagging

During 1967 a total of r,679 haddock were tagged from a Faroese line boat. By the end of the year 33 of these had been returned.

R. JONES, A. S. jERMYN

Marine Laboratory, Victoria Road, Torry, Aberdeen, Scotland.

Scottish investigations of the west coast stock of haddock in 1967

(Table so)

Commercial statistics

The landings of haddock by Scottish vessels fishing to the west of Orkney are shown in Table so.

-ro6-

Table 48. Aberdeen Trawlers' market samples - Faroese haddock - 1967

a) Estimated numbers landed per ro hours fishing by British trawlers landing in Scotland

Year class Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sept. Oct. Nov. Dec.

1966 ........ - - - - 2I.I 5.2 73·6 II 5-5 1965 ........ 2.2 20.7 I.4 2.3 20.0 341.3 634·5 243·6 522.9 398.8 335·2 286.2 1964 ........ 107·5 8r.o 70·9 188.3 82.8 364.0 241.6 367·7 91.0 175·0 63.6 163·7 1963 ........ 186.1 103·9 258.6 356·4 172.1 18o.o 60.2 230.6 154·6 67·3 52·7 83.0 1962 ........ 222.2 187.2 203·4 258.1 16r.o 144·4 145·4 278.0 130.6 69·3 49·3 65.2 1961 ........ 162.1 151.5 171.5 131.0 168.0 8r.6 86. 5 164·7 96.o 43·9 23.1 43·2 1960 ........ 45·6 57·6 13·4 46.6 32·9 35·8 5·8 64.0 19.6 II.8 13·5 9·3 1959 ........ 2.6 25.6 12.6 25-5 q.o 6.6 8.5 18.8 17.6 8.4 2.7 15.4 1958 ........ 4·8 4·3 2.7 9-4 8.3 I.4 0.4 17.1 0.8 0-4 !.2 3·0 1957 and older I.1 0.2 0-4 2.2 7·9 0.5 0.04 I.1 0.1 0.03 0.07 0.5 Total ....... 734·2 632.0 734·9 1,019.8 667.0 1,155.6 1,182.9 1,385.6 1,054·3 780.1 615.0 785.0

b) Estimated*) weights landed per 10 hours fishing (cwt) by British trawlers landing in Scotland Year class Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sept. Oct. Nov. Dec.

1966 ............ - - - - - 0.08 0.02 0-47 0.54 1965 ............ O.OI 0.13 O.OI O.OI 0.13 2.03 3·91 I.6I 4·24 3.08 3·29 2-42 1964 .......... · · 0.99 0.84 0.72 1.96 0.79 3.80 2.73 4-50 1.34 2.50 0.97 2.53 1963 · · · · · · · · ·. · · 2.62 I.38 3.8r 4·95 2.46 2.73 I.OO 3·85 2.79 I.20 I.I3 I.63 1962 ............ 4.11 3·57 3.8r 4.86 3·13 2.8r 2.86 5-70 2.89 I. 57 I.I7 I.69 1961 ............ 4-14 3·64 4·14 3.16 3·92 1.94 2.08 4-40 2.58 1.33 0.71 I.27 1960 ............ I.36 1.51 0.45 1.20 0.91 o.82 0.19 I.84 o.6o 0.38 0-47 0.34 1959 ............ 0.11 0.90 0.44 o.85 0.58 0.22 0.27 0 ·74 0.53 0.34 0.13 0.57 1958 ............ 0.19 0.17 0.14 0.31 0.36 0.05 0.02 0.59 0.04 0.02 0.06 0.13 1957 and older ... 0.06 0.01 0.02 0.10 0-44 0.02 N 0.06 N N N 0.03 Total ........... 13.59 12.15 13·54 17.40 12.72 14-42 13.06 23.29 15.09 10-44 8-40 1I.I5 Wt. landed per

ro hours fishing 15.05 12-42 14.14 16.79 12.45 14.63 13·55 24-76 r6.7r I 1.39 9.01 12.30

*) Using data from RussELL, E. S., 1914- Fish. Invest. Lond., Ser. 2, r (r). N = Negligible

Table 49· Mean Lengths (em) of each haddock age group sampled from Aberdeen trawlers

Year class Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sept. Oct. Nov. Dec.

1966 ............ - - - - - 29.5 30.1 34·5 3I.I 1965 ............ 31·5 34-4 33·2 33·5 34·4 33·7 34.1 34·9 37·3 36·7 39·7 37·8 1964 ............ 38·9 40-4 40.2 40·5 39·3 40·5 41.6 42·7 45·4 44·9 45·9 46.r 1963 .......... · · 44·7 43·8 45·4 44·5 44·9 45·8 47·3 47·3 48·5 48·3 5I.3 49·9 1962 ............ 48·9 49-4 49.1 49·2 49·7 49·7 49·9 50.6 51.9 52.3 53·1 54·7 1961 ............ 54-4 53·3 53·4 53·4 52.8 53·1 53·3 55·2 55·3 57·5 57·9 56.9 1960 ............ 57·2 54·8 59·6 54·5 55.8 52·4 59·2 56.5 57·8 59·0 60.3 6I.4 1959 ............ 64.0 60.4 60.4 59·3 63·7 59.6 58.8 62.6 57·4 63·3 66.2 6I.4 1958 ............ 62.2 63.0 64.0 59·2 64·7 59·9 66.7 6o.o 69.2 73·1 69-4 64.2 1957 and older ... 68.1 72.8 70.6 66.0 70·3 66.5 73·5 7I.O 65.5 82.5 74·5 69.7

Age and length composition

One routine survey of West Coast grounds was made by F. R. S. "Explorer" in January rg67. The data from this cruise were published in the previous volume of Annales Biologiques.

tagged off the Scottish north and west coasts. By the end of the year, 68 of these had been returned.

Tagging

During rg67 a total of 1,132 haddock were

R. JONES and A. S. jERMYN

Marine Laboratory, Victoria Road, Torry, Aberdeen, Scotland.

-!07- Gadoid Fish Haddock

Table 50. Haddock landings (nominal catches) and fishing effort by British vessels at all Scottish ports in 1967 from the north and west coast of Scotland

North Coast

North Minch

Outer Hebrides

South Minch

South of Lat. 56°N

Firth of Clyde

Landings ('oo tons)

Motor Trawl .................. . Light Trawl ................... . Seine ....................... .

Fishing Effort ('oo tons)

Motor Trawl .................. . Ligth Trawl ................... . Seine ......................... .

Landings per Unit Effort

Motor Trawl (tonsj1oo hrs) Light Trawl (tonsj1oo hrs) Seine (tonsjwo hrs) ............ .

6o.o 0.8

16.1

433 43

276

13.8 2.0

s.8

20.5 1.4

35-03)

158 501 6943)

12.9 0.3 s.o3)

o.9 1) 0.034) 1.3 2)

61) 94)

132)

16.41) 0.34) 9-72)

0-4 0.1 7-0

3 40

187

15.8 0.3 3·7

6.75) 0

0.86)

465)

0.2

1o6)

14-75) 0

8.26)

I.8 8.2

276 557

o.6 1.5

1) Includes 18TT, 2) Includes 15SS, 14TT, 3) Includes 18XX, 4) Includes 18SS, r8TT, r6VV, 5) Includes 8TT, 6) Includes 8SS

Scottish investigations of the North Sea stock of haddock in 1967

(Tables 51-54)

Commercial statistics

Landings of haddock by motor trawlers fishing in the North Sea in rg66 and rg67 are shown in Table 51. North of latitude 57°3o'N, the landings per unit effort were higher in rg67 than in rg66 in the first quarter of the year. In the remaining three quarters they were lower. Between latitude 55oN and 57o3o'N, landings per unit effort were lower in the first quarter and higher in the last three quarters of the year.

Age composition

The age compositions of the haddock caught by F. R. S. "Scotia" in the North Sea are shown in Table 52. The rg6z year class was still well represented in the catches, and especially so in the northern area. The rg63-r965 year classes were poorly represented but the rg66 year class was strongly represented in all but the northern area. This appears to be about a quarter of the strength of the rg6z year class, but even so, it can be classed as very strong.

Table 5r. Landings (nominal catches) of haddock by British motor trawlers at all Scottish ports from the North

Sea in 1966 and 1967

Quarterly Period Year

Wt. landed ('oo tons)

a) North of Lat. 57°30'N

Jan.-March 1966 1967

April-June 1966 1967

July-Sept. 1966 1967

Oct.-Dec. 1966 1967

44·3 90-3 22.!

22.3

34·6 49·7

Il3.6 s6.o

b) Lat. 55°N to Lat. 57°3o'N

Jan.-March 1966 5.6

April-June

July-Sept.

Oct.-Dec.

c) All Areas

Jan.-March

April-June

1967 3-9 1966 1967 1966 1967 1966 1967

9-4 9-3

21.6 22.5

17.6 20.3

49·8 94-2

Wt. landed Effort tons per

('oo hrs) roo hrs

228

354 155 r68

222

371 481 481

140 IIS 233 191

259 234 22!

239

19·4 25-5

14·3 13-3 rs.6 13-4 23.6 II.6

4·0 3-4 4-0 4·9 8.3 9.6 S.o 8.s

13-5 20.!

S.r 8.8

Length composition July-Sept.

1966 1967 1966 1967 1966 1967 1966 1967

31.5 31.6

56.2 72.2

368 469 388 359 481 6os

II.7 11.9

The mean lengths of the haddock caught by Oct.-Dec. F.R.S. "Scotia" are shown in Table 53. Compari-

131.2 76·3

702 720

r8.7 10.6

-ro8-

Table 52. Numbers of haddock caught per IO hrs fishing by F. R. S. "Scotia" in the North Sea in I967

Area Northern North Central Central Moray Firth and Orkney Cruise June March/ June All June March/ June All

April cruises April cruises

Number of hauls ....... 7 7 I8 25 2 9 6 IS Year class Weighted

mean

I966 ................... 640 3,248 I,024 I,647 5.745 4.375 2,587 3,66o I 965 ................... 44 7 I3 II I30 !28 I7 84 I964··················· I4 I 3 2 - 9 2 6 I963·· ................. 6 I I 2 5 3 I962 ................... 475 I3 72 55 45 221 30 145 I96I and older . . . . . . . . . 3 I I 2

Table 53· Mean lengths (em) of haddock of each age group from the North Sea in I967

Northern

Year class Cruise Mean No. of length fish

I966 ....... March/April -June 22.0 448

I965 ....... March/April -June 34.I 3I

I964 ....... March/April June 35-9 IO

I963 ....... March/April -June 44·9 4

I96'z ...... · March/April -June 39·4 333

North Central

Mean No. of length fish

I7·4 2,274 21.2 I,843

32-9 5 33·0 23

39·5 37·8 5

0 34·5 I

46.2 9 42·3 130

Central

Mean length

No. of fish

22-4 I,J49

34·5 26

0

0

46·4 9

Moray Firth and Orkn:ov

Mean No. of length fish

I9.8 3,938 22.5 I,552

JI.8 II6 32.8 IO

34·6 8 35-5

33-5 2 35-5 2

37-3 I99 41.2 IS

Table 54· Mean lengths of five recent year classes in the summer of each sampling year, compared with the mean lengths of other year classes, also sampled in the summer during I950-62

Area Northern North Central

I962 I963 I964 1965 I966 I962 I963 I964 I965 I966 Year Year Year Year Year Years Year Year Year Year Year Years

Age*) class class class class class I950-62 class class class class class I950-62

I+ .... I9-9 - 20.0 24.0 22.0 21.4 I9.6 20.1 25.1 21.2 2I.9 2+ .... - - 31.2 34-I - 28.7 - 33-2 33·0 - 29.3 3+· ... 33-0 35-9 33·2 33·9 40·3 37·8 - - 34·5 4+·· .. 37·0 44·9 - 36-s 39·5 34·5 - - 38·4 5+· ... 39-4 - 39·7 42·3 - - 41.9

Area Central Moray Firth and Orkney

I962 I963 I964 I965 I966 I962 I963 I964 I965 I966 Year Year Year Year Year Years Year Year Year Year Year Years

Age class class class class class I950-62 class class class class class I950-62

I+ .... 22.5 - 22.4 22. I I9-7 - 26.6 22.8 22.8 2+ .... - 34·5 - 29-9 - - 35-9 32.8 - 3I.I 3+· ... 33.I - - 36.I - 35·5 - - 37.6 4+· ... - 40.0 36·3 35·5 - - - 42-9 s+ .... 46·4 - - 44-4 41.2 - - - 48-4

*) For the purpose of this table, April Ist has been retain~d as the birthday of a haddock.

sons of the mean lengths of recent year classes with the average lengths of haddock sampled from 1950 to 1962 are shown in Table 54· Only in the Moray Firth and Orkney areas is the 1962 year class still below average size. Elsewhere it is close to the average for each area.

Tagging

During 1967 a total of 1,726 haddock were tagged. By the end of the year 99 of these had been returned.

R. JoNES and A. S. jERMYN

Marine Laboratory, Victoria Road, Torry, Aberdeen, Scotland.

"------

-rog- Gadoid Fish Haddock

Table 55· Numbers of haddock caught per hour fishing (17.7 m Trawl) by F. R. V. "Okhta" in the North Sea in May 1967')

Year class Northern North-central Central All regions (Weighted mean)2) No. of fish % No. of fish % No. of fish % No. of fish %

I966 ..................... . I965 ..................... . I964 ..................... . I963 ..................... . I962 ..................... . I961 ..................... .

and older

55 28.2 250 62.3 220 98.5 I92 69.I 4 2.I I 0.2 I 0.5 2 0.7 2 I.O I 0.2 - I 0-4

29 14-9 I 0.2 - 7 2.5 I03 52.8 Io8 26.9 I 0.5 6I 2I.9

2 I.O 4I 10.2 I o.s I5 5-4

All ages .................. . I95 IOO.O 402 IOO.O 223 IOO.O 278 IOO.O

Hours trawling ............ . 21/2 41/4 5 rr3f4

') Hours of trawling and mean number of specimens per I hour trawling are given only for catches, in which length measurements and age determinations of haddock were made.

2) The results were weighted in accordance with the area of the regions.

Soviet investigations on the North Sea stock of haddock in 1967

(Tables 55-58)

Methods Soviet investigations on the North Sea stock of

haddock were undertaken in rg67. Trawl surveys were carried out by AtlantNIRO fishery research vessels during the second and third quarters of the year (by the SRT-R gorg, "Okhta", and SRT-M 1257 "Langust" respectively).

The North Sea was divided in regions similar to those used by Scottish investigators ("Annales biologiques" 20:135, Figure rg). Trawl hauls of half an hour's-duration were carried out in these regions by squares (zr d, zr e, etc.). The speed during trawling, with due regard to interaction of wind and drift, was 3·5 knots. Each square was pre­liminary searched by hydro-acoustic means. Within each square the hauls were made where the most dense fish concentrations were observed. Where hydro-acoustic readings were lacking, the hauls were made in the centre of a square. The cod end

Table 56. Numbers of haddock caught per hour fishing (32.05 m Trawl) by F. R. V. "Okhta" in the North Sea

in June 19673)

Year class

Ig66 .... I965 .... I964 .... I963 .... I962 .... 1961 and older

All ages Hrs. trawling

Northern

No. of % fish

257 28.I 4 0.4

I3 I.5 3I2 34.1 326 35·6

3 0.3

9I5 IOO.O

93/4

North-central

No. of % fish

2,68o 99-0 5 0.2

4 O.I 4 0.1

l4 o.s

2 0.1

2,709 100.0

83/4

All regions (Weighted

mean) 4)

No. of % fish

I,7IO 85.9 5 0.2

8 0.4 I27 6.4 139 7-0

2 O.I

I,991 100.0

181/2

3) Hours of trawling and mean number of specimens per I trawling hour are given only for catches, in which length measurements and age determinations of haddock were made.

4) The results were weighted in accordance with the area of the regions.

Table 57· Numbers of haddock caught per hour fishing (24.6 m Trawl) by F. R. V. "Langust" in the North Sea in August-September 1967

Year class Northern North-central Central No. of fish % No. of fish % No. of fish %

I967 ...................... 5,923 98.o 476 87.6 I07 76·5 I966 ...................... I8 0.3 54 IO.O 27 I9-3 I965 ...................... 6 0.1 3 0.6 3 2.1

I964 ...................... 3 + + + + + I963 ...................... 3 + - - + + I962 ...................... 9I I.5 IO r.8 3 2.I

I96I ...................... 6 O.I + + + + I96o and older ............. 2 + + + + + All ages ................... 6,052 IOO.O 543 IOO.O I40 100.0 Hours trawling ............. 91/2 2I 491/4

5) The results were weighted in accordance with the area of the regions. 6) The I967 year-class excluded.

All regions (Weighted mean)5) No. of fish % %6)

I,559 95-9 34 Z.I 5I.5

4 0.2 6.I I 0.1 I.5 I O.I I.5

25 I.5 37-9 I O.I I.j

+ + + I,625 IOO.O IOO.O

793/4

-IIO-

Table 58. Mean lengths (em) of haddock of each age group from the North Sea in I967

West Northern North-central Central All regions Year Quarterly Mean No. of Mean No. of Mean No. of Mean No. of Mean No. of class period length fish length fish length fish length fish length fish

I967 ........ III - - - - 12.0 I9 I2.0 19 1966 ........ II - I9.2 87 20.0 !20 22.6 208 2!.2 415

III - - 26-4 9I 25-3 I 53 26.0 77 25.6 321 I965 ........ II - 31.0 3 32·5 2 - - 3!.6 5

III - - 32-4 IO 3!.6 I2 34·6 13 32.8 35 I964 ........ II - 33-5 2 - - - 33-5 2

III - - 39·0 2 33·0 I 40.0 I 37-7 4 I963 • .... ·. · I - 33·0 I - - - - 33·0 I

II 32.0 I 37-7 82 - - - 37.6 83 III - - 38.0 2 - - 38.0 2

I962 ........ I 38.I 86 38.6 250 - - - 38·4 336 II 39·0 36I 40·9 ISO 37·6 III 43-I So 39.6 702

III - - 42-4 138 42.6 6r 47·4 40 43-2 239 I96I ........ I 44·6 5 45·4

II 44-9 22 48·3 III - 46.!

I96o ........ I - - so.o II - -

III - 46.0

I959 · · · · · · · · III - -

of the trawls had a cover with a mesh size of 8-ro mm.

Since it was the first time such studies were being made, several types of standard commercial bottom trawls were tested, viz.: IJ.J m, 32.05 m and 24.6 m trawls. Trawls of the two first mentioned types were tested in all squares, but length measure­ments and age determination of haddock were not made in all catches. Therefore, the absolute values of these catches (number of specimens per trawling hour) are not representative. Only the percentage of different year classes in the catches are of interest.

Since the catches were too large for carrying out counting work it was decided that from 1968 the studies would be made by means of the standard commercial bottom herring trawl of 27.1 m which is less efficient. In future parallel trawlings will be made by the 24.6 m and 27.1 m trawls in order to make it possible to calculate a conversion factor and to obtain data in terms of catches per r hour trawling by the 27.1 m bottom herring trawl as well. For 1967 samples were taken by the 24.6 m trawl in all sqares and length and age of the haddock were determined in all hauls.

The total length of the haddock was measured to the nearest em. When the catches were too large, the counting and measuring of species were carried out only in one half, one third, etc. of the total catch and calculations were made regarding the whole catch. The number of fishes of each year class

I7 - 45-2 22 3 45·5 I2 48·9 r6 46·4 53

IO 40·5 2 so.o 3 46.! IS 2 - - - so.o 2

- - so.o 4 so.o 4 2 - - - - 46.0 2

- - - 63-5 2 63·5 2

was determined by agejlength keys calculated for each area in the corresponding quarter of the year by age determination by otoliths.

In summing up the results for the whole North Sea, the figures were weighted with regard to the area of each region.

Age composition Trawl surveys were carried out in May, June and

August-September. The results show (Tables 55, 56, 57) that the strongest mature year class of had­dock for all regions was the 1962 one.

In catches from May and June the 1966 brood dominated. It was also prominent in August___:Sep­tember, provided that the 0-class (the 1967 brood) is not taken into account. This group was represen­ted only in August-September.

The results of the trawl surveys suggest that in view of its considerable predominance in the catches, the 1966 brood is at least moderate, and perhaps abundant, and the 1967 brood is probably abundant.

Length composition The mean lengths of haddock caught in different

regions of the North Sea are shown in Table 58.

A. S. PoLONSKY

Atlantic Research Institute of Marine Fisheries and Oceanography, AtlantNIRO, Kalininingrad, USSR.

-III-

SAITHE

Distribution of young saithe (Pollachius virens) in the Barents Sea in 1967

(Figures 135-137; Table 59)

% 30

20

10

Gadoid Fish Saithe

n -13451

II&

A strengthening of the warm West Spitsbergen Current was registered in rg67. The near bottom isotherm of 4°C in September reached 80°30'N, and in the so-room layer the water temperature was about soc. Such an increase in temperature of this current, as compared with rg6S and rg66, affected the distribution of some thermophile fishes.

Usually young saithe at the age of o+ are met with in Spitsbergen waters in warm years. This was so in rg6o and rg6r. Only single specimens are, however, caught by trawl, and in cod stomachs they are nearly never found.

01 20 I '\;

In rg67 saithe of rz-IS em in length (Figure I3S) were found in bottom trawl catches all over the area from Bear Island and further to the north along the West Spitsbergen Current up to 80°3S'N and IS 0 oo'E; single specimens were caught in the

• ~

'180

'120

• 9

• ••

10

0 t2 13 t4 i5 t6 17 18 em

Figure 135. Size composition in fishing areas lib and I.

~~J • <10 • >to • >SO

.>100

.>300

Figure 136. Distribution of young saithe in the Barents Sea in 1967.

-II2-

Table 59· The occurrence of saithe fingerlings in cod stomachs in September - October, 1967

Number of Occurrence of Areas stomachs saithe in the

West Spitsbergen .. . South Cape Deep .. . Western Slope of Bear

Island .......... . Southern Slope of

Bear Island ..... Eastern Slope of Bear

Island .......... . Hopen Island area .. .

!062 507

I9I

J7I

35 25

stomachs (in%)

4! !7

23

5

6 8

Hinlopenstredet and Wijdefjord. In these regions dense concentrations of saithe were observed over the whole area. They were feeding intensively. The greatest number of specimens (300 kg per trawling hour) were caught by trawl in the latitude of Bellsund at a depth of so m. Here dense concen­trations of saithe were registered by the "Lodar" sonar system (Figure 137).

Much saithe was also caught by midwater trawl in Kongsfjorden at 6o-7s m depth and saithe was registered in Isfjorden as well.

The bulk of the catch consisted of silver-blue fishes, ro% were of a golden tint.

In the West Spitsbergen area young saithe is the main food of cod (Table Sg). In some large cod stomachs up to so specimens of saithe were found.

During the last ten years there has not been observed such a mass approach of young saithe to the coast of Spitsbergen.

The wide distribution of young saithe was affected not only by the warming up of the water, but by other factors as well.

·~ )·· ~~~ r

!

Figure 137. Echogram of saithe concentrations near the bay of Bellsund in October 1967 (77°5o'N 13°4o'E, o-300 m range in the layer 25-70 m, "Lodar" V- 3·5 k.

It is quite possible that the spawning grounds of saithe in rg67 were displaced more to the north than usual, and therefore the young ones may have been caught by the Spitsbergen Current and brought to the north in great quantities. Besides, it is suggested that this year class is among the most abundant ones, because young saithe were met with in the central, eastern and north-eastern regions of the southern part of the Barents Sea up to Novaya Zemlya (Figure I3S), allthough in considerably smaller numbers.

In the southern part of the sea young saithe were during the last years mainly caught off the Murman coast.

T. S. BERGER

Polar Research Institute of Marine Fisheries and Oceano­graphy (PINRO), 6 Knipovich Street, Murmansk,

USSR.

WHITING

Scottish investigations on the west coast stock of whiting in 1967

(Table 6o)

Commercial statistics

Table 6o shows the landings (nominal catches), fishing effort and landings per unit effort by traw­lers and Danish seine net vessels fishing off the north and west coasts of Scotland during rg67.

Age and length composition Only one routine trawl survey of the north and

west coasts of Scotland was made by F. R. S. "Explorer" during rg67. The data from this cruise were published in the previous volume of Annales Biologiques.

Tagging Of the IS3 tagged whiting released off the Scottish

west coast during rg67, 13 had been recaptured by the end of the year.

]. R. G. HISLOP, A. S. jERMYN

Marine Laboratory, Victoria Road, Torry, Aberdeen, Scotland.

-II3- Gadoid Fish Whiting

Table 6o. Whiting landings (nominal catches) and fishing effort by British vessels at all Scottish ports in 1967 from the north and west coasts of Scotland

North North Outer South South of Firth of Coast Minch Hebrides Minch Lat. 56°N Clyde

Landings ('oo tons)

Motor Trawl ........................... 9.8 z.s o.os1) 0.02 0.32) Light Trawl . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 r6.3 o.os3) o.s 0.002 3·6 Seine ................................. 4-9 27-44) 0.76) 12.4 0-46) zs.o

Fishing Effort ('oo hours)

Motor Trawl ........................... 433 158 61) 3 462) Light Trawl . . . . . . . . . . . . . . . . . . . . . . . . . . . 426 501 93) 40 0.2 276 Seine ................................. 276 6944) 135) 187 ro6) 557

Landings per Unit Effort

Motor Trawl (tonsfroo hours) ............ 2.3 I .6 0.91) o.6 0.72) Light Trawl (tonsfroo hours) ............. 2.3 3·3 0.63) 1.2 I .0 1.3 Seine (tons/roo hours) ................... r.8 3·94) s.r5) 6.7 4-16) 4·5 1) Includes r8TT; 2) Includes 15SS, 14 TT; 3) Includes r8XX; 4) Includes r8SS, r8TT, r6VV; 5) Includes 8TT; 6) Includes 8 SS

Scottish investigations on the North Sea stock of whiting in 1966 and 1967

(Tables 61-63)

Commercial statistics

The landings (nominal catches), fishing effort and the landings per unit effort of whiting landed by motor trawlers from the North Sea in rg66 and 1967 are shown in Table 6r.

Age composition

F. R. S. "Scotia" made two routine trawl surveys of the North Sea in rg67. Table 6z gives the age compositions of the catches taken during these surveys.

The rg6z year class, even asS+ fish, was abundant and in most areas this year class was numerically superior to the poor year classes of 1963 and 1964. The rg65 and rg66 year classes were taken in more or less average numbers. As no survey was made towards the end of the year it was not possible to form any idea of the strength of the 1967 year class.

Length composition

Table 63 shows the mean lengths of whiting of age groups r-5 sampled by F. R. S. "Scotia" in the North Sea in rg67.

Tagging During 1967 a total of r,ZJI whiting were tagged

and released in the North Sea. By the end of the year 41 tags had been returned.

J. R. G. HISLOP, A. S. JERMYN

Marine Laboratory, Victoria Road, Torry, Aberdeen, Scotland.

Table 61. Landings (nominal catches) of whiting by British motor trawlers at all Scottish ports from the North

Sea in 1966 and 1967

a) North of Lat. 57°3o'N Wt. landed Effort Wt. landed

Quarterly period Year ('oo tons) ('oo hours) (tons) per roo hours

Jan.-March 1966 4·7 228 2.1 1967 9·8 354 2.8

April-June 1966 3·3*) 155 2.1 *) 1967 3·8 r68 2.3

July-Sept. 1966 7-2 222 3-2 1967 II.9 371 3-2

Oct.-Dec. 1966 10-4 481 2-4 1967 r8.5 481 3·8

b) Lat. 55°N to 57°3o'N Wt. landed Effort vVt. landed

Quarterly period Year ('oo tons) ('oo hours) (tons) per roo hours

Jan.-March 1966 4·8 qo 3-4 1967 5·3 IIS 4·6

April-June 1966 2.6 233 I. I

1967 1.4 191 0.7

July-Sept. 1966 8.o 259 3.1 1967 4:2 234 r.8

Oct.-Dec. 1966 5·6 22I 2.5 1967 5·8 239 2.4

c) All areas vVt. landed Effort \Vt. landed

Quarterly period Year ('oo tons) ('oo hours) (tons) per roo hours

Jan.-March 1966 9-5 368 2.6 1967 rs.r 469 3-2

April-June 1966 6.o*) 388 1.5 *) 1967 5-2 359 1.4

July-Sept. 1966 15.2 481 3-2 1967 r6.I 6os 2.7

Oct.-Dec. 1966 r6.o 702 2.3 1967 24·3 720 3-4

----·

*) Adjustment made to value given in the previous issue of A nnales Biologiques.

-II4-

Table 62. Numbers of whiting caught per IO hours fishing by F.R.S. "Scotia" in the North Sea in 1967

Area Northern North Central Central Moray Firth and Orkney Cruise June Mar.JApr. June All cruises June Mar.fApr. June All cruises

No. of hauls 7 7 I8 25 2 9 6 IS Weighted Weighted

Year class mean mean

Ig66 .................. 9 5I7 20 I 59 430 I,478 I,594 I,524 I965 .................. 25 I 54 55 83 45 299 I 55 24I I964 .................. 27 56 23 32 25 go 99 94 I963 .................. 5 6 3 4 0 4 2 3 I962 .................. 37 32 49 44 20 I 55 I24 143 Ig6I and older ......... 9 4 II 8 0 8 0 5

Table 63. Mean Lengths (em) of whiting of each age group from the North Sea in 1967

Area Northern North Central Central Moray Firth and Orkney

Year class Cruise Mean No. of Mean length fish length

Ig66 Mar.jApril I7-75 June 22.50 6 23-30

I965 Mar.jApril 27-49 June 27-59 I8 27-5I

I964 Mar.fApril 30.64 June 30-39 I9 31.05

I963 Mar .j April 35-09 June 33-67 4 34-37

I962 Mar .fA pril 35-65 June 35-94 26 34-48

Soviet investigations on the North Sea stock of whiting in 1967

(Tables 64-67)

Soviet investigations on the North Sea stock of whiting commenced in rg67. Trawl surveys were conducted by AtlantNIRO research vessels in the second (SRT-R gorg "Okhta") and in the third (SRT-M 1257 "Langust") quarters of the year.

The methods of investigation is described on p. rog in this issue. The total length of the whiting was measured to the nearest em.

Age composition

The age composition of whiting is represented in Tables 64, 65, and 66.

The rg66 year class was absent from the trawl catches taken in the northern region in May, June and August-September, but was significantly represented in the catches from the central region in May, as well as in those from the north-central region in June. In August-September this year class dominated in the catches taken in the north­central, central and south-central regions.

No. of Mean No. of Mean No. of fish length fish length fish

362 I8.88 I,330 35 Ig.g6 86 Ig.6o 958

Io8 26.62 269 99 28.so 9 27.69 93 40 30-45 8I 4I 3!.30 5 30-46 6o

4 32.0I 3 5 - 35-50

22 32-73 139 88 34-00 4 33-25 75

Table 64. Numbers of whiting caught per fishing hour (17.7 m trawl) by R. V. "Okhta" in the North Sea in May

1967')

Year class

I966 ........... 1965 · · ......... I964 ........... I963 ........... Ig6z ........... I96I and older .

All ages .......

Hours' trawling .

Northern No. of

North-central Central No. of No. of

fish % fish % fish %

0 + + I40 30.2 I 0.7 90 2I.4 II5 24.8 I 0.7 67 I5.8 56 I2.0

20 J4.6 rr8 28.I 79 I7.0 48 35-I 88 20.9 59 IZ.8 67 48-9 58 13.8 15 3-2

I37 100.0 42I IOO.O 464 IOO.O

23/4 41/2 51/2

1) Hours of trawling and mean number of specimens for r hour's trawling are shown only for catches where length measurements and age determinations were under­taken.

The 0-group (the rg67 brood) was found in the August-September catches only, predominating in the northern region of the sea, while it was not significant in the areas more to the south.

-II5- Gadoid Fish Whiting

Table 65. Number of whiting caught per fishing hour (32.05 m trawl) by R. V. "Okhta" in the North Sea in

June 1967')

Year class

I967 ................ . I966 ................ . I965 ................ . I964····· ············ I963 ................ . I962 ................ . 1961 and older ...... . All ages ............ .

Northern No. of %

0

0

26 34

152 r88 I94 594

4-4 5·7

25.6 31.6 32·7

Ioo.o Hours' trawling . . . . . . 1(2 -------

North-central No. of %

0

75 r89 83 46

0

0

393

19.0 48.2 21.!

II.7

IOO.O

') Hours of trawling and mean number of specimens for I hour trawling are shown only for the catches where length measurements and age determinations of whiting were undertaken.

Size composition

Table 67 shows the mean length of the whiting caught in the different areas of the North Sea.

A. S. PoLONSKY

Atlantic Research Institute of :Marine Fisheries and Oceanography (AtlantNIRO), Kaliningrad, USSR.

Table 66. Numbers of whiting caught per fishing hour (24.6 m trawl) by R. V. "Langust" in the North Sea in August­September rg67

Northern North-central Central South-central* No. of fish % No. of fish % No. of fish % No. of fish %

I967 ............... . SIO 88.I 6 3·6 2 I. I 0 1966 ............... . 0 54 32·3 II6 66.7 144 59·5 I965 ............... . I964 ............... .

2 0.3 so 29.9 37 21.3 55 22.7 6 I.O 31 I8.7 9 5·2 I6 6.6

I963 ............... . I2 2.I IO 5·9 5 2.9 I3 5·4 1962 ............... . 30 5·2 I2 7·2 4 2.3 IO +I 196I and older ...... . I9 3·3 4 2-4 I o.s 4 I.7 All ages ............ . 579 IOO.O I67 IOO.O I74 IOO.O 242 IOO.o

Hours' trawling ..... . 91/2 21 491/4 zlfz

*) 55ooo'N to 53°3o'N.

Table 67. Mean lengths (in em) of whiting of each age group from the North-Sea in 1967

Northern North-central Central South-central*) Year- Quarterly Mean No. of :Mean No. of :Mean No. of Mean No. of

class period length fish length fish length fish length fish

I967 ...... III - - - II.O 22

I966 ...... II - - I4.0 35 III 24.I 25 24.I IOO 21.9 I3

I965 ...... II - -· - - 24.I I9 III 31.0 I 30.0 IO 28.3 43 29.0

I964 ...... II - - - 26.9 I4 III 33·3 3 32·5 II 30·5 I6 33·0

I963 ...... II 34·0 2 - - 28.4 32 III 38·3 3 34·8 4 32·9 I3

I962 ...... II 37·6 I9 - 31.4 I7 III 39·2 I2 40.I r6 33·9 II

I96I ...... II 40·5 2I -· - 34·0 5 III 4+7 4 40.0 4 35·5 2

1960 ...... II 46·5 4

*) sooN to 50°3o'N.

-II6-

Clupeoid Fish

HERRING

Introduction

The number of contributions, mainly on Baltic and North Sea herring, is somewhat smaller than in rg66. The information available, however, still permits the construction of a fairly comprehensive picture of distribution, abundance and composition of the major herring stocks in the north-eastern Atlantic for the year rg67.

From Norwegian, Islandic and German contri­butions on the Atlanto-Scandian herring the main events in this important herring stock can be summarized as follows. The summary includes the results of the Soviet and Islandic survevs, carried out in the Norwegian Sea in the early ~ummer of rg67, which link the distribution of the Atlanta­Scandian herring with oceanographic conditions. The results of these surveys have been reported as an appendix.

The pre-spawning and spawning concentrations of the Norwegian spring-spawners appeared in rg67 towards the end of January for the M0re-coast, coming as usual from the overwintering areas off south-east Iceland and moving in a north-easterly direction along the coast. Spawning started in the end of February, while the fishery in the region lasted until the end of March.

The spawning concentration in the Lofoten area, where in the last few years younger 5pecimens of the stock appeared in February-March, did not exist in rg67, as indicated by special research vessel surveys and by the absence of a fishery. Besides, no herring larvae were found in the area, in contrast to the situation off the M0re coast, where herring larvae did occur.

Islandic surveys in late winter indicated, that part of the Atlanto-Scandian stock visited the banks to the east and south-east of the Faroe Islands in February and the beginning of March.

The catches of winter herring mainly comprised specimens belonging to the 1959, rg6o and rg6r year classes. Recruit spawners were becoming rare in the rg67 catches. The Norwegian catches were lower than in rg67, both the total catch and the catch per purse seiner declined, due partly to ad­verse weather conditions during the season.

The summer f1shery was characterized by a very unusual distribution of the herring in the Norwegian

Sea. Instead of occupying their normal feeding grounds off the north and east coast of Iceland or to the south of Jan Mayen as in rg66, the herring moved along the polar front to the area west of Spitsbergen and Bear Island, so that they were found in a far more easterly position than usual. It has been suggested that this unusual distribution of the herring in the Norwegian Sea was related to the presence of cold water in the whole western area of the Norwegian Sea with extremely low temperatures in the core of the East Islandic cur­rent and a subsequent late development of Calanus in the western area.

The summer fisheries showed a large decline in landings, which was mainly attributable to the aberant distribution. The Icelandic catch for in­stance, declined from 770,000 tons in rg66 to 34r,ooo tons in rg67.

In September the herring started to move again, now in the south-westerly direction towards the overwintering area east and south-east of Iceland. On these overwintering concentrations a fishery took place off south-east Iceland. Especially the newly developed pelagic trawl fishery yielded good catches, although the catch per day was lower than in rg66.

The total catch of adult Atlanto-Scandian her­ring, using Norwegian, Icelandic and German figu­res only, declined from r,z million tons in rg66 to o.g million tons in rg67. The cause of this decline was most likely both the lack of recruitment and the unusual summer distribution of the herring. Young fish surveys, carried out in the Barents Sea and adjacent waters indicate a very poor abundance for the rg67 year class, lower even than the ab­undance of the poor rg66 year class. Norwegian catches of juvenile herring amounted to about 450,000 tons, of which approcimately a quarter consisted of 0-group herring.

Other groups of herring in northern waters, as the Icelandic spring and summer spawners, are re­ported to be in a poor state. Icelandic investigations indicate a low abundance of both stocks and a considerable change in the age composition during the last decade, the herring catches now comprising much younger fish than in the late fifties. A re-

-IIJ- Clupeoid Fish Herring

lation with the increase rate of fishing on these stocks in recent years (purse seine) has been sug­gested. Iceland reported the introduction of a ban on the fishery for spring-spawners during the months March-May in rg67.

Contributions from England, France, the Nether­lands, Norway, Poland, and Scotland report on the situation in the North Sea. Some information from the German fisheries in the North Sea, not reported in this volume, has also been included.

All countries experienced declining landings com­pared with rg66, between 6% (Germany) and over so% (the Netherlands), with the exception of Scot­land whose landing increased by about rso/o. The landings of the Norwegian purse seine fishery, since its rapid development in rg65 the largest fishery on North Sea herring, declined by about z6% compared with rg66 and by 45%, compared with rg65, the year with the highest landings. Almost all countries mention the decline in the landings to be at least partly due to a reduction in effort. The Norwegian purse seiners, for instance, shifted their effort partly to mackerel fishing in the North Sea, which yielded not less than 835,000 tons. Some countries have diverted their effort to other areas, for instance to the area west of the British Isles. From the contributions it is difficult to assess the abundance of the North Sea herring in rg67 relative to the preceding years, as some countries report lower, but others higher catches per unit of effort. The fact, however, that the effort has been diverted to other areas and to other species, seems to indicate a generally lower abundance level.

The main fishing grounds in the North Sea were situated on the edge of the Norwegian Channel (Egersund area, Skagerak), the Shetland area and in the western part of the central North Sea. Ac­cording to Norwegian and Polish information the Norwegian Channel fishery, which used to be a winter fishery in rg63-rg66, has turned to mainly a summer fishery in rg67. Poland reported extre­mely poor catches in the area, Norway reasonably good catches. The Shetland fishery, a summer fishery mainly, was reported poor by Norway, but fair by Scotland. Landings from the central North Sea, which showed a decline in the last few years, were lower again in 1967. Very little fishing with generally poor results took place in the once famous Southern Bight-English Channel region. France reported, that the decline of the herring landings in the area has been accompanied by a reduction of the number of fishing grounds.

In the age compos1t10n of autumn-spawned North Sea herring, the major component of the landings, the rg63 year class dominated. Whereas the fishery in the north-western North Sea (Shet­land area) has been dependent mainly on older fish (rg63- and rg6o year class), the Norwegian Channel fishery in summer depended for a large part on young fish belonging to the rg64-rg65 year classes. The central North Sea fisheries for spawning her­ring were based on rg63 year class fish mainly, recruitment to the area of the year class rg64 being rather poor. The landings of the summer fisheries in the central North Sea consisted some­times for a large part of rg64- and rg65 year class herring.

Norwegian and Scottish tagging experiments in the northern North Sea both indicated a connection between the Norwegian Channel and Shetland her­ring concentrations.

English data on Southern Bight and central North Sea herring showed an extremely large growth of the three year old herring in their first year of life. (L1).

From the herring stocks to the west of the British Isles there are reports from Ireland, the Netherlands and Scotland. Landings from the area south-east of Ireland seem to have increased in the case of the Irish fishery, but decreased in the Dutch fishery. Both countries mention the rg6z year class as a very rich one in the area. In the Irish landings the rg64 year class too proved to be abundant.

In the area north of Ireland and west of Scotland the rg63 year class is reported to be very abundant. Scottish catches in the Minch declined somewhat in summer, but the winter catch was at about the same level as in rg66. Both Germany and the Netherlands reported an increase in their catches from the area just north of Ireland (Donegal). The landings consisted mainly of autumn spawners.

Polish and East German contributions reflect on the situation in the western Baltic, where due to a record year class (rg64) of autumn spawning her­ring, landings were very high. This very large rg64 year class of the autumn spawning herring, com­bined with a moderate recruitment to the spring spawning stocks in the area, made the autumn spawners the most important component of the herring landings in the western Baltic.

J. J. ZIJLSTRA

Rijksinstitut voor Visserijonderzoek, IJmuiden, Netherlands.

