REFmEYCT C O W Do N o t Remove from the Library

U. S. Fish and Wi ld l i fe Service Nntinnnl Wctlnndq RP- C ~ n w r

FWSlOBS-82111.22 700 Cajun Dome Boulevard TR EL-82.4 July 1984 Lafayette, Louisiana 70506

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (North Atlantic)

ATLANTIC. SALMON

Fish and Wildlife Service Coastal Ecology Group

Watetwavs Ex~eriment Station U.S. Department of the Interior U.S. Army Corps of Engineers

FWS/OBS-82/11.22 TR EL-82-4 J u l y 1984

Species P r o f i l e s : L i f e H i s t o r i e s and Envi ronmental Requi rements o f Coastal F i s h and Inve r teb ra tes

(North A t l a n t i c )

ATLANTIC SALMON

Dwi ght S. Dani e Joan ti. T r i a l

and Jon G. Stanley

Mai ne Cooperat i ve F ishery Research U n i t 313 Murray H a l l

U n i v e r s i t y o f Maine Orono, ME 04469

P r o j e c t Manager La r r y Shanks

P r o j e c t O f f i c e r Norman Benson

Na t i ona l Coastal Ecosystems Team U.S. F i s h and W i l d l i f e Serv ice

1010 Gause Boulevard S l i d e l l , LA 70458

Th is study was performed f o r Coastal Ecology Group

U.S. Army Corps o f Engineers Waterways Experiment S t a t i o n

Vicksburg, MS 39180

and

Nat iona l Coastal Ecosystems Team D i v i s i o n o f B i o l o g i c a l Serv ices

Research and Development F i s h and W i l d l i f e Serv ice

U.S. Department o f t h e I n t e r i o r Washington, DC 20240

Th is s e r i e s should be referenced as f o l l ows :

U.S. F i sh and W i l d l i f e Service. 1983-19-. Species p r o f i l e s : l i f e h i s t o r i e s and environmental requi rements o f coas ta l f i shes and i nve r teb ra tes . U.S. F i sh Wi ld l . Serv. FWS/OBS-82/11. U.S. Amy Corps of Engineers, TR EL-82-4.

Th i s p r o f il e shoul d be c i ted as f o l 1 ows :

Danie, D. S., J. G. T r i a l , and J. C. Stan1 ey. 1984. Species p r o f i l e s : 1 i f e h i s t o r i e s and environmental requi rements o f coas ta l f i s h and i n v e r t e b r a t e s (Yo r th At1 a n t i c ) -- At1 a n t i c salmon. !I.$. F i sh W i l d l . Serv. FWS/OBS-82/11.22. U.S. Army Corps o f Engineers, TR EL-82-4. 19 pp.

PREFACE

This species p r o f i l e i s one o f a se r i es on coas ta l aqua t i c organisms, p r i n c i p a l l y f i s h , o f spor t , commerci a1 , o r eco log i ca l importance. The p r o f i l e s a re designed t o p rov ide coas ta l manayers, engineers, and b i o l o g i s t s w i t h a b r i e f co~nprel iensive sketch o f t he b i 01 og i c a l c h a r a c t e r i s t i c s and environmental requ i re - rnents o f the species and t o descr ibe how popu la t ions o f the species may be expected t o r e a c t t o environmental changes caused by coas ta l development. Each p r o f i l e has sec t ions on taxonomy, 1 i f e h i s t o r y , ecol og ica l r o l e , environmental requ i ranents , and economic importance, i f appl i c a b l e. A t h r e e - r i n g b inde r i s used f o r t h i s se r i es so t h a t new p r o f i l e s can be added as they are prepared. Th is p r o j e c t i s j o i n t l y planned and f inanced by t he U.S. Army Corps o f Engineers and the U.S. F ish and W i l d l i f e Service.

Suggestions o r quest ions regard ing t h i s r e p o r t should be d i r e c t e d t o :

I n fo rma t i on Trans fer S p e c i a l i s t Nat ional Coastal Ecosys tems Team U.S. F ish and W i l d l i f e Serv ice NASA-S l i d e l 1 Computer Compl ex 1010 Gause Boul evard S l i d e l 1 , LA 70458

U. S. Army Engineer Waterways Experiment S t a t i o n A t ten t i on : WESER Post O f f i c e Box 631 Vicksburg, MS 39180

iii

CONTENTS

Page

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CONVERSIONTABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ACKNOWLEDGMENTS

NOMENCLATURE/TAXONOMY/RANGE . . . MORPHOLOGY /IDENTIFICATION AIDS . REASON FOR INCLUSION I N SERIES . LIFE HISTORY . . . . . . . . . .

Spawning . . . . . . . . . . . Fecund i ty and Eggs . . . . . . Larvae and Juven i les . . . . . Smolts and Sea Migran ts . . . . Sea L i f e and Homeward M i g r a t i o n

GROWTH CHARACTERISTICS . . . . . COMMERCIAL/SPORT FISHERIES . . . . . . . . . . . . ECOLOGICAL ROLE . . . . . . . . . . Food Hab i ts . . . . . . . . . . . Preda t i on ENVIRONMENTAL REQUIREMENTS . . .

. . . . . . . . . . Temperature . . . . . . . D i sso l ved Oxygen pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D e p t h a n d v e l o c i t y . . . . . . . . . . . . . . . . . . . . . . . . . . . L i g h t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S a l i n i t y . . . . . . . . . . . . . . . . . . . . . Subst ra te . Sediment. T u r b i d i t y

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . LITERATURE CITED

CONVERSION FACTORS

M e t r i c t o U.S. Customary

m i l 1 imeters (m) cent imeters (cm) meters (m) k i 1 ometers ( km)

square n e t e r s (m2) square k i l ome te rs (km2) hec ta res (ha)

l i t e r s ( 1 ) cub i c meters (m3) cub i c meters (m3)

m i l l i g r a m s (mg) grams ( g ) k i l og rams (kg) m e t r i c tons ( t ) m e t r i c t ons k i 1 ocal o r i es ( kcal )

Cel s i us degrees

& -- To Obta in

inches inches f ee t mi 1 es

10.76 square f e e t 0.3861 square m i l e s 2.47 1 acres

gal 1 ons c u b i c f e e t ac re - f ee t

0.00003527 ounces 0.03527 ounces 2.205 pounds

2205.0 pounds 1.102 s h o r t t ons 3.968 B r i t i s h thermal u n i t s

1.8(C0) + 32 Fahrenhe i t degrees

U.S. Customary t o M e t r i c

inches 25.40 inches 2.54 f e e t ( f t ) 0.3048 fa thoms 1.829 m i l e s (mi ) 1.609 n a u t i c a l m i l e s (nmi) 1.852

square f e e t ( f t 2 ) acres 2 square m i l e s (mi )

ga l l ons ( gal ) cub i c f e e t ( f t 3 ) ac re - f ee t

ounces (oz) 28.35 pounds ( 1 b) 0.4536 s h o r t t o n s ( t o n ) 0.9072 B r i t i s h thermal u n i t (BTU) 0.2520

m i 11 imeters cen t imeters meters n e t e r s k i lometers k i 1 one ters

square meters hectares square k i l ome te rs

1 i t e r s c u b i c meters cub i c meters

grams k i 1 ograms m e t r i c tons k i l o c a l o r i e s

Fahrenhei t degrees 0.5556(F0 - 32) Ce ls ius degrees

ACKNOWLEDGMENTS

We thank Kenneth F. Be1 and, Maine At1 a n t i c Salmon Commission, Macclias; Edward T. Raum, Maine A t l a n t i c Salmon Commission, Rangor; and A l e x i s E. Knight , U.S. F ish and W i l d l i f e Service, Laconia, New Hampshire, f o r rev iew o f t h e manu- s c r i p t and f o r suggestions o f a d d i t i o n a l m a t e r i a l f o r i n c l u s i o n i n t h e t e x t .

F i g u r e 1. A d u l t A t l a n t i c salmon.

ATLANTIC SALMON

NOMENCLATURE /TAXONOMY /RANGE

S c i e n t i f i c name . . . . . .Salmo -- s a l a r Common name . . . . . A t l a n t i c salmon O the r common names . . . . Ouananiche,

Kennebec salmon, l and locked salmon, Sebago salmon. French common names: Saumon a t l a n t i c , saumon d 'eau douce, b r a t a n

L i f e s t age names . . . . . . . . P a r r ( f r e s h w a t e r j u v e n i l e ) , smo l t ( j u v e - n i l e m i g r a t i n g t o sea), g r i l s e ( F i g - u r e 1) ( a d u l t r e t u r n i n g t o f r e s h - wa te r t o spawn a f t e r 1 y e a r a t sea), b r i g h t salmon ( a d u l t r e t u r n i n g a f t e r 2 o r more y e a r s ) , k e l t o r b l ack s a l - mon ( a postspawning o r spen t a d u l t ) ( A l l e n and R i t t e r 1977).

C lass . . . . . . . . . . O s t e i ch thyes Order . . . . . . . . . . Clupe i fo rmes Fami l y . . . . . . . . . . Salmoni dae

Geographic range: The A t 1 a n t i c salmon i s ind igenous t o t h e N o r t h A t l a n - t i c Ocean b a s i n ( F i g u r e 2). T h e i r range i n t h e eas te rn A t l a n t i c extends from t h e A r c t i c Ocean t o Po r t uga l , i n c l u d i n g t h e Ba1 t i c Sea. I n t h e wes te rn At-

l a n t i c , t h e y range from I ce l and , sou thern Green1 and and Ungava Bay, Quebec, t o t h e Connec t i cu t R i v e r ( S c o t t and Crossman 1973).