-IIS-

Icelandic herring investigations 1967 (Tables 68-79)

Surveys \Vinter surveys

During the period 4· January to S. April asdic echo-surveys were carried out on the "Hafth6r", a 250 brt. vessel. The purpose of these surveys was to assist the purse seiners on the overwintering grounds of the Atlanto-Scandian herring off the east coast and later to follow the beginning of the spawning migration and survey the winter herring grounds around the Faroe Islands. The spawning grounds of the Icelandic spring spawning herring off the south coast were also investigated.

The main concentration of Norwegian spring spawners which had been more or less stationary about 65°N, some 6o-roo n.m. off the east coast, began a slow easterly migration early in January. By the end of the month these were observed in an area north-east of the Faroes.

During February and the first week of March considerable quantities of herring were observed to the east and south-east of the Faroes, mainly in the so-called Sand0 Bank area.

In March and early April the shelf-area south of Iceland, between the Reykjanes peninsula and Stokksnes was surveyed twice. As last year the surveys were much hampered by bad weather and appreciable concentrations of spawning herring were not found nor were any egg patches located.

Summer surveys

During the period 29. April to ro. September the "lEgir" was engaged in environmental and accous­tic surveys on the herring grounds. The new research vessel "Arni Fridriksson" then replaced the "lEgir" to continue her work until 20. De­cember. In addition the "Hafth6r" and a chartered boat of similar size assisted in this work. The first herring shoals were located in the area from 65°55' to 66°I5'N between I 0 and 3oW on g. May but the main concentrations were found to be a little further east "Jiz. from 65° to 67°30'N between 2°W and 0°30'E. Only minor concentrations were found west of 2°W in May. During the latter half of May and the first week of June the invasion moved, first in a northerly and then north-westerly direction and by 7· June most of it had reached the area between 69° and 70°2o'N from 2°30' to 5°3o'W. At this point at least a good proportion of the invasion moved on west-wards and then

south-westwards and on 20. June these shoals had arrived in an area approximately I30 n.m. south of Jan Mayen.

In May and the first half of June, Soviet re­search vessels surveyed the Norwegian Sea from as far south as the Faroes north of Jan Mayen. A meeting between Soviet and Icelandic scientists was held on rS.-rg. June at Akureyri in order to compare the findings in the survey area. A joint report was prepared and presented at the annual ICES meeting (seep. 206-q).

In May and June the herring concentrations kept well clear of the cold waters of the East Icelandic Current remaining in waters of 6-7°C (20 m). North of 6g 0 N, however, a part of the stock pene­trated cold waters of I-2°C further to the west. As in rg65, good concentrations of Calanus fin­marchicus did not form until later in the summer and in fact the stock did not settle in the Lan­ganes-Jan Mayen area but as from 22. June began a north-easterly migration to feeding grounds west and north-west of Bear Island. By the end of June the concentrations were about So miles east of Jan Mayen and then crossing the Polar Front arrived on the feeding grounds before the end of next month. The herring then remained feeding in a large area between 74°30' and 76°ro'N from the so to I3°E until mid-September.

Despite intense surveying no herring shoals of commercial importance were located on the tradi­tional summer fishing grounds between Langanes and Jan Mayen nor to the east of Iceland, through­out July, August and September. As has been the case since rg63 no herring concentrations were located north of Iceland but together with the scarcity of Calanus finmarchicus went an extreme coldness of the waters of the shelf area north of Iceland (2 to 5° below normal) and those of the East Icelandic Current (anomalies of - 0.7 to -rf).

Around mid-September the herring started migrating towards Iceland from the Bear Island­Spitsbergen area. The course of migration was mainly along the polar front, being first southerly, then westerly along the southern border of the polar waters towards Jan Mayen. Finally, having arrived in the area south-east of Jan Mayen the shoals headed for the overwintering grounds east of Iceland. Around the ro. October the first part of the invasion was observed about I30 n.m. east of Langanes but at this point there was a change of course to the south and the SSE. The migration continued in that direction to a position south of 65oN between 6°30' and S0 W.

-·-- -··--------------------- ---

-rrg- Clupeoid Fish Herring

Table 68. Monthly yield of the north and east coast fishery

Month Number of boats Catch, tons

May 0- 10 71 June 10-110 46,967 July 110-120 55.713 August 120-130 53,698 September 130-140 83,793 October qo 64,579 November 140-120 24,972 December 120- go 10,895

A few days later a second invasion was discovered which, following essentially a similar course as the first, arrived in the same area about one week later.

As it turned out the usual large overwintering shoals did not form this year at all. Instead scattered shoals of lesser dimensions were observed on the fishing grounds during the last week of October, all November and December. The concentrations settled along the warm-cold water boundary (7-8°C/5.5-6.5°C) which gradually was pushed southwards due to prevailing northerly winds throughout the rest of the year. In late November and December a slow westward movement was observed and on and after mid-December herring concentrations were located in an area from 64°30' to 65oN between roo and rr 0 W. The bulk of the stock, however, still retained a more southerly distribution south of 64°N and east of the roth meridian.

The fishery

The winter and spring fishery

In January the herring fishery continued on the overwintering grounds off the east coast and lasted throughout the month. Although fishing operations were somewhat hampered by bad weather in the area total landings from this fishery amounted to 29,4000 tons.

As last year a section of the spawning migration of the Atlanta-Scandian herring detached itself to visit the banks to the east and south-east of the Faroe Islands. Some Icelandic purse seiners continued working in this area during February and the first ro days of March but the fishing was not profitable due to bad weather and total landings amounted to only 3,500 tons in all.

This year no winter herring fishing took place off the eastern south coast. During January and February a number of purse seiners worked off the western south coast, mainly in the vicinity of the Vestmannaeyjar but due to the scarcity

of herring and generally bad weather the total catch amounted to only ro,6oo tons. On 28. Febru­ary a ban was enforced on the fishing of the Ice­landic south coast herring, lasting until r5. May, but fishing operations did not in fact start again until June.

The total landings of winter and spring herring thus amounted to 43,600 tons as compared with 24,500 tons in rg66, the increase being due to the more successful J anu:ary fishing off the east coast.

The summer and autumn north and east coast fishery

Although good herring concentrations were located by the survey vessels as early as ro. May, the summer east and north coast fishery did not commence until the beginning of June. This was partly due to the great distance to the herring grounds, with the main reason, however, being of economic nature.

In June and July the fishery followed the route of migration, first to the area south and south-east of Jan Mayen and later north-eastwards towards Bear Island and Spitsbergen. During August and the first half of September all the catch was taken on the feeding grounds between 74°30' and 76oro'N between 8° and r3°E. With the onset of the autumn migration the fishery again moved south-east­wards and after mid-October was pursued over a wide area 6o-r5o n.m. off the east and south-east coast of Iceland. Table 68 shows the monthly catch and the approximate number of boats participating in the fishery.

As compared with previous years this year's fishery was much less effective, the total catch amounting to about 34r,ooo tons as against 7oo,ooo tons in rg66 and 54r,5oo tons in rg65. Due to the great distance to the fishing grounds during the first 4 months of the season a valuable fishing time was spent in transporting the catch, and probably also in searching an unfamiliar area, which was far in excess of anything pre­viously experienced. Although two tankers serviced the fleet at the time, their transport capacity was not sufficient during periods of good fishing.

The autumn and early winter fishery off the east and south-east coasts likewise was a com­parative failure. Weather conditions were singularly bad and together with the unusual pattern of behaviour, described earlier in this report, it resulted in a total catch during this period of only r22,ooo tons, a quantity that sometimes has been realised during only one month of fishing on the overwintering grounds.

-!20-

Table 69. South coast winter and spring herring 1967

1966. 1965. 1964. 1963. 1962. 1961. 1960. 1959· 1958. 1957· 1956.

Year class

Total Number Mean •

ISPR ISUM

162 459 162 203

14

1,000

74 4-4

4 122

34° 327 94 49 24 20

8 12

1,000 2 45 4·9

41 216 591 qo 12

1,000

171 2.9

Total

14 77

292 289 191

77 26 14 10

4 6

I,OOO

492 4·1

During the summer months some herring fishery also took place in the North Sea and Skage­rak but this was of minor importance, the catch amounting to 7,500 tons.

The summer south coast fishery

This fishery was essentially pursued by the smaller seiners which through limited range of operations were prevented from fishing in the more distant areas. As in rg66, the fishery mainly took place in the Vestmannaeyjar-Selvogsbanki area, the catch from the south-eastern grounds being negligible. Total landings were a little higher than last year's or 47,500 tons in all.

The autumn south- and south-west coast fishery

Although still at a low level the total landing figure of 17,000 tons was a considerable improve­ment on last year's 2,8oo tons. Sporadic fishing also took place off the eastern south-east coast yielding about 5,ooo tons. Thus total landings from this fishery were 22,000 tons.

The total Icelandic herring catch in rg67 thus amounted to 461,400 tons in all.

Biological data

The winter fishery

Owing to the grave situation in the Icelandic herring stocks and the very low prices of herring products (meal & oil) a ban was imposed on the Icelandic spring fishery during March-May. Con­sequently the samples are all taken in January and February with the exception of 50 individuals that were accidentally caught in April. The age and length distribution of the south coast winter season is shown in Tables 69-70. As in previous years, the age is arranged by number of winter

Table 70. South coast winter and spring herring 1967

Length, em ISPR ISUM ? Total

17· 18. 19. 20.

2!.

22.

23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33· 34· 35· 36.

Total Number Mean

18 36 18 71

107 179 196 89

179 89 18

I,OOO

56 29.8

5

-19 I4 57 95

167 176 171 129

76 43 24 24

1,ooo 2!0

30-4

14 5 41 I4 34 12 41 17

48 17 61 22 61 24

163 72 184 75 195 108 82 92 14 113

7 120 I4 104 7 92

20 6o 7 27 7 14

12

I,OOO 1,000

147 413 25.2

rings and the length is measured to the centi­metre below. The dominant year class in the spring spawning stock is that from 1963 or 4 year old herring. The year classes from rg62 and rg6r which were dominant in the previous year seem to have declined very rapidly in this stock. On the other hand, as regards the summer spawners, there are two dominant year classes i. e. from rg62 and rg63 as compared with rg62 and rg6r. The changes in the age distribution from year have recently been much more pronounced than they were, say 5-ro years ago. Thus the year classes only make a significant contribution to the fishery for 2-4 years instead of something like a decade as frequently happened while the exploitation of the stocks was at a much lower intensity than it is now. The immature herring are entered under ? in Table 6g. The vast majority of these are 2-3 years old. The presence of the 4 year old herring year class rg63 in this category gives additional indi­cation that the rg63 year class may be somewhat above average in strength and thus maturing over a longer period than the year classes that have been recruited to the stocks in recent years. The average age of 4-4 and 4·9 years for the spring and summer spawners is considerably lower than in the previous year when the average age was 5-3 and 5.6 years respectively. The average age of the immature herring was on the other hand somewhat higher in 1967 (2.9 years) than in rg66 (2.6 years). The overall average length of 28.5 was somewhat higher in rg67 than in the previous

-I2I- Clupeoid Fish Herring

Table 71. North and east coast summer and autumn herring 1967

Year NN NS ISPR ISUM ? Total

1964. 1963. 1962. 1961. 1960. 1959· 1958. 1957· 1956. 1955· I954· 1953· 1952. 1951 · 1950. 1949· 1948. 1946.

Total Number

Mean

4 15

I

2 r8 37 r8 29 70

266 38 299 28 375 r8

3 r8 5 193 3 5 7

I 2 - roo II

7 8

500 250 12 250 II

II6 318 503

3 3 I

2 3 5 5 5

13

1,000 I,OOO 1,000 1,000 1,000 I,OOO

6,oz5

7·8

2,456

7·3

57 7·0

IO 4 8,552 6.4 3·8 7·6

year (27.9). The average length of the two Ice­landic stocks (29.8 and 30-4 em) on the other hand was somewhat lower than in 1966 (30.3 and 31.0 em respectively). The difference lies in the considerably higher average length 25.2 em of the immature herring in 1967 than in 1966 when the corresponding length was 23.2 em.

The "north and east coast" summer and autumn fishery

The age distribution of the samples taken during the 1967 north and east coast fishery is shown in Table 71. As in the three previous years the dominant year class of the Norwegian herring is the one from 1959, contributing 5600fo0 and 375°/00 to the northern and southern types re­spectively. The importance of the 1960 and r96r year classes is increasing so that the vast majority of both types belongs to these three year classes - the older ones are no longer of any real signifi­cance in the age distribution. In 1966 there was some indication that recruitment of the 1963 year class was about to become important but there does not seem to have been a continuation of this development of any significance in 1967. The ave­rage age for the Norwegian types was 7.8 and 7·3 years as compared with 7·9 and 8.2 years in 1966. The age distribution of the two Icelandic stocks is based on so few individuals in this fishery that any comments are hardly justifiable.

Table 72 shows the length distribution of the north and east coast herring in 1967. The mean length of the Norwegian types was 33·3 and 33·7 em

Table 72. North and east coast summer and autumn herring 1967

Len~th, em

21.

22.

23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33· 34· 35· 36. 37· 38. 39·

Total

Number

Mean .

NN

3 30

203 387 269

72 15 II

7 2

1,000

6,026

33·3

NS ISPR ISUM

r8 I -2 2 - roo 6

II - roo 30 r8 roo

120 175 roo 278 350 200 314 193 200

q8 123 roo 42 70 26 53 roo 14 6

I,OOO I,OOO I,OOO

2,456 57 IO

33·7 33·5 32·7

Table 73· Strength of tribes

Herring tribes

NN. NS . ISPR ISUM

Total

Number

6,025 2,456

57 IO

8,552

Total

3

3

3 5 3 2

5 5 23 30

141 177 283 352 224 279

95 94 82 26 98 19 28 IO

4 3

I,OOO I,OOO

389

33-9 33·4

Percentage

70·5 28.7

0.7 0.1

100.0

as compared with 33-5 and 34.1 em in 1966. It was noticed that in r966 the average weight of each em group had increased considerably as compared with that of the years prior to 1966. In 1967 the average weight of the em groups is still high, although not quite as high in 1966. The strength of tribes is shown in Table 73· There was a further development of the trend that has taken place in the 4 previous years. Thus the Norwegian tribes contributed 99.r% in 1967 as compared with 97% in 1966 and 94% in 1965. At present the Icelandic herring which only a few years ago contributed over so% has now become quite insignificant in this fishery.

The south coast summer fishery

The age distribution of the samples taken during the south coast fishery is shown in Table 74· The dominant year class for both spring and summer spawners is that from 1964 i. e. 3 year old herring. In 1966 the 1963 year class was by far the most abundant. As in previous years immature

-122-

Table 74· South coast summer herring 1967

Year class ISPR ISUM ? Total

Ig66. I I I965. 5 225 98 I964. 349 527 74° 599 I963. 286 275 34 I73 1962. 89 So - 47 1961. 203 45 43 1960. 52 23 - I6 1959· 10 I4 -- 7 1958. 5 3 2 1957· - II 5 1956. 8 -- 4 I955· - 5 - 2 1954· - 2 - I

1953- 5 - - I

1952. -- 2 - l

Total I,OOO I,OOO 1,000 I,OOO

Number I92 875 8oo I,869 Mean 4-4 4-0 2.8 3·5

Table 75· South coast summer herring 1967

Length, em ISPR ISUM ? Total

I8. - - 2 I 19- - - 3 2 20. - - I6 7 21. - - 38 I7 22. -- I 66 30 23. - 5 I35 62 24. 2I 30 I79 96 2j. 42 I03 2II I45 26. Ilj 234 I76 I96 27. 120 I86 94 I38 28. I25 120 34 82 29. 78 51 5 33 30. 63 40 2 25 3I. I6 40 2 2I 32. I6I 64 9 so 33· Ij6 40 IO 38 34· 83 37 6 27 35· I6 33 8 20 36. 5 IO I 6 37· - 6 I 3

Total I,OOO r,ooo I,OOO I,OOO

Number I92 875 862 I,929 Mean 29.8 28.2 24-9 26.9

herring is very numerous and contributes about 40% to the samples. The average age of 3-5 years is practically the same as that of rg66. The length distribution is shown in Table 75· The overall mean length of 26.g em is considerably lower than in rg66 when it was 28.5 em.

The south coast autumn herring

The age distribution of the samples taken during the south coast autumn season is shown in Table 76. As in the previous year the majority of the herring were immature 2 and 3 ringers.

Table 76. The south coast autumn herring 1967

Year class ISPR ISUM ? Total

Ig66. - - 25 q I965. 36 - 266 I47 I964· 482 5I6 66o 592 I963- 304 297 48 I63 1962. 54 58 - 26 1961. 89 5s - 28 I96o. 36 37 - 17 1959· - 9 -· 3 1958. - 9 - 3 1957· 1956. - 12 - 5 1955-1954-1953· - 3 1952- - 3

Total 1,000 I,OOO I,OOO I,OOO Number j6 347 477 88o Mean 3-8 4·0 2.7 3·3

Table 77· South coast autumn herring 1967

Length, em ISPR ISUM ? Total

I7. - - 2 I8. - - 6 3 I9. - - 7 4 20. - - Ij 8 2I. - - 7 4 22. - - z8 I5 23. - 26 I4 24. - - 6I 33 25- 40 8 II8 70 26. 13 8 I42 8I 27. 120 52 208 142 z8. I33 2j0 237 235 29. I74 244 87 I 53 30. I07 I20 35 73 3I. I47 73 6 42 32. 53 55 4 27 33· I33 73 9 43 34· 53 55 2 26 35· 27 39 - I7 36. - r8 - 7 37· - 5 2

Total I,OOO I,OOO I,OOO I,OOO

Number 75 382 543 I,OOO

Mean 29-9 30.0 26.6 28.I

The dominant year class in both the spring and summer spawning stock is that from rg64 or only 3 year old herring. Thus the age distribution of the autumn herring is very similar to that of the summer herring but differs considerably from the winter herring where older year classes are more pronoun­ced. The overall average age of 3-3 years, although very low for an Icelandic fishery, is, however, somewhat higher than in rg66 when it was only 2.9 years. It should be noted that in all the three fisheries based on the Icelandic herring stocks, the summer spawners appear much more abundant than the spring spawners.

-123- Clupeoid Fish Herring

Table 78. Returns from north and east coast factories 1966

Year Norway North South Total coast coast

1952. 3 I - 4 1953· - 8 -- 8 1954· I 2 - 3 1955· 4 I -- 5 1956. I 1 2

1957· 3 5 - 8 rgsS. 3 5 -- 8 1959· 5 21 3 29 rg6o. 13 30 - 43 rg6r. 12 6o I 73 1962. II gS 2 III I963. 23 29 4 56 1964. 9 73 44 !26 I965. 12 29 23 64 rg66. 64 143 153 360

Total 164 506 230 goo

The length distribution of the south coast autumn herring is shown in Table 77· The length distribution of the mature herring is similar to that of the winter herring as shown in Table 70. The overall mean length of 28.1 em is considerably higher than in 1966 when it was only 27.1 em.

Tagging returns Table 78 shows the returns of tags during the

summer and autumn season 1g66. During this season goo tags were returned as compared with 1,242 in 1g65. The quantity reduced in the re­duction plants was, however, considerably higher in 1g66 than in 1g65. Thus the 1g66 returns are somewhat lower per reduced unit than in 1g65 thus indicating a slightly increased quantity of herring on the fishing grounds in the latter year. The high proportion of south coast tags returned from the north and east coast reduction plants in 1g66 was due to landings of south coast herring transported to these plants. Therefore Table 78 does not give a representative illustration of the ratio of Norwegian and Icelandic herring on the

Table 79· Returns from south-west coast factories 1966

Year Norway North South Total coast coast

I958. 1959· 3 ·- 3 Ig6o. 4 - 4 Ig6r. I 6 7 rg62. 3 2 5 1963. 2 I4 r6 1964. I 20 so 71 I965. I 293 294 rg66. I 593 594 Total 2 35 958 995

north and east fishing coast grounds. It should be noted that during the autumn herring fishery 6 tags were returned from the Norwegian tagging experiment carried out in June 1g66 in the Bear Island herring area. Table 7g shows the return of tags from the south coast reduction plants. Considering the fact that ggs tags were returned from only s8,ooo tons of herring reduced at the south coast as compared with goo returns from 62o,ooo tons reduced at the north and east coast clearly reflects the very small size of the Ice­landic stocks at present.

H. VILHJALMSSON, J. jAKOBSSON

Hafranns6knastofnunin, Skulagata 4, Reykjavik, Iceland.

German investigations on the Atlanto­Scandian herring (Figure 138 ;Table So)

With the start of the herring fishery off the Icelandic East Coast in November 1g65 by the German trawlers, investigations on the Atlanta­Scandian herring stock also began. The participa­tion in the fishery was made possible by the deve­lopment of a midwater trawl by the "Institut fUr F angtechnik".

Table So. Total herring landings of the German fleet in tons

Season

Month

Trawler Lugger ...... . Total ....... .

Season

Month

Trawler L,ugger ...... . Total ....... .

Nov.

814

Sq

Oct.

!,887 44

r ,gSr

1965 Dec.

4,824 270

5,094

Ig66

Nov.

6,020 64

6,084

rg66

Jan. Feb.

3,6gg I,307 346

4,045 1,307

1967 Dec. Jan. Feb.

9,760 7,270 qS ss

g,845 7,270 qS

Total

10,644 ( 94·3 %) 6r6 ( 5,7%)

II,26o (roo %)

Total

25,085 ( gg.z%) 193 ( 0.8%)

25,278 (roo %)

- 124-

15° E 50 10°

- X/66 --- XI/66 ···•·· XII/66 ..166° --·- I/66 --+- II/67 u-.I!I/67

,~~ ~ •.• I '' . -, "'" .... ·.... .:-1. -~ ,.·,·-·-~ i ·~:::.:~ '\ - .. ·-· ... - ·, .. _ ·, ]!('/-+- .......... _+-.... _.,..,_ +,..-+'+

I +- I

64° .... \{

! .,....-·-\ I + I \ -·-·-...

c" 'It ........ " .... -~ ·-·-·-· ~-- It •

t~~::~. • ~· If( .·. ,..~

·· .. · ·. --~ '- I ! ·.,_ .. "\ " I

l ~ ,; -~ / ~ I 0 .0 ...... - -- . ,_ v 0 62 I I I I I I I 1-- ,j\;· I I I I I I I I l ~I&"" I I 162

Figure 138. The Fishing area rg66/r967.

The fishery

In the first season 1965-1966 fourteen trawlers (36 trips) were fishing from November to February in the open ocean, whereas in the second season 1966-1967 thirty-one trawlers (86 trips) took part in this fishery from October to February. In addition, two stern-luggers fished in 1965-1966, respectively in December and January and from October to December.

Table So shows the total catch in both seasons. The main catch came from the trawlers (94-3%, 99-2%)- The landings from the luggers were unimportant (5-7%, o.8%). The total catch in­creased from rr,26o tons to 25,278 tons, the catch of the trawlers from 10,644 tons to 25,085 tons (+ 135-7%). The increase of the total catch in the Norwegian Sea was due to a higher effort in the season 1966-1967. The number of trips increased from 36 to 86 ( + 138.9%), the fishing days from 345 to 994 ( + 188.1%). On the other side the catch per day declined from 30.9 tons to 25.2 tons (- 18-4%). In February and March 1966 fourteen trips were made to the Svin0y area yielding 3,4II tons. In 1967 only eight trips were made to the Haltenbank and Svin0y area with a total catch of 2,289 tons. The catch per day was 35.2 tons.

The fishing area was situated from October to December between 63°5o'N and 66°30'N and 9ooo'W and 12°2o'W. The fishing commenced 1965 at the beginning of November off Seydisfjord between 65ooo'N and 65°30'N and by the beginning of December it moved farther south between 64°30'N

and 64°5o'N, and finally south-eastwards towards the middle of December to the beginning of January 1966 to a point between 64ooo'N and 64°4o'N and 8°oo'W and rr 0 oo'W. Thus the catch area lies within the known wintering area. With the start of the spawning migration to the Norwegian coast, the herring form shoals which are distributed over a large area. During migration these shoals may be widely separated. While they make only small movements in the wintering area, their speed increases as they approach the spawning places at the Norwegian coast. The fishing area changed in the middle of January in a south­easterly direction from an area between 64 °10'N and 63°oo'N, and 8°oo'W and 5°oo'W. From the third decade of January until the beginning of February the fishery moved in a more easterly direction between 63°30'N and 62°30'N, and 5ooo'W and 2°oo'W. Here it stopped and was recommenced at the end of the first decade of February in the Svin0y area, where it lasted till March.

In the season 1966-1967 the fishery started in the second decade of October in the area between 64°30'N and 65°30'N, and 9°00'W and 12°10'W. In November the area was situated between 64°30'N and 65°4o'N, and 10°0o'W and 12°0o'W, whereas in December it took place from between 64°2o'N and 65°3o'N, and 10°oo'W and II 0 5o'W. The course of the fishery in January, February and March was similar to the season 1965-1966. Figure 138 shows the fishing areas in the season 1966-1967.

~-·- --- -~-··-~·------------·

-125- Clupeoid Fish Herring

Biological data

The biological data are given in a monthly split by areas in tables in the Statistical News Letters, No. 40 (total length, maturity stages, age composition, V. S. and gillrakers). The data are summarized in the following.

East coast of Iceland

From November 1965 to January 1966 1,243 herring were collected in 6 samples from this area. The average length varied between 31.41 em and 31.93 em. In the next season 13 samples with 4,159 herring were investigated. The average length varied between 32.56 em to 33.65 em and had increased 1.7 em.

In November 1965 maturity stages V (526%0)

and IV (376%0) formed the bulk of the catches, in addition some stages I to III were observed. From December to January stage IV changed to stage V (783%0, 920%0). One year later, in October 1966, stages IV (388%0) and V (545%0) prevailed. The changing from stage IV to V started in No­vember. In January 1967 the dominating maturity stage was V (904%0).

From October 1965 to January 1966 the year classes 1959 (484-507%0), 1960 (226-351%0)

and 1961 (93-152%0) predominated. In November and December some herring of the year classes 1962 and 1963 were observed, whereas in all months some herring of the year classes older than 1957 were present. No herring of the year classes HJ57 and 1958 were found. In the season 1966-1967 the age composition was the same as in the season before. The 1964 year class was of no importance. The mean number of vertebrae varied in both seasons from 57.12 to 57.22 and the mean number of gillrakers from 49.03 to 49.32.

"Rosengarten''

From this area two samples with 276 herring were examined in January 1966. The average length was 31.12 em. The maturity composition was the same as in January east of Iceland. Maturity stage V (835%0) was predominating. The age com­position was similar to the composition east of Iceland. The number of vertebrae, 57.19 was also similar, only the value for the gillrakers, 48.96, was somewhat lower.

Svinoy

In January and March 1966 three samples with 455 herring and in February 1967 four samples with 1,100 herring were investigated. The average

length was in 1966 31.79 em and 32-46 em respective­ly. In 1967 it was 33-32 em. In January 1966 the maturity stage V (85o0fo0) was dominant, whereas in March spawning herring (6oo0fo0), spent (270%0),

and full herring populated the area. In February 1967 full herring (927%0) prevailed. In January 1966 only the year classes 1959 (459%0), 1960 (347%0)

and 1961 (194%0) were observed, whereas in March also the year classes older than 1958 ( 126° j 00) were of some importance. In February 1967 the se­quence of the year classes was the same as in the beginning of the season.

The mean number of vertebrae fluctuated in both seasons from 57.05 to 57.19 and the number of gillrakers from 48.96 to 49.25.

Haltenbank

From this area three samples with 629 herring were examined in February and March 1967. The average length was 32.21 em, respectively 32.80 em. Maturity stage V (891%0) in February and V and VI (4oo0fo0 and 5400fo0) in March were predominant. The age composition was nearly the same as in the Svin0y area. The mean number of vertebrae was 57.23 and 57.12 and that of gillrakers 49-53 and 49.28 respectively.

General remarks

After the fishing data in 1966 the herring stock was at a high level, but lower (- 18-4%) than in 1965.

The bulk of the herring was formed by the year classes 1959, 1960 and 1961. The average lengths of these year classes were 32.59, 32.22 em and 31.82 em. The 1962 year class is poor, the 1963 brood seems to be somewhat better, but cannot be characterized as a strong age-group. From the low abundance of the year classes 1958 and older (as a result of their poor strength) and from our knowledge about the younger year classes, we may assume that the catch per day of the German fleet in the season 1967/1968 will decline.

K. ScHUBERT

Institut fur Seefischerei, BFA fur Fischerei, Hamburg Germany.

Norwegian herring investigations 1967. The mature herring (Figures 139-141)

During the herring seasons since 1963 two migration routes of the Atlanto-Scandian mature herring have been located to the Norwegian coast viz. the old well-known route of the herring

-!26-

66"

6~·

62"

13.XH 19 66

:.·.~3~\ 6"~~~ ~--­

~--~:-:.~­\ ,'

HERRING -J!!!!I!(- VERY DENSE

---- DENSE ::::: SCATTERED ~VERY SCATTERED

12" 10" a·

5"

I 26. I- .27.1- 28.1-

6" 2" o· 2. ~· 10" 12"

Figure 139.

coming from its wintering area east of Iceland to the spawning grounds off M0re, and a second immigration coming from wintering areas off northern Norway to the R0st Bank and the Vest­fjord area for spawning.

The two migration patterns were followed by the Norwegian research vessels in rg64, rg65 and rg66. The plans were made for investigation of the two migration routes of the mature herring also during the season of 1967.

A cruise with R. V. "Johan Hjort" from r8. November to 4· December rg66 had planned to locate the wintering area of the northern com­ponent of the herring. But this cruise gave negative result, and no mature herring were discovered in the most likely area for wintering. Repeated investigations along the expected immigration route in early January and late February gave similarly negative results. During the expected fishing season no mature herring were caught neither on the R0st Bank nor in the Vestfjord.

The further fate of this northern component of the Atlanto-Scandian herring will be treated in a special paper by DEVOLD and JAKOBSSON.

The wintering area of the mature Atlanta­Scandian herring was located by R. V. "G. 0. Sars" early in December rg66. The herring was followed by R. V. "Johan Hjort" during its spawning mi­gration to the Norwegian coast.

Figure 139 shows the migration route and the temperature condition 4 metres below the surface

along the route at the time when the migrating schools pased through the area. The upper 200 m of the ocean in this region has very homogeneous temperatures in late January and February. The isoterms therefore show the temperatures through which the migrating shoals had to pass. The main part of the schools migrated at depths between roo and 250m in temperatures of 6-8°C.

The first commercial catch of winter herring was taken 45 miles off Ona on 31. January, but the main part of the herring was at that time still about r5o miles off the Norwegian coast.

The total catch of winter herring during the rg67 season was 3,gg6,ooo hi, very close to the prognosis of the catch of 4 million hi. This agree­ment of figure is only a lucky coincidence. We still do not know the efficiency of the fleet of ring-net boats. Without doubt the 1967 catch would have surpassed the rg66 catch if the weather conditions in rg67 had been as favourable as during the rg66 season.

After the spawning the herring left the Nor­wegian coast in late March and early April rg67. Large schools of herring were located by R. V. "Johan Hjort" on 25. June in locality 72°4o'N 3°3o'E and further westwards along the polar front, which followed Mohn's Ridge in the direc­tion of Jan Mayen. The Jan Mayen banks were covered by cold arctic water to about 6o miles east of Jan Mayen (see map Figure 140).

75°4-----------------------------------------------------------------------------------------

74

73

72

71

70

69

68

67

HERRING -~VERY DENSE ----11\HIIIIt- D E N S E

--"H*- SCATTERED

50

-, ... ~,-VERY SCATTERED

,)

660 o:·· ,.

BEAR I~

Q

.. JOHAN HJORT" 19.VI - 11 VII 1967

SURFACE TEMPERATURE

~ HYDR. AND BATHY ST. DRIFTNETS •

• TAGGING LOCALITY

10° 5 0° 5 10 15 20 25°

Figure 140.

H t\) ~

I

g ~ 0

:I:'"'" '" p. ~ ~ s· oo·

(JQJ:r'

-rz8-

76

75

74

73

72

.. HAVDRON"

3.Vll - 9.VIII 1967

SURFASE TEMPERATURE

£ PURSE SEINE CATCH

HERRING

---M!*- VERY DENSE

-- 111\IH!f- DENSE

::·::: SCATTERED

JAN MAYEN

6~ '0~--/~

71 0 0

10 5 0

£R:"P1

/ y 5 10

70 I I

:

15

BEAR IS

Q

20

Figure qr.

In July rg67 the herring moved further east­wards along Mohn's Ridge, and later on north­wards. In August the northern border of the schools were located west of Spitsbergen (Figure I4I) in latitude about J7°N. In September and October rg67 the mature herring schools withdrew again to their wintering area east of Iceland.

Apparently Iceland may have lost its very good geographical position during the feeding period of the mature Atlanto-Scandian herring. In August rg67 the Icelandic ring-net ships had to cover a distance of about 8oo miles before they reached the good concentrations of herring. Next years will show if this is to be a lasting occurence.

F. DEVOLD

Fiskeridirektoratets Havforskningsinstitutt, Nordnesparken z, Bergen, Norway.

Norwegian adult herring fisheries 1967

(Tables Sr-Sg)

The winter herring season

The season lasted from JI. January to 25. March. Catch and effort data for the seasons rg64/67 are given in Table 8r. As in previous years, the herring shoals migrated further north-eastward when they approached the coast, and the main fishing took place between Grip and Halten. In rg67 no fishing took place in Lofoten and the total catch off M0re amounted to 3,gg6,ooo hl. Al­most all the herring were caught by purse seine (g8%) and the average catch per purse seiner was 9A35 hl as compared with r2,534 hl in rg66.

- 129 - Clupeoid Fish

Year 1,000 hl vessels

1964 .......... 2,506 268 I965 .......... 2,148 3I8 1966 .......... 4.788 382 I967 .......... 3.944 4I8

I,OOO hl

130 I03 s8 27

vessels

79 127

43 29

Herring

3,078 2,431 4.955 3.996

Table 82. Catch and effort data from the summer herring season, north and east of Iceland and the Norwegian Sea, 1964/67

Industrial herring Salted herring Total No. of vessels No. of vessels

No. of vessels Catch drift net+ Catch during the Year Purse seine 1,000 hl purse-seine barrels season 1,000 hl Tons

1964 .......... 8g 933 59 Ig6s . . . . . . . . . . 24 341 33 Ig66 .......... s8 44° IS 1967 .......... 79 47I 32

Table 83. Length distribution of Norwegian winter herring (Dfo0) 1967. Maturity stages IV-VIII

Off More. Purse sein;, Gill net

em

28 ............. 29 ............. 30 ............. II 3I ............. go 42 32 ............. 320 3II 33 ............. 343 3II 34· ............ I 58 2I9 35· ............ 30 65 36 ............. I9 I9 37· ............ IS 23 38 ............. 9 8 39· ............ 5 2 40· ...........

I,OOO I,OOO

Total number ... 2,558 479

True mean length 33·38 33·66

The summer herring season off Iceland and in the Norwegian Sea

In 1967 almost no herring were caught on the traditional fishing grounds off Iceland and the figures listed in Table 82 derive from the north­eastern part of the Norwegian Sea.

Biological data

\Vinter herring

During the season 31 samples containing 3,085 fish were examined for age, length, maturity and

44,520 148 ggo 92,003 29,500 57 379 35,209 14.458 73 458 42,549 62,000 III 564 52,487

Table 84. Age composition of Norwegian winter herring (Ofo0) 1967, maturity stages IV-VIII

Year class Age Type

I963 ....... 4 I962 ....... 5 I96I ....... 6 Ig6o ....... 7 I959· ...... 8 I958 ....... 9 I957· ...... IO I956 ....... II I955 ....... 12 I954· ...... I3 I953 ....... I4 I952 ....... I5 I95I ....... I6 I950 ....... I7 I949· ...... I8 I948 ....... I9 I947 ....... 20 I946 ....... 2I 1945 ....... 22 1944· ...... 23 I943 ....... 24

Total number

Mean age

Off More Purse seine

N s IO IO

43 373 373 216 550 307

2 2

2

3 7 5

2 16 I 7 4 2

2I 38 2

Gill net

N s -14

40 35I 406 236 SII 350 - -- -- -

3 2I 7

3 3 6

25 2I

3

I,OOO I,OOO !,000 I,OOO

I,693 58o 325 140

7.8o 7·93 7.87 7·34

racial characters. The length (em below) and age distribution of winter herring are shown in Tables 83 and 84. The samples mainly comprised fish of the 1959, 1960 and 1961 year classes, the earlier so numerous 1950 year class constituting only about Z50foo of the herring in the catches.

-130-

Table 85. Distribution of spawning groups of Norwegian winter herring (0/ 00) 1967

Off More

Spawning group Purse seine Gill net

I ........................ . 6g so II ...................... . 48 45 III ...................... . 565 573 IV ...................... . 241 239 v ........................ . 43 57 VI ...................... . 2 VII ...................... . I -VIII ..................... . 2 IX ................ · .... . 3 5 X ...................... . 9 10 XI ..................... . 3 2 XII ...................... . 4 2 XIII ..................... . 5 5 XIV ...................... . 7 IO

I,OOO I,OOO

Total number. . . . . . . . 2,024 422

The distribution of spawning groups (Table 85) shows that the recruit spawners constituted only 6g0fo0 of the herring in the samples (purse seine) off M¢re, compared with zz60fo0 in rg66 and 464%0 in 1965. Third and four time spawners predominated the catches. The maturity stages of the herring caught from the end of January to the end of March are shown in Table 86. As in the last years most of the herring were already in stage V when the winter herring season started. Spawning commenced (So% of the herring in the samples in stage VI or above) during the last week of February, about one month after the fishing season started.

Norwegian Sea

Length and age compositions of herring sampled during 1967 in the Norwegian Sea and in Ice-

Table 86. Maturity characters of Norwegian winter herring. Percentage maturity (all age-groups) 1967

Off More M~ aturity stages

I II III IV V VI VII VIII No.

February Cjl - 0.3 0.2 5-I Sr.o 13.2 0.2

3 0-4 r.S 76.2 2I.5 March '1' - - 0.6 54·5 44·8

3 - - O.I 60.2 38.6

Table 87. Length distribution of samples from the Norwegian Sea (0 / 00) 1967

Gear Drift net Drift net Purse seine Purse seine Purse seine Month June July July August September Sample No. 301-302 303 304-307 308-309 310-314 em

r6 ............ - 27 17 ............ - - -- 27 rS . . . . . . . . . . . . - - 7 19 ............ 20 ............

21 . . . . . . . . . . . . 22 . . . . . . . . . . . . - I4 23 . . . . . . . . . . . . ro I4 24 ............ - - I4 25 . . . . . . . . . . . . - - 41 26 ............ - - I4 27 ............ - 14 28 ............ IO - 7 29 ............ r8 - - 5 30 ............ 31 3 I5 27 31 ............ 25 IO IO 5 27 32 ............ So go roS IIO 121

33 . . . . . . . . . . . . 269 300 379 4°5 269 34 ............ 258 380 352 320 215 35 ............ II7 1IO 95 II5 74 36 ............ rS IO 28 10 54 37 ............ 86 6o IO IS 20 38 ............ 49 10 10 - -39 ............ 49 IO 5 - I4

I,OOO 1,000 I,OOO I,OOO I,OOO

Total number .. 163 roo 400 200 qS

True mean length 34·87 34-22 34-II 33-96 32.00

O.I

Trawl December 315-316

I3

53 53

414 321 133

13

I,OOO

75

33-93

1,072 925 330 420

-I3I- Clupeoid Fish Herring

Table 88. Age composition of samples from the Norwegian Sea (0/ 00) 1967

Gear Drift net Drift net Purse seine Purse seine Purse seine Trawl Month June July Sample No. 30I-302 303 Year class A.ge

Ig65 .... 2 - -Ig64 .... 3 - II Ig63 .... 4 54 li Ig62 .... 5 7 --Ig6I .... 6 I34 I 56 Ig6o .... 7 262 278 Ig5g .... 8 382 467 Ig58 .... g - -Ig57 .... IO - -Ig56 .... II -- -Ig55 .... I2 Ig54 .... I3 7 Ig53 .... 14 I3 22

Ig52 .... I5 7 II Ig5I .... I6 20 II Ig50 .... I7 II4 33

I,OOO I,OOO

Total number qg go

Mean age 8.6 7·g

Norwegian tribe (N + S type) Ofo g4·3 g8.g

Uncertain tribe 5·7 I. I

Table 89. Norwegian herring samples (research vessel samples) from the Norwegian Sea 1967

No. of sample Date Locality Gear

30I 25. June N 72o37' E 03o5o' Drift net 302 2g. June N 71°20' E oi 0 3o' Drift net 303 5· July N 7Io 53' E oz 0 oo' Drift net 304 IO. July N 72°22' E 03°I5' Purse seine 305 I6. July N 73°45' E I0°3o' Purse seine 306 22. July N 73°4o' E I0°oo' Purse seine 307 30. July N 73°33' E o8°oo' Purse seine 308 3· August N 76°I8' E I2°oo' Purse seine 30g 6. August N 76°Io' E rz 0 rz' Purse seine 3IO 3· September N 70°40' E ogo57' Purse seine 3II 5· September N 75°30' E o8°oo' Purse seine 3I2 g. September N 75°o5' E o6°Io' Purse seine 3I3 I3. September N 72o5o' E os 0 oo 1 Purse seine 3I4 Ig. September N 7I 0 4g' E 03°oo' Purse seine 3I5 IO. December N 63°44' W o8°25' Trawl 3I6 I I. December N 63°57' W 08°35' Trawl

landic waters are given in Tables 87 and 88. The sampling localities are listed in Table 8g. In the purse seine samples from the north-eastern part of the Norwegian Sea the 1959, rg6o and rg6r year classes predominated. The drift net catches from the same area were slightly more mixed up with older fish than the purse seine catches. In September a relatively small influx of young fish was noticed in the purse seine samples. The

July August September December 304-307 308-3og 3I0-314 3I5-3I6

- I6 - 85 14

3 3I 3g 27 3 5 8

I07 IOO I40 I37 327 304 I85 32g 534 540 464 47g - - 8 - - 8 - 5

5 - IO I6 I6 - 8

5 5 23 I4 I,OOO I,OOO I,OOO I,OOO

382 Igi I2g 73

7·6 7·5 7·2 7·3

g8.5 g8.5 gz.I g7·3

1.5 !.5 7·g 2.7

age composition of the herring caught in the over­wintering area in late autumn rg67 was similar to that obtained during the summer season.