Anadromous A t l a n t i c salmon once i n h a b i t e d No r t h Ameri can streams a l ong t h e A t l a n t i c coast , p e r h a l s as f a r sou th as t h e Hudson R i ve r , New York , and t h e S t . Lawrence R i v e r t r i b u t a r i e s i n c l u d i n g Lake Champlain and Lake On ta r i o . Anadromous popu l a t i ons a r e now r e s t r i c t e d t o r i v e r s f rom Connec- t i c u t n o r t h w a r d t o Ungava Bay, Quebec, and i n L a b r a d o r as f a r n o r t h as t h e F r a s e r R i v e r , Na in Bay. I n Greenland t hey i n h a b i t t h e K a p i s i y d l i t R i v e r a t t h e head of Godthab F j o r d nor thward f r o m Kap F a r v e l t o Umanak on t h e west coas t and t o Angmagssal ik on t h e e a s t c o a s t (McCr i mmon and Go ts 1979). A t tempts t o r e s t o r e anadromous p o p u l a t i o n s t o t h e Connec t i cu t , M e r r i mack, Penob- s c o t Union and Pawcatuck R i vers i n New England, p r i m a r i l y by s tock ing hatchery-rai sed pa r r

and smol ts , have been p a r t i a l l y success fu l . The range o f land- l ocked popu la t i ons i n Maine, New Brunswick, and Nova S c o t i a has been e x t e n d e d . I n Ma ine , f o r example, l and locked A t l a n t i c salmon endemic t o o n l y f o u r watersheds, have been t r a n s - p l a n t e d t o hundreds o f lakes .

F i g u r e 2. Worldwide range of A t l a n t i c salmon and mi g r a t o r y r ou tes (Net boy 1974).

MORPHOLOGY/IDENTIFICATION AIDS

Body e l ongate, somewhat compres- sed l a t e r a l l y , g rea tes t body dep,th a t dorsa l f i n o r i g i n o r s l i g h t l y p o s t e r - i o r t o d o r s a l f i n , 18% t o 22% o f t h e t o t a l l eng th . Head l e n g t h about equal t o o r s l i g h t l y g r e a t e r t h a n body depth, 20% t o 23% o f t h e t o t a l l eng th , b u t most v a r i a b l e d u r i ng m o d i f i c a t i o n s o f head s t r u c t u r e d u r i n g spawning. Eye moderate, 14% t o 19% o f head l e n g t h ( v a r i a b l e depending on growth r a t e ) ; snout rounded, i t s l e n g t h g r e a t e r t h a n eye d i a m e t e r f o r f i s h over 305 mm long; mouth t e r m i n a l , l a rge , m a x i l l a r y ex tend ing p o s t e r i o r l y

t o p o s t e r i o r marg in o f pup i 1 when 152 mm long, and seldom t o p o s t e r i o r mar- g i n o f eye e x c e p t on m a t u r e ma les , w h i c h d e v e l o p a p r o n o u n c e d hook o r k y p e on l o w e r jaw. W e l l - d e v e l o p e d t e e t h on upper and lower jaws (p re - m a x i l l a r y , m a x i l l a r y , den ta r y ) ; few t e e t h i n a s i n g l e row on s h a f t o f vo- mer and p a l a t i n e s , on tongue i n two rows; n o h y o i d t e e t h . T o t a l g i l l r a k e r count, 15-20. B ranch ios tega l rays u s u a l l y 11-12 ( r a r e l y 10 o r 13) . F ins : ad ipose p resen t p o s t e r i o r t o do rsa l , do r sa l , 10-12; ana l , 8-11; v e n t r a l , 9-10, w i t h a d i s t i n c t p e l v i c a x i l l a r y process; p e c t o r a l , 14-15. Caudal w i t h sha l l ow f o r k . Scales cyc- l o i d , 109-121 i n l a t e r a l l i n e , 10-13 f rom p o s t e r i o r edge o f ad ipose base t o l a t e r a l l i n e ; l a t e r a l l i n e decurved a n t e r i o r l y , s t r a i g h t p o s t e r i o r l y . Py- l o r i c caeca, 40-74. Vertebrae, 58-61 ( S c o t t and Crossman 1973).

P igmenta t ion : C o l o r v a r i e s w i t h age, environment, and l i f e stage. Smal l p a r r have 8 t o 11 pigmented bars a l t e r n a t i n g w i t h a s i n g l e row o f r ed spo ts a l o n g t h e l a t e r a l l i n e on each s i de . M i g r a t i n g smo l ts and a d u l t s a t sea a r e s i l v e r y on t h e s i des and b e l - l y , b u t t h e a d u l t s have brown, green, o r b l u e c o l o r a t i o n on t h e back and numerous b l ack spo ts , usua l l y x- shaped, s c a t t e r e d a l o n g t h e body, more numerous above t h e l a t e r a l l i n e . A few of t hese spo ts a r e a l s o l o c a t e d on t h e head. Landlocked a d u l t s have more numerous and l a r g e r spo ts t h a n anad- romous salmon ( c a l l e d b r i y h t salmon when f i r s t e n t e r i n g f r e s h wa te r ) . A t spawning, p e c t o r a l and caudal f i n s be- come b l a c k i s h and bo th sexes t a k e on a bronze t o p u r p l e c o l o r a t i o n and may a c q u i r e r edd i sh spo ts on t h e head and body. A f t e r spawning, t h e s u r v i v i n y a d u l t s ( k e l t s ) a r e dark co lo red .

D i s t i n c t i o n s : Da rk s p o t s on a l i g h t background d i s t i n g u i s h A t l a n t i c salmon from l i g h t s p o t t e d chars (brook t r o u t and A r c t i c c h a r ) , w h i c h h a v e l i g h t spo ts on a dark background (Leim and S c o t t 1966). A t l a n t i c salmon a l s o

have l a r g e r scales, and have t e e t h on t h e s h a f t o f t h e vomer. They may be d i s t i n g u i s h e d f rom rainbow t r o u t by t h e absence o f s e r i a l rows o f b lack s p o t s on cauda l f i n and f r o m brown t r o u t by t h e s h o r t e r m a x i l l a r y , nar- r o w e r pedunc le , l a c k o f r e d on t h e adipose, and l a r g e r scales. Species o f i n t roduced P a c i f i c salmon a re d i s - t i n g u i s h e d by t h e l a r g e r number o f anal f i n rays, 12-19, whereas t h e A t - l a n t i c salmon has 8-11.

REASON FOR INCLUSION I N SERIES

The anadromous A t l a n t i c salmon has h igh s o c i a l and economic value be- cause o f i t s myst ique as a s p o r t f i s h and t h e h i g h q u a l i t y o f i t s f l e s h . Once r e l a t i v e l y widespread, t h i s species i s now r e s t r i c t e d t o severa l r i v e r s o f New England (F igu re 3) , where dams, p o l l u t i o n , and f i s h i n g have excessi ve l y reduced rep roduc t i ve p o t e n t i a1 . Dur ing t h e egg, l a r v a l , and p a r r stages, t h i s salmon i s especi a1 l y vu lnerab le t o t h e conse- quences o f coas ta l development pro- j e c t s ; t he re fo re know1 edge o f t he 1 i f e h i s t o r y and envi ronmental requ i rements o f t h i s species i s e s s e n t i a l f o r dec i - s ions t h a t w i l l assure i t s con t inued ex is tence and enhancement.

LIFE HISTORY

Spawning

A t l a n t i c salmon spawn d u r i n g t h e p e r i o d o f m i d-October t o mi d-November i n g rave l areas o f f reshwater streams (B i gelow and Schroeder 1953). Spawn- i n g s i t e s a r e l o c a t e d a t t h e down- stream end of t h e r i f f l e s w i t h water p e r c o l a t i o n through t h e grave l o r a t upwel l i ngs of groundwater. Redds a re cons t ruc ted by t h e female u s i n g he r cauda l f i n i n a f a n n i n g m o t i o n . A redd cons i s t s o f severa l depressions o r p i t s excavated f rom t h e st ream bottom (Leim and Sco t t 1966). Water temperatures d u r i n g spawning u s u a l l y

range between 4.4" and 5.6"C (DeCola 1970). The male a l i g n s h imse l f w i t h t h e female and f e r t i l i z e s t h e eggs as they a re depos i ted i n t o each p i t (Jor- dan and Beland 1981). Some male p a r r become s e x u a l l y ma tu re and t a k e an a c t i v e p a r t i n f e r t i l i z i n g eggs. The female then covers t h e eggs w i t h about 10-25 cm o f t h e grave l excavated w h i l e bu i l d i ng another p i t j u s t upstream. Th is process i s repeated u n t i l spawn- i n g i s completed.

Fecundi ty and Eggs

Fecund i ty depends l a r g e l y on body s i ze . Fo r example, anadromous A t l an - t i c salmon produce more eggs than t h e landlocked fo rm because i t s females a re l a r g e r . A r u l e of thumb i s t h a t anadromous females produce 1,5UU t o 1,800 eggs/kg. Rounsefel 1 (1957) re - po r ted t h a t females weighing about 5 k g produced about 1,800 eggs/kg. Pope e t a1 . (1961) used t h e f o l l ow i ny f o r - mula ( m o d i f i e d by Baum and M e i s t e r 1971) t o es t imate t h e number o f eggs produced by f i s h w i t h d i f f e r e n t body lengths :

Eggs a r e s p h e r i c a l , 5-7 mm i n diameter, and p a l e orange o r amber. The eggs a r e s l i g h t l y adhesive i n i t i - a l l y and s t i c k t o t h e subs t ra te i n t h e p i t u n t i 1 they are covered w i t h grav- e l . The i ncuba t i on p e r i o d va r i es w i t h s t ream temperature. I n Maine t h e eggs ha tch i n A p r i l o r e a r l y May a f t e r 175 t o 195 days under normal w i n t e r condi- t i o n s (Jordan and Beland 1981). An i ncuba t i on o f 110 days a t 3.g°C c i t e d by Leim and S c o t t (1966) probably i s f o r hatchery eggs.