0. DRAGESUND

Fiskeridirektoratets Havforskningsinstitutt, Nordnesparken 2, Bergen, Norway

Norwegian investigations in 1967 on eggs and larvae, small and fat herring

(Tables go-g3)

Surveys

From 7· to 17. March a cruise was undertaken with R.V. "Johan Hjort" in order to locate the spawning grounds by means of grab sampling. Unfortunately no concrete spawning patches could be located, mainly due to exceptionally bad weather conditions. The larvae and their distribution were investigated during two cruises from 28. March to 14. April. The most dense concentrations of larvae were found on the shelf between Runde and Grip, whereas further north off Fr0ya, Halten and Sklinna almost no larvae were recorded. In the Lofoten region no larvae were observed.

-132-

Table 90. The landings of immature herring (mill. hl.) in the different districts, 1967

Area

Finnmark ...... . Troms ........ . Nordland/

N. Trondelag ... S. TrondelagfMore

and Romsdal ... Sogn and Fjordane Hordaland.

Rogaland .... . Skagerak ........ .

Total .......... .

Small herring mill. hl %

o.I5I 0.484

0.355

O.I2I O.OI3

0.020

0.007

I.I5I

I3.2 42.0

30.g

Io.s I. I

!.7 0.6

IOO.O

Fat herring mill. hl %

2.g30 o.I88

0-43I

O.I6I 0.004

0.007

3·72I

78·7 5-I

II.6

4·3 O.I

0.2

IOO.O

Table 91. The landings per month (in million hl) of immature herring, 1967

Month Small Fat herring Total herring

January ...... . February ..... . March ........ . April ........ . May ........ . June ........ . July ........ . August ...... . September .... . October ...... . November December .... .

Total ........ .

0-4g4 0.035

O.OOI 0.062 o.258 o.ogi O.OI2 0.043 0.067 o.o6g o.oig

I. I5 I

o.oos

0.32g 0.257 0.674 o.88s 0.76I 0.308 0.323 O.I4g 0.030

3-72I

0-4gg 0.035

0.330 0.3Ig o.g32 o.g76 0.773 0.35I 0.3go o.2I8 o.o4g

4·872

From rs. August to 20. September a joint international 0-group fish survey in the Barents Sea and adjacent waters was carried out. 0-group herring were only located in small numbers in isolated patches in the south-western part of the investigated area and off North Cape. The abundance of the rg67 year class was probably lower than that of the rg66 year class, which was a very poor one. Thus, in all three years during which the joint surveys have been carried out, the recruitment to the Norwegian spring spawning stock of herring appears to have been extremely low. It is, there­fore, to be expected that the impact of these three very poor year classes on the abundance of the exploited stock will in due time be seriously felt.

The fishery

The total catch of immature herring landed in Norway in rg67 amounted to 4,872,ooo hl, r,rsr,ooo hl being taken as small herring and 3,72I,ooo hl as fat herring and "forfangstsild". The yields landed in the different districts are shown in Table go. It will be seen that the most important fishing areas for small herring were Troms and

Table 92. Length distribution of small and fat herring in the different districts (0 / 00) 1967

II.5 12.0

-.s I3.0 -.s

14·0 -.s

I5.0 -.s

I6.o -.s

I7.0 -.s

I8.o -.s

Ig.o -.s

20.0 -.s

2!.0

-.s 22.0 -.s

23.0 -.s

24.0 -.s

25.0 -.s

26.0 -.s

27.0 -.s

28.o -.s

Length em

Total number ..

True mean length

Finnmark

3 6 g

g 2g

63 6I

86 72

I2I I24

66 66

52 66

55 26

14 23

g

14 I4 6

3 3

I,OOO

347 2I.g5

Nordland

IO

30 30

so gi

III 8I

I4I I4I

I62 gi

4I

20

I,OOO

gg

I5.I7

Sogn og Fjordane

5

40 go

gs go

I35 I35

I 50 8s

70 so

30 20

5

I,OOO

zoo

I6.67

Nordland/North Tnmdelag, whereas the majority of the fat herring were caught off Finnmark.

Nearly half of the total catch of small herring was landed in January, whereas the most important fat herring fishery took place during the summer (Table gr).

Biological data

The small herring catches consisted almost entirely of the 1967 and rg66 year classes.

Length and age compositions of small and fat herring are presented in Tables 92 and 93· It should be noted that small and fat herring are recorded in the fishery statistics according to weight (length).

-I33- Clupeoid Fish Herring

Table 93· Age composition of small and fat herring in the different districts (Ofo0) 1967

Year class Finn mark Nordland Sogn og Fjordane

1966 ........... - I,OOO I,OOO

1965 ........... 1964 ........... 661 1963 ........... 339

1,000 1,000 1,000 Total number ... 239 99 200

Thus fat herring comprise fish ranging in weight from about 55 to r50 g or in length from r8.o to 28.0 em. The herring therefore listed in Tables 92 and 93 for Nordland, Sogn and Fjordane will be recorded as small herring, whereas those for Finnmark will be grouped as fat herring. The length distribution of 0-group herring (the r967 year class) is not listed in Table 92 and 93· Judging from Table 93 it will be seen that the fat herring sampled off Finnmark comprised two year classes, the r964 one predominating.

0. DRAGESUND

Fiskeridirektoratets Ha vforskningsinstitutt, Nordnesparken 2, Bergen, Norway.

Norwegian herring tagging experiments and tag returns

(Tables 94-98)

The tagging localities and number of fish tagged according to type of tag are listed in Table 94· All the herring were caught by purse seine.

The amount of winter herring reduced to oil and meal in r967 were 3,I33,000 hl compared with 3,98r,ooo hl in r966 (Table 95). In the summer of r967 47r,ooo hl were caught by the Norwegian fleet in the north-eastern part of the Norwegian Sea for oil and meal processing (Table 96).

A comparison of the recaptures from the summer herring fishery during the last four years is shown in Table 96. In r967 a total of 29r internal tags

Table 95· Landings (mill. hl) for oil and meal processing in Norway, 1963-1967

Season Year 1963 1964 1965 1966 1967

Norwegian winter herring season

Summer herring season north and east of Iceland and in the Nor­wegian Sea

0,079 2,497 1,939 3,981 3,133

1,046 0,877 0,341 0,+37 0,+71

were received from the different factories, 270 during the winter herring season and 2I during the summer season in the Norwegian Sea. Out of a total number of 270 recovered tags during the winter herring season, r2o were tagged· as spring and large herring, "forfangstsild" and fat herring, and r5o were tagged as north and east coast herring. Out of the 2I tags recaptured during the summer fishery in the Norwegian Sea, 12 had been released off north and east Iceland and in the Norwegian Sea, whereas 9 were tagged as winter herring and fat herring off the Norwegian coast. The per mille returns per mille hl of I-tags (herring tagged off Iceland andjor in the Nor­wegian Sea) and N-tags (herring tagged off the Norwegian coast) during the seasons r959-r967 are shown in Table 97-

During r967 a total of 4,300 herring were tagged in the north-eastern North Sea, Skagerak and the Shetland waters. Except 250 herring tagged with Scottish combination tags, all the herring were tagged with internal steel tags. The details of liberation are listed in Table 94-

The overwhelming part of the recaptures was returned from Norwegian plants equipped with magnets. The amount of North Sea herring re­duced to oil and meal in r967 were 3,532,000 hl compared with 4,8r5,ooo hl in r966. During r967 a total of 44I returns were received from herring tagged in the North Sea area.

The corresponding figure for r966 was r,o58 re­turns. 9 of the recaptures in r967 were from the

Table 94· Tagging experiments, 1967

Number of liberations Category Date Area by type of tag

Spring herring ............. 10. March Runde 294 Internal North Sea herring .......... 30. May N 60°28' w 02°35' 250 Internal North Sea herring .......... 30. May N 60°28' w 02035' 250 External North Sea herring .......... 31. May N 60°43' w 01°53, 300 Internal North Sea herring .......... 17. June N 61°10' w 00035' 1,000 Internal North Sea herring . . . . . . . . . . 18. June N 60°36' w 02°48' 700 Internal North Sea herring .......... I. July N 58°n' E 03°48' 500 Internal Open Ocean herring ......... 5- July N 71°53' E 02°oo' I,OOO Internal North Sea herring . . . . . . . . . . 24- November N 57°32' E 07oi5' 1,300 Internal

-134-

Table 96. Number of returns of internal tags in 1964, 1965, 1966 and 1967 from the different experiments. The within season recoveries and tags received from factories without magnets are excluded

The summer herring season, Number The Norwegian winter herring north and east of Iceland,

Year of tagging Category tagged season and in the Norwegian Sea I964 I965 I966 I967 I964 I965 I966 I967

I95I ......... NH 3,064 I952 ......... NH I7,308 2 I953 ......... NH IO,I8I I954 ......... NH 8,783 3 2 - I 2 I955 ......... NH 9,24I - - I

I956 ......... NH 8,443 I 2 I - I 2 I957 ......... NH 7.550 2 I I I I958 ......... NH 9,594 2 I 4 6 I959 ......... NH 9.946 I2 6 7 5 7 5 I960 ......... NH 6,847 5 3 5 I 9

I96I . . . . . . . . . NH 9,450 28 17 18 IO 25 I4 I962 ......... NH Io,668 30 2I 32 I3 40 II I963 ......... NH 2,900 I3 7 9 2 27 I I I964 ......... NH 4,987 - I9 42 I3 - 6 2

I965 · · · · · · · · · NH 999 - IS II - - - 2

I966 ......... NH I,soo 54 - - - 6 I966 ......... NH 4.8so - - - 39 - 2

Total ........ 97 82 I34 ISO !21 43 6 I2

I951 ......... SH 9,986

I952 ......... LH I0,295 I952 ......... SH ro,863 2 2 I 3 I952 ......... FH 7.971

I953 · · · · · · · · · LH Io,o8o I953 ......... SH I0,046 I953 ......... FH 8,496

I954 ......... LH I0,042 - I - - 2 I954 ......... SH I0,29I 4 I - - 2

I954 · · · · · · • · · FH !4.970 2 - - 2

I955 ......... LH I0,045 I955 · · · · · · · · · SH 9,087 I955 ......... FH I3,586 3

I956 ......... LH 4.998 2 I I956 ......... FH I2, 799 I 2 2

I957 ......... LH 9,500 2 I

I957 · · · · · · · · · SH 8,450 I - I

I957 ......... FH 3,900

I958 ...... · · · SH 9,998 I 3 2 I958 · ..... · · · FH 6,200 I I I 2

I959 · · · · · · · · · SH I3,950 9 2 3 I 3 I959 ......... FH 8,Ioo I2 4 5 3

I960 ...... · · · LH 2,449 II 7 3 - 2 I960 ....... · · SH I,soo 4 - 5 I960 ..... · · · · FH 2,000

I96I . . . . . . . . . LH 400 2 I96I ......... FH I,450 7 2 7 8

I962 ..... · · · · LH I,SSO II II 5 6 3 I962 ..... · · · · FH 2,700 IS II II 6 4

I963 · · · · · · · · · SH 3,000 9 9 5 3 7 I963 ......... FH 2,500 II 7 2I I3

I964 · · · · · · · · · SH s.soo - I I

I964 · · · · · · · · · FH 3,300 - 9 I7 I4 - - 5 3 I965 · · · · · · · · · SH 700 - I7 I2

I966 ....... · · LH I,soo - - 2I I966 ..... · · · · SH I,8oo - - 29 - - - 3 1966 ......... FH I,989

Total ........ Io8 78 I05 120 40 2 9 9

-135- Clupeoid Fish Herring

Table 97· Returns' of Icelandic tags (1-tags) and Norwegian tags (N-tags) off Iceland and in the Norwegian Sea and · during the Norwegian winter herring fishery

I-Tago N-Tags Returns Returns per mill. hi Returns Returns per mill. hi

Year of Year of off off in o/oo off off in o/oo tagging return Iceland* Norway Iceland Norway Iceland* Norway Iceland

I958 I959 40 22 I9.95 !.52 2 6z 0.96 I959 I960 63 34 I5·37 3·37 5 I6 o.87 I963 I964 27 I3 IJ.ZI 3·39 7 9 4-3I I964 I965 6 I9 I3·37 3·14 0 IO 0.00 I965 I966 0 I3 0.00 s.oz I I7 I r.8I I966 I967 8 93 IZ.I9 9·I9 4 so 8.59

* Returns in I967 derive from the summer herring fishery in the north-eastern Norwegian Sea.

Table 98. Returns of tagged North Sea herring in 1967

Returns Year of Area of Number North Sea tagging tagging tagged Shetland NE North Sea Skagerak (not specified)

I965 Skagerak 4,000 1966 Sheltland 4,000 35 I966 NE North Sea 4,000 I7 I967 Skagerak I,300 I967 Shetland z,soo 43 I967 NE North Sea soo z

Total 97

Norwegian winter herring fishery off Mv.>re, whereas the remaining ones came from different parts of the North Sea and Skagerak. Table g8 shows the num­ber of returns by area for the North Sea herring.

0. DRAGESUND, S. HARALDSVIK

3 z 37 I 57

IZ6 6 43 I 4 7

IZ I8 II I 6

I90 IZ I33

Scottish herring fisheries, 1967 (Tables 99-I2Z)

North Sea

The fisheries

Drift net

Norway

4.I6 I. I5 2.2]-

2-49 9·37 6.97

More

I

6 z

9

Fiskeridirektoratets Havforskningsinstitutt, Nordnesparken z, Bergen, Norway.

In rg67 the drift net fishery commenced at the beginning of May and continued until the second

Catch in crans ......... . No. of hauls .......... . Average catch

per haul (crans) ..... .

Catch in crans ....... . No. of hauls .......... . Average catch

per haul (crans) ..... .

Catch in crans ....... . No. of hauls .......... . Average catch

per haul (crans) ..... .

I964

6,146 2!2

29.0

6z,zs8 2,58I

24.I

38,607 Z,234

IJ.3

Table 99· Drift net fishing

Scotland, East Coast, I964-67 I965 I966 I967

2,292

202

II.3

65,ZII Z,960

22.0

42,86o 2,IJ8

I9·7

Total May June July

North-eastern North Sea (east of Z0 E)

so6 392 39Z z6 IS IS

I9-5 z6.I z6.r

North-western North Sea (North (west of Z0 E and north of 59°N)

J2,8Z4 77.453 II,382 20,072 I5,Z73 Z,JI9 z,638 4Z4 773 740

z6.8 Z9-4 26.8 z6.o zo.6

North-western North Sea (South) (west of Z

0 E, south of 59°N and north of 55°3o'N)

I2,5JI 5,092 IO 4,5I9 14 58o 289 7 2z6 I7

ZI.7 IJ.6 !.4 20.0 0.8

Aug.

30,053 664

45·3

IZ7 I6

7·9

Sept.

673 37

I8.z

42Z Z3

I8.3

-136-

Table 100. Purse seine fishing

Scotland, East Coast, 1966-67

1966 Total June

1967 July Aug. Sept.

Catch in crans No. of arrivals Average catch per arrival (crans) ............ .

Catch in crans No. of arrivals ............................ .

30 I

30.0

North-eastern North Sea (east of z 0 E)

North-western North Sea (North) (west of Z0 E and north of 59°N)

I0,4IZ I,3Z6 4,076 4,503 85 14 35 34

507 z

Average catch per arrival (crans) ............ .

5.756 33

174·4 IZZ.5 94·7 116.5 13z.5 Z53·5

North-western North Sea (South) (west of Z0 E, south of 59°N and north of 55°30'N)

Catch in crans IZO IZO No. of arrivals ............................ . z

6o.o z

Average catch per arrival (crans) ............ . 6o.o

Table 101. Trawled herring landed in Scotland-East Coast 1964-67

Catch in crans Hours fishing ............. . Catch(roo hours (crans)

Catch in crans .......... . Hours fishing ............ . Catch(roo hours (crans)

Catch in crans Hours fishing ............. . Catch(1oo hours (crans)

Catch in crans .......... . Hours fishing ............. . Catch(1oo hours (crans) ... .

1964

5,331 I,OZZ

5ZI.6

1965 1966 1967 Total Feb. April May June July Aug. Sept. Oct.

North-eastern North Sea (east of Z0 E and north of 57°3o'N)

5,6r6 3,073 558 z5r - 140 I,Z05 830 Z07 37 105

466.1 370.3 z69.6 678.4 - 133.3

!67 65

Z56·9

Fladen-Shetland (north of 57°3o'N and between Z0 E and Orkney-Shetland)

5,896 1,718 1,637 1,588 16Z 17Z - 100 710 Z37 16Z 45 1,943 641 8z3 68o z5 159 70 zz5 76 95 30

303.0 z68.o 198.9 Z33·5 648.0 108.z - 14z.9 315.6 311.9 170.5 150.0

7,Z50 898 807·3

West of Orkney and Shetland

554 - - 75 3ZO 159 Z46 - - so 104 9Z zzs.z 150.0 307·7 17Z.8

Gut and southwards (south of 57°30'N and west of Z0 E)

z,z68 76 477 5 475·5 1,514.0

Table 10z. Length, age and maturity composition- north-eastern North Sea - drift 1967

July 1 ••••••••

Year class

July ... · · · · ·

July . · · · · · ·

A. Per mille length composition (all age groups) Length in ems.

Z3 Z4 zs 26 Z7 z8 29 30 31 32 Mean No.

ZI.7 - ZI.7 87.0 15Z.Z 304·3 z6o.9 87.0 6s.z Z9.14 46

B. Percentage age composition Number of winter rings

z 3 4 5 6 7 8 9 10 10+ No.

1965-66 1964-65 1963-64 1g6z-63 1961-62 1960-61 1959-60 1958-59 1957-58 1956-57 1955-56

z.z 19.6 63.0

I II

z.z

6.5 Z.2 6.5

C. Percentage maturity (all age groups) Maturity stages

III IV V VI

34·8 45·7 13.0

VII

and older

VIII

4·3

No.

46

46

-137- Clupeoid Fish Herring

Table 103. Age composition of spring- and autumn-spawned herring north-eastern North Sea

week in September. The monthly catch and effort statistics and the total for the year are given in Table 99 together with the totals for the pre­vious three years.

Drift I967

Spring group Autumn group

Year Winter Number Year Winter N urn ber Throughout the season most of the fishing was centred around Shetland, 88% of the drift net herrings being caught in these waters. The drift net fishery at Shetland can be divided into three periods. During May, June and early July good catches were made mainly to the west and north of the islands. A period of two weeks followed in which catches were poor all round the islands, the average

class rings July

I966 ... . I96s ... . I964 ... . I963 ... . I962 ... . I96I. .. .

Total

2

3 4 5 6

6

6

class rings July

I965 .... I I964 .... 2 9 I963 .... 3 23 I962 .... 4 3 I96I. ... 5 I I960 .... 6 3

Total 40

Table 104. Length, age, and maturity composition -north-western North Sea - north of 59°N - drift 1967

A. Per mille length composition (all age groups) Length in em

22 23 24 25 26 27 28 29 30 3I 32 33 34 35 36 Mean No.

May ........ - - 2.6 24-6 II9.2 I73.6 I30.8 99·7 I2I.8 I73.6 I04·9 27.2 IS-S 5-2 1.3 29.06 772 June ........ - - 4·7 45-I 94·8 I62-4 I25.8 I07.0 123.0 191.6 97-7 34·7 II.3 1.9 - 29.07 I,o6s July ........ -5-2 I8.4 6s.s u8.o IS2.0 I84.8 I48.I 97·0 I12.7 6::>.3 24-9 10.5 2.6 - z8.44 763 August ...... 1.8 8.o 6.2 II.S 36·3 I38.2 I76·3 I83-4 194·9 132.0 8o.6 18.6 9-7 2.7 - 29-14 I,I29 September ... - - - 40.0 6o.o 26o.o I6o.o I8o.o I40.0 I40.0 20.0 - - - 29-46 so

B. Percentage age composition Number of winter rings

2 3 4 5 6 7 8 9 IO Io+ No.

Year class I965-66 I964-65 I963-64 I962-63 I961-62 1960-6I I959-60 I958-59 I957-58 I956-57 I955-56 and older

May ...... - 2.7 45·3 I0.7 12.7 15.8 2-4 3·5 3-2 3-2 0.3 772 June ...... - 6.o 46.8 8.9 9-3 17-5 I. I r.s 3-I 4·9 o.s I,o6o July ...... - 20.2 51.6 6.7 4·6 9-4 1.0 0.6 1.9 3·1 0.3 759 August .... 1.3 I4.8 57·3 6.I 6.o 9-9 0.7 0.4 0.7 1.4 0-4 I, I I7 September . - I4.0 48.0 S.o I4-0 IO.O 2.0 2.0 - 2.0 so

C. Percentage maturity (all age groups) Maturity stages

I II III IV v VI VII VIII No.

May ........ 0.3 2.3 23.6 19.6 0.9 1.8 2.6 49·0 772 June ........ 1.2 7·0 46·5 22.5 2.6 0.1 0.2 I9.8 I,o6s July ........ 3·7 13.0 30.1 30.8 7·5 O.I 0.3 q.6 763 August ...... 3-I 11.4 I3.6 I8.I II.7 4·7 I. I 36·3 I,I29 September ... - 4·0 IO.O 2.0 I8.o IO.O - 56.0 so

Table 105. Age composition of spring- and autumn-spawned herring- north-western North Sea: North of 59°N- drift 1967

Spring group Autumn group Total sample Year Winter Number Year Winter Number Number class rings May June July Aug. Sept. class rings May June July Aug. Sept. Spring Autumn

I966 ... I - - IO - I965 ... I - - 5 - IO 5 I965 ... 2 6 27 57 78 2 I964 ... 2 IS 37 97 88 5 I70 242 I964 ... 3 45 94 I8I 263 5 I963 ... 3 304 403 2IO 379 18 588 1,3I4 I963 . · · 4 I 4 3 2 - I962 ... 4 8I 90 48 66 4 IO 289 I962 ... 5 II 9 3 2 - I96I ... 5 87 9I 3I 66 6 25 z8I I96I ... 6 IZ 24 IO IS - I960 ... 6 IIO I6I 62 94 5 64 432 I960 ... 7 5 5 2 3 - I959 ... 7 I4 6 5 4 - IS 29 I959 ... 8 14 9 4 3 - I9S8 ... 8 I3 7 I I I 30 23 I958 ... 9 - - I - - I957 ... 9 25 32 I4 8 I I So I957 ... IO I - - - - I9S6 ... IO 24 52 24 I6 - I II6 I956 I955 and older Io+ - - - - - and older Io+ 2 5 2 4 I I4

Totals .. 95 I72 26I 379 7 Totals .. 675 884 494 731 4I 914 z,Szs

-138-

Table 106. Length, age, and maturity composition- north-western North Sea- south of 59°N and north of 55°3o'N- drift 1967

A. Per mille length composition (all age groups) Length in em

20 21 22 23 24 25 26 27 28 29 30 31 32 Mean No.

June .......... 5·3 3·9 13.2 15.8 7I.I 219-7 294-7 256.6 97·4 15.8 5·3 1.3 - 26.oo 760 August ........ - - 8.6 86.2 137-9 r8r.o 284-5 q6.6 103-5 43·1 8.6 27·77 rr6

B. Percentage age composition Number of winter rings

2 3 4 5 6 7 8 9 IO ro+ No.

Year class 1965-66 1964-65 1963-64 1962-63 1961-62 196o-6r 1959-60 1958-59 1957-58 1956-57 1955-56 and older

June ..... 2.6 37·0 52.2 7-I 0.3 0.5 758 August ... 19.8 59·5 13.8 0.9 5-2 - II5

C. Percentage maturity (all age groups) Maturity stages

I II III IV v VI VII VIII No

June ...... 4-5 13-9 49·9 12.1 1.3 - O.I r8.2 760 August ...... 1.7 31.9 65·5 0.9 - rr6

Table 107. Age composition of spring- and autumn-spawned herring- north-western North Sea- south of 59°N and north of 55°30'N - drift 1967

Spring group Year class Winter Number Year class

rings June August

1966 ..... I I - I965 . .... I965 ..... 2 40 3 I964 ..... r964 ..... 3 14 2 I963 ..... I963 ..... 4 I - 1962 . .... I962 ..... 5 - - I96I ..... 196I ..... 6 I - I96o ..... I96o ..... 7 - I959 ..... I959 ..... 8 - I958 . .... I958 ..... 9 - -· I957 ..... 1957 ..... IO I956 ..... I956 I955

and older Io+ - and older Total .... 57 5 Total . ...

catch falling to 8 crans per haul. The fishing then revived at the end of July and very good catches were made to the east and south of Shet­land (d. Annls biol., Copenh., 23.) The poor fishing at Shetland coincided with a short-lived, but pro­ductive, fishery on the Noup grounds, to the west of Orkney. This area was formerly well known as a herring fishing ground but there has been little fishing in this area for many years.

From the Buchan grounds there were only occasional small catches except for a period of two weeks in June when there was a fairly productive fishery in an area 50-60 miles E x N from Fraser­burgh.

The spawning fishery at Clythness, on the north coast of the Moray Firth, was late in starting and lasted for only a week in September.

Autumn spring Total sample Winter Number Number rings June August Spring Autumn

I I9 I I9 2 239 20 43 259 3 383 67 r6 450 4 53 I6 I 69 5 2 I - 3 6 3 6 I 9 7 8 9

IO

Io+

699 IIO 62 809

Purse seine

Nine Scottish vessels fished with purse seines between June and September rg67. The catch and effort data by months and the total for the year, and for rg66, are given in Table roo.

Most of the landings were from Shetland waters and the average catches by purse seine from that area do not show the division into three periods found in the drift net catches.

In addition, foreign purse seiners landed over 30,000 crans of herring at Lerwick, all for reduction to meal and oil.

Trawl Herring trawlers, mainly Swedish and Danish,

landed catches at Aberdeen throughout the year. In previous years it was possible to separate the

-139- Clupeoid Fish Herring

Table 108. Mean length (em) of 2-5 ringed herring in north-western North Sea, south of 59°N and north of

55o3o'N

2 3 4 5 1950 ....... 24-51 24-92 26.o5 27-73 1951. · · · · · · 24-73 25-76 25-93 26-49 1952 ....... 24.86 26.25 26.82 27.26 1953 · · · · · · · 24-54 26.37 27.00 28.09 1954 ....... 24.69 26.92 28.12 28.71 1955 ....... 24.18 26.81 28.68 29-34 1956 ....... 24-76 26.97 28.36 29·43 1957 ....... 24.28 26.r6 28.30 29-31 1958 ....... 24-51 26.76 28.09 28.97 1959 ....... 24.88 26.28 28.25 29.25 1960 ....... 24-57 26.14 27-75 28.86

1961 ....... 24-96 26.84 28.22 28.96 1962 ....... 25.67 27.10 28.35 29.05 1963 ....... 25.81 27-46 28.47 29.29 1964 ....... 25.86 28.28 28.28 29-49 1965 ....... 24-78 27-94 29-45 29-50 1966 ....... 24-90 26.73 29-43 30.03 1967 ....... 25-32 26.79 27.27 28.33

fishing grounds in the north-western North Sea into three distinct areas, Fladen, Shetland, and Gut. In 1967, it was not possible to separate the landings in this way because of the wide spread of the grounds fished. The catches have been grouped as Fladen-Shetland and west of Orkney-Shetland: there were no landings from south of 57°3o'N. This is the first year in which there have been landings of trawled herring at Scottish ports from grounds west of the Orkney and Shetland Islands.

Biological data

Drift net

North-eastern North Sea (grounds east of Z

0 E) There was very little fishing in this area and

only one sample was examined. The length, age, and maturity compositions of this sample are given in Table 10Z and the age compositions of the spring- and autumn-spawned fish are given in Table 103.

The 1963 autumn year class supplied half the fish sampled.

North-western North Sea (grounds west of zoE and north of 55°30'N)

The samples from this area have been divided into those taken north and south of 59°N.

Samples from north of 59°N The length, age, and maturity compositions

of these samples are given in Table 104, and the age compositions of spring- and autumn-spawned herring are given in Table 105.

In May and June spring-spawned herring made up 14% of the fish sampled and in the period July to September 34%- The dominant spring year class throughout was the 1964 (3-ringed) one which contributed 64% of the spring-spawned herring. The 1963 year class (47%) was the pro­minent one among the autumn-spawned herring

Table 109. Length, age, and maturity composition- north-western North Sea-- north of 59°N- purse seine 1967

A. Per mille length composition (all age groups) Length in em

21 22 23 24 25 26 27 28 29 30 31 32 33 34 Mean No.

June ............ II.6 SI.4 r86.o 127-9 139-5 69.8 162,8 162.8 58.1 29-33 S6 July ............ 25.0 37-5 II2.5 50.0 150.0 225.0 2S7·5 87-5 25.0 30.68 So August .......... 20.0 93-3 73-3 20.0 13-3 6o.o 106.7 qo.o IOO.O 173-3 140.0 46·7 13-3 27.71 150 September ....... so.o 25.0 50.0 125.0 150.0 325.0 zzs.o 25.0 zs.o 30·45 40

B. Percentage age composition Number of winter rings

2 3 4 5 6 7 s 9 IO ro+ No.

Year class 1965-66 1964-65 1963-64 1962-63 1961-62 1960-61 1959-60 1958-59 1957-58 1956-57 1955-56 and older

June ........ s.s 39·5 II.6 ro.s 15.1 1.2 4-7 11.6 86 July ........ 2.5 25.0 5-0 8.8 33·8 L3 5.1 2.5 13.8 2.5 So August ...... 19-3 1S.o 44·7 7·3 3-3 4·0 0.7 0.7 2.0 149 September ... 7-5 42-5 17-5 IO.O 17-5 2.5 2.5 40

C. Percentage maturity (all age groups) Maturity stages

I II III IV v VI VII VIII No.

June .......... +7 14.0 43·0 26.7 !.2 ro.5 86 July .......... r8.8 62.5 13.8 s.o So August ........ 20.7 12.7 24·7 5-3 L3 2.0 0.7 32·7 150 September ..... 17-5 2.5 8o.o 40

-I40-

Table no. Age composition of spring- and autumn-spawned herring- north-western North Sea- north of 59°N- purse seine 1967

Spring group Autumn group Total sample Year Winter Number Year Winter Number Number class rings June July Aug. Sept. class rings June July Aug. Sept. Spring Autumn

I966 ... I - 20 I965 ... I - - 9 20 9 I965 ... 2 I - IS I I964 · · · 2 4 2 I2 2 I7 20 I964 · · · 3 5 6 46 9 I963 · · · 3 28 I4 20 8 66 70 I963 · · · 4 - I962 ... 4 IO 4 II 7 - 32 I962 ... 5 - - -- -- I96I ... 5 9 7 5 4 - 25 I96I ... 6 - 3 I 2 I96o ... 6 I3 24 5 5 6 47 I96o ... 7 - I I - I959 ... 7 - - - - 2 I959 ... 8 -- I - - I958 ... 8 I 3 - - I 4 I958 ... 9 - - - - I957 ... 9 4 2 I I - 8 I957 · · · IO 2 - - - I956 ... IO 8 II 3 -- 2 22 I956 I955 and older Io+ - - - and older Io+ - 2 - I 3 Totals .. 8 II 83 I2 Totals .. 77 69 66 28 IJ4 240

Table III. North Minch herring catches 1967

Catches (crans) No. of arrivals Catch per arrival (crans) Drift net Ring net Pair trawl Drift net Ring net Pair trawl Drift net Ring net Pair trawl

January ...... I0,595 I8,5oi II,749 260 February ..... I5,398 7.647 5.759 380 March ........ II,321 I,748 4,873 474 April ......... I,932 709 I3 I78 May ......... I03 I,354 - IO June ......... 39 3I7 - 8 July ......... I63 I,046 - I4 August ....... I,700 3,I25 - 88 September .... 2,065 2,554 - I4I October ...... 3,I58 I,359 363 203 November ..... I8,3o8 II,459 3.57I 476 December .... 9.547 7,076 4,0I5 277

but there was a wide spread of age groups with the rg6o year class (rs%) noticeable and the rg56 year class (as ro-ringed fish) still contributing 4% to the autumn stocks.

There were only a few ripe herring in the samples and it would appear that the fish at maturity stage VIII in August (mostly autumn-spawned) had moved on to the Shetland grounds after spawning elsewhere.

Samples from south of 59°N

The corresponding data for these samples are given in Tables ro6 and IOJ.

Spring-spawned herring made up only 7% of the samples and the rg65 (z-ringed) year class contributed 6g% of the spring fish. Among the autumn-spawned herring the rg63 year class (56%) was the dominant one as in the northern area but older fish were scarce and the rg64 year class which contributed less than ro% to the stocks sampled north of 59 oN made up 32% of the samples south of 59°N.

293 207 40·75 63.I4 56.76 I86 I30 40.52 4I.I I 44·30 55 79 23.88 3I.78 6I.68 34 3 Io.Ss 20.85 4·33 49 - I0.30 27.63 37 - 4.88 8.57 So - II.64 I3.08

I29 - I9.32 24.22 66 - I4.65 38·70 32 I5 I5.56 42·47 24.20

I88 97 38.46 60.95 36.8I I47 99 34-47 48.I4 40·56

Table ro8 gives the mean lengths of the two­to five-ringed herring in the samples from Fraser­burgh and Peterhead up to rg6r and from the north-western North Sea, south of 59°N, since rg6z.

Purse seine

The length, age, and maturity compositions of the purse seine samples from Shetland waters are given in Table rog and the age compositions of the spring and autumn-spawned components in Table no.

There is a general similarity between the samples taken by purse seine and by drift net in the north­western North Sea, north of 59°N. Spring-spawned herring made up rz% of the purse seine samples in June-July and so% in August-September. The dominant spring year class was the rg64 one (58%). Among the autumn-spawned herring the rg63 year class was again prominent amongst a wide range of age groups but made up only 29% of the autumn fish in the purse seine samples while the rg6o (zo%) and rg56 (9%) year classes both contributed more than in the drift net samples.

-141- Clupeoid Fish Herring

Table II2. South Minch herring catches 1967

Catches (crans) No. of arrivals Catch per arriva1(crans) Drift net Ring net Pair trawl Drift net Ring net Pair trawl Drift net Ring net Pair trawl

January ...... -February ..... -March ........ -April ......... 2 May . . . . . . . . . 6 June ......... -July ......... -August ....... 195 September .... srr October ...... 149 NovEmber ..... 774 December ....

17,946 5,280

272 41

1,347 685 450

4,124 4,509 2,959

rs,66g 9,077

22,983 12,676

7,032 163

541 4,251

19,676 14,300

6 30

6 13

306 II4 rg 3

84 so 51

145 134

95 332 235

413 197 125

12

17 r8o 381 207

2.00

6.00

32-50 17.03 24.83 59-54

s8.6s 46-32 14-32 13.67 r6.o4 13-70

8.82 28-44 33·65 31.15 47-20 38.63

ss.6s 64·34 s6.26 13-58

31.82 23.62 51.64 6g.o8

Table II3. North Minch drift net 1967

A. Per mille length composition (all age groups) Length in em

20 21 22 23 24 25 26 27 28 29 30 31 32 33 35 Mean No.

January ...... - -- -- 29.2 36·5 197.1 277-4 167.9 8o.2 rog.5 5I.I 438 7-2 28.58 137 February ..... - 4·1 4-I 32-5 r62.6 260.2 174·8 150-4 r26.o 73-2 8.r 4·1 - 27-95 246 March ........ - - - 3-6 r8.r 90-3 306.g 267.1 r48.o 93-9 65.0 7-2 - - 28.oo 277 April ......... -- 11.4 17.0 45-5 187.5 306.8 159.1 113.6 113.6 34·1 11.4 - - 27-55 176 September .... - 14·5 2!.7 43·5 58.0 130-4 340.6 130·4 144·9 87.0 2g.o -- - - 27.26 138 October ...... -- 10.8 - 21.5 53·8 107-5 408.6 236-5 64·5 64·5 32-3 - - .- 27-35 93 November ..... 24-5 ITS 31.5 35-0 52-4 87·4 213-3 237·8 157-3 !04-9 38·5 - - - 27.36 286

B. Percentage age composition Number of winter rings

2 3 4 5 6 7 8 9 10 ro+ No.

1965-66 1964-65 1963-64 1962-63 rg6r-62 rg6o-6r 1959-60 1958-59 1957-58 1956-57 1955-56

January ... - 0.7 58.4 7·3 ro.g February .. - r.6 61.8 7-7 !2.2

March ..... - 0.4 66.4 g.o g.o April ...... - 2.3 59·7 12.5 11.4 September . 2.9 41.3 39·9 2.2 5.1 October ... 2.2 48·4 37·6 3-2 3-2 November .. g.8 17.1 5°·3 6.6 8.o

The differences between the purse seine and drift net samples may be accounted for by the difference in depth of sampling and by the fact that, in August-September particularly, the purse seine vessels were fishing slightly further off shore than the drift net ones although both groups were fishing to the south east of the Shetland Isles.

Herring Trawl

Only one sample taken by herring trawl to the south-east of Shetland was examined.

The spring rg65 year class supplied over half the spring-spawned herring in this sample and the rg64 year class supplied almost all the rest. The rg63 year class made up 64% of the autumn­spawned herring.

and older

8.0 2.9 2.9 5.1 2.2 1.5 137 7·3 r.6 !.2 4·5 r.6 0-4 2-1-6 g.o I. I 0.7 r.8 r.8 0.7 277 2.8 2.3 1.7 2.8 3-4 I. I 176 4·3 3·6 - 0.7 - - 138 4·3 - - I. I - - 93 4·2 I.O I.O 1.4 0.3 - 286

West Coast (Minch)

The fisheries

In rg67 drift net, ring net, pair trawl and purse seine vessels fished in the Minch from the ports of Stornoway and Ullapool in the North Minch and from Mallaig and Oban in the South Minch. Landing statistics from ports in both areas in rg67 are given, in Tables III and nz, by months. As in previous years, some fishing took place in all months with the best catches being made in the late autumn and winter period. The summer fishery in rg67 was much less successful than in rg66. The total catch by all methods of fishing from June to September amounted to only zs,ooo crans compared with 40,000 crans in the previous year. During the rest of the year the total catch was almost identical with that of rg66; the drift

-142-

Table II4. North Minch pair trawl 1967

A. Per mille length composition (all age groups) Length in em

r8 19 20 21 22 23 24 2S 26 27 28 29 30 31 32 Mean No.

January . February March .. . April ... . October . November December

20.0

7-4

6.7

20.0 20.4

6.7 6r.2 20.1

6o.o 140.0 480.0 6r.2 142.9 142.9 20.1 40·3 87.2

27.8

260.0 183.7 194·6 SS·S

40.0 r83.7 6r.2 208.o 174·5 III.I 83.3

40.0 320.0 340.0 200.0 40.0 7·4 29-4 44-1 SI.S 22.1

2I.I 105.3 200.0 210.5 52.6

40.0 73-S 132-4 242.6 220.6 ro.s 73-7 us.8 42.1

2 3

B. Percentage age composition Number of winter rings

4 5 6 7

20.4 I34·2 222.2

66.2 63.2

8

2S.OO 40.8 8r.6 2S-98 40·3 S3·7 I3-4 27.09

333.2 138.9 27.8 29.II - - 2I.92

66.2 22.I I4-7 26.6s 63.2 42.1 - 24.65

9 IO ro+

so 49

149 36 so

136 9S

196s-66 1964-65 1963-64 1962-63 1961-62 r96o-6r r9s9-6o r9s8-s9 I9S7-S8 I9S6-S7 I9SS-56 No. and older

January ... . February .. . March ..... . April ...... . October ... . November .. . December ..

Month r8 19

January­February-May 3.0 S-9 June July August September 7-P October 6.8 November 20.1 December

94·0 14·7 54·7

6.9 10.2

7-4

6.0 r6.9 II.6

20 21

6.1 12.2 IO.I IS.I 17.8 17.8

6.8

4·1 12.3 77·5 147·9

6.8 II4.1 94.0

94·0 67·3 76·5 22.2

47·8 24.2

6.1 4·0

s.r 3·2

4·1 4·0

33·3

5·9 2.1

4·1 2.7

13-9

s.r I. I

2.7 s.6

2.2

Table II5. South Minch ring net 1967

2.0

0.7

A. Per mille length composition (all age groups) Length in em

22 23 24 2S 26 27 28 29

38·7 44·8 8s-4 6o. 3 47·3 62.1 13·7 27-4 32·3 S3·8 12.3 12.3

197·2 63-4 40·5 47·3 73·8 33·6

1I.O

107.9 179.2 189-4 II2.0 93·7 90.S 20I.O rso.8 r6o.8 60.3

139.1 r89.3 r8o.s ro6.5 47·3 123.3 17r.2 19r.8 102.7 9S-9 150-S 204·3 3S4·-s 107·5 2I.5

28.8 14o.o 366.2 267.5 65.8 2I.1 63-4 176.1 126.8 49·3 40.S IOI.4 310.8 223.0 I5S-4 13·4 40·3 214.8 134·2 60-4

I I.O I42.9 I97 .8 164.8

B. Percentage age composition Number of winter rings

87.6 85-4 76·9 9S-9 43·0 4!.2 3S-2 33·8 73·8

I6{.8

4·I I.3

13-9

30

89.6 6S·3 65.I

137·0 32·3 4I.2 14.1 27.0 8o.s

I97·8

3I

26.s I0.1 35-S 34·2

8.2 2I.1

6.8 33·6 65·9

I.3 2.8

r.s 3·2

32

10.1 s.o S-9

I3·4 33·0

2.0

8.3

so 49

149 36 so

I36 95

33 Mean No.

2.0 26.35 49I 25.84 I99 25.80 338 26.71 I46 2S.6I 93 26.36 243 24.I5 J42 26.21 I48 2S.29 I49

I I.O 28.37 9I

I 2 3 4 S 6 7 8 9 IO ro+ No. I96S-66 I964-6s 1963-64 I962-63 I96I-62 196o-6I I9S9-60 I958-s9 I957-s8 I9S6-S7 I9Ss-s6

and older

January February May June ..... . July ..... . August ... . September . October ... November .. December .