Egg s i z e i s i n f l u e n c e d by t h e age, s i ze , and p h y s i o l o g i c a l c o n d i t i o n o f t h e female. Egg s i z e i s a l s o de- t e r m i n e d by t h e l e n g t h o f t i m e t h e female l i v e s i n t h e ocean, t h e t ime of spawning, and t h e p o s i t i o n o f t h e egg i n t h e ovar ies . Average egg weight i s 164 mg. The r a t e o f embryo develop-

NARRAQUAGUS R.

UNK STREAM

A TL A N TIC OCEAN

KILOMETERS

Figure 3. R i ve rs suppor t ing A t l a n t i c salmon i n t he Nor th A t l a n t i c Region.

ment i s n o t a f f e c t e d by egg s i ze , b u t Chadwick (1982) a l s o r e l a t e d y e a r embryo s i z e i s l a r g e r i n l a r g e r eggs c l a s s s t r e n g t h o f smol ts t o egg and t h e r e s u l t i n g l a r v a e have h i g h e r d e p o s i t i o n i n t h r e e New Brunswick s u r v i v a l (Kazakov 1981 ) . Egg s i z e streams w i t h t h e equat ion: increases w i t h f e c u n d i t y and s i z e o f females (Pope e t a l . 1961). I n Y = 1.29 I n X - 8.014

Larvae and Juven i l es

A f t e r hatching, t h e e leu the ro - embryos ( a l e v i n o r yo1 k-sac 1 a rvae) , about 15 mm long, remain b u r i e d i n t h e g rave l absorb ing t h e i r y o l k sacs f o r nourishment f o r about 6 weeks (B i gelow and Schroeder 1953). When t h e y o l k sacs a r e f u l l y absorbed, t h e 25-mm f r y begin t o fo rage f o r f ood i n t h e sub- s t r a t e , and t hen emerge from t h e sub- s t r a t e . I n a Maine stream, between May 12 and 28 emergence was a lways a t n i g h t (Gustafson-Marjanen 1982). I n New Brunswi ck streams, peak emergence and d i spe rsa l were between June 12 and 23 (Randal 1 1982). A f t e r emergence, f r y d isperse and immediate ly e s t a b l i s h t e r r i t o r i e s . The compe t i t i on f o r t e r - r i t o r y may l i m i t t h e number o f f i s h i n t h e popu la t ion . The young salmoh' a r e a l s o d i sp laced downstream by wa te r f low. By l a t e summer p o p u l a t i o n den- s i t y o f \ p a r r i s u s u a l l y l e s s t h a n 50 /100 m2, b u t may be as much as 370/100 m2 i n New Brunswick (F ranc i s 1980).

O f t h e eggs deposi ted, o n l y about 5% r e s u l t i n p roduc t i on o f f r y . Mor- t a l i t y r a t e s a l s o a r e h i g h d u r i n g emergence and d i s p e r s i o n (Ottaway and C la rke 1981). Egg- to - f ry s u r v i v a l i n .

Newfoundland streams was i n f l u e n c e d by w i n t e r temperatures and change i n water l e v e l s descr ibed by Chadwick (1982) i n t h e equat ion:

where X = t h e lowest mean monthly tem- pe ra tu re (OC) and Y = t h e d i f f e r e n c e between t h e November mean d ischarge and t h e l o w e s t w i n t e r mean m o n t h l y d ischarge ( l / s e c ) . Egg- to -par r sur - v i v a l i n Cove Brook, Maine, was 10% (Mei s t e r 1962).

where X i s t h e number o f eggs ( thou- sands) and Y i s t h e number o f smol ts o f t h a t y e a r c l ass .

On reach ing a l e n g t h o f about 4U mm d u r i n g t h e f i r s t summer, young salmon a r e c a l l e d p a r r o r f i n g e r l i n g s . These j u v e n i l e salmon a re tound pre- dominate ly i n r i f f l e sec t i ons o f t h e stream. Young p a r r a r e more numerous i n r a p i d l y f l o w i n g water d u r i n g t h e day and e a r l y evening. A t n i g h t they r e s t on t h e bot tom i n t h e q u i e t e r wa- t e r s (Gibson 1966). O lder p a r r a re r e s i d e n t s o f t h e deeper poo ls i n streams. They defend t e r r i t o r i e s and a t t a c k o t h e r p a r r e n t e r i n g t h e defend- ed zone. Th i s p r a c t i c e a l l o c a t e s space and food t o ensure adequate growth and reduce p r e d a t i o n by o t h e r species (Gustafson-Marjanen 1982). P a r r f r e q u e n t l y move upstream o r downstream, perhaps as t h e r e s u l t o f aggress ive i n t e r a c t i o n s , and some p a r r may m ig ra te t o t r i b u t a r i e s p r e v i o u s l y unpopulated w i t h salmon. I n New Brunswi ck streams abundance i s u s u a l l y l e s s t h a n 15 /100 m 2 b u t i n a tew streams may be as high as 62/lUU m2 (F ranc i s 198U).