I. I

2.9 46·5 14·2 30.2

1.1

6.7 IS.I 26.3 2 4·7 3I.2 27.6

7·7 r6.2

8.7 2.2

60.9 56·3 49·7 39·0 60.2 58.0 36.6 62.8 41.6 50·5

3-9 2.S r.s 3·4

2.S 0.7 2.0 I.3 4·4

9·2 8.o 8.9 9.6 3·2 2.5 2.8 2.0 S·4

I6.s

net catch decreased by almost one-third and there was a lesser decrease in the catch by ring net vessels but pair trawlers landed almost twice the amount they did in the same period of rg66. In addition to the landings given in Tables rrr and rrz, 13,776 crans were landed from 176 purse seine arrivals at the Minch ports.

7·I 9·0 4·7

14·4 3·2 2.S 3·5 2.0

2.0 I3.2

2.9 3·0 3·3 L4

I.2

4·0 5-S

Biological data

2.2

I.O 0.6 2.1

o.8

I.3 3·3

2.0

I.5 2-4 L4 I.1 1.2

0.7 2.0 3·3

2.9 2.0

2.1

0-4 I.4

3·4

2.2

I.S 2.7 2.1

0-4 0.7

491 199 338 146

93 2 43 142 148 I49 91

Length and age compos1t10n data from North and South Minch samples are given in Tables II3, II4, II5 and rr6. For the North Minch these are derived from drift net and pair trawl samples and for the South Minch from ring net and pair trawl samples. Up to August the samples from

January ... February .. March .... . October .. . November .. December .

January ... February .. March .... . October .. . November .. December .

20 2I

-143-

Table n6. South Minch pair trawl 1967

A. Per mille length composition (all age groups) Length in em

22 23 24 25 26 27 2S 29 30 3I 32 33

I40.0 I60.0 I6.7 23-4 S].O I]0.6 227-4 I70.6 66.g

- Io.o So.o 2Io.o 250.0 I70.o Ioo.o

zSo.o 73·6 6o.o

220.0 I60.0 20.0 20.0 33-4 20.I IO.O

Clupeoid Fish Herring

34 Mean No.

so 299 IOO

I06-4 42.6 -· 2!.3 42.6 2I2.S 297·9 63.S I27·7 I73·7 Izg.s

II0.4 IIO.O 42.6

IS6.S Igo.6

2!.3 2!.3

29.24 26.77 26.64 26.43 zS.2S 2S.6S

47 236 2]S

- 4.2 - s.5 I4S.3 254.2 I3g.s 3.6 3.6 3.6 !4-4 9].I I65.5 2I5.S

B. Percentage age composition Number of winter rings

So.s 21.2 I2.7 II !.5 43.2 IO.S IO.S

2 3 4 5 6 7 S g 10 Io+ Total

I965-66 I964-65 I963-64 I962-63 Ig6I-62 Ig6o-6I I959-6o I95S-59 I957-5S I956-57 I955-56

I4-9 0.4 !.4

2.0

4·7 3.0 4-3 o.S 2.5

28.o 67.2 70.0 61.7 56.8 47·8

6.o 2.0

4-0

3·0 5·4

IS.o 6.7

I3.0 s.s

II.9 I2.6

20.0 7-4 ].0

6-4 S.g

IO.S

4·0 4·0 I.O 2.1

S·I 4·7

6.0 0.7

3·4 z.g

6.0 2.3 2.0

2.I

7·6 S.3

S.o 2.3

!.7 !.4

and older

2.0

2.7

0-4 2.2

Table n7. Percentage of spring- and autumn- spawned herring North Minch (drift net) 1967

January-March April-June July-September

so 299 IOO 47

236 27S

Year class Rings No. Spr. Aut. No. Spr. Aut. No. Spr. Aut. October-December No. Spr. Aut.

I965-66 I964-65 I963-64 Ig62-63 Ig6I-62 Ig6o-6I I959-6o I95S-59 I957-5S and older

2

3 4 5 6

7 s S-t-

6 40S

54 70 52 II

9 40

33 42

7

2

67 ss 93 99 gS

IOO IOO 100

4 104

22

20 5 4 3

I3

so 7

so 93

IOO 100 IOO IOO IOO IOO

4 54 55

3 7 6 5

IOO 30 33 l4

40

70 67 S6

IOO IOO

6o

IOO

29 93

I7S 22

26 I6

3 3 6

45 62 30

4

55 3s 70

IOO g6

IOO IOO IOO IOO

Percentage of spring- and autumn- spawned herring South Minch (ring net) I967

January-March April-June July-September October-December No. Spr. Aut. Year class Rings No. Spr. Aut. No. Spr. Aut. No. Spr. Aut.

I965-66 I964-65 I963-64 I962-63 Ig6I-62 Ig6o-6I I959-6o I95S-59 I957-5s and older

2

3 4

6o 407

23 6I

62 I6

4 5 9

3S s4 g6 95 9I

!20

223 IO

53 4

IO 5 6 7

53 20

44 36 I3

3

s I3 45

IS IOO s5

IOO 5

25 20

S+

both areas for all methods of fishing were dominated by the rg63 year class. In the last quarter of the year the rg65 year class was of some importance in the South Minch ring-net and the North Minch pair trawl catches and the rg64 year-class in the North Minch drift net catches. The percentages of spring- and autumn-spawned herring in the samples are given in Tables II7 and rr8. As in previous years the catches from both areas through­out the year were predominantly of autumn-

47 g6 go

IOO 97

IOO So

IOO

74 I04 246

6 I2 I4

3 2

9

spawned fish represented in 3-ringed fish.

The fisheries

32 73

9 I7 s 7

33

6S 27 gi S3 92 g6 67

IOO IOO

66 3S

I99 9

25 IS II

5 I2

II

53 I4

2S 39

9 20 I]

Sg 47 S6

IOO 72 6I 9I So S3

but spring-spawners were well both areas amongst the r, 2 and

Clyde

The catch and effort statistics of the ring net and trammel net fisheries for spawning herring for the years rg6z-67 are given in Table rrg.

-144-

Table n8. Percentage of spring- and autumn- spawned herring (pair trawl) 1967

North Minch

January-March April-June July-September October-December Year class Rings No. Spr. Aut. No. Spr. Aut. No. Spr. Aut. No. Spr. Aut.

Ig65-66 I - - - - - - - - II6 g gi Ig64-65 2 1g 68 32 - - - - - 35 31 6g Ig63-64 3 1g4 30 70 8 IOO - - - 87 15 8s Ig62-63 4 g - 100 - - - - - IO IO go Ig6I-62 5 8 - IOO I2 IOO - - - IO 10 go Ig6o-6I 6 6 - IOO 5 100 - - - 8 13 87 1g5g-6o 7 5 - 100 2 100 - - - 3 - IOO Ig58-5g 8 - - - - - - - - I - IOO Ig57-58 8+ 7 - IOO g 100 - - - 5 - IOO and older

South Minch January-March April-June July-September October-December

Year class Rings No. Spr. Aut. No. Spr. Aut. No. Spr. Aut. No. Spr. Aut.

Ig65-66 I - - - - - - - - - 7 2g 7I Ig64-65 2 I8 8g II - - - ·- - - 2 IOO Ig63-64 3 285 I3 87 - - - - - - 2g 3 g7 Ig62-63 4 I3 I5 85 Ig6I-62 5 42 I2 88 - - - - - - 4 75 25 Ig6o-6I 6 3g IO go - - - - - - 3 33 67 Ig5g-6o 7 I5 27 73 - - - - - - I IOO Ig58-5g 8 5 - IOO Ig57-58 8+ 32 - IOO - - - - - - I IOO and older

Table n9. Statistics of Clyde spawning fishery 1962-67

Ig62 Ig63 Ig64 Ig65 Ig66 Ig67

Ring net Number of arrivals .......................... . 532 378 goo I,314 I,7g3 I,270 Total catch (crans) .......................... . 5,g6o 4.637 14.732 28,3gg 22,86g I I, 733 Catch/arrival (crans) .......................... . II.2 I2.3 I6.4 21.6 I2.8 g.2

Trammel net :-<umber of arrivals . · ......................... . 2I7 33I qg I63 22g I65 Total catch (crans) .......................... . I,642 854 2,029 2,gi3 3,252 I,6go Catch/arrival (crans) .......................... . 7·6 2.6 I3.6 I7.g q.2 I0.2

Table 120. Mean length and meristic data of 1962-65 year classes in 1967 Clyde spawning fishery

3 Ringers Ballantrae 4 Ringers Ballantrae 5 Ringers Ballantrae 6 Ringers Ballantrae

Mean length V. S. K 2

27.74 (84) 56.86 '(28) I4.I0 (3I) 28.56 (IS) 57.00 (8) 14.25 (8) 2g.88 (255) 57.I8 (I37) 14.07 (I35) 30.04 (II3) 56.82 (55) I4.II (56)

3 Ringers South Arran 26.7I (42) 57.00 (2o) 4 Ringers South Arran 27.86 (7) 58.oo (2) 5 Ringers South Arran 2g.5I (I36) 57.2I (68) 6 Ringers South Arran 2g.gg (67) 57.03 (30)

I4·35 (23) I3.50 (2) I4.03 (67) I3.g6 (28)

In the ring net fishery the total catch fell to just over half that caught in rg66 and the catch per unit effort was the lowest recorded for several years. The trammel net total catch was also

little more than half that of rg66 and the catch per arrival also showed a sharp decrease. The catches from both sections of the fishery were again dominated by the rg6r and rg62 year classes. Recruit spawners of the rg64 year class were scarce in the catches by both methods of fishing.

Biological data

Length and meristic character data for the rg6r to rg64 year classes are given in Table 120. The rg64 year class again showed the high mean size which has characterized recent recruit year classes to this spawning fishery. The rg6z year class again showed the high V.S. count which was characteristic of it as 3 year old and 4 years-old.

-!45- Clupeoid Fish Herring

Table I2I. Scottish herring tagging I967

Liberations Recaptures Area Period Number Area Number (Days at liberty)

A) Scottish Combinationtags

I) Utsira area April sao North-eastern North Sea 2 (47-76) Skagerak I (I44) Kattegat I (I6g) North Sea 2 (I2-I23) Unknown 3

Total 9

2) Shetland July rrg

B) Internal tags

Utsira area April I 50 North-eastern North Sea 3 (52-!28) North Sea 2 (I69-229) Unknown

Total

Table I22. Further recaptures from the I966 tagging in the Utsira area

Area Recaptures Number

A. Scottish Combination tags

North -eastern North Sea Kattegat ........... . Unknown ........... .

Total

B. Internal tags

North-eastern North Sea Skagerak ............ . Shetland ........... . West of Bear Island .. Faroes ............. . Unknown ........... .

Total

3 2

8

I3

I8 2

II I

I4

47

Tagging

(Days at liberty)

(4II-527) (427-528)

(375·-486) (474-526) (420-507)

(486) (6o5)

During April rg67 a further tagging experiment in the Utsira area was carried out. Unfortunately, bad weather and a scarcity of herring hampered the experiment. A small tagging experiment was carried out in Shetland waters during July. Details of liberations and recaptures are given in Table r2r.

Sixty more tags have been returned from the rg66 tagging in the Utsire area. The details of recapture are given in Table 122.

G. McPHERSON, A. SAVILLE

Marine Laboratory, Victoria Road, Torry, Aberdeen, Scotland.

6

Scottish fisheries on adolescent herring r967

(Tables I23-I26)

North Sea

The catch and effort statistics for the halflin fisheries in the Moray Firth and Firth of Forth during the rg66-67 season are given in Table 123. In the Moray Firth the pair-trawl catch of herring in the rg66-67 season, for the first time, was considerably larger than the drift-net catch, and the statistics are given independently for both methods of fishing. For both methods of fishing the catch and catch per effort were very much lower than in the preceding season. In the Forth all the herring caught were taken by pair-trawl, as a by-product of the sprat fishery.

In the Moray Firth r-ringed and 2-ringed fish each supplied about 42% of the catch, the remainder being principally 0-group. The pro­portion of spring spawners in all age-groups was very small. The mean length and mean V. S. of these fish are given in Table 124. They give values typical of fish of these age-groups in this fishery.

Clyde

The catch and effort statistics for the Clyde ring net fishery for adolsescent herring in the rg67 season are given in Table 125. The total catch was about ro% greater than in rg66 and the catch per arrival was appreciably higher. Much of the improvement in the total catch and catch per unit effort was due to the results achieved in the last

-I46-

Table 123. Statistics of halflin herring fisheries 1962-67

1962-63 1963-64 1964-65 1965-66 1966-67

Upper Moray Drift Pair trawl Firth

Duration of season ............. . 6. 10. 62 to 12. I. 63

23. rr. 63 to 12. 10. 64 to 25. 9· 65 to r. ro. 66 to r. ro. 66 to II. 3· 67

388 rr,266

30·9

21. 12. 63 27.3-65 9- 4- 66 10. 12. 66

Number of arrivals ............ . 6o 286 1,388 Total catch (cram;) ........... . 588 2,768 68,460 Catch/arrival (crans) ............ .

524 9,934

rg.o g.8 9·7 49·3

217 3,384

15.6

Upper Firth of Forth

Duration of season . . . . . . . . . . . . . . rg. r. 63 to 25. r. 64 to 6. 3· 65 to 3· 12. 66 to 28. I. 67

225

23.2.63 11.4.64 27. 3· 65 Estimated catch of halfiins (crans) . 2,014 7,162 51 Estimated catch of halfiins per

arrival (crans) . . . . . . . . . . . . . . . . 23.4 28.6 4·6 32.1

Table 124. Length and mean V. S. of herring year classes in inshore waters off Scottish east coast in 1966-67

Locality Date Length range Mean (em) Mean V.S. (em)

Autumn 1963 year class

Moray Firth Oct. rg66-March 1967 19-28 23-47 (154) 56.6o (151)

Autumn 1964 year class

Moray Firth Oct. rg66-March 1967 r6-25 20.37 (155) 56.58 (q6)

Autumn 1965 year class

Moray Firth Jan. 1967-March 1967 14-18 15.68 (61) 56.51 (59)

Table 125. Statistics of Clyde adolescent herring fishery 1962-67

1962 1963

Number of arrivals ............. 1,274 3,001

Total catch (crans) ............ 10,143 38,782

Catch/arrival (crans) ........ , .... 8.o 12.9

Table 126. Mean length and meristic characters of I, II and III ringed herring in Clyde adolescent fishery in 1967

Rings Length V. S.

I {Spring spawned 23.08 (550) 56.82 (224) Autumn spawned 23.18 (r4) 56.89 (9)

II {Spring spawned 25-41 (1762) 57.00 (896) Autumn spawned 25.86 (28) 56.38 (13)

III f Spring spawned 27.71 (205) 56.8o (roo) l Autumn spawned 27.45 (27) 56.40 (15)

K2

14.23 (219) 14-38 (8) q.15 (8go) 14-31 (13)

14.24 (99) 14.69 (13)

four months of the year when the Ig66 year class recruited to the fished stock. This year class and the I965 one provided the bulk of the catches at this time. The mean lengths and meristic characters of the principal age-groups are given in Table IZ6. The Ig66 year class as I year old showed a continuation of the trend of increasing length as I-ringers which has been such a notice-

Season 1964 1965 1966 1967

4,172 4,925 4,5II 3.754

?7.413 54,081 32,743 35,849 16.2 11.0 7·3 g.6

able feature of recruit year-classes to this fishery in recent years.

A. SAVILLE

Marine Laboratory, Victoria Road, Torry, Aberdeen, Scotland.

Polish herring catches on the slopes of the Norwegian Channel in the years 1965-1967

(Figures 142-145; Tables 127-129)

The region of investigations has been divided into three parts differing in respect of their exploitation and the occurrence of herring stocks:

I - Northern fishing grounds z - Southern fishing grounds 3- Skagerak

-147- Clupeoid Fish Herring

20 62°

G

\

21

JO 40 so 60

H

70 ao

L M N

go

0

10° 11° 62°

p

61°1 \1 I \ v-IQ--="" I I Fishing grounds -.~61 o 20 Vikin

18

17

\ bank

( I

A Northern

8 Southern

C Skagerak 60°

59°1 I :utsi ra I J t-1_h I I I ?~~ 159° 16

\ Coral bank··--.. .. Egers\Jn

115 Ling bank l .. bank ,, ~- I 58° 6 I '· ·., ..

Klondyke B\

·. ........... ""' ----t58°

14

13 57°1 ' I I I I , 7'7-l ~ 157°

12

20 30 40 so 60 70 ao go 10° 11°

Figure 142. Fishing grounds in the Norwegian Channel area.

The boundaries of these fishing grounds are given in Figure 142.

Catches In rg65 Polish herring catches on the slopes

of the Norwegian Channel amounted to zs,8oo tons.

It was the highest catches taken by the Polish fishing fleet in this region (Table 127). In subsequent years the catches dropped, to 3,6oo tons in rg67. These comparatively poor results were the con­sequence of a decrease in abundance of the herring stocks, which in turn was reflected in the mean

-148-

21 25 29 33 37 1 2 3 4 5 6 7 8 9 10 o/o I' I I I I A I em I - VIr.

o/o 201-1965 I \ 40

1183 I I March

10~ I 1 20

10

10 May

201-1966 March

10

10

20 ~ 1967

10

10

21 25 29 33 3711 2 3 4 5 6 7 6 9 10 Length c.m wr.

ISpring spawnersDAutumn spawners

Figure 143. Length and age of the herring caught in area A (Figure 142) in the years 1965-1967.

fishing yields (Table rz8), obtained by various types of fishing vessels. Along with low fishing yield there was also a decreased fishing effort, expressed by the number of vessel-days. In Table rzg the number of herring caught on the slopes of the Norwegian Channel is given in proportions for northern

Table 127. The relation between the catches of herring on the slopes of the Norwegian Channel and total Polish

catches from the North Sea (in tons)

Years North Sea Norwegian % Channel

1953 ........... 20,664 469 2,3 1954· .......... 25,977 I,I47 4-4 1955 ........... 39,851 2,r8o 5·5 1956 ........... 45.729 4,670 10.2 1957 ........... 49,290 4,700 9·5 1958 ........... 55,909 6,074 ro.9 1959· .......... 70,379 3,6r8 s.r 1960 ........... 76,304 8,o58 I0.6 1961 ........... 78,082 I0,044 12.9 1962 ........... 59,933 7,898 13.2 1963 ........... 72,790 4.956 6.8 1964. · ..... · · · · 94,015 19,202 20.4 1965 ......... · · !04,908 25,822 24.6 1966 ........... 74.552 12,239 r6.4 !967 ........... 35,!49 3.588 10.2

Table 128. Fishing results obtained by various types of vessels in herring fisheries on the slopes of the Norwegian

Channel in the years 1965-1967.

Type of vessel, and fishing gear

Steam trawlers a Bottom trawl b

c Steam trawlers a Pelagic pair trawl b

c Motor trawlers a Bottom trawl b

c Freezing trawlers a Bottom trawl b

c Drifter trawlers a Drift nets b

c Drifter trawlers a Pelagic b Pair trawl c Drifter trawlers a Bottom trawl b

c Cutt~rs a Pelagic b Pair trawl c Cutters a Bottom trawl b

c

1965

4·7 8,659.8 r,857

5·3 905·5 172

6.3 2,841.9

453 3·0

roo.8 34

3·! 2,678.6

852

3·1 6,87!.3 2,206

2.8 33·7 12

2.9 3,7r8.r 1,302

Years 1966

5·0 5,043·1 r,oo9

7·3 1,502.7

206

!.7 50·4 30

2.8 3.947·2 1,427

!.4 587.6 415

2.4 947·6 397

!.4 120.5

84

1967

o.8 212.6 283

I. I

6.7 6

0.9 130.0 149

2.9 2,077·4

728 I.O

72.6 70

2.5 498.0 199

r.6 2.3 39·6 35.2 25 IS

a = mean yield per day fishing on the basis of annual data. b = landed herring in tons. c = number of fishing days.

fishing grounds, southern fishing grounds and Skagerak. The most important ones were the fishing grounds in the southern part of the Nor­wegian Channel.

-149- Clupeoid Fish

21 25 29 33 1 2 3 4 5 6 7 8 9 10 %1 Wr.

10 1965

20 40

10~ 20 f\/\:_9 October

1or 20 April

zo 1A:o 20f 40~ I U lnJ I ___ a -1

n . 1or

20

10

10

10

10

I \

J A,._,.._.-,

July 20~ II n

October

1 2 3 4 5 6 7 8 9 10 Wr.

ISpri ng spawner.s DAutumm spawners

I

Figure 144· Length and age of the herring caught in area B (Figure qz) in the years 1965--1967.

Biological data

The studies on herring from the slopes of the Norwegian Channel showed the differences in stock composition on particular fishing grounds and in different seasons of the year. Winter-spring spawners occurred on the fishing grounds mainly

Herring

17 21 25 29 0 1 2 3 4 5 6 7 8Wr.

%1 I I I I I I Clffi

1965 1\%1 - nJanuary 10

20f

60

October

40f November !\ n 4657 December

1 o I r-..1 \ In II \1

f 1~bb n 4240 f January

10 ~ 20 February May

I I l l

n 142160

~ October NovembQr

10 L 201l_ December

20 {'\1967

401 ~ n 639 April

~ 20 80 AU9USt n 277

10 20

012 3 45678 em 1 Wr.

ISprin~ spawners 0 Autumn spawners

Figure 145. Length and age of the herring caught in area C (Figure 144) in the years 1965-1967.

in March. They were particularly large-sized (Figure 143). In all three years, specimens born in the spring of rg6r predominated.

Most of the herring caught on the slopes of the Norwegian Channel belonged to the group of autumn spawners. On the fishing grounds situated

-150-

Table 129. Polish herring catches on the slopes of the Norwegian Channel on particular fishing grounds Months Total

Fishing grounds Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. tons % 1965

Northern ...... rr6 1,143 733 4.877 1,137 g66 19 - 2 - 145 9,138 35 Southern ...... 6g8 500 1,528 460 1,033 73 1 r6o r,rgr 422 3.341 762 734 rr,56o 45 Skagerak ...... 263 837 5 - - I 1,429 2,063 525 5,123 20

Total ......... 1,077 2,480 2,261 5.342 2,170 !,697 r6o 1,210 423 4.772 2,825 1,404 25,821 roo

rg66 Northern ...... 442 259 2,!06 390 483 755 r6r - - - 67 4,663 38 Southern ...... 596 504 780 1,023 641 1,437 1,599 167 41 84 I 55 7,027 ss Skagerak ...... - 35 43 30 - 403 6 32 549 4 Total ......... 596 946 1,039 3,129 r,o66 1,963 2,384 vs - 444 go 254 12,239 roo

1967 Northern ...... - 207 107 Southern ...... 6 - 6r 533 Skagerak ...... - -

Total ......... 6 - 268 640

in the southern part of the Norwegian Channel herring born in rg6o and rg6z predominated in the catches in rg65 (Figure 144). In subsequent years most of the herring were of the 1963 year class.

In Skagerak mainly herring of younger agegroups were caught (Figure 145). Only in the winter of rg65 did numerous older individuals occur; they were autumn spawners, wintering in Skagerak. Their age composition was similar to the age composition of the herring found at that time in the southern part of the Norwegian Channel.

In both commercial and research catches in Skagerak in the years rg65-1967 it was found that the predominant number of herring belonged to the age-groups 0, I and II.

J. SOSINSKI

6 74

So

29 - 4 - 353 IO r,872 - 614 9 r6 3,185 Sg

- - so 50

r,gor - - 6r8 9 66 3,588 roo

The Norwegian herring fisheries in the North Sea and Skagerak 1967 (Figure 146; Tables 130-143)

Surveys During the period 15. June to 4· July the R.V.

"G.O. Sars" was engaged in environmental and acoustic surveys in the northern North Sea. The route of the ship and the records of herring are shown in Figure 146. Concentrations of herring were located north and east of Shetland, in the

Table 130. Catch and effort statistics for the Norwegian North Sea and Skagerak herring fisheries rg65-67

Purse-seine Trawl Total

Year I,OOO No. of 1,000 No. of I,OOO Tons hl vessels hl vessels hl

1965 6,277 284 rg8 439 6,475 602,175 rg66 4,820 334 6g 338*) 4,88g 454,667 1967 3,585 326 I3 193*) 3.597 334,557

Sea Fisheries Institute, Aleja Zjednoczenia r, Gdynia, *) Only included vessels with catch of value of more Poland. than 5,ooo N.kr.

Table 131. The landings of herring (r,ooo hl) from the North Sea and Skagerak, 1967

Area Month Total % % Jan. Feb. March Apr. May June July Aug. Sept. Oct. Nov. Dec. 1967 rg66

NW North Sea (north of N57°30') - 217.7 59·5 I6I.3 4·0 - - 442·5 12.3 45.1

NE North Sea (north of N 59°) . - 46·5 O.I 175·3 48.! 99·7 3·0 - - 372·9 10.4 2.0

NE North Sea (south of 59°) ... 3·5 - 0.7 s.o 219.6 695.6 287.s r68.3 7·3 rg.6 0-4 r8.4 1,526.4 42·4 46.2

Central North Sea (south of N57°3o') - - 2I.5 !84-4 15.9 I2.0 - -- 233·8 6.5

Skagerak ........ 6.4 o.g - - !76·4 713.0 93·8 6.4 2.0 23.0 I,02I.9 28.4 6.7

Total ....... g.S o.g 0.7 5I.5 241.3 I, 273· I 587 · 7 I, 254·3 ro8.2 26.0 2-4 4 L4 3.597.4 !00.0 100.0

60

59

··~

58

'">;,·.

2 o• 2 3 4 6 Figure q6.

.. G. 0. SARS" 15.VI.- 4.VII 1967

• TAGGING LOCALITY

-o-- HYDR. AND PLANKTON ST.

--==--VERY SCATTERED

::::::::SCATTERED

-ttHtiH/- D E N S E

7 8

H Ul H

(")

= '"C ('I) 0

~ ..... "~ :: ~

g• s· tn· aq::T

-152-

Table 132. Length and age composition, north-western North Sea, north of N 57°30' - 1967

A. Per mille length composition

May June Aug. Sept. Length Purse- Purse- Drift- Purse- Purse-in em seine seine net seine seine

20 - - 35-0 21 - - - r6o.o 20.0 22 - - - 260.0 8o.o 23 - - 20.0 145·0 140.0 24 - 3-5 so.o 6s.o IIO.O 25 20.0 23.0 270.0 6o.o 40.0 26 45·0 44·0 190.0 120.0 so.o 27 6s.o 79-2 130.0 65.0 250.0 28 6o.o 140.8 !00.0 zs.o 70.0 29 8o.o 142.6 30.0 35·0 8o.o 30 245·0 237·7 8o.o 20.0 so.o 31 300.0 zo6.o IIO.O IO.O 70.0 32 130.0 88.0 !0.0 - 40.0 33 so.o 17.6 !0.0 34 s.o 15.8 35 r.8

True mean 30.56 30.03 27-49 24.18 26.82

Number 200 568 roo 200 roo

B. Percentage age composition

Number of winter rings

2 3 4 5 6 7 8 9 9+ Year class 1965-66 1964-65 1963-64 1962-63 1961-62 1960-61 1959-60 1958-59 1957-58 1956-57 Number

and older May (Purse-seine) I. I rs.6 12.2 15.0 37·2 3·3 !.2 5·0 9-4 r8o June (Purs~-seine) 0.6 32-5 7.6 15-3 z8.o 2.2 3·5 3·3 7-0 5II June (Drift-net) - 27·7 43·6 12.8 5-3 5·3 2.1 I. I 2.1 94 Aug. (Purse-seine) 55.8 22-4 r8.4 - I. I I. I 0.6 - 0.6 174 Sept. (Purse-seine) 33·7 23.1 26.3 4·2 4·2 7-4 - - - I. I 95

Table I33· Maturity and vertebral count, north-western North Sea, north of N57°30'-r967

A. Percentage maturity (All age-groups)

Maturity stage I II III IV v VI VII VIII Number

May (Purse-seine) .... - !.5 57·8 r8.6 - - - 22.1 199 June (Purse-seine) ... 2.1 49·5 13-5 I. I !.4 32-4 562 June (Drift-net) ..... II.O 59·0 23.0 I.O - 6.0 roo Aug. (Purse-seine) ... 12.2 49·5 2.6 4·1 0.5 3!.1 196 Sept. (Purse-seine) ... I.O 38.o II.O J .0 - - 49·0 roo

B. Vertebral count (Actual numbers, all age-groups)

Number of vertebrae

52 53 54 55 56 57 58 59 Mean Number

June (Purse-seine) ... - I 22 262 231 43 - 56.524 559 June (Drift-net) ..... 2 41 42 13 - 56.673 98 Aug. (Purse-seine) ... I 5 64 86 9 2 56.6r r 167 Sept. (Purse-seine) ... I I 2 33 sr 12 - 56.670 roo

Gut area and on the Egersund Bank. Elsewhere only very scattered concentrations of herring were found. From the records of herring obtained it

was suggested that the abundance of herring in the Shetland waters was not so high as in the previous year.

-153- Clupeoid Fish Herring

Table 134. Age composition of spring and autumn spawned herring in the north-western North Sea, north of N 57°30'- 1967

Spring group

Number

Winter­

rings

May June June Aug. Sept.

Year class Purse-seine Purse-seine Drift-net Purse-seine Purse-seine

43 II 2 7 5 6

rg66 1965 1964 1963 rg62 rg6r rg6o 1959 rg58

3 5 54 2 3 3

<r958

Total .....

4 5 6

7 8 9 9+

Winter-

2 2

7 5 5 5 6

6

2! So

Autumn group

Number

May June

II 51 2!

Total sample

Number

June Aug. Sept. Spring Autumn

Year class rings Purse-seine Purse-seine Drift-net Purse-seine Purse-seine

!965 .... I -1964 .... 2 I 3 1963 .... 3 23 1!2

rg62 .... 4 20 37 rg6r .... 5 26 JI rg6o .... 6 62 !38 1959 .... 7 I 5 1958 .... 8 I !2

1957 .... 9 8 IJ <I957 .... 9+ IJ 36

Total ..... I 59 431

From 18. October to 8. November a herring survey, with R.V. "G. 0. Sars", was carried out in the north-eastern North Sea and Skagerak. Good concentrations of herring were located in two separate areas, one about 30 nautical miles NNW of the Skaw and one about 25 nautical miles SW of Lista. In both areas the herring were dispersed in a scattered layer having a pronounced diurnal migration. These concentrations of herring were not suitable for purse-seining, but gave rise to a profitable fishery for pair-trawlers.

As in the previous year the herring in the north­eastern North Sea and Skagerak consisted mostly of immatures. The herring in eastern Skagerak were entirely built up by 0- and !-ringers, while the herring SW of Lista were dominated by I- and 2-ringers. Members of the Bank herring stock contributed to the dominant part in both areas.

The fishery

The total Norwegian landings of herring from the North Sea and Skagerak decreased from 4,889,000 hl in 1966 to 3,597,000 hl in 1967;

- 54 2! 54 75 19 34 r6 19 73 39 29 22 67 225 !2 - 4 4 73

5 2 4 8 ro8 4 2 6 12 2!2

- - II 6 I I - 8 15 I - I 26 2 I I - 57

83 123 74 !84 870

i.e. a decrease of 26-4%- This decline was largely due to a reduction in effort. About 98% of the total catch was processed in fishmeal and oil factories. The difficult marketing situation for these products in 1967 resulted in several fishing stops, in total 73 days, and a restriction of the landings for 3 months. The purse seine fleet was most of the year also taking part in a flourishing mackerel fishery which yielded no less than 835,500 tons.

Catch and effort data (maximum number of vessels participating) for the years 1965(67 are given in Table 130. The average catch per purse­seiner was II,313 hl compared with 14,431 hl in 1966. The corresponding figures for the trawlers were 67 hl in 1967 and 204 hl in 1966. The trawlers were mainly fishing for other species, particularly Norway pout and shrimps.

The landings from different areas, by months, are given in Table 131. The fishery in the Skagerak, the central North Sea and the north-eastern North Sea north of 59°N was more productive than in 1966, whereas the landings from the other

-154-

Table I35· Length and age composition, north-eastern North Sea, north of N 57°30'- 1967

A. Per mille length composition

Jan. Feb. March April May July Aug. November

Purse- Pair- Purse- Pair- Purse- Purse- Purse- Purse- Purse- Pair-Length in em seine trawl seine trawl seine seine seine seine seine trawl

16 .......... - - 5·7 17 .......... - - - 54·8 18 . . . . . . . . . . - - - - 107·7 19 ........ •. - - - 138.0 - 14.1 20 .......... - 5-0 102.r 38.2 21 .......... 2.5 25.0 - 20.0 3-6 47-3 10.0 96.6 22 .......... 5-0 110.0 - 25.0 7·3 22.7 20.0 237·4 30.0 ro.O 23 .......... 22.5 110.0 - 45·0 73·0 5!.0 ro.o II4.7 r7o.o 120.0 24 .......... 52-5 140.0 ro.o 65.0 54-8 58.6 30.0 r24·7 390.0 240.0 25 .......... 97-5 125.0 130.0 55-0 32.8 62.4 r9o.o 163.0 110.0 240.0 26 .......... 145·0 165.0 18o.o 110.0 25·5 30.2 270.0 ro4.6 70.0 IIO.O 27 .......... 170.0 IIO.O r9o.o 75·0 r57-0 49.r r6o.o 62.4 90.0 50.0 28 .......... r37·5 65.0 rro.O 105.0 54·8 62-4 r6o.o 38.2 90.0 30.0 29 .......... 77-5 35-0 18o.o 155·0 76.6 56·7 30.0 6.r 30.0 6o.o 30 .......... 137·5 60.0 140.0 195-0 69·3 58.6 8o.o - 20.0 50.0 3I .......... 82.5 30.0 50.0 125.0 ro9.5 62.4 40.0 - - 70.0 32 . . . . . . . . . . 57·5 ro.O ro.o 20.0 69.3 20.8 33 . . . . . . . . . . 7·5 15.0 - - r27·7 9-5 - - - 10.0 34 .......... 2.5 - 95-0 - - ro.o 35 .......... 2.5 - - 29.2 36 .......... - - 14.6

True mean ... 28.28 26.10 28.17 28.23 29.89 23-93 27.18 24.14 25-42 26.37

Number ..... 400 200 roo 200 274 529 100 497 100 roo

B. Percentage age composition

Number of winter-rings

2 3 4 5 6 7 8 9 9+ Year class 1965-66 1964-65 1963-64 1962-63 r96r-62 r96o-61 1959-60 1958-59 1957-58 1956-57 Number

and older Jan. (Purse-seine) - 1!.3 47·4 9.0 8.1 16.7 0.2 2.2 !.6 3·5 37r Feb. (Pair-trawl) 4!.5 38.o 7-2 2.6 8.2 - I.O !.5 195 March (Purse-seine) 4·5 37.1 15.7 13-5 19.1 - 3·4 !.1 5.6 89 March (Pair-trawl) 17.2 24-4 10.6 r5.0 17.8 3·3 o.6 3-9 7-2 r8o April (Purse-seine) ·- 9·3 5-2 May (Purse-seine) 63.8 25.6 7·4 r.r July (Purse-seine) !.1 64-9 26.6 4-2 Nov. (Purse-seine) 66.3 15.4 r6.3 2.0 Nov. (Pair-trawl) 67.0 6.4 15.9 3-2

fishing grounds were smaller. In particular, the fishery off Shetland proved to be a complete failure and yielded only 4I,r5o tons compared with 205,000 tons in rg66. More than go% of the total catch was taken during 4 months, namely from May to August. During this period the fishing activity was more or less covering the northern North Sea and Skagerak. Good catches were taken in the Shetland waters in June and August. On the Egersund Bank a rich fishery took place in all the months from May to August. The Gut area yielded the highest catches in June, whereas July and August proved to be the best fishing months in the Skagerak.

9-3 54·6 r2.3 5-2 3.1 I.O 97 - 2.1 - - -· 94 !.1 2.1 - - - - 94

2.1 - - - - - 98 3-2 r.r - !.1 - 94

Biological data During the year, 49 samples, totalling 5,422 her­

ring were examined. The biological details for the herring sampled from the various areas in rg67 are summarized in Tables 132-143· They contain length, age, maturity and vertebral count distributions, together with the age compositions of the spring and autumn spawned components (separated on otolith characters).

North-western North Sea (grounds west of 2°E and north of 59°N).

The spring spawned herring made with r8% a smaller contribution to the samples than in rg66.

-rss- Clupeoid Fish Herring

Table 136. Maturity and vertebral count, north-eastern North Sea, north of N 57°30'- 1967

A. Percentage maturity (All age-groups)

Maturity stage

I II III IV v VI VII VIII Number

Jan. (Purse-seine ........ . !.7 r6.7 ro.o 7·3 s.o - o.8 s8.s 400 Feb. (Pair-trawl) ........ . 2.j 54·0 r.o 3-0 13-5 26.o 200

March (Purse-~eine) ...... . 28.o 28.o 3-0 2.0 3-0 -- 36.0 roo March (Pair-trawl) ....... . 2.0 23.0 2.0 2.5 r.o o.s - 6g.o 200 April (Purse-seine) ....... . - r.o 91.0 5-0 3-0 roo May (Purse-seine) ....... . 2.3 62.8 J.O - - 27-9 43 July (Purse-seine) ....... . 2.0 r6.o 70.0 12"0 - - - roo Nov. (Purse-seine) ....... . 70.0 r.o 2.0 - 27.0 roo Nov. (Pair-trawl) ........ . 7-0 6r.o 2.0 r.o 3-0 - - 26.0 roo

B. Vertebral count (Actual numbers, all age-groups)

Number of vertebrae

54 55 56 57 s8 59 Mean Number

Jan. (Purse-seine) ....... . 14 95 75 12 s6. 42r 197 Feb. (Pair-trawl) ........ . 13 78 88 9 - 56·495 r88 March (Purse-seine) ...... . 4 s6 35 3 56-378 g8 March (Pair-trawl) ....... . 8 44 46 2 56-420 roo April (Purse-seine) ....... . 14 63 22 57.081 99 July (Purse-seine) ....... . 5 45 35 8 I 56-521 94 Nov. (Purse-seine) ....... . 7 43 39 I 56·378 90 Nov. (Pair-trawl) ........ . 9 3I 55 5 - s6.sso roo

Table 137. Age composition of spring- and autumn spawned herring in the north-eastern North Sea, north ofN 57°30'- 1967

Spring group Number

Winter- Jan. Feb. March March April May July Nov. Nov. rings Purse- Pair- Purse- Pair- Purse- Purse- Purse- Purse- Pair-

Year class seine trawl seine trawl seine seine seine seine trawl

rg66 .... I - - - - I - 12 1965 .... 2 3 7 I I - I 2 4 1964 .... 3 43 33 5 9 9 I 3 2 3 1963 .... 4 4 2 I - 5 1962 .... 5 I I 2 2 9 rg6r .... 6 5 2 2 - 53 rg6o .... 7 I - I 12 1959 .... 8 I - - 5 1958 .... 9 - - - 3

<rgs8 .... 9+ Total ..... s8 45 II I3 97 3 5 6 I7

Autumn group

Number

Winter- Jan. Feb. March March April May July Nov. Nov. Total sample rings Purse- Pair- Purse- Pair- Purse- Purse- Purse- Purse- Pair- Number

Yearclass seine trawl eine trawl seine seine seine seine trawl Spring Autumn

1965 59 65 51 13 176 II 5 14 !2

1964 2 39 74 3 30 1963 3 133 41 28 35

23 59 6 22

20 244 ro8 291

1962 4 29 12 13 19 4 2 3 12 83 rg6r 5 29 4 IO 25 2 IS 71 rg6o 6 57 14 IS 32 2 2 3 62 125 1959 7 - - 5 14 5 1958 8 7 3 7 II

1957 9 6 2 I 7 3 r6

<1957 9+ 13 3 5 13 I 35

Total 313 150 78 !67 91 89 92 77 255 1.057

-156-

Table 138. Length and age composition, central North Sea, south of N 57°30' - 1967

A. Per mille length composition

Length in em

8 ............ . 9- ........... .

IO ............ .

II ............ . I2 ............ . I3 ............ . 14· ........... . I5 ............ . I6 ............ . I7 ............ . I8 ............ . I9 ............ . 20 ............ . 2I ............ . 22 ............ . 23 ............ . 24 ............ . 25 ............ . 26 ............ . 27 ............ . 28 ............ . 29 ............ . 30 ............ . 3I ............ .

True mean .... .

Number ...... .

June Purs=­seine

10.0 45·0 70.0 45·0 40.0

r6o.o 310.0 I70.0 IIO.O

30.0 5·0 5·0

26.09

200

Aug. Purse­seine

5·0 75·0

125.0 190.0 200.0

8o.o I6o.o 8o.o 20.0 30.0 30.0

5·0

23-91

200

B. Percentage age composition

Number of winter-rings 2 3 4 5 6 7

Aug. Bottom trawl

25.6 92-3 71.8

107·7 61.5

I02.6 25.6

20.5 97·4

II2.8 I07·7

36.0 56.4 46.2 20.5 I 5-4

I6.2o

I95

8 9 9+ Year class I965-66 I964-65 1963-64 I962-63 I96I-62 1960-6I I959-60 1958-59 I957-58 I956-57

and older June (Purse-seine) I4.6 34·2 41.7 8.o 1.5 - - - -Aug. (Purse-seine) 56.6 33·3 8.6 r.o - 0.5 - - -Aug. (Bottom trawl) 94.2 5·8 - - - -

Table I39· Maturity and vertebral count, central North Sea, south of N 57°30'- 1967

June (Purse-seine) ....... . Aug. (Purse-seine) ....... . Aug. (Bottom trawl) ..... .

June (Purse-seine) ........ Aug. (Purse-seine) . . . . . . . . Aug. (Bottom trawl) ......