I n t h e f a l l , many male p a r r be- come sexual l y mature (precocious p a r r ) , ensu r i ng a m i x t u r e o f b reed ing s t o c k ( R e f s t i e e t a l . 1977 ) . P a r r remain i n t h e st ream u n t i 1 they a r e 125-150 mm leng th , which may t a k e up t o 2-3 years; they remain i n streams u n t i l t h e y a r e 180 mm l o n g and 4-8 years o l d i n t h e Ungava Bay r e g i o n o f Canada (Scha f fe r and t l s o n 1975). P a r r t h a t t a i l t o reach t h e c r i t i c a l l e n g t h by s p r i n g o r e a r l y summer i n any one y e a r do n o t t r a n s f o r m i n t o smol t s u n t i 1 t h e f o l l o w i n g spr ing , regard1 ess o f subsequent growth ( R e f s t i e e t a l . 1977). I f smol ts a r e

p reven ted f r o m seaward mi g r a t i on t hey aga in become p a r r and l o s e t h e i r ab i l- i t y t o s u r v i v e i n s a l t wa te r (Lund- q v i s t and F r i d b e r g 1982).

Smol ts and Sea M ig ran t s

The s m o l t i s t h e n e x t s t a g e i n t h e l i f e h i s t o r y o f t h e A t l a n t i c s a l - mon. I n Maine, about 80% o f t h e juve- n i l e s spend 2 y e a r s i n f r e s h w a t e r and 20% spend 3 yea rs . Acco rd i ng t o E l son (1975) 38% o f t h e p a r r i n t h e P o l e t t R i v e r , New Brunswick s u r v i v e d t o s m o l t i f i c a t i o n ( s u r v i v a l f r o m egg t o smo l t was 1.1%). Chadwick (1982) r e - p o r t e d 3.6% and 3.2% s u r v i v a l f rom egg t o smo l t i n two Newfoundland streams. M e i s t e r (1962) observed s u r v i v a l o f 5% f r o m f r y t o t h e smo l t i n Cove Brook, Mai ne. Symons (1979) ana lyzed egg- to- smo l t s u r v i v a l i n t h e M i ram ich i R i v e r , New Brunswick, and conc luded t h a t pe r - centage s u r v i v a l was i n v e r s e l y r e 1 a t e d t o t h e i n i t i a l number o f eggs depos- i t e d . Abso lu te numbers o f smo l t s p ro - duced, o f course, was h i g h e r i n streams r e c e i v i n g heavy egg deposi - t i o n , up t o a b o u t 300 eggs /100 m2, above which dens i ty -dependent m o r t a l - i t y compensated f o r increased numbers.

A f t e r t h e p a r r reach 125 t o 150 mm, t h e p a r r marks d isappear and d e p o s i t i o n o f guanine i n t h e s k i n c rea tes a s i 1 ve ry p i gmentat i on. The t a i l l eng thens and becomes more deep ly fo rked . Schoo l i ng behav io r rep1 aces t e r r i t o r i a l behav io r .

D u r i n g t h e s p r i n g , r i s e s i n wa te r l e v e l s due t o f r e s h e t s and w a t e r tem- p e r a t u r e i nc reases t4.5 t o t5.5"C i nduce downst ream smol t mi g r a t i on i n t h e Thurso R i v e r , S c o t l a n d ( A l l e n 1944). F r i e d e t a1 . (1978) r e p o r t e d t h a t a r i s e i n t e m p e r a t u r e t o 5°C t r i g g e r e d downstream m i g r a t i o n i n t h e Penobscot R i ver , Mai ne. Smol ts ex- p ressed f u l l m i g r a t o r y behav io r a t 9"-10°C. Peak movements were a t dawn and dusk. I n r i f f l e s and l o w - v e l o c i t y s t ream s e c t i o n s , smol t s o r i e n t down

stream; b u t i n s w i f t c u r r e n t s , they o r i e n t upstream. Mi g r a t i ng smol t s p a s s i v e l y d r i f t i n t h e main c u r r e n t o f t h e s t r eam away f r o m t h e s h o r e l i n e . On r e a c h i n g t h e es tua r y , smo l ts swim seaward d u r i n g t h e f l o o d t i d e . Im- poundments de lay o r r e s t r i c t mi gra- t i o n . F r i e d e t a l . (1978) t ound t h a t t h e e n t i r e j ou rney f r o m f r eshwa te r t o seawater t ook l e s s t h a n 48 h r ove r a d i s t a n c e o f 57 km. Smol t movement i n e s t u a r i e s i s dependent on t h e charac- t e r i s t i c s o f t h e e s t u a r y ( C l a r k e 1981) . S t o c k - s p e c i f i c sun compass o r i e n t a t i o n and t i d a l t r a n s p o r t a re r e s p o n s i b l e f o r smo l t movement o u t of an es tua r y . Movement i n deep wa te r i s para1 l e l t o c u r r e n t d i r e c t i o n , whi l e i n s h a l l o w wa te r sun compass o r i e n t a - ti on i s dominant ( C l a r k e 1981).