A. Percentage maturity (all age-groups)

Maturity stage

I II III IV v VI

1.5 I6.o 57·0 22.0 3·0 28.o 28.5 r6.5 24·5 2.5 12.5 74-2 9-7 3-2

B. Vertebral count (Actual numbers, all age-groups)

Number of vertebrae

53 54 55 56 57 58

- 2 90 8I I9 I 4 I2 70 74 7

- I 54 63 I2

VII VIII

0.5

59 Mean

- 56.609 - 56-387

I 56.679

Number

I99 198 I89

Number

200 200

93

Number

I92 I68 I3I

-157- Clupeoid Fish Herring

Table 140. Age composition of spring- and autumn spawned herring, central North Sea, south of N 57°30' - 1967

Spring group Autumn group Number Number

June Aug. Aug. June Aug. Aug. Total sample

Year Winter- Purse- Purse- Bottom Year Winter- Purse- Purse- Bottom Number class rings seine seine trawl class rings seine seine trawl Spring Autumn

1967 0 1966 0 91 - 91 1966 I I 1965 I Z9 liZ 86 I ZZ]

I965 2 I z I 1964 z 6] 64 IO 4 141 1964 3 I - I963 3 82 I] - I 99 I963 4 I I962 4 IS 2 - I I] 1962 5 - - - I96I 5 3 - - 3 1961 6 --- 1960 6

Total 3 2 2 Total 196 196 !87 7 579

Table 141. Length and age composition, Skagerak- 1967

A. Per mille length composition

Oct. Oct. Oct. Nov. Length Purse- Pair- Pelagic Pelagic in em seine trawl trawl trawl

I I. ........ - - IO.O IZ ......... - - - !0.0 13 ......... - - 7·5 I8o.o 14· ........ - - 37·3 4]0.0 IS ......... - - 20!.5 230.0 I6 ......... zo.o - 604·5 IOO.O I] ......... 5·0 - III.8 r8 ......... 5·0 - 2Z-4 I9 ......... 5·0 zo ......... 75·0 - 7·5 ZI ......... ZI5.0 50.0 zz ......... 305.0 270.0 7·5 Z3 ......... 250.0 3]0.0

24 ......... 6o.o 200.0 25 ......... 20.0 50.0 z6 ......... 15.0 30.0 Z7 ......... IO.O IO.O 28 ......... 5·0 Z9 ......... 30 ......... 31 ......... 3Z ......... s.o 20.0

33 ......... 5·0

True mean. ZZ.63 23-74 r6.43 14·70

Number ... zoo IOO 134 roo

B. Percentage age composition

Number of winter-rings

0 I z 3 4 5 6 7 8 9 9+ No.

Year class 1966-67 1965-66 1964-65 1963-64 r96z-63 1961-62 r96o-6r 1959-60 1958-59 1957-58 1956-57

Oct. (Purse-seine) ..... 3·1 93-3 z.6 0.5 0.5 193

Oct. (Pair-trawl) ..... 90.6 7·4 - I.O I.O. 96

Oct. (Pelagic trawl) ..... 99-2 0.8 IZ]

Nov. (Pelagic trawl) ..... 100.0 94

-r58-

Table 142. Maturity and vertebral count, Skagerak- 1967

A. Percentage maturity (All age-groups)

Maturity stage

I II III IV v VI VII VIII Number

Oct. (Purse-seine) ........ . 8.I 87·4 2.0 0.5 - - - 2.0 198 Oct. (Pair-trawl) ........ . go.o 6.0 2.0 - - - 2.0 roo Oct. (Pelagic trawl) ...... . g8.5 I.5 - - I32

B. Vertebral count (Actual numbers all age-groups)

Number of vertebrae

54 55 56 57 58 59 Mean Number

Oct. (Purse-seine) ........ . 3 8 85 84 II 56.482 I9I Oct. (Pair-trawl) ........ . 4 39 46 8 56·598 97 Oct. (Pelagic trawl) ...... . I2 53 57 2 56·376 I25 Nov. (Pelagic trawl) ..... . 5 46 35 5 56-44I 93

Table I43· Age composition of spring- and autumn spawned herring, Skagerak 1967

Spring group Autumn group Number Number

Oct. Oct. Oct. Nov. Oct. Oct. Oct. Nov. Total sample Year Winter- Purse Pair Pelagic Pelagic Year Winter- Purse Pair Pelagic Pelagic Number class rings seine trawl trawl trawl class

I967 0 - - I966 Ig66 I I8 4 - I965 I965 2 2 I - I964 I964 3 - - - I963 I963 4 - - I962 I962 5 - - I96I I96I 6 - - Ig6o

Total 20 5 - Total

The rg64 and rg66 year classes were equally represented in this spawning group and contributed each 30%.

During May and June the rg6o and rg63 year­classes of the autumn spawned herring supplied 30% and z6%. In this period II years old (rg56 year class) were represented with 8% of the autumn herring sampled. During August and September younger fish were dominating among the autumn spawners, the rg66 year class dominating with 38% and the rg65 and rg64 year classes following with 25% each.

North-eastern North Sea (grounds east of 2°E and north of 57o3o'N).

One sample in April consisted entirely of spring spawned herring, elsewhere the spring spawners made up 13% of the stocks sampled. The spring herring in April, of which gr% were in maturity stage VI, were dominated by the rg6r year class, making up 55% of the sample. Of the total spring

rings seine trawl trawl trawl Spring Autumn

0 6 I26 94 - 226 I I62 83 I - 22 246 2 3 6 - 3 9 3 4 5 I I - - - 2 6

I73 9I I27 94 25 485

spawned herring sampled the rg64 year class was the dominant one and contributed 41%.

Among the autumn spawned herring the rg63 year class dominated the catches during the winter, although the rg64 and rg6o year classes also made appreciable contributions to the catches. In the samples from May to November the 1964 year class supplied 46% and the rg65 year class 33% of the autumn spawning group.

Central North Sea (grounds south of 57°3o'N).

The purse-seine samples were from the Great Fisher Bank and the Gut area, whereas the trawl samples were from the Bl0den ground. The autumn spawned herring were strongly dominant in both areas. The rg65 and rg64 year classes prevailed on the Great Fisher Bank and the Gut area, and these two year classes provided 36% and 33% of the samples. In the samples from the Bl0den ground the rg66 and the rg65 were the strongest year classes, each giving 49% and 46% respectively.

-rsg- Clupeoid Fish Herring

Skagerak The autumn spawning component were forming

more than 95% of the sampled herring. This area was almost entirely populated by juveniles. The age composition show that while the rg65 year class predominated in some samples, other samples were entirely build up by the rg66 year class. S. HARALDSVIK

Fiskeridirektoratets Havforskningsinstitutt, Bergen, Nordnesparken 2, Norway.

o/o 30 ~17 21 f'\'25 29 33

~m

o/o 20~

I ' 80

n-422 20

80

n- 289 20

10

10

10

em

1234567

0 f'l

Wr.

~ April n -100

1\

May n -96

June n-489

September

n-1766

The Polish herring fishery in the North Sea in 1967

(Figures 147-151; Tables 144-146)

The catches Polish herring catches decreased substantially in

rg67 (Table 144). This was mainly due to a great reduction in fishing effort, but the catch per effort was also lower than in previous years. The catch and effort statistics for different kinds

Table 144. Polish catches of North Sea herring in 1964-1967

ICES statistical areas Year Ilia IVa IVb IVc Total

in tons

1964 4.324·4 28,910.5 s8,726.r 1,188.9 93.149·9 1965 5.330.0 52,078·3 44,815.4 328.2 102,551.9 1966 SILO 38,889.0 34,085.0 1,097·0 74.582.0 1967 127.0 11,440,0 26,370.0 s.o 37.942.0

17 21 25 29 33 1 2 3 4 5 6 7 8 910

o/o %I ' ' ' ' ' ' ' ' cin r "'fr.

20~ /\ 40 n April

10

10

30

20, n-421

10

n- 617

May n-565

June n-606

July

n-95

11 21 2 5 29 33 I" 2 3 4 s 6 1 a 910 Length em Wr.

ISprin9 spawners 0 Autumn spawners ISpring $pawners DAufumn ipawners Figure I47· Length and age of the herring catches in the Figure q8. Length and age of the herring catches in the

Fame Deeps area in 1967. north-western North Sea in 1967.

-r6o-

Table 145· Catch and effort data of the Polish herring fisheries Year

I965 I966 I967 Catch No of Catch Catch No of Catch Catch No of Catch

Type of vessel Fishing gear

Steam trawler 600-700 gross tons bottom trawl

Steam trawler 6oo-7oo gross tons pelagic pair-trawl

Motor trawler 700-Soo g. t. bottom trawl

Freezer trawl I300-1400 g. t. bottom trawl

Drifter trawl ISO-ISO g. t. bottom trawl

Drifter trawl ISO-ISO g. t. pelagic pair-trawl

Drifter trawl I50-ISO g. t. drift net

Cutter So gross tons bottom trawl

Cutter So gross tons pelagic pair trawl

Cutter So gross tons bottom pair-trawl

in tons

fishing days

4S.353 ?,OI2

92I I94

I6,I7o I,756

5o4I6

I,20I

7,967

4.933 II,979 s,6I2

797

535

2,375

I,IS9

3.39I I,S49

per day

6.9

4·7

9·2

6.S

2.2

3·3

2.6

3·5 3·0

in tons

fishing days

3S,305 7,III

I2,304 2, I IS

2,192

3,6ro

935

S,245

S,S03 rSS

623

I,533

sSS

2,693

3,366

II4

per day

5-4

5.s

3·5

2.3

r.6

3·I 2.6

r.6

in tons

fishing days

I6, 7S6 3,935

7

I,5sS

3,2S6

I3I

6,3SO

6.577

33I IoS

6

466

I,?SO

S5

I,S69

3,023

75 46

per day

4·3

I. I

3·3

r.S

!.5

3·4 2.2

4·4 2.3

Table 146. Catch per fishing day in 1967 in tons

Month Type of vessel

NE North Sea

Steam trawl Drifter trawler Drifter trawler

Fishing gear Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec.

NW North Sea

Steam trawler Drifter trawler Drifter trawler Cutter

The Gut

Steam trawler Drifter trawler Drifter trawler

Farne Deeps Ana Steam trawler Steam trawler Drifter trawler Drifter trawler Drifter trawbr Cutter Cutter

Dogger area

Steam trawler Drifter trawler Drifter trawler Cutter

bottom trawl bottom trawl drift net

bottom trawl bottom trawl drift net bottom trawl

bottom trawl bottom trawl drift net

bottom trawl pel. pair trawl bottom trawl pel. pair trawl drift net bottom trawl pel. pair trawl

bottom trawl bottom trawl drift net bottom trawl

6.o 4·0

S.3

!.2

of fishing vessels and gear are given in Table 145. For comparison the corresponding data for rg65 and rg66 are included. Table 146 gives the catch per effort in different months. As can be seen from this table the results were in general very

I.O

I.O

0.9

0.2

2.2

r.s

I. I

I.9

I.O

I.7

3·S 2.3

I. I

0.7

0.6

3·3 2-4

2.2

2.3

2.0

!.4

!.9

2.1

I.O

3·4 4·0

2.S 0.9 !.2 2.6

2.7

0.6 r.6

S.o 3·2 6.I 5·3

2.1

7·0

2.I

2.3 2.2

3·4

r.S 3·I 2.6

4·2

6-4 II.2

3·2

3·3

r.S 3·6

2.6

o.6

r.6

3·4

4·3 3·2 r.S I. I

!.4 2.7

0.3

!.4

poor. Only the catches with drift nets in the north­western North Sea in the period August-Septem­ber were good. In August some good spawning concentrations were also exploited by the steam trawlers.

-r6r- Clupeoid Fish Herring

21 25 29 33 37 1 2 3 4 5 6 7 8 9 10 o/o tm Wr.

ZOf n-jl\_ o/o February I

n n-98 10~ 20

I II n I

n-923 201- fio 10f ~~201 •••••• I

10f"-/ \_20

2or- 1\ 40 n-160

101- 20

~~44/\ 10~, ~ "' 20

1 25 29 33 3711 2 3 4 5 6 7 8 910 Length em Wr.

ISprins spawners DAutumn spawners

Figure 149. Length and age of the herring catches in the north-eastern North Sea in 1967.

Biological data

Figures 147-151 gives the length and age com­position of herring catches, taken by commercial vessels (Figures 147-148) and by research vessels (Figures 149-15I) in different months and parts of the North Sea.

In the north-western North Sea the year class 1963 predominated in the catches. In the Fame Deeps area the year classes rg64 and rg65 were also important. The 1965 year class predominated also in the Skagerak and on the Bl0den Ground.

J. PoPIEL, J. SosiNSKI

Sea Fisheries Institute, Aleja Zjednoczenia r, Gdynia, Poland.

13 17 21 25cm1 2 Wr.

o/o o/o

20 40 April

10 20 n-181

80

30 60 August

n-275 n-100 20 40

10 20

13 17 21 25 1 2 Length em Wr.

I Sprin9 spawners 0 Autumn spawners

Figure 150. Length and age of the herring catches in the Skagerak in 1967.n (length, april) = 670

o/o o/o

80 June

60 n-198

20 40

~ nn 10

17 21 25 1 2 3 LQngth em Wr.

0 Autumn spawnHs

Figure 151. Length and age of the herring catches on the Bloden Ground in 1967. n (length) = 1023

-162-

The English herring fisheries in 1967 (Tables 147-157)

Table I47· Catch and effort of the English herring fisheries

The fisheries

The catch and effort statistics are summarized in Table 147 to show the catch, effort and catch per effort in each of the fisheries for each type of fishing gear used. The decline in the size of the drifter fleet continued in 1967, but this was com­pensated for to some extent by an increase in the pair trawler effort off the north-east coast, and in fact these vessels landed just over 87% of the total catch in the Longstone spawning fishery.

The 1967 fisheries were all affected by poor recruitment of the rg64j65 year class to both the Bank and Downs stocks as a whole, although recruitment of Downs herring to the Hinder spawning grounds in November appeared to be the best since rg64. Recruitment of the rg64j65 year class (three years old) was not expected to be very good, in view of the fact that the two years old of this year class did not show up strongly in rg66.

Catches in the North Shields fishery, which is based very largely on three year old recruits, were therefore very small during May and June but a marked improvement took place in July, and this was maintained in August, when catches were boosted by th~ influx of considerable numbers of two years old (rg65(66 year class) and four year old herring (rg63j64 year class). By the end of the season the total catch was 3,2r8 crans down on the rg66 figure although the mean catch per effort was much the same in both years.

The longstone spawning fishery in August was most productive while it lasted with, as already mentioned, the bulk of the catch being taken by pair trawlers. The season total was 4,654 crans higher than in the previous year, and this increase was probably due to the fact that although the abundance of recruiting three year old herring in this fishery was somewhat lower than in rg66, the surviving four years old were exceptionally plentiful.

The Whitby fishery further south was, how­ever, a very bad one in rg67, due mainly to the extremely poor recruitment of the rg64(65 year class to this fishery. Recruitment here was the worst since rg6z when the rgsg(6o year class almost completely failed. The total catch of 6,286 crans was ro,367 crans lower than in rg66 and the mean drifter catch per effort was down by 7·3 crans per shot. Had it not been for four year old sur­vivors of the rg63(64 year class turning up in

in 1967

I. Drift net Month Crans

North Shields fishe1'Y

May ......... 20 June ......... 153 July ......... 5731 August ....... 2909 Season ....... 8813

Whitby fishery

July .......... 0 August ....... 5479 September ..... 85 Season ....... 5564

Longstone fishery

August . . . . . . . 428

H aisborough fishery

September ..... 6717 October ....... 2848 Season ....... 9565

East Anglian fishery

October ....... 197 November ..... 201

Season ....... 398

Hinder fi.shery November ..... II82 December ..... 23 Season ....... 1205

Sandettie fishery

November ..... 132

2. Trawl

Month Crans

Whitby Single boat trawlers

August ....... 202

Whitby pair trawlers August ....... 518 September ..... 2

Season ....... 520

Longstone single boat trawlers

August ....... 7

Longstone pair trawlers

August ....... 13,155

3· Ring net

Month Crans

North Shields fishery

July ......... 54

Longstone fishery August ........ 1514

shots Crans per shot

18 !.1 37 4·1

255 22.5 144 20.2

454 19-4

I 0.0 347 rs.8 40 2.1

388 14·3

26 16.5

310 2!.7 151 r8.9

461 20.7

14 14.1 37 5-4 51 7·8

34 34·8 7 3·3

41 29-4

4 33·0

Land- Crans ings per landing

9 22.4

29 17·9 2 r.o

31 16.8

3 2.3

302 43·6

Landings Crans per landing

4 13·5

69 2!.9

-!63- Clupeoid Fish Herring

Table 148. Age distributions (as mean number per net per shot) for the drift net fisheries

North Shields Long- Hais- East Age (Years) Year·class May June July August Whitby stone borough Anglia Hinder Sandettie

2 """"""" I965/66 O.I I2.2 44·0 48·9 0.0 0.0 I3.6 7-I 22.2 I3-4 3 """"'"'"" I964/65 I2.8 31.0 143-3 I0?-3 74-9 202.7 I9I.6 83.2 336.8 3I9-5 4 . " ........ I963/64 6.1 29.I rr6.9 38.0 241.5 I57-5 II2.3 30.1 73-5 91.3 5 ........... 1962/63 2.0 2.8 16.6 4·8 I6.3 4·9 37-5 9-6 5·0 2.7 over 5 ....... 1.2 0.7 3·5 2.7 0-4 o.8 3·4 4·3 1.9 I6.2 ? ........... 1.2 2.4 7·3 6.2 - 3·9 Total ....... 23-4 78.2 331.6 207·9 333-I 365·9 358·4 I38.2 439-4 443·I

The Age distribution for the Whitby, Longstone, Haisborough, Hinder and Sandettie fisheries are for the spawning components only. i.e. fish in maturity stages V, V-VI, VI and VII-I at Whitby Longstone and Haisborough, stages V-VI, VI and VII-I at Hinder and Sandettie.

Table 149. Maturity distribution (drift caught herring)

Hais- East North Shields fishery Whitby Longstone borough Anglian Hinder Sandettie

May June July August fishery fishery fishery fishery fishery fishery Maturity stage % % % % % I ............. I3·9 12.6 12.5 22.4 0.0 II . . . . . . . . . . . . 37·6 q.o I3A I3.I 0.0 III ........... I5.8 6.9 I9-3 I3-3 0.5 III-IV ........ 1.4 8.6 I3-3 7-I 0-4 IV ............ 3-2 I8.o I2.I 19-3 0.3 IV-V ......... 0.0 II.7 8.6 II.? 0.9 v ............. 0.0 II.? 16.8 I2.3 13.I V-VI ......... 0.0 I.O 0.2 0.0 I0.3 VI ............ 0.0 0.0 0.0 0.0 72.8 VII-I ......... 0.0 0.0 0.2 0.0 1.5 VII-II ........ 12.7 0.0 0.0 0.0 0.0 VIII .......... I 5-4 I5·3 3-6 o.8 0.0

Number of fish . 252 447 3189 2505 8783

Table 150. Maturity distributions (trawl caught herring)

Maturity stage Whitby fishery Longstone

I .......... " .... . II .............. . III .............. . III-IV .......... . IV .......... " .. . IV-V .......... . v ....... " ....... . V-VI .......... . VI .............. . VII-I .......... . VII-II .......... . VIII ............ .

Number of fish .... .

fishery % % O.I 0.0 I.7 r.6 0.7 I. I

II. I 3-6

79·4 o.8 0.0 0.0

I903

0.0 0.0 0.0 0.0 0.0 0.0 2.2

I.7 91.2

3-5 o.8 0.6

2883

reasonable numbers, the Whitby :fishery would have been a dismal failure.

The Haisborough drift net :fishery in the autumn was satisfactory even though only half as many recruit three years old were present in the catches compared with the previous year. The total

% % % % %

0.0 1.2 1.2 0.0 0.0 0.0 3·8 2.4 o.8 r.6 0.0 1.0 0.0 0.0 0.0 0.0 0.6 0.0 0.2 0.7 0.0 4·3 7·6 0-4 0.0 0.0 7·3 15-4 3·0 0.7 o.8 28.8 44·7 I3-5 7·8 0.6 16-4 10.5 I7.8 12.4

94·6 30.2 7·6 63·3 76.8 2.3 3-4 3·3 0.3 0.0 I.O 2.5 4·6 o.8 0.0 0.7 0.5 2.7 O.I 0.0

883 5090 I674 I97I I84

Table I5I. Mean 11 in Age (years) Year class

the spawning fisheries in 1966

Whitby spawners .......... . Number of fish ............ . cr2 ........••.......•......

Longstone spawners Number of fish ............. .

cr2 ·········"·"·········· Haisborough spawners ..... . Number of fish ............ . cr2 •........•.............•

Hinder spawners .......... . Number of fish ............ .

cr2 ······""""·······"· ·-----~-··-

3 1963/64

13-90 q,646 4·0476

14·76 825

4·8582

I3-59 6,577 3·f4II 13.27 1,310

2.0857

4 1962/63

II. 51 I,520

3·750I

Ir.68 2,472

3-2780

The sample 11/fish length keys were raised to the market measurements of the spawning components in each fishery.

catch was 4,626 crans lower than in rg66 for practi­cally the same effort while the mean catch per effort of 20.7 crans per shot was g.6 crans per shot down on the very good rg66 :figure. The best catches were made during the early part of this :fishery in the Dowsing area.

-164-

Table 152. Mean 11 in the spawning fisheries in 1967 returned home after a few weeks. Scarcely any herring were caught on the traditional East Anglian grounds and most of the seasons total 398 crans (at a mean rate of 7.8 crans per shot) came from the vicinity of the Brown Ridges.

Age (years) 3 4 Year-class I964/65 I963/64

Whitby spawners .... . Number of fish ............. . cr2

I7.II 2II7

I ·5377 Longstone spawners ....... . Number of fish ............ . cr2 ......•.•..............

Haisborough spawners ..... . Number of fish ............. . cr2

Hinder spawners .......... . Number of fish ............ .

I6.43 867

I -4593

14-43 I246

14-07 2423

3-9794

14·72 456

3-9857 q.64 478

3·8725 I3.25 252

However, the remaining three English drifters enjoyed a most profitable fishery during November and early December on the Hinder spawning grounds further south, and landed a total of 1,205 crans at a mean rate of 29-4 crans per shot. Most of the herring caught at the Hinder were recruit three years old of the 1964/65 year class.

cr2 3-I967 1.97I8

Biological data The sample 11/fish length keys were raised to the market measurements 0f the spawning components in each fishery.

The East Anglian drift net fishery in October and November was once more virtually a complete failure. A maximum number of 20 drifters fished from Great Yarmouth and Lowestoft, but catches were so poor that the 17 Scottish drifters all

The biological details for the herring sampled from all the English North Sea herring fisheries in 1967 are summarized in Tables I48-I57· They contain distributions of age, maturity and otolith type together with the mean length, mean V. S., mean K 2 and mean L1 of the spawners by age-

Table 153. Mean length for age (drift caught herring)

Age (years) Year class

Mean length .................. . Number of fish ................ . cr2 ........................... .

Mean length .................. . Number of fish ................ . cr2 ........................... .

Mean length .................. . Number of fish ................ . cr2 ........................... .

Mean length .................. . Number of fish ................ .

2 ()" ····························

Mean length .................. . Number of fish ................ . cr2 ........................... .

Mean length .................. . Number of fish ................ . cr2 ......................•....•

2

I965/66 3

I964/65 4

I963/64

Whitby spawners (fish in maturity stages, V, V-VI, VI and VII-I)

25.85 27.35 3,879 4.396

2.0430 0.9457

Longstone spawners (fish in maturity stages V, V-VI VI and VII-I)

26.I3 27-33 457 389

o.6962 o.878I

Haisborcugh spawners (fish in maturity stages V, V-VI, VI and VII-I)

24.67 I78

0-4429

26.32 2,340

0.7296

27-32 1,097

0.7225

East Anglian herring (fish in all maturity stages)

24-52 26.05 27.04 9I I,I62 270

0.5303 o.8778 0.9284

Hinder spawners (fish in maturity stages V-VI, VI and VII-I)

24.03 78

o.6665

25.87 I,246

I.0350

Sandettie spawners

26.77 25I

1.0460

(fish in maturity stages V-VI, VI and VII-I)

23-75 5

26.04 Il9

I.0870

26.8I 34

0.6025

5 I962j63

27-98 314

0.8467

28.38 IS

2.23IO

28.09 369

I. I 770

27-57 I07

1.3260

28-47 I8

2.1830

26.25

6 I96I j62

28.25

31.25

30-7I 23

0.4526

29-72 40

o.6582

30.25 7

0.5833

30-42 3

7 I96oj6r

31.33 6

30.83 6

31.25 2

26.25 5

30.05 5

1.0750

29-75 3

The mean lengths are based on raised length distributions. i. e. sample age/length key x market measurements. 0.25 em has been added to each mean length.

-r6s- Clupeoid Fish Herring

Table IS4· Mean length for age (trawl caught herring)

Age 2 3 4 5 6 7 8 9 Year class !965/66 1964/65 1963/64 !962/63 1961(62 196oj6I I959/6o 1958/59

Whitby spawners (fish in maturity stages V, V-VI, VI and VII-I)

Mean length .......... . z6.13 27-32 27-99 z8.zs 3I.25 Number of fish ........ . 8sr 875 78 cr2 ..........•.......•. 0.7033 0.9623 I.0570

Longstone spawners (fish in maturity stages V, V-VI, VI and VII--I)

Mean length .......... . 26.23 27-48 29-38 3I.48 3I.IO Number of fish ........ . I,I62 1,509 92 24 5I a2 . . . . . . . . . . . . . . . . . . . . o.66r8 0.8667 2.0750 0.0648 0.8129

Table ISS· Mean V. S. by age in the spawning fisheries

Age (years) Year class

Whitby spawners (Mat V, V-VI, VI and VII-I) Number of fish ................ . cr2 .••.........................

Longstone spawners (Mat V, V-VI, VI and VII-I) Number of fish ................ . cr2 ........................... .

Haisborough spawners (Mat V-VI, VI and VII-I) Number of fish ................ . cr2 .....•......•...........•...

Hinder spawners Mat V-VI VI, and VII-I) Number of fish ................ . 0"2 .••.•.••••••••••.......•..•.

2

1965/66

s6.zso r6

0.3333

56.308 13

0.2308

3 1964/65

56-400 75

0.3784

56·370 54

0.5395

56·330 179

0.5143

56-447 304

0.7431

4 5 1963/64 1962(63

56·357 56-421 252 19

0.5253 0.3684

56·343 s6.7oo ro8 IO

0-4329

s6.369 56-423 122 52

0.5322 o.s6z6

56·446 s6.soo 92 6

0.4256

3!.75 2

6 1961/62

57-000 2

56.soo 6

s6.667 6

32-75 2

7 196oj6r

57-000 2

-

56·571 7

57-250 4

Mean V. S. is based entirely on laboratory samples of commercially caught herring (drift and trawl caught herring combined).

Table 156. Mean K 2 by age in the spawning fisheries

Age (years) 3 4 5 Year-class r964/6s 1963/64 1962/63

Whitby spawners ............... (Mat V, V-VI, VI and VII-I) 14-919 15.103 IS-333 Number of fish ................. 37 97 6 cr2 ............................ 0-4099 0.3226 0.2667

Longstone spawners (Mat V, V-VI, VI and VII-I) .... I5.120 15-140 rs.ooo Number of fish ................. 25 so 6 cr2 ............................ 0·4433 o.z86r

Haisborough spawners (Mat V-VI, VI and VII-I) ...... 14.831 14-910 15.000 Number of fish ................. 59 67 z6 cr2 ............................ 0.6604 0.7494 o.s6oo

Hinder spawners (Mat V-VI, VI and VII-r) ....... 15-523 rs.86z 17.000 Number of fish ................. !07 29 ., cr2 ............................ o.6858 0-4089

6 I96Ij6z

I'i-333 3

7 196oj6r

r6.ooo 4

r6.soo 2

-r66-

Table 157. Percentage distribution of otolith types in the 3 and 4 year old spawning fish

Age 3· 1964/65 year class Longstone Whitby Haisborough Hinder

Otolith type fishery fishery fishery fishery

-vv ................. . r.8 - !.7 !0.2

N 96-4 98·7 93·8 85.2 r.8 !.3 4·5 4·6

Number of fish ...... . 55 75 176 344

Age 4· 1963/64 year class "' ................. . 2.7 N ................. . 93·7 ? .................. . 3·6

Number of fish ...... . 112

Maturity stage-; ..... . V, V-VI, VI and VII-I

groups, in the various fisheries. Mean L1 's of the spawners in rg66 are also included in this contri­bution as it was not possible to publish them in the previous issue.

The recruitment of the 1964/65 year class (the three years old) and the abundance of the survivors of the rg63/64 year class (the four years old) have been commented on in the preceding section. Herring of the rg65j66 year class (the two years old) were exceptionally numerous in the North Shields catches in July and August, but did not show up strongly in the other fisheries.

The mean lengths of the recruiting three year old herring were approximately r to 1.5 ems larger than those of the recruits in rg66, and were on the whole rather similar to the mean lengths of the recruits in rg64, i.e. the rg6rj6z year class.

The mean L1 values of the three year old re­cruits in 1967 were exceptionally high, and were in fact the largest recorded to date, being even higher than those of the 1959 year class. Not surprisingly therefore, the proportion of "wide" type otoliths amongst the three years old was low in all the fisheries.

It should be noted that mean K 2 's were high in all the age-groups, in each fishery in rg67. Although there is no obvious explanation for this, it must be pointed out that the total numbers of fish on which all these means are based, are rather small.

R.]. WooD, W. G. PARNELL

Ministry of Agriculture, Fisheries and Food, Fisheries Laboratory, Lowestoft, Suffolk, England.

6.8 7·8 30·3 88.8 85·3 66.7

4·4 6.9 3·0

251 II6 99

V, V-VI, VI V-VI, VI and V-VI, VI and and VII-I VII-I VII-I

The herring fisheries of the Netherlands 1967 (Tables r58-r61)

The fisheries

Trawl

North Sea

The decline in catches of the last years persisted during the season rg67. The total landings dropped from 37,670 tons in rg66 to IJ,OZ3 tons in rg67.

The decrease in the total landings was caused by the poor to moderate recruitment of year class 1964 in all the North Sea fisheries and the low abundance of fish older than four years. Predo­minant in the catches in the N.W. and Central area was the year class rg63.

Catch and effort statistics of the herring trawl fisheries are given in Table r58, separated by month and area. The areas used are the same as defined in A nnales Biologiques, Vol. 16. The considerable change in the fishing pattern in time and place, occurring during the last years in the Netherlands' herring trawl fishery, was continued in rg67.

The Fladen, the old fishing ground during the pre-summer and summer fishery, has almost been abandoned. The fishery, during this time, has been shifted to the grounds between the 55° and 57° N.L. and is based largely on pre-recruits (three year old herring) and four year old herring. Part of the fleet moved over to the south- and north-Irish waters during the summer months, and was followed in September by the remainder of the fleet, when the spawning fishery on the Flam­borough/Whit by grounds had come to an end.

-167- Clupeoid Fish Herring

Table 158. Catch and effort data of the herring trawl fisheries in 1967

Top figures: Total catch in tons Middle figures : Effort, roo fishing hours of a motor trawler of 500 B.H.P. Bottom figures: Catch per Ioo hours fishing

Area Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Total

N.P ......... IS 27 66 433 237 26 I3 4 73 8 99 1,004 7I.7 I28.6 I08.7 248.2 224.8 4I.2 43·0 27·7 52·4 56.2 88.r - I,ogo.6 0.3 0.2 o.6 I.7 I. I 0.6 0.3 O.I I.4 O.I I. I o.g

N.W ........ 4 6 - 135 2,820 333 I I93 - 4 4-496 30·7 20.4 rg.o - 32·7 233-9 47-4 2.9 II.9 -- 4·0 5·9 408.8

0.2 0.3 - 4·1 I6.3 7·0 0.4 r6.2 - 0.6 II.O

Central ...... - IS 2 8 r6g 6I3 7,015 3,544 I 53 I II,523 I5·5 I.9 23·5 30.2 66.6 254·5 I3I.5 32-7 5-5 56I.g

1.2 o.g 0.3 5.6 g.2 27.6 27.0 4·7 - - 20.5

South . . . . . . .

S.P. Ireland .. 326 3 - - 2,445 7II 1,400 2,745 I,62o I,284 10,534 22.2 0-4 0.7 - I44·5 54·9 59-4 I5I.2 79·9 83.0 596.2 14·7 8.5 - - I6.g I3.0 23.6 I8.2 20.3 I 5-5 I7.7

N. W. Ireland - - - - I28 !,686 555 I,29I - 3,66o 8.1 59-I 3I.8 46·7 145·7

I5.9 z8.5 I7·5 27·7 - zs.r

Table I 59· Catch data (tons) of the pair trawl fisheries in 1967

Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Total

Central ...... - - -South ....... 292 308 I -

The spawning fishery in the central North Sea is becoming shorter every year. Compared with rg66 the fishing effort in the central North Sea in 1967 was down by 44%·

The spawning grounds in the southern North Sea and the English Channel have not been fished by the trawler fleet for the second year in succession.

Irish Sea

The increase of the effort in the S.E. Irish waters 35% in 1967, as compared with 1966, did not result in an increase of the catch. Instead of this, the catch dropped from 14,634 tons in rg66 to 10,534 tons in rg67.

The decrease of the catch was probably due to the moderate recruitment of the year class rg64. The year class 1962 in this area has been very strong and is followed by two moderate year classes. Consequently the abundance in the south Irish waters has been declining during the last two years. The north-Irish waters have in rg67 been fished commercially for the first season by the Dutch trawler fleet.

64 1,226 1,177 497 22 2,985 - 34 700 I,536 719 3,589

The overall abundance was better than in the North Sea, and the total catch amounted to 3,66o tons.

Pair trawl

This fishery took place in the central and southern North Sea. The catch statistics are shown in Table I59· The total landings increased from 5,430 tons in rg66 to 6,574 tons in rg67.

The pair trawl fishery was the only Dutch fishery exploiting the herring stock in the southern North Sea, on the Hinder, Galloper, and Sandettie banks and in the Strait of Dover. These stocks did not show signs of a substantial recovery. The catches in the southern area increased from 3,302 tons in rg66 to 3,589 tons in rg67.

Drift net

The drift-net fishery of the Netherlands is almoot extinct. Statistical data on the number of shots and the fishing area are no longer available. The total catch amounted to 2,100 tons in 1967.

Purse seine

The purse seine fishery initiated in rg66 was con­tinued in rg67 by three ships. The total catch amounted to r,8g2 tons.

-r68-

Table 160. Mean length (em) for age (:years), for different areas

Year class I965 I964 1963 I962 I96I I96o I959 I958 I958 Area/age 2 3 4 5 6 7 8 9 9

N.W. . . . . . . . . . . . . . . . . . . 22.2 24·9 26. 5 26.5 30·9 Central ................. 24.0 26.3 27-4 28.o 30·5 3!.3 31-4 3I.3 Dogger ................. 24.8 26.3 27.2 27·9 3!.8 30.8 - 3!.1 32.8 Sandettie . . . . . . . . . . . . . . 23·5 z6.z 27.0 28.9 29-9 30·4 East Anglia ............. 23·7 26.0 27.0 28.2 30.0 30.8 30.2 S.E. Ireland ............ 23.8 26-4 27·7 28.8 29·7 30.2 30.2 29.8 30·5

Table 16r. Age composition, in number caught per unit effort per day (Io hours fishing)

Year class I965 I964 I963 I962 Areajage 2 3 4 5

N.W. ......... 95 3,064 4.465 928 Central ........ 70 2,854 I I,054 I,204 Dogger ........ I98 6,o82 3,I76 2,I67 *Sandettie .... 0.7 65.I 27.0 !.2

*East Anglia ... I. I 68-4 2!.0 3·0 S.P. Ireland ... 722 2,I28 I,I65 2,84I

*age composition in %

Biological data

Length and age data are compiled in the tables r6o and r6r, for the following fisheries:

r. Fladen; Period: June; Area: between 58° and 6o 0 3o'N, West of I

0 E.

2. Central; Period: August-September; Area: be­tween 54° and 56°N, west of o0 E.

3. Dogger; Period: September-October; Area: be­tween 53°45' and 55°N and I

0 and 3°E.

4· East Anglia; Period: November; Area: between 53°30' and 52° N.L. in the North Sea. Gear: pair trawl.

5· Sandettie; Period: November; Area: Sandettie, Hinder banks; gear: Pair trawl.

6. S.E. Irland; Period: November; Area: between 50° and 52oN and 6° to g0 W.

As already stated, the recruitment of the year class rg64 in the central North Sea was moderate to poor. On the Fladen and Whitby grounds the year class rg63 dominated the catches.

]. ]. ZIJLSTRA, K. H. PosTUMA

Rijksinstituut voor Visserijonderzoek, Haringkade I, IJmuiden, Netherlands.

I96I I96o I959 I958 I958 6 7 8 9 9

64 I46 3I8 - I8 I2

I2 2I7 - 43 I6 4·2 !.7 3·9 2.2 0-4

645 no 279 347 732 9,630

Growth data for herring of the Southern Bight, derived by back-calculation of scales. The 1967

East Anglian samples (Table I62)

The rg67 East Anglian herring samples con­sisted of three year old fish of the newly recruiting 1964(65 year class, together with survivors of earlier year classes sampled in rg66. The rg64(65 year class provides newly available data on the first three years of growth and data from the earlier year classes afford a check on the growth estimates listed in Vol. 23 of the Annales Biologiques (Table 152).

The comparison of growth indices in Table r62 differs from that given in Vol. 23 in that data from the rg65 six year old fish are omitted and data from all ages sampled in rg67 are included.

Comparisons for each age of growth are made to the grand mean initial length for that age of growth, by using suitable correction factors. Growth indices are compared over a consecutive period of five years for 0, I and II group growth- a progressively shorter period for higher growth ages.

The rg67 data confirm the main features of recent growth changes as described in Vol. 23 of the Annales Biologiques. In addition, the new data from the rg64j65 year class and data for the growth year rg67 from older year classes indicate that marked growth changes have occurred in the last three years.

-r6g- Clupeoid Fish Herring

Table 162. 1967 East Anglian herring. Comparative growth estimates

Age Mean Mean Regres- Comparative Av:orage Age of Year of Year No. in Year of initial length sion Correlation growth growth growth growth class sample of fish length increment slope coefficient mean per year

sample (years) (em) (em) (R) (em) (em)

0 1961 196oj61 78 1965 5 0 I3·38 - I3.39 I4 I966 6 0 13-4I

1962 1961 j62 I99 I965 4 0 I2.87 - I2.74 42 1966 5 0 I3.00 19 1967 6 0 12.34

1963 1962/63 121 I965 3 0 I 1.55 -- 1!.66 37 1966 4 0 II.66 33 1967 5 0 I 1.78

I964 1963/64 72 I966 3 0 13·48 - I3-31 173 1967 4 0 I3-14

I965 1964/65 542 I967 3 0 14-71 - I4-71

I ... I962 I96oj61 78 I965 5 13-38 7-48 -0.278 -0-403 7·58 7-57 14 1966 6 I3..f1 7·44 -0.386 -0.595 7-55

Mean I3.39 Mean -0.332

I963 1961/62 I99 1965 4 I2.87 8.88 -0-458 -0.671 8.75 8.64 42 1966 5 13.00 8.70 -0..{69 -0.785 8.63 I9 I967 6 I2.34 8.9I -o.62o -0.728 8.54

Mean I2.73 Mean -0.5I5

I964 I962j63 121 I965 3 I !.55 8.99 -0-483 -0.673 8.26 8.Io 37 I966 4 I I.66 8.73 -0.367 -0.599 8.o5 33 I967 5 I 1.78 8.6I -o.566 -0.537 7·98

Mean II.66 Mean -0-472

I965 I963/64 72 1966 3 I3-48 7-48 -0-435 -0.620 7·63 7.66 I73 I967 4 13.14 7·7I -0-.{I I -0.59I 7·70

Mean I3.3I Mean -o-423

I966 I964/65 33 I967 5 14-7I 7·84 -o.szr -0.702 8.54 8.54 Grand Mean I3.I6 Grand Mean -0-453

II .. I963 I96oj6I 78 I965 5 20.86 4-59 -0.394 -0.537 4-42 4·36 I4 I966 6 20.84 4-41 -0.653 -0.722 4·24

Mean 20.85 Mean -0.523

1964 I96I/62 I99 I965 4 2!.75 4.26 -0.36I -0.546 4-46 4-43 42 I966 5 2!.70 4·33 -0.314 -0..{92 4·5I I9 I967 6 2!.25 4·36 -0.5Io -0.622 4·36

Mean 21.56 Mean -0.395

I965 I962j63 121 I965 3 20.53 3·78 -0.366 -0.640 3-48 3.60 37 I966 4 20.39 4·04 -0.526 -0.657 3.68 33 I967 5 20.38 4.I I -0.395 -0.624 3·65

Mean 20.43 Mean -0-429

I966 I963/64 72 I966 3 20.96 3·59 -0.364 -0.598 3.60 3.66 173 I967 4 20.84 3·77 -0-484 -0.648 3-73

Mean 20.90 Mean -0-424

I967 1964/65 542 I967 3 22.54 3-49 -0.298 -o.50I 4.02 4.02

Grand Mean 21.26 Grand Mean -0.414

III I964 I96oj6I 78 I965 5 25·44 2.6I -0.234 -0.436 2.68 2.57 I4 I966 6 25.25 2-.fO -0-467 -o.667 2-45

Mean 25.34 Mean -0.350

I965 I96I/62 I99 r965 4 26.oo !.74 -o.I67 -0.356 !.99 2.08 42 I966 5 26.03 I.85 ·-0.23I -0.436 2.1 I

I9 I967 6 25.6I I.88 -0.220 -0.525 2.I.'j

Mean 25.88 Mean -0.206

-IJO-

Table 162 (continued).

Age of Year of growth growth

1966

1967

IV .. 1965

1966

1967

v ... 1966

1967

Year class

1962/63

1963/64

1960j61

1961/62

1962/63

r96oj61

1961/62

No. in Year sample of

sample

37 1966 33 1967

542 1967

Age Mean of initial

fish length (years) (ern)

4 24-43 5 24·49 Mean 24-46

3 24.62 Grand Mean 25.08

78 1965 5 28.o6 l4 1966 6 27.65

Mean 27.85

42 1966 5 27.87 19 1967 6 27-49

Mean 27.68

33 1967 5 26.75 Grand Mean 27.43

l4 1966 6 28.82 21 1967 6 28.76

Grand Mean 28.79

The rg65 0-group growth, at 14.71 em was the highest .ever recorded for East Anglian fish ; it is some 4 em higher than the immediate post-war level and represents an increase of 1.4 em over the already high rg64 0-group growth.