M o r t a l i t y due t o f r e e f a l l o v e r dams and n a t u r a l t a l l s i s l i k e l y i f t h e v e l o c i t y o f t h e f i s h exceeds 15 m/sec on impact w i t h t h e wate r . 1 h i s v e l o c i t y i s reached by smo l t s f a l l i n g a v e r t i c a l d i s t a n c e o f 27 m whe re d i s cka rge i s 0.4 m3/sec ( g r i l s e , 18 m, and k e l t s , 16 m) acco rd i ng t o Sweeney and R u t h e r f o r d (1981). Kuggles (198U) c i t e d t h a t smo l t s may w i t h s t a n d f r e e f a l l o f up t o 90 m.

Sea L i f e and Homeward M i g r a t i o n

Once i n t h e sea, A t l a n t i c salmon t r a v e l t o d i s t a n t f e e d i n g grounds (Netboy 1974). Most American and sou the rn European salmon mi g r a t e t o t h e Dav i s S t r a i t s between Labrador and Greenland ( F i g u r e 2 ) . Salmon f r o m t h e B a l t i c Sea and B r i t i s h I s l e s m i g r a t e t o t h e c o a s t o f t h e F a r o e I s l a n d s . The pos t smo l t s swim w i t h i n 3 m o f t h e ocean s u r f a c e a t a r a t e o f up t o 5U kmlday . One p o s s i b l e e x p l a n a t i o n f o r t h e i r n a v i g a t i n g such l o n g d i s t ances on t a r g e t i s t h e i r a b i l i t y t o d e t e c t changes i n e a r t h ' s e l ec t r omagne t i c g e o e l e c t r i c f i e l d s caused by t h e passage o f ocean c u r r e n t s t h rough t h e f i e l d s (S tasko e t a l . 1973).

A f t e r f e e d i n g a t sea, most A t l a n - t i c salmon r e t u r n t o t h e i r n a t a l s t ream t o spawn. Retu rn t o t h e home st ream may be a ided by d e t e c t i o n of o l f a c t o r y s t i m u l i f rom t h e s t ream t h a t i n i t i a t e behav io ra l response medi a ted by memory o f t h e home s t r e a m o d o r (Stasko e t a l . 1973). One hypo thes is f o r homeward n a v i g a t i o n i s t h a t d u r i n g t h e downstream mi g r a t i o n , smo l ts r e - lease a pheromone, c r e a t i n g an odor t r a i l s p e c i f i c f o r each p o p u l a t i o n f rom t h e home st ream t o t h e feed ing ground (F isknes and Doving 1982). A d u l t s may f o l l o w t h i s t r a i l t o r e t u r n t o t h e i r home stream.

Some a d u l t s ( g r i l s e ) r e t u r n t o t h e i r home s t ream a f t e r 1 y e a r a t sea, we igh ing 1-3 kg. Other a d u l t s ( b r i g h t salmon) r e t u r n a f t e r 2 o r 3 yea rs a t sea and weigh 3-9 kg, a l though much l a r g e r salmon have been recorded ( S c o t t and Crossman 1973). F i s h re - t u r n i ng t o Maine r i vers usua l l y have spent 2 yea rs a t sea (Beland e t a1 . 1982). A t sea t h e r e t u r n i n g a d u l t s swim a t r a t e s o f 0.08-0.68 m/sec (Smi th e t a1 . 1980).

Salmon congregate i n es tua r i es , bays, and r i v e r mouths b e f o r e mi g r a t - i ng upstream. M i g r a t i o n o f t e n co in - c i des w i t h f r e s h e t s o r o t h e r s u s t a i n e d inc reases i n wate r f l ow . F reshe ts a r e l e s s impo r tan t i n s p r i n g when wate r i s c o l d e r and t h e f l o w h i g h e r t h a n i n summer o r i n autumn (Brawn 1979). Salmon a r e r h e o t a c t i c and r e q u i r e a minimum s t ream v e l o c i t y o f 0.3-0.6 m/sec t o con t i nue movement ups t ream (Weaver 1963). Stasko e t a l . (1973) r e p o r t e d t h a t t h e r a t e o f p r o g r e s s upstream a g a i n s t an average f 1 ow v e l o c i t y o f 0.5 m/sec (35 km/day) was 4.3 km/day .