!-group growth increased sharply in rg67, compared with rg66, to reach a level only a little lower than that for rg63, which itself was the highest recorded for second-year growth.

II-group growth also increased substantially in rg67, from the relatively low rg65 and rg66 levels, but was still less than the peak rg64 value.

III-group growth was perceptibly higher in rg67, but was 17% below the high level of 1954.

IV-group and V-group growth were at much the same level in rg67 as in rg66.

Growth in East Anglian herring showed a general increase in the early rg6o's for all year classes, and highest recorded levels were attained at all ages of growth. These highest levels were reached in rg6o and rg6r in 0-group fish, and progressively later for older fish. A decline in growth followed and again the trend began with 0-group fish, whose growth fell in rg62; !-group growth fell over rg64 and rg65, and that of older fish declined in rg65. The rg67 data indicate that this decline in growth has been arrested for the older age-groups and reversed for the younger groups.

T. D. lLES

Fisheries Laboratory, Lowestoft, Suffolk, England.

Mean Regres- Comparative Average length sion Correlation growth growth

increment slope coefficient mean per year (ern) (R) (ern) (ern)

2.39 -0.273 -0-494 2.21 2.15 2.25 -0.345 -0.594 2.09

Mean -0.306

2.40 -0.239 -0.367 2.27 2.27 Grand Mean -0.276

!.05 -0.110 -0.351 !.13 !.16 I.17 -0.134 -0.380 1.18

Mean -0.122

I.J4 -o.oo6 -0.016 1.17 1.22

!.27 -0.168 -0.361 !.27 Mean -o.o87

!.26 -0.015 -0.034 I.2 I I.2I

Grand Mean -0.075

0.90 -0.176 -0.327 0.90 0.90

o.89 -0.057 -0.178 o.89 o.89 Grand Mean -0.116

Notes sur le hareng de la region du Pas-de­Calais; observations pour la periode de 1963 a

1967 (Figures 152-r56; Tableau 163)

Production et rendements

Production, lieux et epoques de peche (Figure 152)

La chute des tonnages de harengs debarques a Boulogne, signalee depuis plusieurs annees, est accompagnee d'autres phenomenes comme, notam­ment, une diminution des zones d'exploitation tant en Mer du Nord qu'en Manche orientale et ce malgre ]'augmentation du potentiel de capture. D'autre part, si l'epoque de peche semble toujours aussi etendue, elle est entrecoupee de periodes sans activite.

a) Peche industrielle

Cette peche qui occupait 20 a 25 chalutiers jusqu'en rg64-65 n'interesse plus maintenent que quelques bateaux; trois chalutiers seulement se sont rendus ce dernier hiver sur les lieux de peche.

Ainsi qu'il a ete signale dans un precedent rapport, les chalutiers ont completement deserte le Sandettie. Il semble que les zones marginales des frayeres du Pas-de-Calais ont ete les premieres touchees par la disparition du hareng.

Cet abandon progressif des frayeres qui a com­mence par les zones les plus meridionales c' est-a-dire Antifer et Ailly, s'est poursuivi par les zones nordiques de la region du Gabbard et meme du

-IJI- Clupeoid Fish Herring

T.

4 000

2 000

BOO

4 00

0

PEkhe indust,

Peche artisan.

, ..... / ......

/ ..... / .....

/ ...... /

/

1963-4 1964-5 1965-6 1966-7

Figure 152.

Galloper au cours de ces deux dernieres annees. Les peches sont maintenant realisees essentiellement entre les banes de l'Hinder au nord et ceux de Bullock et du Vergoyer au sud.

La plus grande partie des mises a terre sont faites entre la mi-novembre et le debut de decembre. Enfin, si la chute de la production est tres specta­culaire, elle a ete particulierement catastrophique pour la derniere campagne puisque seulement 8o tonnes ont ete debarquees.

b) Peche aJitisanale

Les lieux frequentes par les chalutiers-boeufs s'etendent le long de la cote fran<;:aise (Bassure de Baas, Vergoyer) et, au nord, entre le Sandettie et la cote belge. L' exploitation debute sur le hareng plein et bouvard en novembre et decembre et se termine sur le hareng guai en janvier et fevrier; cependant on a pu voir des peches de hareng bouvard au mois de fevrier rg65 pres du bateau-feu >>Royal Sovereign<< et vers la mi-janvier rg67 au Sandettie tandis que la peche de hareng guai se poursuivait jusqu'a la mi-mars.

Pour ces quatre dernieres campagnes, la pro­duction a ete plus stable que celle de la peche industrielle. Cependant, hormis 1964-65, le niveau moyen de cette production est assez bas.

T.

10

8

6

4

2

........ "" _.... ' ' ' ' ' ,.

' ., ,..,. /

/ /

1 963-4 1 964-5 1 965-6 Figure I53·

Effort de Peche et Rendement (Figure r53)

a) Peche ind'btS!Jiielle

/ /

, ..,.

1 966-7

L'effort de peche, calcule en nombre de jours de peche effective, a, lui aussl., fortement decline ces dernieres annees, avec sensiblement les memes fluctuations que celles de la production. Il a ete de zr8 en rg63, 382 en rg64, 251 en rg65 et 31 seulement pour la derniere campagne. Le rendement accusant le contre coup de la chute de la production est tombe a un niveau tres bas.

b) Peche aJitisanale

L'effort de peche a ici aussi fortement diminue et peu de bateaux se sont armes pour le chalutage en bceuf. Cette annee, 7 paires seulement se sont fmmees et bien souvent il n'y avait que deux a quatre couples ce qui, en fonction d'une production stable, a favorise les rendements. C'est ainsi que pour les deux dernieres campagnes, les rendements de la peche artisanale ont depasse ceux de la peche industrielle.

La signification de ces rendements, lorsqu'ils sont utilises dans les estimations des parametres biolo­giques pour les populations de harengs, doit etre prise en consideration attentivement en raison de !'evolution des techniques (recherche plus active par le developpement de l'emploi du sonar) et des

-172-

% Ensemble du Pas de Calais Campagne 1966-67

80

% 60 60

sud Mer du Nord

40 40

1963-64

20 20

01 = l=h) 0 L-~--~--~~L-~--~~

40 1964-65 60

,----

Manche orientale

20 40

Q! I I I t===j I )

20 40 1--.----

ol n I I L ~ 20

0 L-~-~--L-~-~~~~ Harengs gua1s

40 40

20 20

0 L-~---L--~--L-~---L~ OJ r===-1 I I I I ~

2 3 4 6A + annees 2 3 4 5 6 &+ annl'!e5

Figure 154.

engins (effi.cacite accrue avec l'utilisation des chaluts semi-pelagiques et pelagiques). D'autre part, il semble que l'on doive considerer sous un nouvel angle l'abondance et la taille des stocks, ainsi que le rapport entre ces stocks et les pecheries qui les exploitent. En effet, l'indice d'abondance d'un stock est plutot fonction de la production que du rendement. C'est ainsi que la mortalite due ala peche ne peut etre estimee de la meme fa<;on que lorsque les stocks etaient tres abondants et les methodes sensiblement moins effi.caces.

Etude de population

Composition en age et recrutement (Figure 154)

La comparaison des compositions en age et du stock etablie pour chaque annee montre nettement la predominance des harengs jeunes. Pour les deux premieres annees de rg63-64 et de rg64-65 le pourcentage des 3 ans etait exceptionnellement important. En rg65-66 on a retrouve !'influence du bon recrutement de l'annee precedente car cette

-173- Clupeoid Fish Herring

%

J '\ ---- sud Mer du Nord 30 I

:/ ..... , \ _ _ Mane he orientale

•I '\ f/ \ __ Horengs guais

:J \. 20 I I I :1 \'.

!! \\ :t I ~ 3 \ \

1oJ I I j I ~

/_~.,. 1\ / / \ ~

/_, ,' L \ ...... , \~1

0 1/ /( -- ,-r:::_- ___ I I

20 22 24 26 28 30 32 em

Figure I55·

predominance des 3 ans (classe de rg6r) etait liee a une production relativement bonne, ce qui n'avait pas ete le cas pour 1963-64. L'infiuence de cette classe de rg6r s'est encore fait sentir cette annee ou le pourcentage moyen des harengs de s ans a ete sensiblement plus eleve que celui des annees precedentes.

La composition en age du stock pour rg66-67 etablie en fonction des lieux de peche montre une difference sensible entre d'une part les harengs bouvards pcches dans le sud de la Mer du Nord et la Manche orientale et d'autre part les harengs guais peches dans l' est du Sandettie. La composition en age est en effet plus etalee pour ces derniers.

Taille par age et repartition des tailles (Tableau 163)

Depuis rg6s-66, on peut observer une diminu­tion sensible de la taille moyenne par age des harengs. Ce phenom€me qui avait deja marque la

classe de rg62 (harengs de 3 ans en rg6S et 4 ans en rg66), semble se poursuivre puisqu'une diminu­tion du meme ordre affecte la taille des harengs de 3 ans etudies lors de la dernicre campagne.

Par ailleurs, la repartition des tailles, qui a ete faite chaque annee, montre l'infiuence de la representation par classe d'age qui provoque un deplacement du mode en relation avec le pourcent­age de harengs plus ou moins ages. Cependant, la repartition pour rg6s-66 etablie en fonction des lieux de peche (Figure ISS) montre une particularite interessante qui n'apparait pas dans l'examen de la representation par classe d'age faite pour I' ensemble des echantillons preleves. En effet, le deplacement du mode, en ce qui concerne l'echantillon de hareng guai, montre que cette pecherie s' est exercee sur une population differente qui etait constituee de harengs a caracteres c6tiers assez prononces. Ces caracteres se traduisent par une taille nettement inferieure a celle observee habituellement pour des harengs de me me age; cette difference s' observe en effet aussi bien a 3 ans que dans le calcul de L 1 .

De plus, la moyenne vertebrale, particulicrement faible, est venue confirmer ces observations.

Moyenne vertebrale (Tableau r63)

Si l' on considere les valeurs obtenues dans les calculs de la moyenne vertebrale pour chaque annee et en fonction des lieux de peche, on se rend compte qu'une seule moyenne depasse s6,6o. Ces valeurs ne sont done pas en rapport avec celles donnees habituellement pour le stock des «Downs>> qui a pourtant ete defini comme representant le hareng frayant dans le sud de laMer du Nord et la Manche orientale, en novembre et decembre.

Tableau 163. Taille moyenne par age et moyenne vertebrale en fonction des lieux de peche et pour chaque campagne

(Entre parentheses sont indiquees les classes d'origine correspondant a chaque age)

L I 3

1963-64 (r96o)

Sud Mer du Nord ............... 24,87 ~Ianche Est . . . . . . . . . . . . . . . . . . . . 25,24 Harengs guais .................. - 25,34

1964-65 (1963) (1961)

Sud Mer du Nord ............... 12,8! 25,90 Manche Est .................... 13,04 25,70 Harengs guais .................. 12,84 25,69

1965-66 (1964) (1962)

Sud Mer du Nord ............... 12,81 24,!0 Manche Est .................... 12-43 24,17 Harengs guais .................. Il,30 23,59

1966-67 (r965) (r963)

Sud Mer du Nord ............... 12,88 24,29 Mauch'> Est .................... 12,78 24,06 Harengs guais .................. 12,7-f 24,74

4

(1959)

25,83 26,62 26,95

(1960)

27,90 27,92 27,74

(1961)

27,70 27,76 25,97

(1962)

26,32 26,64 26,40

5

(1958)

27,17 28,26 27,66

(1959)

(1960)

29,00 28,85 28,50

(1961)

28,92 29,11 28,64

Moyenne vertebrale

56-43 ± 0,15 56,6r ± 0,17 56-49 ± 0,31

56,36 ± 0,15 56,54 ± 0,12 56-47 ± 0,15

56,54 ± 0,20 56-49 ± 0,20 56,22 ± 0,21

56, 55 ± o,r 3 56,55 ± 0,34 56,38 ± 0,30

-174-

9

250

200

150

100

20 25

(st. v-v1)

I I Manche orientale

(st.V-VI)

--- Harengs guais (st. VII-VIII)

30 em

Figure I56.

Relation taille-poids (Figure I 56)

Cette relation est traduite par une courbe qm fait apparaitre un decalage sensible entre les harengs bouvards peches dans le sud lela Mer duN ord par leN. 0. "Thalassa" en novembre rg66 et ceux, au meme stade de maturite, peches entre le bateau­feu Dyck et le Colbart en janvier rg67 par les chalutiers-boeufs. A taille egale ces derniers ont un poids nettement plus faible. Les harengs guais que 1' on peche ala me me epoque montrent un poids encore plus faible, mais, dans ce cas, 1' ecart s' expli­que par les stades de maturite differents.

M. A. MAUCORPS

Institut des Peches Maritimes, ISO, Quai Gambetta, Boulogne-sur-Mer (Pas-de-Calais), France.

The Dunmore East herring fishery, 1966/67 and 1967/68

1966/67 The season opened on the 22. October and

continued until the r8. January. Fifty Irish boats

using paired mid-water and bottom trawls took part and landed 47,560 crans which was an increase of 2J,OI8 crans on the previous season. The increas­ed landings were due to the good weather during the season, the increased number of boats using mid-water trawls and the very good recruitment of three year old fish during the rg65j66 season. Landings per type of gear were:

Paired mid-water trawls

Bottom trawls

27,870 crans

rg,6go crans

In spite of the increased landings the catch per landing of bottom trawls decreased from 43.0 crans (rg65j66) to 35.0 crans (rg66j67). Heaviest fishing took place in Baginbun Bay and off Bally­cotton.

Biological investigations were continued through­out the season. The dominant age-groups were four, three and two year old fish. Maturity examina­tions revealed a tendency for earlier spawning in the Baginbun Bay area.

-I75- Clupeoid Fish Herring

1967/68 The season opened on the 23. October, rg67 and

continued until r6. February, rg68. Fifty eight Irish boats took part and landed a total of 63,343 crans, an increase of IS-774 crans on the rg66/67 figure. As in rg66/67 mid-water and bottom trawls were used. Landings per gear were as follows:-

Paired mid-water trawls Single mid-water trawls Bottom trawls

24,280

I70 38,8g3

In spite of market difficulties which restricted fishing to a large extent the average catch per landing for bottom trawls increased from 35.0 crans to 42.8 crans while the average catch per landing for paired mid-water boats decreased slightly from 93.0 crans to 87.00. Baginbun Bay again yielded good quantities of herrings while good fishing was also experienced off the mouth of Cork Harbour, an area which was not exploited at all in recent years. Recruitment during rg67j68 was very good and three year old and five year old fish dominated the samples. Once again there was a tendency for an earlier appearance of stage VI fish. Tables for both the rg66/67 and rg67j68 season showing mean lengths and mean vertebral counts per age class per maturity stage, percentage distribution of maturity stages per month, and numbers of fish examined per month are shown in the relevant issues of Statistical News Letters.

]. P. MoLLOY

Department of Agriculture and Fisheries, Fisheries Division, 3, Catha! Brugha Street, Dublin r, Ireland.

Changes in herring stocks in the western and central Baltic

(Figure 157; Tables r64-r66)

In the area from the southern Belt Sea to Born­holm, the spring spawning herring of the Rugen stock and autumn spawners are the most important ones for the fisheries. Small populations of spring spawning herring seem to have their spawning areas at the western and eastern coasts of the Bay of Mecklenburg. The main spawning areas of autumn spawners are found more offshore in the Bay of Mecklenburg, in the Arkona Basin and off the west coast of Bornholm.

The Riigen spring spawning herring

The main spawning places of this stock are the Greifswalder Bodden and the area off the coast of the Usedom island. For inshore trawl

estimation

strorg

rredium I

I

weaK _j

7958

\ I

I I

\ I I I I

I

1960 1$2 j

I

I

I

I

I

'I I 1

I

1964 year classes

I t•

1936

Figure I 57· Estimation of year classes of herring stocks spring spawners

- = autumn spawners

fishing and for fishing with passive gears in coastal waters this stock is very important. The last period with large catches in this fishery ended in I954- Up to rg65 the catches were relatively small, with a minimum in I957 and a slight increase in rg6r. Only in rg65 did the catches increase more markedly, and in rg66 the top catches of the early fifties have nearly been reached. A new decrease in catches was evident in rg67. The size of the Rugen spring spawning stock increased from the beginning of the sixties and reached its peak in rg65 and rg66. When at the same time the fishing effort was improved and increased, the result was a strong increase of the yield.

The year classes rg6o to rg62 of the Rugen spring spawning herring were medium sized to very large. The year class rg6r was especially strong and dominated the large catches of rg65 and rg66 and also in rg67. This year class has been the strongest one over a period of thirteen years (rg52-rg64), but the year classes rg6o and rg62 have also positively influenced the catches.

After rg62 there has been no further increase in the stock of spring spawning herring. Only the rg65 and rg66 year classes seem to be above average. The same tendencies in the development of the stock are found in the spring spawning herrings in the southern Belt Sea.

-176-

Table 164. Age composition (%) of herring in the Bay of Mecklenburg during the autumn spawning seasons 1963 to 1967

s = spring spawners a = autumn spawners Age-groups 0 I II III IV v VI VII VIII Years s a s a s a s a s a s a s a s a s a s a

1963 - - - I8 IS IS 29 3 7 I - 2 - 2 I 42 58 I964 - - 2 I6 28 6 7 I2 3 I2 I 8 3 I - 4I 59 I965 - - 9 - 23 I I2 20 I9 4 6 I I 2 - I - I 7I 29 I966 6 36 I3 2 2 34 - 5 I I I - - 45 55 I967 2 39 I2 6 2I 3 I3 2 - 2 I I 55 45

Table 165. Age composition (%) of herring in the waters around Rugen during the spring spawning seasons 1963 to 1967

s = spring spa·wners a = autumn spawners Age-groups 0 I II III IV v VI VII VIII Years s a s a s a s a s a s a s a s a s a s a

I963 - - - 2 I2 - 33 I 27 I5 I 5 4 98 2 I964 14 I 28 4 I2 4 I2 2 IO I 6 - 3 2 88 I2 I965 - - I - 2I 34 I 2I 4 8 3 4 I 2 9I 9 I966 - - IO I I6 I 20 - 22 I2 6 - 2 98 2 I967 - 2 14 IO - I9 + 22 + 2I + IO - 98 2

Table r66. Age composition (% of weight) of herring in the Bay of Mecklenburg and the catch of cutters per fishing day (kg) in summer (MayJJuly) in 1965 and 1967

s = spring spawners

Age-groups I II III IV Years s a s a s a s a

I965 ...... - - 9 I IS 2 I3 7 I967 ...... 4 4 5 I 48 - 24

Autumn spawning herring

A period of increasing landings of autumn spawning herring ended in our fishery in 1965, after they had in 1963 and 1964 decisively in­fluenced our catches. With large catches of juvenile autumn spawners the importance of this stock has increased again in 1966.

The stock of autumn spawning herring increased from 1960 to 1962 after it had been weak in the second half of the fifties. The year classes 1959 and 1960 were abundant and the 1961 year class was of medium size. The following year classes, 1962 and 1963, were very weak and near medium, respectively. Accordingly, the strength of the stock has diminished quickly. The 1964 year class, however, has caused a new augmentation in the stock of autumn spawning herring. It is very strong and seems to be the strongest one since the "famous" year class of 1937.

As a consequence of the positive influence of the autumn spawning herring, our catches increased in 1967 in the area from the Southern

a = autumn spawners

Mean catch

v VI VII VIII per day

s a s a s a s a

5 II I I9 I IO 6 soo I 2 3 8 - I.ooo

Belt Sea to the Middle Bank, except for the autumn spawning season in the Bay of Mecklenburg. The catches in the autumn spawning season were in 1967 small in the Bay of Mecklenburg, but very high in the Arkona Sea. The dense spawning shoals of the 1964 year class moved in an easterly direction, probably because of the extraordinarily high water temperature in August and September.

0. RECHLIN

Institut fur Hochseefischerei und Fischverarbeitung, Rostock-Marienehe.

Polish herring fisheries in the Baltic in 1967

(Figure I 58; Tables I67-I69)

The catches

In 1967 the catches in the Baltic continued to increase. The increase was not evenly distributed over the whole southern Baltic, but was observed mainly in the Bornholm area, which now yields about 70% of the Polish catches (Table 167).

-177- Clupeoid Fish Herring

D ® ® CD

CD

Figure 158. Area in the southern Baltic, key to Table 167.

The largest catches were as usual made in the period from May till November, but the winter catches (especially in the Bornholm area) were much higher than in previous years (Table r68).

The catches of young herring in 1967 were smaller than in r966 when about 4,6oo tons were caught.

Biological data

Table r69 gives data onthe age composition of the catches. In the Bornholm area autumn­spawners predominated. This was visible not only in the spring/summer period as usual but also in the winter and summerjautumn seasons.

The extremely rich year-class which was hatched in the autumn of r964 constituted a very important

Table 167. Polish herring catches (in tons) in different parts of the Baltic in 1957-1967

For area numbers see Figure 158

Year Area

2 3 4 Total

1957 ..... 3,911.2 1,292·3 2,282.0 899.0 8,384·5 1958 ..... 8,277.1 1,889.1 4,049·2 1,240.0 15.455·4 1959 ..... 8,397·0 1,930.0 4,233·0 764.0 15,324.0 1960 ..... 8,644.3 2,622.0 5,248.0 1,981.2 18,495.5 1961 ..... 8,312.6 2,585·3 5,962.0 722.0 17,58r.9 1962 ..... 8,8o8.2 1,836.0 4,703.0 1,563.0 16,910.2 1963 ..... 14,865.0 3,000.8 8,156.o 2,855.0 28,876.8 1964 ..... 11,410.2 2-482.0 3.930.0 1,022.0 18,844.2 1965 ..... 11,476.1 3.558·4 4,588.1 1,101.1 20,]23·7 1966 ..... 16,530.6 3,241.4 6,445·1 1,525.6 27,742·7 1967· .... 22,970.0 3,156.0 5.340.8 901.4 32,368.2

part of the catches.

In the Gulf of Gdansk the autumn-spawners were not so numerous and, as in previous years, the spring-spawners were prevailing. The rich year class 1959 still made up a large part of the catches.

The length-weight coefficient was very high in r967. In the Gulf of Gdansk it reached the value of o.7r5 and in the Bornholm area 0.705.

The large increase in catches was mainly due to the high catch rates and to a lesser degree to a rise in fishing effort. The high catch rates were in turn caused by the influx of the 1964 year class of autumn-spawners in the Bornholm area.

Table r68. Polish herring catches (in tons) in the Baltic, 1967

Month Adult Young Total herring herring

January ............. 1,378.8 185.2 1,564.0 February . . . . . . . . . . . 1,272-4 161.6 1,434·0 March ............... 1.409·5 129.1 1,538.6 April ............... I,6J4.3 160.6 1,774·9 May ............... 3,562.2 251.6 3,813.8 June ............... 2,970.6 71.1 3,041.7 July ............... 4,277·0 40·4 4,317-4 August ............. 5,327.1 51.6 5.378·7 September ........... 4.460.5 27.6 4-488.1 October ............. 2,066-4 52.1 2,II8.5 November ........... 2,148.9 155·1 2,304.0 December ........... 489·5 105.0 594·5

Total ............... 30,977·2 1,391.0 32,368.2

- IJ8-

Table 169. Age composition of herring catches in 1967 in °/00 • The Bornholm Basin winter season

Winter rings

Year class

Autumn spawners ..... Spring-spawners .......

Autumn-spawners ..... Spring-spawners .......

Autumn spawners ..... Spring-spawners .......

Autumn-spawners ..... Spring-spawners .......

Winter rings

Year class

Autumn-spawners ..... Spring-spawners .......

Autumn-spawners ..... Spring-spawners .......

Autumn-spawners ..... Spring-spawners .......

Autumn-spawners ..... Spring-spawners .......

I 2 3 4 I965 I966 I964 I965 I963 I964 I962 I963 I96I

I9 - 830 IO I 7 4 III - 9 6

Bo1'nholm Basin springjsummer season

833 6 6 - 20 - 8 - Ij I2

Bornhclm Basin summerjautumn season

I03 - 442 - I6 - I4 IO - 8s - 30 - 23 I4 -

Gulf of Gda;isk summerjautumn season

2I 86 2 - 3 - 3 - 22! I 57 - 43 - I6 -

7 8 9 IO rr+ I959 I96o I958 I959 I957 I958 I956 I957

- - I - - -- - - - - -

Bornholm Basin spring/summer season

6 I - I I 8 34 - 8 I - IO

Bornholm Basin summer/autumn season

- - - - - -42 95 47 IO 6

Gulf of Gda1isk summerjautumn season

3 - - - - I -55 - I75 - 40 34 - 37

The stock of the spring-spawning herring which in the preceeding years formed the bulk of the catches, decreased in the last year.

J. PoPIEL, K. STRZYZEWSKA

Sea Fisheries Institute, Aleja Zjednoczenia I, Gdynia, Poland.

5 I962

-7

25

4I

Total

870 I30

895 I05

6oo 400

I20 88o

I96o I966

2

2I - 2

IS - 23

- 63

Numbers

595

350

500

8oo

-179- Clupeoid fish Sprat

SPRAT

The English sprat fisheries, results of the r967j68 season

(Figures IS9-I64; Tables I70-I]2)

The fisheries

The North Shields fishery

The yield from this fishery (1,310 tons) was much less than in the previous season (rr,361 tons). This was primarily due to reduced fishing effort, the majority of Scottish and Grimsby vessels partici­pating last season not being interested due to good fishing in home waters.

The catch statistics are outlined in Table 170. Only two or three vessels worked the area regularly throughout the season, and during the peak week only 6-7 landings were made on any single day. The catch per unit effort was also considerably less than the previous year (when it averaged 5r.8 tons per hour for single boat trawlers). This was partly due to the reduced fleet (and hence searching power) having difficulty in maintaining contact with the main shoals, and continuous periods of very bad weather tended to keep the shoals dispersed. About 10 per cent by weight of the catch consisted of immature herring.

The Wash fishery

This fishery produced a record catch of 8,103 tons (compared with only 1,135 tons in 1966/67), with some of the highest catch rates yet recorded for this area. The catch statistics are summarized in Table 171.

This unexpected increase in catch was largely due to the appearance in great quantity of large first year fish (7.0-9.5 em) which localized into

Table 171. Catch statistics of the ·wash sprat fishery

Boston and Wells Grimsby Seiner-Type 40 ft vessels vessels (5o-6o ft) pair trawl Single boat

mid-water trawl rg66(I967 I967/Ig68 Ig66/I967 I967/Ig68

Total tons . 392.6 2>468.0 742·5 5,634·8 Tons/landing s.8 IO.O I6.9 27·5 Tons/hour . 4-I s.6 0-4 3-I

very dense patches. This age-group contributed nearly 70 per cent by number and 50 per cent by weight to the catch. An echo-survey carried out in December located two main concentrations each about 3 square nautical miles (10.3 Km2) in extent and up to 5 fathoms (9 metres) thick in daylight. Extremely high catch rates of 20-30 tons per hour were recorded at this time within these patches.

The Thames Estuary

This fishery yielded only 125 tons and was again almost a complete failure (75 tons in 1966/67), and although first year fish figured prominently in the catch they did not form localised high density patches as in the Wash area. Fishing effort was also reduced by several of the Thames pairs trans­ferring to Boston and Wells for the season.

Research vessel echo-surveys carried out in Nov­ember and February showed only thinly scattered trace over the whole region.

The South Coast fisheries (Ramsgate-Plymouth)

The total catch from these fisheries amounted to 2,196 tons, an increase over the previous season (1,762 tons), largely due to an improvement in the

Table 170. Catch statistics of the North Shields sprat fishery for the 1967/68 season (North Shields landings only) (Single boat mid-water trawl)

Maximum Number of Number of Total catch C.P.E. C.P.L. Month number of landings hauls (tons) (tons per (tons per

vessels hour) landing)

November ........... 4 8 23 9I.5 2.8 u.s December ........... 4 12 32 267·7 28.2 22.3 January ............. IO 24 59 40I.I 7·7 I6.7 February ............ II 30 83 458·5 I3-5 15-3 Season .............. II 74 197 I,2I8.8 9-5 I6.5

*91.5

1,3I0.3

* (landed at Grimsby)

-r8o-

50

50 I I

"' \

00

I

I \ u-l

'" '---...__

50 10°

r-,_

'""' ........_ - /;:;::: '- ,.---::/·?

( 'iP7::?;:Y a

6 .. /';) \r. i/ • r· ... . , (

;" ... _ •• ·..-........:> :

r.J l ... --·<-.. J·. I

. _.... .··_-;:r . ./ -~·· '· ., (: ~' •. -·' . (1..-'/ 7 . 'I e5 ,-. .; e .

. . / ,' \ 5 5° /

55° 9 a/· \

/1\ ... (''· / .. --- .. ;:)

• .r··

Aug 1967-Feb 196B

5 00 ~::r··~ .:.-_, - <'-. f--'v II Commercial fishing areas --i 50° ~ .. :,/ - .~·

• Research vessel hauls ' ' - . ---..,_ c::-- &>

' v

50 00 50 1 0° Figure 159.

Poole fishing (970 tons compared with 170 tons in rg66j67), although the Torbay fishery registered a reduction in catch (1,175 tons compared with 1,577 tons in rg66j67). This was due to conflicting white­fishing interests and a reduction in size and quality of the sprats early in January. First year fish were strongly represented in the eastern half of the region and appeared in greater quantities than usual in the Torbay fishery.

General analysis of age-group distributions in the rg67j68 season

The regular sampling of the commercial fisheries has again been supplemented by a number of re­search vessel samples taken within, near and well beyond the main fishing areas. The position of the research vessel hauls, together with the main fishing areas in the rg67j68 season are shown in

-r8r- Sprat

Table 172. Composition by percentage age-groups and average mean lengths of commercial catches and research vessel hauls

Overall

General area

Farne Deep (September)

Farne Deep (October)

North Shields (November-February)

vVest Edge Dogger ..... . (March rg68)

Central Dogger ........ . (March rg68)

South end (~reat Fisher .. Bank (March Ig68)

Tail end Dogger ...... . (November)

White Bank-Borkum ... Outer Ground (March Ig68)

S.E. Edge Clay Deep .... (March rg68)

Outer Silver Pit ....... . (November)

Skate Hole ........... . (September)

Skate Hole (October)

Inner Silver Pit ....... . (September)

vVash ................ . (November-February)

S.E. Broken Bank ..... . (March rg68)

East Anglian Coast ..... (North Sector) (November)

East Anglian Coast ..... (South Sector) (November) Thames Estuary ....... . (November)

Thames Estuary ....... . (February

Dungeness ............ . (December)

Offshore Poole ........ . (December)

Torbay ............... . (October)

Torbay ............... . (December-January)

Bristol Channel ........ . (October)

Chart number

%No. L (em)

2 %No. L (em)

3 %No. L (em)

4 %No. L (em)

5 %No. L (em)

6 %No. L (em)

7 °/cl No.

8

9

IO

II

I2

I3

14

I5

r6

I]

r8

I9

20

2I

22

23

24

L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

%No. L (em)

14-I 9·3

I6.I g.o

5·3 g.I

1.3 g.2

..p.8 9-9

4·5 8.6

gr.6 8.2

88. 5 7·9

I6.2

8.4

6g.I 8.o

38·5 8.2

]8.6 8.o

46·3 7·5

6o.5 6.I

43-4 7·4

57-9 7-9

5·7 g.I

r.6 8.]

Figure rsg. The position of all the research vessel hauls are given except those in the East Anglian coast-Thames area, where they are far too numerous to be conveniently shown. The information from this sector has also been grouped into three sub­sectors, these being north and south East Anglian

2

84.6 I0.6

68.g I I -4

56.2 Ir.6

J8.g I2.4

78·4 !2.)

SO.]

I2-4

]8-4 Io.g

].I

Io.g

II. I IO.O

36.I 12. I

31.2 Il.3

I7·4 I2.]

]0.6

11.2

2].0

g.8

48.I Io.s

I].8 !0.2

48·4 g.S

30·5 8.s

38.5 IO.I

34-5 I0.6

66.I 12.2

4·5 Ir.6

6o.s Ir.6

8.3 Il.3

3

5·5 rr.8

II.9 12.0

I6.o I2.8

Io.s I3·3 20.3 I2.8

7·5 I3-4

I3-7 II.4

I.O I2.I

0.4 12.2

38-4 I2.]

37·6 I2.8

36.0 13·6 zs.o Ir.8

3-I II.6

I3.2 I3.2

2.2

I2-4

3-I Il.3

2.9 !2.0

9-7 Il.O

6.g 12.5

26.3 IJ.O

74·5 I3.I

28.8 I2.6

41.7 I3.6

4

9-9 II.]

4·5 I2-4

Io.5 13-7

5·3 I3-7

3-4 I3-9 0.2

9-7

8.s 14·5 20.8 I3.8

34·9 14-4 2.9

I3·7 0.6

I3.0

0.]

12.0

2.!

!2.2

5.2 Io.6

].I

Io.s

0.3 !0.2

5-9 q.8

14·5 I3.6

4-4 I3.8

41.7 14·3

5

0.6 12.]

!.2

14·3

0-4 q.2

].2

q.8 Io.5 I5.2

r.s 14·7

O.I I4.2

0.2

I 5-7 0.]

10.2

0.4 I4-4 0.]

I2.8

0.3 rs.z

I. I I5.2

6.5 I3-5

0.2

I5.2

4·2 14·7

6

0.6 I4·7

3·2 I3-9

1.2

I5.2

O.I II.]

0.3 I4.0

0.2

I2.]

0.6 I6.2

0-4 14·7

2.5 I5.0

7

o.s 13-9

mean (age)

length

(2.25) IO. 9

(2.09) II. 3 (2.25) I I. 6

(2.16)

I2. 4

(2.I9) I2. 6

(r.66) II. 5 (2.r6) I I. 0

(r.Io) 8. 4

(r.I2) 8. 2

(2-43) I I. 8

(3-14) IZ. 8

(3-42) 14· 0

(2.35) I I. 5

(r .36) 8. 6

(I.JS) IO. 0

(1.27) 8. 5

(r.6I) 8. 8

(r.55) 7· 3

(r.86) g. I

(r.5o) g. 2

(2-44) I2. 6

(3.23) I3. 2

( 2 -34) I I. 9

(3-46) I3. 8

coasts, and Thames Estuary. The position and areas were also numbered for ease of reference with the information given in Table 172 and Figures r6o-r64. (The unnumbered positions represent the August survey, which also covered the East Anglian coast-Thames sector).

-r8z-

General summary table

General area Chart I number

Fame Deep-Dogger ..... 1-6 %No. 13.1 L (em) 9-3

German Bight .......... 7-9 %No. 6r.s L (em) 8.2

Outer-Inner Silver Pit ... 10-13 %No. 4·0 L (em) 8.4

EjS.E. Coast ........... 14-20 %No. 56-3 (Wash-Du ngeness) L (em) 7·6 S.jS.W. Coast .......... 21-24 %No. r.8 (Poole-Bristol Channel) L (em) 8.g

Range and modes of 1967 year class at 1 year

Length group:- 4 5 6 7 B 9 10 11 (em)

(Chart no.) FARNE DEEPS

t OCT. I r-L-1 2 NORTH S HEllOS

I NOV.-FEB. I DOGGER AREA

(MARCHI t--'---1 s.END GREAT FISHER BANK 1 A I

(MARCH I WHITE BANK-BORKUM OUTER 1------"'----j

(MARCH I CLAY DEEP

!MARCH I OUTER SILVER PIT

INDV.J WASH

(NOV. FEB. I S.E. BROKEN BANK

I MARCH I

I ' I

EAST AHGLIA NORTH f------J..---i (NOV.)

EAST AHGLIA SOUTH 1----..._ _ __.__--i (NOV.)

THAMES I NOV.)

THAMES I FEB.)

OUNGEHESS I DEC.)

TOR BAY (DEC. JAN.)

f--L--..1

Figure 160.

3

4/5

B

g

10

1 4

15

16

17

1 B

19

20

23

Table 172 summarizes the age-group distributions and mean lengths for age in samples taken from different areas between September rg67 and March rg68. This shows clearly the predominance of first year fish along the east coast of England between the Wash and Dungeness (probably also in the Poole area where, although no commercial fishery samples were examined, the bulk of the catch was reported as being very small throughout the season. The research vessel haul made in this region was in deeper water outside the main fishing area closer inshore). This age-group was also strongly repre-

Overall mean

2 3 4 5 6 7 (age) length

6g.6 12.0 s.o 0.3 - (2.Io) II.8 12.7 I2.9 I3-5 - II. 6

32.2 s.o !.2 - - (q6) Io.6 1I.9 II.8 - - g. 2

38.8 34·3 16.8 4·9 I.Z (2.83) II.8 12.7 14.1 14·7 q.6 12. 5

35·0 5-9 2.3 0.3 0.1 (r.ssl 9-9 12.0 1!.4 13-7 12.8 8. 8

34·9 42.8 16.6 3·0 o.g (2.87) 1I.7 13.1 J4.1 q.6 15-3 12. 8

Range and modes of 1966 year class at 2 years

Length group:- 6f--T7-.::;.B ---'gT--T--..:..r-T--r--;-

FARNE DEEPS I SEPII

FARNE DEEPS IOCTJ

f.ORTH SHIELDS INOV.-FEB.I

W. EO GE DOGGER I MARCHI

CENTRAl DOGGER I MARCHI

S. END GREAT FISHER BANK I MARCHI

TAll END-DOGGER I NOV.)

WHITE BANK-BORKUM OUTER !MARCHI

SKATE HOLE I SEPT. I

INNER SilVER PIT ISEPT.I

WASH INOV-FERI

S.E. BROKEN BANK !MARCHI

EAST ANGLIA NORTH I NOV I

I ' ' I

I ' t

I ' ' I

I ' '

EAST ANGLIA SOUTH I NOV.)

I A 4 A A I

THAMES !NOV.)

THAMES IFEB.J

DUNGENESS IDE C. I

OFFSHORE POOLE I DEC.)

TORBAY I DEC:-JAN.I

Figure 161.

3

6

11

13

14

15

16

17

16

19

20

21

23

no.)

sented in the German Bight samples (8-g) and at the south end of the Great Fisher Bank (6). Pre­vious experience has shown that a strong represent­ation of large first year fish in the catch has usually been indicative of a strong year brood to follow, and it is hoped that the English coastal fisheries will benefit in the next one or even two seasons

-183- Sprat

Runge and modes of 1965 year class at 3 years

Length group,-8 9 10 11 12 13 14 15 16(cm) ! Chart no.)

~Hmw 3 I NOV~FEB.I

DOGGER AREA I MARCHI

S.END GREAT FISHER BANK !MARCHI

SKATE HOLE ISEPTI

SKATE HOLE IDCT.I

WASH INDV.-FEB.I

S. E. BROKEN BANK I MARCH I

THAMES IFEeJ

GffSHORE POOLE I DEC.}

TOR BAY IOCT.I

TOR BAY (DEC.-JAN}

BRISTOL CHAI{NEL IOn.J

J-----L-.l

1 A A A

I A ' I

I A A A I

I A A I

I ' ' I

Figure r62.

4/5

6

11

12

14

15

19

21

22

23

24

from what appears to be a large and widespread stock of young sprat. The largest first year fish were found in the offshore samples, particularly those from the Fame Deep-Dogger region (2-7), and the smallest in those from the east coast of England (14-20).

Second year fish constituted the next commonest age-group in most areas whilst third and fourth year fish only appeared in significant quantities in a few areas, mainly in deeper water near the Dogger Bank (10-12) and in the south west (22-24).

Fish beyond the age of four years were only found in insignificant quantities, although one interesting feature of the February samples from the Thames Estuary was the presence of a few 7 year old fish, these being survivors of the strong 1961 year-class which made a large contribution to the fishery in this area between 1962 and 1964.

A summary table grouping the information into more general areas is appended to Table 172 and this shows more clearly the differences in age-group representation and mean length for age. The off­shore deeper water North Sea samples taken to the north west, around and to the south of the Dogger Bank (1-6; 10-13) show close similarities, as do those from the German Bight and eastjsouth east coast of England (7-9; 14-20), whilst the south and south west coast material (21--24) shows a greater similarity with that from the North Sea deeper water.

Entry of the 1967 year class

The August east coast survey (sampling within 5 miles of the coastline) showed a strong entry of 0-group sprat taking place along the east and south eas~ coastal region between Winterton on the Nor­folk coast (52° 40' N) and H ythe in the Straits area. The larger fish showed a strong mode at 5.5-6.0 em, whilst in several places large quantities of larval and immediate post larval stages were meshed on the trawl. Good echo-traces were also present over all this coastal area and throughout the main Thames Estuary channels. (A tin townet survey carried out during the last week of May over the southern Bight and eastern end of the English Channel recorded fairly high sprat egg and larval densities over most of the survey area). However, this influx was not then evident in the coastal region north of Winterton, in the Wash area, or along the north east coast up to Tees Bay.

In September a research vessel sample from a large concentration of sprat and young herring (about 2/3 sprat and 1/3 herring) 15 miles east of the Humber (13) contained no first year fish, but in the last week of November very large quantities of this age group had appeared and were being exploited in the Wash. First year sprat were not as strongly represented in the North Shields fishery (3), and less than in the previous season.

As previously noted research vessel samples incli­cated that this year class was also strongly repre­sented near the Norfolk Banks (15), in the German Bight (7-9), and at the southern end of the Great Fisher Bank (6). It was not so evident around the Dogger Bank (4-5; 10-12) or in the deeper water north west of this region (1-3).

Comparison of length distributions of sprat year classes between regions

The length ranges and main modes of each year­class are shown by areas in Figures 160-164 wherever sufficient numbers were available to give a reasonable distribution.

(i) Length distribution of the 1967 year class (first year fish) (Figure r6o)

Where smaller members of this group were pre­sent ( < 7.0 em) they would probably not be pro­portionately represented due to mesh selection, but their modes should still be apparent even though these would be considerably reduced in amplitude.

-184-

The largest first year fish were found at the southern end of the Great Fisher Bank (6), these having a modal length in the 9·5 em group with some up to 10.5 em long (the largest yet recorded in our samples from any area). A mode in the g.ocm group appeared in the Fame Deep, North Shields and Dogger samples (2-5), whilst in the central and southern North Sea, and along the eastjsouth east coast of England an 8.o-8.5 em mode predomin­ated (8-20) together with smaller modes in the English coastal material (17-20). An almost iden­tical length distribution was shown between the northern East Anglian coast samples taken in No­vember and the Wash fishery samples. The No­vember and February situations in the Thames area were somewhat different, a greater proportion of larger fish being present in February (marked by the appearance of an 8.0 em mode and a half cen­timetre shift in the two smaller modes). The greatest length ranges were found in the east coast area (14-19) and central North Sea (8-g).

(ii) Length distribution of the 1966 year class (second year fish) (Figure r6r)

The length distributions of this year class showed considerable differences between areas, some being highly skewed and multi-modal, whilst others were nearly normal with a single prominent mode. A smaller mode ranging between the 8-g em groups was evident in the east coast samples (14-20), and a larger one between 12-13 em in the Dogger­Fisher Bank area (4-6) and southjsouth west coast region (21-23). with intermediate modes also pre­sent in some of these and other areas. The greatest length ranges were found in the English east and south east coast samples.

(iii) Length distribution of the 1965 year class (third year fish) (Figure r6z)

This year class was relatively sparsely represented in most samples and as with the second year fish showed marked differences in length distributions and modes between areas.

The smallest modes (g-ro em) were found in the Thames area (19) and the largest (13.0-14.scm) in most of the deeper water offshore samples (4-12; 21-24), but with intermediate modes also present in several areas.

(iv) Length distribution of the 1964 year class (fourth year fish) (Figure r63)

This age-group was also generally scarce and only present in significant numbers in a few areas. The smallest modes (g-rr em) appeared in the

Range and modes of 1964 year class at 4 years

Length group'- B 9 10 11 12 13 14 15 16 [em)

fARNE DEEPS I SEPT.)

OUTER SILVER PIT I NOV. I

SKATE HOLE I SEPT.}

SKATE HOLE IOCT.I

THAMES I NOV}

THAMES IFERI

TORBAY IOCII

BRISTOl CHANNEl IOCII

' [Chart no) 1

I I I 10

11

12

f---'----.L 18

Figure r63.

19

22

24

Thames Estuary in both November and February (r8-1g), and the largest in deeper water material (10-12; 22-24).

(v) Discussion

These results underline the problem of obtaining a true population estimate in terms of age and length for sprat, particularly within an area such as the central/southern North Sea.

Differences in size between the same age group in different areas could be brought about in one or more of several ways, these being:-

(1) Genetically distinct isolated stocks showing intrinsically different growth rates.

(2) Varying proportions of earlier or later spawned fish with correspondingly longer or shorter time periods available for growth in their first year.

(3) Differences in feeding conditions between areas.

(4) A gradual dispersion process involving the mo­vement of fish from shallow to deeper water as they . . . mcrease In size.

There is no evidence for the first of these propo­sitions and it is doubtful whether genetically iso­lated stocks could arise within a relatively open area such as the North Sea unless very intricate segre­gation mechanisms are involved.

The second situation could be responsible for some of the differences, particularly where the period of peak spawning is known to differ, as in the case of the south west (February-April) and southern North Sea (April-June). The same effect could also be producbd by a difference in the

-185- Sprat

"' = c

<=

"' <..>

20

15

10

Wash sprat fishery -19 64 year class

Years In= 495)

~ 20 ~ 3 Years ln=100)

15

10

04 0·5 06 0-7 O·S

Diameter of otolith first winter ring lmm)

Figure r64-

0·9

tlmmg of peak survival conditions between areas possessmg the same peak spawning period. The range of length within a given age-group in a par­ticular area might also be governed to some extent by the pattern of survival over the spawning period. Eggs have been recorded in the southern North Sea between the end of January and August, which gives this area a wide potential time base for com­mencement of development in any one year, al­though the main spawning period is more limited. Information concerning the spawning cycles in the central and north western North Sea is very limited and not sufficient to draw any conclusion on the possible influence of these on the range of length within an age-group.

The third factor, involving differences in food availability between areas (brought about by either natural fluctuations in production or intra/inter specific competition processes) might also be of some significance, but no information is available on this point.

The final situation, where the sprat shows a progressive movement from shallow to deeper water as it grows could be largely responsible for the differences observed within the central and southern North Sea. It was shown in the previous season's assessment (JOHNSON, rg68) that there was a

significant correlation between the mean size of 2, 3 and 4 year old sprat and the depth of water where captured, and the same relationship is apparent in the present results. It was also pointed out that the English coastal fisheries show a scarcity of fish beyond the age of three and these older fish are relatively small for their age, which often causes an apparent decrease in length with increasing age. This could be interpreted as an emigration loss, which may even commence with first year fish but become more pronounced in the older age-groups.

Changes in the relative composition of a year class within any particular region can be more clearly shown by a comparison between the distributions of otolith first winter ring diameters (used as an index of L1) in successive seasons. If the exploited population has remained unchanged between seasons (that is showing no gains or losses apart from those due to natural mortality in the inter­vening period) the distributions of first winter ring diameters should remain much the same.

A comparison of these distributions for the rg64 year class in the Wash sprat fishery at 2 and 3 years old (Figure r64) provides an example of a change, showing a much greater proportion of 3 year old fish with smaller first winter rings. This could be due to an emigration loss of the larger component of thi:: brood, and it is significant that this year class was relatively poorly represented in the fishery at 3 years old compared with their superabundance when 2 years old the previous season.

It thus seems likely that out of the four pro­positions outlined to account for the observed differences in size within the same age group in different areas, the first is the least likely, whilst the others could apply in varying degrees, but evidence to decide the relative importance of each of these factors is either inadequate or entirely lacking.

P. 0. JoHNSON

Fisheries Laboratory, Lowestoft, Suffolk, England

Reference

JoHNSON, P. 0., rg68. "The English Sprat Fisheries". Annls.biol., Copenh., 23: rSs-gr.

-r86-

Scombriform Fish

MACKEREL

English mackerel investigations

Three mackerel tagging experiments were carried out during 1967. The first of these was of fish caught from R.V. "Ernest Holt", the second from a beach seine net, and the third from a small inshore fishing vessel. The fish used in experiments r and 3 were caught on feathers. Those which were hooked lightly and not bleeding were selected to be tagged.

The details of these experiments are:

Experiment number

2 .................. .

3 .................. .

Hoy Sound, Orkney Islands Abbotsbury, Dorset Mevagissey, Cornwall

The four recaptures to date are as follows:

Liberated Month Recaptured

Abbotsbury, Dorset August Teignmouth Bay

three-year-olds (27.8 per cent) among the feather­caught samples, but there is a marked falling off in the percentages of seven- to nine-year-old fish.

G. C. BOLSTER

Fisheries Laboratory, Lowestoft, Suffolk, England.

Month

July August

October /November

Latitude

50°32'N

Number liberated

103 249 333

Longitude

03°3o'W

E.eca pturcs to date

0

4 0

Days at liberty

17 N. of Dieppe, France 5ooo5'N OI

0 I5'E 48 N.E. of Labadie Bank 50°5o'N 07°5o'W c. 70 Off Berry Head c. 50°2o'N 03°17'W rr6

There have been six recaptp.res from liberations made in previous years:

Liberated Date Recaptured

"Ernest Holt" 4/66 Fastnet area Celtic Sea . . . . . . . . . . . 4/66 Jones Bank Newhaven, Sussex .... 6/66 Donegal Bay

9/66 Winchelsea Beach Mount's Bay, Cornwall 6/65 Clyde

1oj65 N. of Dieppe

Fourteen samples, compnsmg 1,040 mackerel, were examined for length, weight, sex and maturity. Otoliths were taken for age-determination. In the drift-caught samples the 1962 year class shows as a high percentage of five-year-olds (33.8 per cent) and is supported by the 1964 year class as three­year-olds (23-4 per cent).

The 1962, 1963 and 1964 year classes are strong as five- (r4.7 per cent), four- (r7.0 per cent) and

Latitude Longitude Days at liberty

51°2o'N 09°5o'W 368 49o2o'N 07°2o'W c. 365 54°3o'N o8°2o'W 405 50°54'N ooo33'E 266 55o25'N 05°1o'W 741 50°12'N 01°03'E 597

Netherlands' mackerel fishery in the North Sea in r967

(Tables 173-175)

The fishery (Table 173)

The total catch of mackerel in 1967 amounted to 9,945.1 tons and was again lower than in the pre­vious year (IIA43·9 tons in 1966). The main overall density was somewhat higher than in 1966,

-187- Scombriform Fish Mackerel

Table I73· Total catch, effort and catch per effort in four fishing areas during 1967 in the North Sea

Numbers of hours fishing, Catch in kg per roo hours Total catch in kg. trawler 500 B.H.P. fishing. Trawler 500 B.H.P.

Monthjarea N.N. N.E. N.W. S. N.N. N.E. N.W. S. N.N. N.E. N.W. S.

January .. 13,638 13,650 -- 6,961 2,003 1,276 197 68r February . 126,249 36,468 I 1,504 3,385 I4 r,r98 1,071 March .... 360,271 99,048 695 11,039 2,5!4 - 768 3,264 3.940 - 91 April ..... 3,130,024 1,370,832 130 17,972 6,845 - 194 17,416 20,027 -May ..... 1,151,240 1,132,048 350 74,094 13,723 12,576 72 r,897 8,389 9,002 486 June ..... 36,700 I7I ,252 48,240 649,151 1,387 2,909 7,257 r8,968 2,646 5,887 667 July ..... 20,675 56,238 8,738 120,478 3.435 I ,302 1,387 8,807 602 4,319 630 August ... 189,277 51,500 - 154,818 2,675 379 - 25,448 7,076 13,588 September 82,481 I 15,808 1,200 93.582 3,566 3,143 12,859 2,313 3,685 October .. 8r,rq 250,788 -- ro,683 r,8oo 4,8r6 - 2,274 4,506 5,209 470 November 12,438 194.709 10,488 930 8,429 402 -- 1,337 2,3!0

December 15,898 53.343 6,763 2,512 5.547 - 633 92

Total .... 5,220,005 3.545,684 69,022 1, I 10,394 J7,504 53,848 10.408 71,215

Grand total 9.945,105 kg 2,129,75 hours 4,669 kg/roo hours

Table 174· Age composition of the catch in number per 100 hours fishing of a standard trawler in April and May in the area N.E.

Year class 1966 1965 1964 1963 1962 1961 1960 1959 1958 <1958 Month Age I 2 3 4 5 6 7 8 9 9 Total

April .......... 770 40,105 5,613 1,976 6,606 3,287 2,264 5.554 2,986 12,614 81,775 May .......... 36 3,282 1,367 939 2,I6I IA32 1,545 2,674 r,8r6 8,233 23,485 April-May ..... 403 21,693 3.490 1.457 4.383 2,359 1,904 4,IJ4 2,401 10,423 52,627

Table 175. Instanteneous mortality. Z, 1966/1967 of mackerel stock in April-May in the area N.E.

Year z/3 3/4 4/5 5/6 6/7 7/8 8/9 >8/9 >2/3

1966jr967 -1,43 0,59 -o,68

but was apparently not high enough to counter­balance the decline in fishing effort. This decline in fishing effort was experienced in all areas except the area N .N.

Age composition (Table 174)

The noteworthy fact in the age composition of the spring catches in the area N.E. is the appear­ance of a new strong year class (year class rg65).

o,r9 o,58 0,28 o,86 0,57 0,4I

The part of the stock older than mne years was still substantial.

The total instantaneous mortality (Z) of the stock as measured with the stock density data in spring in the area N.E. in rg66 and rg67 appeared to be 0-41 (Table 175).

K. H. POSTUMA

Rijksinstituut voor Visserijonderzoek, Haringkade r, IJmuiden, Netherlands.

-r88-

Anadromous and Catadromous Fish

SALMON

Investigations on salmon and sea trout of the river Axe, Devon, 1967

In 1967, 382 salmon and 4,303 sea trout were counted upstream through the trapping installation. The salmon were tagged dorsally with tags of differing colours for each month but no tagging of sea trout was carried out.

Year class analysis from scale reading showed showed that 39 % of the salmon run consisted of grilse.

The sex ratio of the salmon was 2.2 females to I male, which is considerably higher than in rg65 and 1966. The sea trout count was markedly higher than any previous year. In the Spring, 4,218 salmon smolts and 4,2I6 sea trout smolts were passed down. All the salmon smolts were measured, tagged and marked by clipping the adipose fin but the sea trout smolts were merely counted. The mean length of the salmon smolts was I6.3 ems. which was almost identical to the I966 run. The percentages of I, 2, and 3-year old fish were IO, 86 and 4 respectively, the higher proportion of 3-year old smolts probably being attributable to the exceptionally large run of salmon in I963, just as in I965 and Ig66 there was an unusually large number of l-year old and 2-year old smolts respecti­vely. The second catch of hatchery smolts was released into the Axe in the Spring of I967. 5,I99 hatchery-reared salmon smolts, mostly 2-year olds were tagged and released. The mean length of the 2-year olds was 14·9 ems. and that of the I-year old fish was I2-4 ems.

The estimated spawning run of salmon in I966, based on the marked and unmarked kelts passed down, was 334 compared with an actual count of 302 - an escapement of approximately Io%. Similarly, with the sea trout the estimated run was 3,34I compared with a count 3,J 45 - an escape­ment of about 6%.

In the autumn of Ig66, I3 Axe salmon were caught off Greenland. All but one were tagged as smolts in I965. In I967, 6 recaptures of Axe salmon off Greenland have been reported so far; 5 of these were tagged as smolts in I966 and I as a kelt in 1967. In October, a salmon which had been reared in the

Swedish hatchery at Laholm a'1d released as a smolt into the River Lagan in the Spring of I966 was passed up through the Axe trap.

A. SWAI"

Salmon and Freshwater Fisheries Laboratory, ro, ·whitehall Place, London SW I, England

Smolt tagging programme in the rivers Usk, Wye and Severn

A further I9 tagged fish from the I964 smolt tagging experiment were recaptured in I967. These were all large spring fish bringing the final total of recaptures to 226 (92 Severn, 8I Wye and 53 Usk). Over go% of the recaptures were made in the Bristol Channel/Severn Estuary area or in the 3 rivers in which tagging was carried out, and only r.8% were caught elsewhere in United Kingdom waters. The remaining 8% were caught off the west coast of Greenland. Fish tagged in all three rivers were taken in the upper part of the Severn estuary between the mouth of the Usk and Gloucester, indicating that there is a consider­able mixing of the stocks in these waters. Although a large number of the salmon were caught in the estuaries of rivers other than their parent rivers, only 9 (or 4 %) of the recaptures were taken in the freshwater reaches of non-parent rivers; eight of these were taken in either the Usk, Wye or Severn but one was caught on rod in the upper waters of the River Exe in south Devon.

A. SWAIN

Salmon and Freshwater Fisheries Laboratory, ro, V/hitehall Place, London SW I, England

German investigations on salmon 1967 (Figures r6s-r66; Tables r76-178)

The fishery

The output of the German salmon fishery in the open Baltic was I70 tons in I967, this figure being even a little lower than the yield of the Ig66 fishery (I77.5 tons). There was almost no change in the average weight (3.24 kg in Ig66) and in the proportion of large-sized fish (I2.2% in I966) as compared with the data of I966 (Table I76). It can also be seen from Figure I66 that the number

66

64

62

-r8g- AnadromousjCatadromous Fish Salmon

25 Figure I65. Recaptures of salmon tagged as feeding fish Ig66/67 at a bout 55°N, I9°E.

-rgo-

80

40

20

10

80

40

ISO

100

50

nb. 1967 Sept 4th

net 516 Gotland

1967 Nay 16th net 370 Danziger Tie f

1967 Jan. 24 th net, hook 963

Bornholm

L----,---L,----.-----.----.---~-- -, 50 60 70 80 90 100 110

Ltcm

Figure 166: Length-composition of German salmon lan­dings 1967.

of salmon of the A.z+ sea age-class is very low. Almost no individuals of this particular age are left in May when the spawning migration is in progress, i. e., when the maturing individuals have left the fishing places of the open sea. The

recruitment of the new A.r+ sea age-class mainly took place in July and in the first half of August, so that length measurements on the fish market on 4· September show a fully recruited catch.

Once the recruitment starts, the new group of salmon is heavily fished upon so that only very few individuals will grow to an age of more than two years in the sea. Several years ago the fishery mainly exploited the A.z+ sea age-group. At about rg65 a change in the selection took place when the fleet applied Japanese drift nets.

The seasonal course of the catches in rg67 also shows a remarkable change as compared with former years. The yield used to increase from summer to December and declined thereafter. Quite another pattern was observed in rg67. After bad catches in spring there was a sudden rise in June and a maximum yield in September. This does not in the least confirm the theory of salmon searching for deeper and colder water layers during summer time.

The German catch has mainly been taken by drift nets since the proportion of drift lines gradual­ly decreased. The proportion of salmon caught by means of gill nets was 76% in rg65j66 and 72% in rg66/67. Hooks have only been used be­tween November and February. In the spring of rg67 the German fleet stuck more to the Born­holm area than in the spring of rg66, the effort being rather evenly distributed in the southern Baltic; whereas the Gotland area has not been visited during this time of the year.

Tagging experiment

500 feeding salmon of a size of 28-76 em in total length, but mainly 55-74 em, have been tagged between November rg66 and February

Table 176. German landings of salmon from the Baltic 1967, gutted weight

% of annual total Average > 5 kg,% of Monthly total Month Tons Number tons number ·weight, kg number weight

January ....... 17.95 5.866 I0.6 ro.9 3.06 II.6 25-9 February ...... I4.65 4-726 8.6 8.8 3.10 13.1 28.7 March ......... ro.89 3,582 6.4 6.7 3-04 1I.O 24.8 April .......... 6.95 2,r86 4·1 4-I 3.18 13.1 28.8 May .......... 7-45 2,411 4·4 4·5 3-09 6.7 I5.I June .......... 17.78 5,627 10.4 ro.5 3-16 3-2 6.0 July .......... August ........ September ..... 29,24 9-463 17.2 17-7 3-09 12.4 23.0 October ....... 25-44 7-756 15.0 14.5 3.28 13.9 25-4 November ..... 2I.34 6,2?6 12.5 II.? 3-40 17.9 32.1 December ..... r8-42 5,668 10.8 I0.6 3-25 r6.o 31.6

Total ......... 170.10 53,56I IOO.O IOO.O

Average ....... - - - 3.18 I2.1 24-2

-rgr- AnadromousjCatadromous Fish Salmon

Table 177. Distribution of the German fleet on the fishing places 1966/67, number of vessels in % (for statistical areas see: Annis biol., Copenh., 23:201 (1966) Fig. 139).

Statistical area Month 3/4 5 6

August . . . . . . . . . IOO September . . . . . . . . roo October . . . . . . . . . roo November. . . . . . . . . 6r 26 I3 December ....... . 98 2

January ........ . 41 59 February ........ . 52 48 March . . . . . . . . . . . 3 97 April ............ . 22 78 May ............ . IOO June ............ . 41 59 July ............ . IOO

1967. Most places of release were in the Danziger Deep, at 55°N and between r8° and Z0°E. One year after liberation about zs% of the salmon have been recaptured. Of these z8% were recorded from rivers and from the Bottnian coastal region and thus are considered to be on their spawning migration. These fish come exclusively from Swe­dish and Finnish rivers. None was recorded from rivers in Poland or the Soviet Union neither during the experiment in question nor during two small experiments in 1959 and 1964. This is a surprising result, because the Daugava river is supposed to produce a remarkable number of smolts. It would of course be extremely interesting to investigate the exchange between the Riga Bay and the Baltic proper by means of a tagging experiment.

Considering now the recaptures for different size­groups (Table 178), the highest total percentage is recorded for fish of 6o-65 em in length. This is exclusively due to a large proportion of spawners, as the percentage of fish caught in the open sea is nearly equal for the length-groups 6o__:__65 em

Table 178. Recaptures in different size-groups

Size-group 28-59 ern 6o-65 ern 66-76crn No % No % No %

Tagged ....... 97 222 183 Recapt., total 13 I3 7I 32 47 26 Recapt., spawn .. 5 5 22 IO 8 4 Recapt., open sea 8 8 49 22 39 2I

and 66-76 em, both of which belong to the A.r+ sea age-class. A more detailed analysis shows that the equal proportion for both size groups is not due to a wide-spread selectivity. Roughly 25% of the individuals of the second length-group (60-65 em) have been recaptured during the first half of the period, the rest during the second half. In contrast roughly so% of the salmon of the third size-group were caught in each of the periods. This points to the fact that the third group is well within the range of the highest selectivity. As for the high proportion of mature fish recorded for the second group there is no clear-cut explanation. A calculation of the length-weight coefficient of either size group gives values of K 2 = 0,913 (60-65 em) and K3 = 0,897 (66-76 em). Thus the relation between condition and maturation process may give a possible explanation. No far reaching migrations in the open sea are demonstrated on Fig. r65. 38% of the individuals caught in the Baltic proper have been recorded within a circle of 50 n.m. from the point of release, 56% within a range of roo n.m. and 87% within a range of 150 n.m. There was an equal trend for movements in northerly and westerly directions.

F. THUROW

Bundesforschungsanstalt fur Fischerei, Institut fUr Kusten­und Binnenfischerei, Labor Kiel, Kiel-Seefischrnarkt,

Germany.

-192-

Flatfishes GREENLAND HALIBUT

Investigations on and fisheries for Greenland halibut north of Iceland in the summer of 1967

(Tables 179-181)

In July/August 1967 Soviet trawlers fished for Greenland halibut north of Iceland. The main halibut concentrations were found at depths of 500 to 6oo m between 18° and 20°W in 67°40'N. The extension of the zone of halibut concentrat­ions north-south was not great, the halibut occupied a narrow band only.

When fishing with bottom trawl, even small departures of a trawling vessel from the right course gave no catches. On the other hand, when an east-west course was held, the trawlers took big catches. Table 179 presents some results of the fisheries.

The distribution of Greenland halibut was m good agreement with the location of a boundary between warm and cold waters. The densest concentrations were found in an area where the near-bottom temperature was about - o.5°C. It was interesting to see that directly above the zone of the mass distribution of halibut, a sharp temperature gradient was also distinctly traced near the sea surface. Thus, even measurements of surface temperature may help finding the near­bottom concentrations of Greenland halibut.

Tagging data confirm that the halibut remains for a long period at the boundary between cold and warm water masses. In July, August and September 1967 Soviet ichthyologists tagged about 8oo Greenland halibuts with hydrostatic tags in the Iceland area. Four tagged specimens were recorded by fishing vessels from the USSR and German Democratic Republic (Table 180). They showed that tagged fishes stayed near the area of release for some months.

Halibuts of 30-95 em in length were found in bottom trawl catches. The females were on an average larger than the males (Table 181).

Table 179. Some results of the Greenland halibut fishery in 1967

July The yield in tons ........ . Number of hours trawling . Average catch per hour (in tons) .................. .

August

The yield in tons ........ . Number of hours trawling . Average catch per hour (in tons) .................. .

Trawlers of 3500 t

displacement (BMRT)

9,942 4,917

2.02

3,862 2>415

r.6o

Trawlers of 1200 t

displacement (RT)

1,300 1,086

1.20

1,667 1,760

o.9s

Table 180. Recapture of tagged Greenland halibu1 in 1967

Released Recaptured Lati- Longi- Length Lati- Longi-

Date tude tude of fish Date tude tude (N) (W) in em (N) (W)

23. July 66° 41' 12034' 51 28. Sept. 65°oo' I I 0 00'

30. July 67°39' 19o 42' 68 19. Sept. 68° 40' 20°401

30. July 67°29' 22o 43' 71 13. Nov. 67030' z6°ro' 12. Sept. 67°25' 21°25' so s.Nov. 67°29' 21°!8'

As a rule, the stomachs of the halibuts were empty or only slightly filled. Most often they contained shrimps, Cephalopoda and digested fish. In September the halibut started feeding intensively on sandeels in the same area.

The gonads were far from being mature, and the fish investigated could evidently not spawn earlier than in November and December.

K. KoNSTANTINov

The Polar Research Institute of Marine Fisheries and Oceanography (PINRO), 6 Knipovich Street, Murmansk,

USSR.

Table IS I. Length composition of Greenland halibut (in %) taken in July 1967 north of Iceland Average Number

Length-groups length of fish Sex 31-35 36-40 41-45 46-50 51-55 s6-6o 61-65 66-70 71-75 76-8o 81-85 86-90 91-95 in em measured

c:M 0.1 0.1 0.5 I.7 5·7 15.3 41.3 30·3 5·0 - - 63.8 1,336

'!''!' - 0.4 I.1 2.4 4·3 4·I 6.5 14·7 3I.4 25.8 6.6 2.3 0.4 7I.5 1,629

-193- Other Fishes Redfish

Other Fishes RED FISH

Distribution of young redfish, 5. mente/fa, and 5. marintts, in the Barents Sea in 1967

(Figures 167-168; Tables r8z-r83)

Collection of data on the distribution of young redfish were carried out on board the R. V. "Tunets" between September and December 1967, as part of the investigations on the abundance of young bottom fishes, with the help of a common bottom trawl with a nylon net with 8 mm meshes inserted in the cod-end.

•

0

79

-.:: r .--

Division lib

Young redfish of 6-30 em in length were met along the branch of the warm Spitsbergen Current up to 80°4o'N rsozo'E.

The greatest number (about r,soo fishes per trawling hour) were caught near Bellsund and off the southern end of Prince Charles Island. About 300 specimens per trawling hour were taken north of Prince Charles Island and south of West Spits­bergen (Figure r67). Catches near the Bear Island

• 1-10 e H-50 • SHOO • i0!-300

• >300

->500

---.· -=----

0

74

. 69

w·

IIB

·---'9= . -· .. - .. - ..

• ••

• 1.-J·=·· I

=-!...

• IIA

zo·

-· -· . .. • =-= _----. 0 0 • --·--==-- __ .- .g--• •

30°

•• oo • 0 • • • ... -• •

~ ~

so· Figure r67. Distribution of young 5. mentella in the Barents Sea in 1967.

Circles indicate the distribution of 0-group redfish.

-194-

gave 50 to roo specimens per trawling hour. At the same period in 1966 the catches of young redfish in the West Spitsbergen area did not exceed 300 speCimens.

It is interesting to note that in the Hopen Island area (to the east of the island) where young redfi.sh are usually found in very small numbers, catches during the last three years (1965, 1966, 1967) amounted to roo and more specimens.

In Division II b 5. mentella of 14-16 and 9-II em in length accounted for Z/3 of the catch (Table r8za). The age of redfi.sh in the 1967 catches has not yet been determined, but on the basis of the data on age-size composition from previous years, it is

79°

=-r

concluded that they belong to the 1962, 1963 and 1964 year classes, which are considered to be abundant.

Young 5. marinus constituted I/3 of the catches, and they were, like the young of 5. mentella, distributed along the West Spitsbergen Branch of the current, approximately up to 79°30'N. North of this, young 5. marinus were not registered (Figure r68). The greatest quantity of this species (300 specimens) were caught off the southern end of West Spitsbergen and off the Hopen Island (Table r8zb). The greater part of the catches were specimens 6-8 and 9-II em in length, i.e. of the rich 1966 and 1964 year classes.

• l-10 e H-50 • Si-lOO

• 101-300 ·--- • >300

74.

69°

10.

liB

•··=:v-

•

.- .. ••• ••

IIA

•

:j •

30

->500

• T

- J. • ••• -·-!,~· -- . -

Figure r68. Distribution of young 5. marinus in the Barents Sea in 1967.

-195- Other Fishes Redfish

Table 182. Average catch (in numbers) of young redfish taken per trawling hour in Division lib in September-October 1967

a. 5. mentella Number of Length in em Mean number Total

Areas trawling 6-8 9-II I2-I3 14-I6 I7-30 per trawling yield hours hour

North Spitsbergen .......... 9 I I I 2 5 9 88 West Spitsbergen ........... 53 4 IO 6 88 24 I3I 6,968 South Cape Deep ........... 25 I I Western Slope of the

8 7 I6 403

Bear Island Bank ......... IO I I 2 22 Southern Slope of the

Bear Island Bank ......... 9 4 4 I 8 I I9 Hopen Island area .......... 9 8 I6 I 24 222 Western Deep .............. 5 I 3 I 6 I I2 6I Total ..................... 120 334 7I8 360 5,009 I,964 8,335 Average yield per trawling

hour .................... 3 6 3 39 I5 69

b. 5. marin us Number of

Areas trawling 6-8 hours

West Spitsbergen ........... 53 3 South Cape Deep ........... 25 Western Slope of the

Bear Island Bank ......... IO 4 Southern Slope of the

Bear Island Bank ......... 9 Eastern Slope of the

Bear Island Bank ......... 3 I Hopen Island area .......... 9 23 Total ..................... 109 406 Average yield per trawling

hour ....................

Sub-area I

In the southern Barents Sea young redfi.sh were distributed along the main branch of the Murmansk Current up to the northern part of the Novozemels­kaya Shallow, and also along the coastal branch to the Swjatoy Noss Cape.

The greater part of the catches taken along the main branch of the Murmansk Current consisted of young 5. mentella, while in the catches along the coastal branch, 5. marinus was predominant.

A great number of young 5. menteUa (up to 300 specimens) were registered in the western part of the Norwegian Deep, in the Murmansk Tongue and in the Central Elevation, and more than 100 specimens were caught in the northern part of the Novozemelskaya Shallow. Together with the age groups I-II, II and IV, were found specimens of the 1967 year class (o-group). The young of the o-group are shown in Figure 167 by circles. This was the most eastern distribution of redfish during the last ten years.

4

Length in em Mean number Total 9-II I2-I3 14-I6 I7-30 per trawling yield

hour

3 I I 4 I3 687 I I 3

I I I 6 13 I33

I I 3 5 42

2 3 IO 9 I 33 297

294 37 98 337 I, 172

2 I I 3 IO

Specimens of 6-8 and g-n em in length, belonging to the 1966 and 1964 year classes, were most often found in the eatches (Table 183a).

Great quantities of young 5. marinus of the 1966 year class were brought into the inlets and bays of Murmansk. Thus, for example, in the Kola Bay young redfish were in the summer of 1967 found in such great numbers, that it was possible to take them by hand in the ebb-zone.

Big catches of young 5. marinus were registered in November-December on the Finnmarken, Murmansk, Nordkyn and Demidov Banks. The 7-group of 5. marinus was found east of the Murmansk coast and in the central regions. Redfish of 6-8 em in length predominated in the catches, most of them belonging to the 1966 year class (Table 183 b).

T. S. BERGER, R. A. CHEREMISI;:-;'A

The Polar Research Institute of Marine Fisheries and Oceanography, 6 Knipovich Street, Murmansk, USSR.

-rg6-

Table 183. Average catch (in numbers) of young redfish taken per trawling hour in Sub-area I in November-December 1967

a. S. mentella

Number of Length in en :_lilean number Total Areas trawling <5 6-8 9-II I2-I3 q-I6 I7-30 per trawling yield

hours hours

West -coastal ............... 6 I I I 5 North-eastern Slope of the

Murmansk Bank .......... 6 I I I 5 North-central .............. 7 I I I I 22

Western Slope of the Goose Bank .............. 8 I I I 3 I 6 so

Northern Slope of the Goose Bank .............. 6 I 3 I 6 36

Central Deep ............... 2I I I I I IS Northern part of the

Novozemelskaya Shallow .. II I I 7 3 IS I6l Novozemelskaya Bank ...... 3 I I 2 Goose Land Shallow ........ 7 I I I I II Central Elevation ........... 7 I 36 35 2 5 I So 56 I Total ..................... 75 9 340 377 93 46 3 943 Average yield per trawling

hour .................... I 4 5 I I I I2

b. S. marinus

Number of Length in em Mean number Total Areas trawling <5 6-8 9-II I2-·I3 I3-I6 I7-30 per trawling yield

hours hour

East-coastal area ........... 5 I I I I I 5 7 36 West-coastal area ........... 2 I 5 I I I 9 55 North-eastern Slope of the

Murmansk Bank .......... 6 I 2 l I I 2 5 3I Northern Slope of the

Murmansk Shallow ....... 8 I I I I I I I2 Murmansk Shallow . . . . . . . . . 6 I I 5 North -central area . . . . . . . . . I4 I I I 5 Western Slope of the

Goose Bank .............. 8 I 3 I 3 I I 8 68

Total . . . . . . . . . . . . . . . . . . . . . 49 I2 67 25 28 IS 62 2!2

Average yield per trawling hour .................... - I I I I I I 4

SANDEELS

The German sandeel fishery in 1967 (Table I84)

The catches of the German sand-eel fishery which still amounted to 4082 tons in 1966, declined to a minimum of 324 tons in 1967. In 1967 only 9 fishing trips were made against 125 in the previous year.

The length composition of 5 samples of Am­modytes lancea marin~ts was as follows:

5 samples of unsorted catch comprising 2,494 fish ( = 27 kg) were analysed as to their species and length composition. 89.8% of the total catch (weight) were A.lancea marinus, 6.o% A.lanceo­latus, 1.5% cod, 0.9% sprat, o.g% whiting, 0-4%

Table 184. Length distribution (0 / 00) of A. lancea marinus of the 1967 catch

em ...... IO.O II.O II.5 I2.0 I2.5 I3.0 I3-5 I4.0 0/oo ..... 0 4 7 27 40 II4 II6 I5I em ...... 14·5 IS.O IS-5 I6.o I6.s I7.0 I7.5 I8.o Ofoo ..... I27 I04 67 68 46 so 26 25 em ...... IS.s I9.0 I9-5 20.0 20.5 22.0 23.0 0/oo ..... I2 IO 4 I 0 I 0

gurnard, 0.3% haddock, 0.2% dab. Undersized protected fish were only 0.5% of the catch, i.e. 0.3% haddock and 0.2% dab.

K. TIEWS

Bundesforschungsanstalt fUr Fischerei, 2000 Hamburg­Altona I, Palmaille 9, Germany

- 197- Other Fishes Grenadier

GRENADIER

Feeding of Macrurus rttpestris in the Iceland area

(Figures 169--170; Tables 185-186)

During the last few years commercial fishing for M acrurus began to develop in the north­western Atlantic. This lead to the necessity of studying the biology of this species, and in parti­cular, its feeding. The macrurid fishes in that area are comparatively large ones forming the densest concentrations in August-November (according to PINRO) i. e. in the period of poor concentrations of other demersal fishes. The investigations were carried out on the most frequent species of M acrurus, M. rupestris, which form the main commercial concentrations. Sometimes the samples contained M. berglax as well.

The material on the feeding of M. rupestris was collected in three areas south-west and south­east of Iceland in June-August 1967 (Figure r69) by workers from PINRO and the author. In total, 44 trawlings were made in those areas; the depths ranged between 400 and 750 m, the gear used was a commercial bottom trawl.

M. rupestris was represented by specimens

Table r85. Food composition of iVI. rupestris in the Iceland area, summer 1967 (frequency of occurrence is expressed

as percentage)

Food components Occurrence (%)

Pasiphaea ...................... . Euphausiacea .................... . Themisto sp. . ................... . Calanus ........................ . Cephalopoda (Decapoda) ......... . Limacina spp .................... . Ctenophora spp. . ................ . Digested fish .................... . Non-determined ................. . silt ............................ . sand ............................ .

Total .......................... .

74-40 8.80 3·77 3.00 I.26 o.So o.So 2-47 r.So I.60 !.30

100.0

Table r86. Total index of M. rupestris stomach content in June-August r967 (in Ofoo) *)

Length in em June July August

61- 70. · · · · · - 28.3 (18) 6o.5 ( 6) 71- So 50·4 (4) 95-4 (30) 39.0 (2o) 81-- go ...... 62.0 (7) 65.6 (17) 42.5 (17) 91-100 ...... 74·5 (1) 17.2 ( 6) 17.0 ( 6)

Total ....... 62.3 51.6 39·7

of 46 to 170 em in length. The ratio of females *) In brackets are shown the number of fish in each size to males was 3 : r. group.

25° 20° 15°

6 6 o I I ~ \;•t '• "' F1\ ~ "'• '• 'v' lj.-, 166 o

65° ~

Iceland

64°r---t---c~~+----r-~~-~~ 0

0 00

0~0

630 ~0 0

25° 20° 15° Figure 169. Areas of catches of JW. rupestris, Icelandic region, summer 1967

-rg8-

Sampling was impeded by the decrease in pressure when the fi.sh was lifted to the surface, as a result most of the specimens came up with everted stomachs. Of the bulk of trawl-caught M acntrus, 25 specimens with stomachs in normal state were sampled, fixed with 4% formaline or frozen. Before the extraction of the stomach, each fish was weighed, measured and determined as to sex. r,867 specimens were treated; 1,735 specimens were analysed in the field and 132 stomachs were fixed.

The material was treated according to the follow­ing three methods:

r. Determination of the frequency of occurrence of each food component.

2. Determination of the total index of stomach content.

3- Determination of the degree of stomach content to show the intensity of feeding.

Determination of the frequency of occurrence of food components is used by many Soviet ichthyo­logists. This method takes into account the relation between the total number of stomachs and those containing food. The total number of M. rupestris examined was r,867, of these 685 specimens (37%) had empty stomachs.

Table r85 shows that shrimps and their young stages (probably subgenus Phye) made up the main food of M. rupestris in the summer of 1967 in the area of Iceland. Euphausiidae and Themisto spp. were consumed in smaller numbers. Other components of the food were comparatively scarce: specimens of fish, Calanus spp., Ctenophora spp., sand and silt are sometimes found in the stomachs of M. rupestris.

The quantitative _estimation of the degree of fish feeding is expressed by the total indices of stomach content, i. e. the ratio (in % 0) of food weight to the weight of the fish itself. The com­parison of the total indices of stomach content by month (Table r86) shows a tendency to de­crease from June to August.

The degree of stomach content is estimated visually and a five mark system was used: o = emp­ty stomach, r =stomach with little food, 2 = aver-

Fat content "/.

6

5 2o~ 4o-----:..,___,_-::::o 3o---~~--- -8

4 1 o ________ o

3

2L-____ L_ __________ L_ ________ ~L-----

June July August

Figure I 70. Changes in fat content of M. ''upestris, Icelandic region, summer I967.

Size groups of 1'v1. rupestris: I. 6I- 70 em 2. ?I- So em 3- 8I- go em 4- gi-Ioo em

age degree of stomach filling, 3 = full stomach, 4 = greatly dilated stomach.

The marks were averaged for the whole group of examined stomachs. The same data averaged for months show a gradual decrease in stomach content during June, July and August (averages: 2.0, r.5, r.o4, respectively).

M. rupestris flesh is poor with the fat concen­trated in the liver, and its weight can indicate the "condition" of the fish.

Fatness in the fish is characterized by the per­centage of liver weight to body weight. The de­crease in the intensity of feeding towards the end of the summer is shown both by lower indices of stomach content and by the variation in fatness, given in Table r86 and Figure 170.

References

"Pacific ocean. The biology of the Pacific ocean" book 3" Fishes of open seas. "Nauka" publishing house, I967.

MARSHALL, N. B., I965. "Systematic and biological studies of the Macrurid fishes". Deep-sea Research, I2 (3).

S. G. PODRAZHANSKAYA All-Union Research Institute of Marine Fisheries and

Oceanography (VNIRO), Verkne-Krasnoselskaya I?, Moscow B-qo, USSR.

CUTLASS FISH

Biology of the cutlass fish, Lepidopus caudatus (Figure I7I)

Until recently, the biology of the cutlass fish has not been studied. Therefore, the material collected by AtlantNIRO during the period from

1964 to rg67 off the north-western African coast would be of interest. The main observations were made during a research cruise of AtlantNIRO RTM "Belogorsk" in October-November rg66 where 27 ,ooo specimens were analysed.

- rgg- Other Fishes Cutlass Fish

0/oo 160

140

120

100

80

60 JUV.

40

2:l .. I

~;..:_::~:..:.:.:-·<

r;d'

I

I I

I I I I I I

' ...

N = 27.000

\

\

\ - ...... ------=.:=:.:-.:...-=-:=--·-·-·-·-·--40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 em

Figure 17r.

As shown by control trawlings, the cutlass fish occurred in a southern and a northern area off Africa, between 37°N and I7°N and between I7°S and 37°S.

The most dense concentrations of Lepidopus ca~tdatus have been found on the Morocco Shelf at a depth of roo to 3SO m. In other areas it could be met with as by-catch.

The cutlass fish can reach a very large size. Sometimes specimens of more than two metres in length are found. However, owing to its form, the weight is not great and only rarely exceeds 7-8 kg.

Individuals of U:O:-I3S em with a weight of o.g-2.0 kg make up the main part of the Morocco stock. Two clearly expressed size groups are found, viz. 46 to go em and roo to I4S em (Figure I7I). A similar picture has been observed in the other areas. Fishes of intermediate size probably occur outside the shelf.

The species mature at a length of more than 8o em. The main part of the males are mature at a length of rro em and the females at rzo em. The cutlass fish is a schooling and rather mobile fish of predatory habit. Effective trawlings have been conducted with a speed of not less than 4-4.s knots.

The main diet of the cutlass fish off Morocco is Euphausiidae (their length is about 4 em), but they also prey on different fish species such as horse mackerel, mackerel, sardine, whiting and

smaller species like phosphorescent anchovy and pellonula (Pellonula vorax). Cannibalism may occur, young cutlass fishes of 70 to roo em in length are frequently found in the stomachs of larger fishes (from 130 to zoo em). Rather frequently are shrimps and squids found in the stomachs.

The cutlass fish does not feed before the spawning period. After spawning the intensity of feeding increases. Two peaks of intensive feeding can be distinguished during the day: from o to 4 o'clock and from 4 p.m. to 8 p.m. o'clock. Small fish predominate in the food after midnight, and then also a great number of Euphausiidae are found. In spite of the rather small size of the feeding objects, the total indices of stomach fullness reach r,6oo.

The best catches are as a rule made from ro to 3 p.m. After 7 p.m. during the night, and till 8 a.m., the catches were small and did not exceed so to roo kg per hour of RM T trawling.

During daytime, the fish is found in the bottom layer with a temperature of I3° to IS.So C and a salinity of 3S.8 to 36.o0fo0. Probably, when it ascends to the upper layers during darkness, the upper border of its distribution is limited by the isotherm of rs.so C. On the deeper parts of the slope and outside, it does not go deeper than the I3° C isotherm.

The densest demersal concentrations of cutlass fish are found in areas where cold water enters with a temperature of IS 0 to rs.so c. Very often

-200-

such concentrations occur in warmer layers be­tween two cold currents. ·when the temperature is lower, catches decrease and with a temperature of 13.5° to 14.5° C the catch per trawling hour is rarely higher than 20 centners. At lower tempera­tures the trawls very often come up empty. This is probably connected with the great vertical movements of the concentrations, which are closer to the ground where comparatively warm water is above.

Spawning occurs on the shelf at a depth of roo to 300 m with a temperature around I5° C and probably on the border between cold and warm waters. The spawning takes place in portions. The eggs are large and pelagic; the main spawning occurs pelagically in the dark.

On the shelf from 34°N to 26°N spawning fishes are caught at different periods during the year. Females with running eggs in maturity stage V have been found in trawl catches in May, August, November, December and January. The catches decreased sharply after spawning. Probably, this reflects changes in behaviour. The species feeds in this period on small bathypelagic crustaceans and spreads widely and pelagically over a large area. Therefore, after spawning this species does not form very dense separate concentrations at the bottom. Spent fishes are very seldom found in the catches, and one may have the impression that after the shedding of the eggs has been

completed, the cutlass fish leaves the shelf for the open part of the ocean. Here the ripening of sexual products, and also of eggs left over after the spawning, occur. At the end of rg66 and in the the beginning of rg67 in the area of 3I 0 N around the middle of November, the gonads of most of the females were in maturity stage III and only a small quantity were ready for spawning (stage IV) or were actually spawning (stage V).

In the beginning of December the gonads of almost all females developed into the maturity stage IV. In the second part of December most of the eggs were spawned, and from the middle of January stages VI-III predominated in the catches. Probably the observed cycle would be repeated during the next months up to a time when there will be a complete shedding of eggs. This means that the cutlass fish spawn during the whole year, because there are favourable hydrographical con­ditions for spawning in the greater part of the regwns.

The spawning intensity is not constant, there are seperate intensive periods from time to time, but every day a small number of females spawn and, therefore, the spawning is prolonged.

L. N. DOMANEVSKY

Atlantic Research Institute of Marine Fisheries and Oceanography (ATLANTNIRO), Kaliningrad, USSR.

-201- Rare Fishes

Rare Fishes

Rare fishes recorded by the Marine Research Institute in Reykjavik during 1967

M aurolimts pennanti (Walbaum) XII, S Iceland (Vestmannaeyjar), four fishes s6, 57, 6r and 63 mm, stranded.

Scombresox saurJ,tS (Walbaum) VI-VIII, S Iceland (Hornafjordur), 33 em, stranded.

MacrurJ,tS rupestris (Gunner) 17. IX, S Iceland (Hafadjup).

M acrurus Jabricii (Sundevall) 2. XII, N Iceland (66°o8'N 2I 0 Io'W), 66 em.

Urophycis blennoides (Brtinnich) 3· VI, S Iceland (63°Ig'N 20°03'W), 35 em; 5· VI, S Iceland (63°5o'N I5°56'W), two fishes

31 and so em; J. VI, S Iceland (64°02'N I4°I2'W), 68 em; 7· VI, S Iceland (63o52'N I4°IO'W), 35 em; 7· VI, S Iceland (63°54'N I4°03'W), five fishes

30, 33, 33, 36 and 37 em; II. VI, S Iceland (63°46'N I4°52'W), two fishes

49 and 55 em; rr. VI, S Iceland (63°46'N I4°55'W), 43 em.

Lampris ltma (Gmelin) 30. VII, W Iceland, two fishes IIO and rr2cm; 14. VIII, W Iceland, III em;

VIII, W Iceland, IIO em.

Morone labrax (L.) I8. VIII, W Iceland, 39 em. First record from Iceland.

Epigonus telescopium (Risso) 17. IX, S Iceland (Hafadjup), 32 em. First record from Iceland.

Pterycombus brama (Fries) 21. VI, S Iceland, 40 em.

Scomber scombrus (L) 20. VIII, W Iceland, 44 em.

Carelophus ascanii (Walbaum) 15. VII, S Iceland (Vestmannaeyjar).

CentrolophJ,tS niger (Gmelin) r8. V, SW Iceland, 44 em.

MJ,tgil chelo (Cuvier) ro. IX, N Iceland (Hunafloi), 48 em.

Bythites J~tscus (Reinhardt) ro. VI, SE Iceland (63°53'5N -14°03'5V), srx fishes 42, 57, 82, go and roo mm. First record from Iceland.

E~drigla gurnardJ,fS (L) 29. IX, S Iceland, 36 em; 13. X, SW Iceland, 39 em.

I eel us bicornis (Reinhardt) 2. V, N Iceland (66°I2'N-Ig 0 I2'V), two fishes I05 and II3 mm.

Scophthalmus maximus (L) 30. VIII, SW Iceland, 63 em.

Linophryne lucifer (Collett) 12. VIII, E Greenland (65°30'N-32°2o'V), 34Cm. Fuller details of these captures are given m

"lEgir", 61 (4-5). G. JoNssoN

Hafranns6knastofnunin, Skulagata 4, Reykjavik, Iceland.

Scottish records of rare fishes 1967

The following rare fishes were recorded in Scotland in rg67. As in previous years this list includes a number of records from waters beyond the Scottish area. Hexanch%s grise%s (Bonnaterre) - r: Faroe Bank,

VII. Oxynot%s paradox%s Frade - 2: (45 specimf'ns):

Porcupine Bank, IV (44 specimens); Fair Isle, IX. Scymnorhimts licha (Bonnaterre) - r: 40'E

Sumburgh Head, Shetland, I. SqJ,ratina sqJ,tatina (L.) 2: off Eagle Island,

Eire, V; 6'W Rhu Rhea, N. Minch, X. Torpedo nobiliana Bonaparte -7: 6' off Dounreay,

N. Scotland, III; ro'NW Macduff, III; Turbot Bank, IV; 4' off Burghead, V; 2' off Noss, Shetland, IX; r2'NE Buckie, XI; 4'ENE Butt of Lewis, XI.

Trygon pastinaca (L.) -I: 6' Ex S Isle of May, X. Myliobatis aquila (L.)- r: 28'NE x N Lossiemouth,

X. Acipenser st%rio L.- I: 3' NE Troup Head, IV. Scomberesox sa#rus (Walbaum) - I: Eshaness,

Shetland, VI. Belone belone (L.) - I: off Gourdon, Kincardine­

shire, XII. M acroramphos%S scolopax (L.)- I: 5'SSE Tiumpan

Head, N. Minch, VI. Lampris gJ,tttat#s (Brunnich) 5: Stokksnaes,

Iceland, VII; off Noup Head, VII; 8o'NW Orkney, VII; Faroe, Summer; Kilmaluag, Skye, VIII.

-202-

Trachyptents arcticus (Brlinnich)- I8: Fraser burgh, II; U nst, Shetland, III; Yell, III; Peter head, III; North Roe, Shetland, III; Little Loch Broom, III; Fetlar, III; Whalsay, IV; IJ'E Easter Horn, Iceland, V; estuary of S. Esk, VI; Montrose VI; IJ'E x N. Lerwick, VI; Aberdeen, VI; E. Iceland, VII; IS' off Saddle back, Faroe, VIII; IS'NW Myggemes, VIII; IS'NW My ling Head, IX: off Sum burgh Head, X.

Marone labrax (L.) - 3 (5 specimens): Ythan estuary, Aberdeenshire, Summer; Forth estuary, Summer (3 specimens); rr'E Copinsay, Orkney, XI.

Brama raii (Bloch) - 39 (62 + specimens): Stornoway, I; I2' off Bard Head, Shetland, VIII; 30'WNW North Rona, IX; Kincardine­shire, IX; so' N Sule Skerry, IX; John o' Groats, X; off Sum burgh Head, X; 40'E Sum burgh, X; Ythan Estuary, Aberdeenshire, X; Dornoch Firth, X; Portobello beach, X; Fair Isle, X; Firth of Tay, X; Tyninghame beach, East Lothian, X; Inverness Firth, X; 6'E Pentland Skerries, X; J'ENE Buchan Ness, XI; S of Greg Ness, XI: Smith Bank, XI; Montrose, XI; 6'E Pentland Skerries, XI; 6'E Bell Rock, XI; Firth of Tay, XI; Io'SE x S Duncans by Head, XI; Cromarty Firth, XI; off Burghead, XI; 6'N Buckie, XI; 6'SE Isle of May, XI; Red Head, Angus, XI; off Buckie, XI; Io'NW Macduff, XI; off N aim, XI; N of Bressay Shoal, XI; off Lossiemouth, XI; 8'NE Lossiemouth, XI; 8'NE Lossiemouth, XII; W Isle of May, XII, Rosehearty, XII; N airn-Cromarty, XII.

Pterycombus brama Fries- I: NE Faroe, I.

Mullus surmuletus L. - 2: 8'WNWjFraserburgh, X; 3'NE Fraserburgh, XII.

Spondyliosoma cantharus (Gmelin) - 2: I4'E x S Girdleness, XII; 4o'E x N Aberdeen, XII.

Cepola rubescens L. - 2: Ailsa Craig, Firth of Clyde, I; grounds unknown, III.

Centrolophus niger (Gmelin) - I: N Burra Isle, Shetland, VIII.

Mugil chela Cuvier- I: Ythan estuary, Aberdeen­shire, VI.

Oncorhynchus gorbuscha (Walbaum) 2: Bonar Bridge, Sutherland, VII; Stromness Voe, Shet­

, land, VIII.

B. B. RAE, S. F. PIRIE

English observations on rare fish in 1967

During the year the following unusual fish were recorded at the Fisheries Laboratory, Lowestoft. A small number of the records came from commer­cial sources, but the majority were caught on the Atlantic Slope west of Britain during one cruise of the R. V. "Ernest Holt". The positions of the "Ernest Holt" stations are: -

St. I2: July 3, 59°SJ'N 5°IJ'W (Wyville Thomson Ridge), 439-477 m depth

St. I4: July 3, 60°II'N 4°45'W (Wyville Thomson Ridge), 6o5-6I5 m depth

St. IS: July 3, 6o 0 I5'N 4°25'W (Wyville Thomson Ridge), 450-570 m depth

St. IJ: July 4, 59°39'N 6o37'W, 5I2-695 m depth St. 29: July IO, 58°23'N 9°20'W, 530-567mdepth St. 33: July I3, 54 o8'N rro 42'W, 457-475 m depth St. 35: July I3, 54°5'N II 0 53'W 494 m depth St. 3J: July I4, 52°39'N I2°45'W (The Farm

area), 466-503 m depth St. 39: July I4, 52°23'N I2°52'W (The Farm

area), 567-595 m depth St. 40: July I4, 52°I3'N I2°48'W (The Farm

area), 622-658 m depth St. 4I: July IS, 52°II'N I2°58'W (The Farm

area), 658-677 m depth St. 42: July IS, 52°IO'N I3°IO'W (The Farm

area), 630-677 m depth St. 56: July I9, 5I 0 33'N II 0 25'W, 420-73I m

depth St. 57: July I9, 50°34'N rrooo'W, 52I-658 m

depth St. 6I: July 20, 49°4I'N II 0 I4'W, 503-530 m St. 62: July 20, 49°36'N II 0 29'W, 604-622 m St. 64: July 20, 49°2I'N II 0 32'W (West of Coral

Bank), 695-73I m depth St. 69: July 2I, 48°27'N 9°3I'W (Little Sole Bank),

I55-2IO m depth

N otacanthus phasganorus Goode: I specimen 94 em, Kidney Bank, S.E. Iceland. Landed February 20, at Grimsby by the M.T. "Princess Royal".

Hexanchus griseus (Bonnaterre): E. H. St. 33, one specimen s;2 70 em total length.

Oxynotus paradoxus (Frade): E.H. St. 57, 2 speci­mens: I, s;!, 43 em, I c)' 73 em total length.

Scymmodon ringens Bocage & Capello: E.H. St. 33· One specimen, about ISO em, E.H. St. 33, St. 39, I 0 84 em total length.

Deania calcea (Lowe): E.H. St. I7. 2 specimens I ¥ I03 em I c)' 83 em.

Marine Laboratory, Victoria Road, Torry, Aberdeen, Alepocephalus rostratus Cuvier & Valenciennes: Scotland E.H. St. 64. I specimen 47 em standard length.

-203- Rare Fishes

A. bairdii Goode & Bean: E.H. St. IS (Wyville Thomson Ridge) I specimen 7 4 em standard length; E.H. St. 17, I specimen 78 em standard length.

Xenodermichthys copei (Gill): E.H. St. 56, 8 speci­mens 8.2-I6.I em standard length; E.H. St. 57, 6 specimens, 6.0-I7.I em standard length.

Stomias boa ferox Reinhardt: E.H. St. 57, 3 speci­mens I3-28 em.

Synaphobranch'VIs pinnat'Vts (Gronow): E. H. St. 37, I specimen, 25.8 em total length.

Notacanthtts bonaparti, Risso: E.H. St. 37, 4 speci­mens 26.6-41.2 em total length.

JYI acrorhamphosus scolopax L: E.H. St. 6g, 2 speci­mens both I3.8 em total length.

Coryphaenoides rttpestris Gunnerus: E. H. St. I7, 2 specimens 6o and 73 em (approximate total length); E. H. St. 42, I specimen, 49 em total length.

M acrourtts berglax Lacepede: E.H. St. 14, numerous; E.H. St. IS, 2 specimens. Four specimens pre­served ss-go em total length.

Nez'VImia aeqttalis (Gunther): E.H. St. 42, 5 speci­mens, 23.5-33.8 em total length.

Mora mora (Risso): E.H. St. 4I, I specimen, 6o em total length.

Lepidiong'Vtentheri (Giglioli): E.H. St. I7, 9 specimens 25-37 em total length; St. 29, I specimen 27 em.

H alargyre'US affinis Collett: E.H. St. s6, I speci­men, 9 em standard length.

Onos tricirratus (Bloch): One specimen, 40.5 em total length, landed by the Lowestoft trawler "Ethel Mary" February IS. Caught west side of the Clay Deep (55°N 4°E. 44 m, approximate position and depth).

Beryx decadactyl'VIs Cuvier & Valenciennes. E.H. St. 35, 3 specimens; St. 57,8 spec; St. 6I, I spec. and St. 62, I specimen. Up to 49 em total length.

Marone labrax (L.): I specimen I9 em brought alive to the laboratory. Caught by the inshore

boat "Pam Pat" off Sou.thwold, Suffolk, No­vember g.

Brama brama (Bloch): One specimen about 45 em, Brancaster, Norfolk, October IS; One about 40 em caught in herring nets off Winterton, Norfolk, October 23; One, 47 em, washed up at Staithes, Yorkshire, October 24. There are records of 9 other occurrences on the north Norfolk coast in this period.

Pagelhts centrodont'VIs (De la Roche): landed at Lowestoft by the M.T. "Suffolk Craftsman" February I6, from west side of White Bank (55°0o'N 5°3o'E 40 m approximately).

Lycodes esmarkii Collett: E.H. St. I7, I specimen 46 em long.

Echiodon dr'Vtmmondii Thomson: E. H. St. 37, 2 specimens 24.2 and 24.9 em total length.

Centroloph'Vts britannic~ts Gunther: E.H. St. 39, I specimen, 47 em total length.

Sebastes ( ?) marimts (L.): One specimen 26 em long landed at Lowestoft by M.T. "Boston Lancaster" July IS, caught north side of the Middle Rough (approximately 55°40'N 2°30'E 64-73 m).

One specimen about 25 em, landed by the Lowestoft trawler "Ocean Crest" on July 25. Caught on the Inner Shoal (56°so'N 4°E, 55 m approximately). (Specimens were not preserved, but they were almost certainly S. marimts. Even S. vivipants would be unusual in these positions).

Mala mola (L.); One specimen, caught on south side of Brucey's Garden (54o45'N ooso'E, 73 m approximate position and depth) by M.T. "Oli­vean" November 22 ;1 one about 6 kg, washed ashore on the north Norfolk coast. (Press and television report). One about 30 kg reported caught in the Clay Deeps by the Lowestoft trawler "Boston Hunter" (a good description was given but the specimen was not landed).

R. W. BLACKER

Fisheries Laboratory, Lowestoft, Suffolk, England.

-204-

Shellfish

PRAWNS

On the biology and distribution of Pandaltrs borealis in the offshore waters of the Barents Sea

Until recently it was considered that the edible prawn, Pandalus borealis form small concentrations only in the coastal south-western part of the Barents Sea.

Investigations conducted in August-October 1967 showed that while catches in the coastal areas are rarely higher than 30-40 kg per trawling hour, in offshore waters there are concentrations covering areas of roo km2 with catches up to 2-3 centners per trawling hour.

Two commercial concentrations of deep-sea prawn were registered, viz. in the Hopen Island and West Spitsbergen areas.

The Hopen Island area is characterized by an even bottom relief with silt and siltjsand grounds. Salinity fluctuations from 34 to 34·5%0 were observed, and the temperature varied between o. 72 and 0-45 o C. A temperature decrease of 0.35° C in October caused a sharp reduction in the catches. In August maximum catches amounted to 3 centners per trawling hour, but in October they were not higher than 0.2 centner. Apparently because of the influx of cold waters from north of the front, the prawns migrated in a southern and south-eastern direction. The catches decreased during the night, possibly because of vertical mi­grations of Pandalus.

The P. borealis in this concentration is character­ized by slower growth-rates as compared with those in the coastal regions of the sea. Analysis of the age composition of the population showed that in August-October the concentration consists of the following age-groups:

1.5 years: lc*) = 13-15 mm. A low per cent of males, mainly young ones.

2.5 years: lc = r8-r9 mm. Mostly males, mainly in the transition stage.

*) The length of carapace according to HoRSTED and SMIDT (1956) and ALLEN (1959).

3·5 years: lc = 23-24 mm. Transitional indi­viduals and first time spawners.

4·5 years and older: lc = > 27 mm. Females of the first and later spawning years.

Specimens older than 6.5 years (lc = 32-33 mm) were not found.

The average weight of the prawns was 6.r5 g at a mean carapace length of 24.9 mm. Females, i. e. large prawns, made up 76-93% of the con­centration. Females with eggs on pleopods con­stituted 79% in August and 87% in October of the total quantity of females. Apparently, the main spawning takes place in August. Soft cara­paces were observed in a great part of the females (up to IO-I5%).

Biometrical analysis of non-fixed data revealed a very high correlation coefficient between lc and la (the total length of the body from the base of the eye to the base of telson), namely o.g83r ± 0.0059. The conversion factor from lc to lo was 3.13.

In the southern part of the West Spitsbergen area concentrations of P. borealis were observed at depths of 275-420 m, with a density of up to 2.5 centners per trawling hour. The bottom in this area was silty and silty-sandy. The near­bottom temperature in October was 2.3-2.5° C. 40% of the concentration in October were females and females with eggs on pleopods made up 8r% of their total quantity. In the northern part of the area, the number of females decreased and was only 25-30% of the catch at 8oooo'N. At the same time, the quantity of females with eggs on pleopods also decreased, and made up 39% of the total number of females.

The correlation coefficient between lc and lo for prawns of this concentration, was 0.9r88 ± o.oo8r, and the conversion factor was 3.16.

V. F. BRY AZGIN

The Polar Research Institute of Marine Fisheries and Oceanography, 6 Knipovich Street, Murmansk, USSR.

-205- Shellfish Shrimps

SHRIMPS

By-catch in the German shrimp fishery (Crangon crangon) in 1967

(Tables 187-r88)

The total Crangon catch amounted to 23,4g6tons. From these 4,670 tons 8.5 Million German Mark) were edible shrimps and 18,826 tons ( = 1.4 Million German Mark) were fodder shrimps. By­catches of crabs, fish etc. amounted to 5,785 tons (= 0.5 Million German Mark). A total of 40,869 fishing trips were made. In continuation of research initiated in 1954, 408 unsorted catch samples (= 2,030 kg) were investigated as to their species and length composition. Samples were collected weekly in Biismn, Cuxhaven, Neuharlingersiel and Dornumersiel.

The by-catches of unsorted protected fish amounted to 1,948 tons and were thus a little lower then in the previous years 2,143 tons in 1966; 2,rr7 tons in 1965).

The by-catch by species is given in tons and %of the industrial catches in Table 187.

As can be seen from Table 187 the by-catches were below 10%. The numbers of the different fish species caught by the German shrimp fishery are given in Table 188.

Table 187. By-catch of undersized protected fish in industrial catches of the German shrimp fishery in tons and %

of total industrial catches

Species r965 1966 1967 tons % tons % tons %

Plaice ....... 1,061 4·0 967 2.9 957 3·8 Sole ......... 344 1.3 248 0.7 310 1.3 Dab ........ 376 1.4 372 I. I 334 1.4 Whiting ..... 274 I.O 219 0.6 307 1.3 Cod ......... 62 0.3 338 I.O 40 0.1

Total ....... 2,II7 8.0 2,J44 6.3 1,948 7-9

Table 188. By-catch of undersized protected fish in the catch of the German shrimp fishery by number (in Millions)

Species 1965 1966 1967 Plaice ........... 154-4 164.1 144·1 Sole ............... sr.6 49-9 97-8 Dab . . . . . . . . . . . . . . 64.0 103.0 87.6 Whiting ........... zr.8 rr.8 z6.5 Cod ............. ·· 3·3 21.1 r.6

It may be noted that sole by-catches were double as high as in the previous years because of a rich 0-group of fish and that the by-catch of cod, which was unusual high in 1966 became normal again. Plaice, dab and whiting by-catches were normal.

K. TIEWS

Bundesforschungsanstalt fur Fischerei, 2000 Hamburg­Altona r, Palamille 9, Germany

-206-

APPENDIX

Report on the joint meeting of Soviet and Icelandic investigations on the Atlanto-Scand­ian herring distribution in relation to oceano­graphic conditions, held at Akureyri r8.-

I9. June 1967 (Figures 172-175)

Introduction

In June rg67 the Soviet oceanographic obser­vations in the Norwegian Sea were carried out along ro standard sections in the area from the straits between the Shetland Islands and Iceland to J4°30N and along two additional tracks: from north-east of the Faroes to 6s 0 oo'N 02°oo'W, and east of Iceland along 64°40N to OS 0 W.

All these investigations were carried out from 30. May to 12. June, by the research vessels "Fritjof Nansen", "Academician Knipovich", "Pro­fessor Somov", "Tunets" and the exploratory ship "Professor Mesjatsev". Besides hydrological obser­vations at most of the oceanographic stations, the total number of which was rg8, a great number of hydrochemical measurements were made.

Plankton observations included 130 phyto­plankton and more than 700 zooplankton samples collected with Hensen net (No. 23/3) in the so-om layer and Juday net (No. 38, 37 em in diameter) at S00-200, 200-IOO, IOO-SO and S0-0 m.

The water displacement method was applied for plankton volume measurements. Qualitative com­position was examined with a binocular microscope. Phytoplankton samples were collected with N ansen bottles (r litre) at depths of o, ro, 20, so, roo and 200 m and the Juday net hauls were used for qualitative determinations. Transparency measure­ments were made by Secchi disc.

The detection of herring concentrations was carried out by vertical echo-sounders. For a more exact species identification horizontal sounders were also used. Besides the qualitative characteri­stics of the herring shoals the number of shoals of different densities per 30' longitude and ro' latitude was calculated.

As in previous years, the Icelandic hydrographic investigations were carried out in conjunction with biological work and herring investigations in the area north and north-east of Iceland. Two surveys were made lasting from 29. April to r8. May and from 29. May to rs. June.

Besides hydrographical observations the Ice­landic surveys included chemical investigations of

dissolved oxygen, inorganic phosphate, nitrate and silicate.

Phytoplankton, for primary production measure­ments using the (14 technique and qualitative analysis, was collected with NIO plastic water samplers at o, ro, 20, and 30 m. Transparency was measured with a Secchi disc and a number of ob­servations were also made with a beam transmitt­ance meter.

Zooplankton was collected with a Hensen net of the same standard as that employed by the Soviet researches and horizontal hauls were made at all stations with the Icelandic High Speed Plankton Sampler.

For detection and determination of herring shoals echo-sounder and asdic were operated continously throughout the cruises. Calculations were made of the number of shoals at different densities.

All Icelandic investigations were carried out from R.V. "lEgir" but in addition the herring scouting boat "Hafth6r" explored the area east of Iceland to 02°0o'E between the Faroes and 68°oo'N.

Unfavourable ice conditions in the area north­west and north of Iceland and north of 74°30'N limited the area investigated by the Icelandic as well as the Soviet expeditions.

The chairman of the general meeting of the various discussion groups was Mr. Y. BENKO of the PINRO Institute, U.S.S.R.

Ice limit

During the first Icelandic survey (29. April to r8. May) the ice limit was almost 6o nautical miles off the north-west peninsula, but a short distance farther east it bent southward toward Hunaft6i. From there it extended all the way east of Langanes. Along the north coast of Iceland the distance from the coast to the ice border was only 20-40 nautical miles. Near I3°W the ice border suddenly bent toward the north and was not observed during the remaining part of the survey.

During the second Icelandic survey (zg. May to S· June) the ice border was less than IS nautical miles off the north-west peninsula, about 30-40 nautical miles off the north coast, extending east toward Skjalfandi from where it bent toward north. Thus the drift-ice had moved closer inshore at the north-west coast between the two surveys, but in the eastern part and in the oceanic area it had

-207- Appendix

40 30

78 ~ .. -~~~~-.... -r·~·

I /

70

c <:

<::(

-./ <: ~ ~

Q: (!)

I

\ II

\~ I:

Figure r72. Temperature distribution at 20 metres 29. May-r2. June rg67.

somewhat receded. Compared with earlier years, the eastward extension of drift-ice north of Iceland was abnormally great in May and early June rg67, and greater than in any year since rgr8, with the possible exception of 1949 and rg65.

Temperature distribution

At zo metres depth in the Iceland Sea (Figure 172) the mean features of the temperature distribution

were as follows during zg. April to r8. May: off the north-western peninsula it ranged between I

0 and 3°C, but dropped to extremely low values off Hunafi6i (less than- I

0 C}. The negative tempera­tures persisted east to Sletta with slightly higher temperatures (about - 0.5°) at nearshore stations off Siglunes and Langanes. In the oceanic area between Langanes and Jan Mayen sub-zero tempe­ratures were found within a tongue that extended east to 9°W and south to 67°N. The lowest tempe-

-zo8 --

rature recorded within this tongue at this time was - 0.98oC. A temperature rise from ro to 3°C occurred between 6° and 8°W. At 0° longitude the temperature had risen to 6°C.

During the second survey, z9. May to 5. June, temperatures ranged between 6° and 7oC off the west coast of Iceland, decreasing to less than 4 oc off the north-west peninsula. Along the north coast the temperatures had increased slightly at zo metres from what they were during the first survey, especially at inshore stations. In the tongue of cold water north-east of Langanes the low tempera­tures persisted with temperatures below - I.5°C in the core of the cold water, some 6o miles off Langanes.

Compared with earlier years, the temperature was about normal or slightly below normal off the west coast, but exceptionally low all along the north coast ,where it was several degrees below the r950-r96o mean. In the tongue of cold water, temperatures were abnormally low. Compared with the last two years, it may be stated that 1967 was slightly colder than r965 along the north coast of Iceland, and much colder than r966, whereas in the tongue of cold water north-east of Langanes the temperatures were similar in r965 and r967. The eastern boundary of the tongue of cold water at zo metres was slightly farther to the east in r967 than in either r965 or r966.

At roo metres depth during z9. April to r8. May the temperatures ranged between 3° and 4oC off the north-west peninsula, r 0-3°C between Hunafl6i and Siglunes, and 0°-r°C between Siglunes and Langanes. In the area between Langanes and Jan Mayen the temperature was below zero at this level, reaching a minimum of less than- roC. The eastern boundary of the tongue of cold water was located in the region between about 9o and 7°W, where the temperature rose from 0° to more than Z0 C. Another horizontal temperature gradient was found between 0° and Z0 E, where it rose from 4° to 6°C.

During z9. May to 5· June the temperatures at roo metres were above 6°C off the west coast, and in the remaining part of the shelf area north of Iceland they were similar to what was found three weeks earlier. In the area between Iceland and Jan Mayen the temperature was even slightly lower than during the first survey, indicating increasing south-<casterly influx of Polar water.

In the whole region covered by the East Icelandic Current, between Jan Mayen and the Iceland-Faroe Ridge, both Soviet and Icelandic investigations showed negative temperature anomalies. Compared with the r950-r96o mean, 1967 must be rated as

exceptionally cold also at roo metres. In the area between Langanes and Jan Mayen the conditions were similar to what they were in 1965 and 1966. According to Soviet investigations the o-zoo metre layer of the East Icelandic Current had a tempera­ture anomaly of -0.7° between Langanes and Jan Mayen, but -- 1.7° in the section along 63°N.

A vertical section north of Siglunes showed exceptionally low temperatures in the uppermost 300 meters and only very slight influence of Atlantic water coming from the west. In early June the temperature in the o-zoo m layer of this section was about 3-4 ° below normal, and about Z0 below normal between zoo and 300m.

In the north-eastern part of the Icelandic shelf area, the Atlantic influence was also very weak, as was shown by the temperature distribution in the section Langanes-Jan Mayen: the mean for the 0-50 m layer being about 3.5° below normal and the mean for the o-zoo m layer being z--z.5° below normal.

In June 1967 the temperature distribution at zo m in the south-eastern Norwegian Sea was similar to what it was at the same time in 1965. On the whole, however, the waters of the Atlantic Current entering the Norwegian Sea were colder than observed during the previous cold years.

In the section along 63°oo'N the mean tempera­ture of the o-zoo m layer in the Norwegian Current was o.8°C below normal and 0.5° below that of the previous year.

In the eastern branch of the Norwegian Current the o-zoo m layer had lower temperatures than normal and also lower than in 1966, the anomalies ranging from - O.Z 0 to - o.6°

In the mixed waters of the central part of the Norwegian Sea the temperatures were about 0.3° below normal.

In contrast, the waters of the western branch of the Norwegian Current, as judged by the tempera­tures in the section along 65 o 45 'N, were warmer than normal. In the o-zoo m layer they had a positive anomaly of 0.3°, whereas between zoo and 500 metres the positive anomaly rose to I.O-I.Z 0

•

In the near-surface layer, however, at 0-50 m, the negative anomalies were still predominant, the mean being o.8° below normal and 0-4° below that of last year.

Since the surface temperatures in the waters of the Norwegian Current as a whole were below normal in June 1967, the warming up by the sun's radiation must have been relatively weak.

<...-.1 200 150 fQO so oo so jQO

JAN MAYEN~ .•

72°

71°

70° I

6 6 6 B 86688 j

68°

,1i/ ~~~ I I(\ J I II <S I I ~

~ 67° '-0

I I

81 66°

~ ICE LIMIT I

~II/A I ~,.Jj . ''----

~\\"I~· ~~ l"'"

67

ICELAND 65°

<B >B

64° )-;.f-.--

63t TRANSPARENCY MEASUREMENTS

SECCHI DISC R"ADINGS IN m JUNE 1967.

I 62oL~~ .. ~ , F~RO~~J_\)W ~% 2T .. ~ .... ~ ·

25° zoo 15° 10° 5° ' ' ' ' U" 50 10° I > "=' "='

Figure 173· Secchi disc transparency (in metres) zg. May~·12. June 1967. ~

= ~ ~·

-210-

Summary and conclusions

The most outstanding hydrographical features in the Iceland Sea and the Norwegian Sea in June 1967 may be summarized as follows:

(1) The extension of drift-ice along the north coast of Iceland in May and early June 1967 was greater than in any other year since 1918, with the exception of 1965 and possibly 1949.

(2) In early June the temperature in the upper layers west of Iceland was slightly below normal.

(3) In the shelf area north of Iceland the tempe­ratures in May and early June in the uppermost 300 meters were 2-5 ° below normal. Thus the spring of 1967 probably nltes as the coldest during the last 40 years. The extremely low temperatures found at all levels are the result of a) abnormally great distribution of ice in the area, b) exceptionally weak influx of Atlantic water from the west and c) low air temperatures and a slow warming up of the surface layers by the sun.

(4) In the waters of the East Icelandic Current between Iceland and Jan Mayen and east of Iceland temperature anomalies ranged between -0.7 and - 1.7°. In this area the hydrographic conditions resembled those of the previous cold years.

(5) The temperatures of the waters of the eastern branch of the Norwegian Current were 0.5-1.0° below normal and also lower than in 1966. However, in the intermediate waters (200-500 m) of the western branch of the Norwegian Current positive anomalies (r.0-1.2°) predominated.

(6) In view of the very low surface temperatures and heat content of the Norwegian Sea as a whole, 1967 may be classified as belonging to the group of recent very cold years.

Plankton Phytoplankton

Towards the end of May a relatively high density of phytoplankton was observed on the shelf to the west of Iceland. Large phytoplankton concentra­tions were observed during both Icelandic surveys in the area north of Iceland to the ice limit. As approximately three weeks elapsed between obser­vations, the high figures obtained during the latter cruise are thought to represent a second phytoplank­ton bloom. The ice appears to have drifted back into part of the area and retreated north again during the intervening period thus causing a prolonged activity in this region.

The Soviet scientists registered a marked development of phytoplankton on the sections

Jan Mayen - Langanes (the cold East-Icelandic and mixed waters), on the Faroe-Shetland Ridge, in the Faroe-Shetland Channel and in the western part of the section along 63°0o'N (west of 2°30'E).

Less intense blooming was observed on the section along 69°2o'N, and on the whole the same is true for the eastern half of the sections along 67°2o'N and 65°40'N.

The phytoplankton distribution in the cold East Icelandic and mixed waters resembled that of previous years.

In the northern sections green blooming prevailed while on the sounthern ones brown blooming dominated.

Phytoplankton was represented chiefly by Phaeo­cystis pouchetii, Chaetoceros spp., Ceratium spp., Thallasiothrix spp., Nitzschia spp., and Rhizosolenia spp. occurred in slight quantities.

In 1967, water transparency over the whole area was in general lower than in the previous year (Figure 173). Low transparencies were observed in the zone of the greatest phytoplankton develop­ment (the section Jan Mayen-Langanes). Maximum water transparencies (up to 26 m) were observed in the south-western part of the Norwegian Sea (the section at 64 o 40'N), and beyond the edge of the continental shelf west of Iceland.

Zooplankton

At the end of May and during the first half of June the Icelandic expedition observed great volumes of Calanus finmarchicus (I-III) in the area west of Iceland together with Euphausiidae, Cirripedia, eggs and nauplii.

In the waters north of Iceland the volume of zooplankton was very small, but began increasing to the east of the ice limit and to the east and north-east of Iceland. In these areas the same species of zooplankton were observed as those found by the Soviet expedition.

According to this year's Soviet research in the section Jan Mayen-Langanes the population of Calanus finmarchicus consisted of adult copepodite stages (V, females) and nauplii. Calanoid eggs were found only on the northernmost stations. Such an age composition of the population of C. finmarchicus indicates a later oncoming of spring in 1967 than in 1966 when specimens of young copepodite stages were prevailing in the population.

Reproduction of C. finmarchicus in the boundary area between the East Icelandic Current and the North Icelandic Irminger Current took place later than last year. Specimens of the new spring genera-

<::'Y' 20° 15° 10° 5° 0° 5° ? 2 ~

JAN MAY~ 7,'

7C'

20 30 2030

& 69'

68' ~ 20 1 30\ 1 20'\' ICE LIMIT ,.----..10 \\')

~~~ 5

67°.

68'

67'

66' 66'

<5

65' ICELAND 65'

'"'"'"'ro 'x ___ j __ /

I IN THE 0-50 N VOLUME ml/21 m>

~ HENSEN N m LAYER

62' JUNE 196:T N23i31

25' 15' 10' ' o'f>r:¥f ~ 0 <U

5' o· ,\j?~"' ' I

5'

64'

63' t/ 10

64'

63"

Figure 174. Zooplankton volume (mlfzr m3) in o-so metres, 29. May-12. June 1967.

tv H H

~ & ~·

JAN MAYEN~

5 -10/VI

1-5/VI

ICELAND

6zoL~-~-::z~so~-~-- 2oo Herring concentrations, ro. May-rz. June rg6]. Figure I75·

--- ----

IQO 720

68°

67°

66°

N ..... N

I

·----~-- ------

-2r3- Appendix

tion of Calanus dominated in rg66 but in rg67 the adult copepodite stages prevailed.

The quantitative analysis of the population of C. finmarchicus in the section along 69°2o'N showed that over the greater part of the section adult stages of the overwintering generation and small young stages of the new spring generation prevailed. Red Calanus was partially registered. It dominated only at the extreme eastern stations of the section.

In the East-Icelandic and mixed waters C. hyperbore'VtS, C. finmarchicus, Metridia longa, Pse~t­docalanus elongatus and Themisto libellula dominat­ed. CollozMtm was practically absent in these waters with the exception of one station. The thermophile Collozoum was observed on all the sections from sow to the east.

In the Atlantic waters C. finmarchicus, PsMtdo­calanus elongatus, Oithona similis and Eukronia haemata prevailed. Other species frequently obser­ved were Themisto abyssorum, Microcalanus spp., and Oncaea borealis.

Aglantha digitale, Oikoplettra spp., Acanthometron and Tomopteris spp. were observed in slight quantities only.

A peculiar feature of this year was a smaller quantity of the thermophile species Collozoum, Limacina retroversa and M etridia lucens than in rg66.

As last year, the lowest biomasses were located in the areas north and east of Iceland. Areas with high biomasses were situated in the east and central parts of theN orwegian Sea (Figure r7 4). Such high biomasses were chiefly due to the development of C. finmarchicus in the more northerly and C. finmarchicus and Collozoum in the more southerly regrons.

In the East-Icelandic and mixed waters the main constituents of the biomass were C. hyperboreus and phytoplankton. In the southern Norwegian sea the observed biomasses were lower than in the two previous years.

Herring

As in previous years, no herring concentrations were located in the areas west and north of Iceland.

In May the main herring concentrations were located by both Soviet and Icelandic vessels in the area between 65ooo'N and 67°30'N from r 0 E to 2°W (Figure r75). The herring shoals gradually moved northwards. The water temperatures at 20m in this region were between 7° and soc. Scattered

herring shoals were encountered west of Z0 W but

these were insignificant in number. In the daytime the herring was distributed at

depths between roo and 300m but by late afternoon and evening they rose to a depth of ro-40 m where they remained for periods of r-3 hours before going down again. The shoals were, however, quite stable at these shallow depths and Faroese purse-seiners operating in the area made good catches during the latter half of May.

During the first half of June herring shoals were mainly recorded in two areas, as shown in Figure r75.

r) Between 67o3o'N and 70°25'N from 0°25'W to 5ooo'W. During this period the herring gradually changed its direction of movement to a north­westerly course but otherwise showed a similar pattern of behaviour as before. As the month of June advanced, however, the shoals had a tendency to become more unstable during the night. Moreo­ver, after ro. June the shoals in the extreme north of the area surveyed generally split into smaller ones. Both of these factors Tesulted in a decline in the efficiency of the purse-seiners working in the area.

2) In early June dense herring shoals were also recorded in the section at 64°4o'N between 05°05'W and 05°3o'W, as well as on the track from position 64o4o'N 05°oo'W to 65°ro'N roooo'W in the area between 05°o7'W and o5°2o'W. The herring concen­trations in this area had a vertical extension of rS-57 m and were recorded at depths of r5-roo m.

Besides this some small scattered shoals of herring were found near 65°r6'N II0 30'W at a depth of r6-23 m, in the section along 65o45'N near 04 °r4'W at 20-30 m depth and in the section extending north-east from the Faroes between 05°20'W and 04°42'W at depths of r2-42 m.

As in the last three years no herring concentrations were recorded in the south-eastern part of the Greenland Sea along the sections at 72o5o'N and 74°30'N. Neither were any herring shoals located along the sections at 7roro'N nor along 69°20'N east of 2°W in the Norwegian Sea.

Samples taken from commercial catches consisted of specimens with a size range of 29-3S em, the great majority (65-75%) being 33-34 em in length.

Conclusions

On the basis of the distribution of herring concentrations and oceanographic conditions as observed in May and the first half of June rg67 the following was concluded:

-214-

r) On the whole the herring had a much more easterly distribution than in previous years. During the month of May no significant concentra­tions were recorded west of 2°0o'W as compared with o8°oo'W in rg66 and I0°oo'W in rg65. The shoals migrated north- and north-westwards and by mid-June they were chiefly located in the area from 68°30'N to 69°45'N between OI

0 30'W and o6°oo'W. Thus at all times they were situated con­siderably farther to the east than in previous years.

2) While it seems unreasonable to attribute a displacement of this magnitude to direct influence of the low water temperatures on the herring, it is likely that deteriorating feeding conditions farther to the west, caused by the strong influence of the East Icelandic Current, discouraged migra­tion in that direction.

3) Since the situation in 1967 resembles physically and biologically that of the recent cold years it was

estimated that during the first half of the summer rg67 the herring would be distributed mainly over an area south and south-east of Jan Mayen with a considerable part of the stock migrating to feeding grounds west of Bear Island. A more westerly distribution was not expected until late August or September i. e. not until migrations to the overwintering grounds east of Iceland begin.

4) No migration of Icelandic spring spawners to the area north-west and north of Iceland was observed. In view of the low level of the stock as well as the unfavourable conditions in north Icelandic Waters, no herring concentrations of commercial importance were expected to be found there this year.

Edited by: H. VILHJALMSSON and U. STEFANSSON

Hafranns6knastofnunin, Skulagata 4, Reykjavik, Iceland