A d u l t salmon do n o t f eed i n f reshwater . As ma1 es mature, t h e i r heads become e longa te and t h e lower jaws become en la rged and hooked, form- i n g kypes. The females choose t h e spawning s i t e . I n c o n t r a s t t o P a c i f i c sa lmon, A t l a n t i c sa lmon do n o t d i e

a f t e r spawning. Many spent f i s h ( k e l t s ) s u r v i v e t h e w i n t e r i n f r e s h - wa te r and resume f e e d i ng. Apparen t l y m o r t a l i t y i s h i g h when t h e k e l t s e n t e r s a l t w a t e r . F i s h t h a t s u r v i v e and mi- g r a t e t o ocean ic f e e d i n g ground may become repeat spawners. Landlocked o r permanent ly f r eshwa te r salmon move f r o m t h e l a k e where t h e y f e e d t o a t r i b u t a r y s t ream where t hey spawn (Havey and Warner 197U).

GROWTH CHARACTERISTICS

Growth o f t h e A t l a n t i c salmon i s i n f 1 uenced by bo th gene t i c and env i r- onmen ta l f a c t o r s . Embryo s i z e and w e i g h t a r e d e t e r m i n e d by egg s i z e , which i s i n f l u e n c e d by t h e age, s i z e and p h y s i o l o g i c a l c o n d i t i o n o f t h e f e - male. Egg d iameter inc reases w i t h t h e age o f t h e f i s h and t h e l e n g t h of t i m e t h e f i s h spend i n ocean feed ing . Eyy s i z e a l s o v a r i e s i n i n d i v i d u a l f e - males, depending on t h e p o s i t i o n o f t h e eggs i n the ovary (Kazakov 1981).

Growth o f f r y and p a r r i n f r esh - wate r i s r e l a t i v e l y s low ( F i g u r e 4) . Salmon f r y o b t a i n maximum growth i n J u l y w i t h l i t t l e o r no growth a f t e r September (Randa l l and Paim 1982). It may t a k e 2-3 yea rs t o reach a 125-15U mm f o r k l e n g t h i n streams i n New tny - land, and 4-8 yea rs t o reach 18U mm i n Ungava Bay (Scha f f e r and E l son 1975). I n p r o d u c t i v e streams i n Maine 1+ p a r r may reach 150-175 mm, and 2+ p a r r o f 210 mm a r e o c c a s i o n a l l y seen.

Normal growth of p a r r occurs a t wa te r temperatures o f 15"-19°C (Kn i yh t and Greenwood 1981). Popu 1 a t i on d e n s i t y a l s o a f f e c t s growth and s u r v i v a l . Growth r a t e s a r e u s u a l l y g r e a t e r where d e n s i t i e s a r e l e a s t (Randal l 1982). From a s tudy on t h e Po l l e t t R i ve r , New Brunswick, E lson (1975) concluded t h a t average smol t p r o d u c t i o n i n an i d e a l salmon Stream shou ld no t exceed s i x smolts/100m2. T h i s c a l c u l a t i o n was based on a spawning i n t e n s i t y o f 170 eggs/100 m2

1 2 3

Year i n s t ream

F igu re 4. Growth o f A t l a n t i c salmon i n f r eshwa te r (McCrimmon 1954).

Chadwick (1982) warned t h a t t h e 2.4 eggs/m2 o f t e n c i t e d by management b i o l o g i s t s as optimum, may be an " a r b i t r a r y " f i g u r e and t h a t op t ima l egg d e p o s i t i o n cou 1 d be cons ide rab l y h i g h e r i n p r o d u c t i v e salmon r i v e r s . Symons (1979) ca l cu 1 a ted i d e a l numbers o f eggs needed i n streams o f d i f f e r i n g s u r v i v a l and a d u l t escapement, r ang ing from 23 eggs/m2 w i t h low esc9pement and h i g h s u r v i v a l t o 591 eggs/m under h i gh escapement and low s u r v i va l .

Lundqvi s t (1980) repo r ted t h a t pho toper i od a l s o i n f l u e n c e s growth. Sexua l l y immature male and female A t - l a n t i c salmon exposed t o a 1 i gh t : da rk (LO) r a t i o o f 20:4 grew f a s t e r t han those exposed t o a n a t u r a l pho tope r i od (nLD) o r LO 6:18. Sexua l l y ma tu r i ng male p a r r , however, grew s lower i n LD 20:4 t han d i d immature f i s h exposed t o t h e same photoper iod. When exposed t o LD 6:18 o r nLD, matur ing males r ipened e a r l i e r .

f i r s t t i m e l a t e r t han those t h a t smol- t i f y i n 2 o r 3 years ( R i t t e r 1975). The mean age o f t h e f e m a l e ' s f i r s t spawning v a r i e s over t h e salmon's range i n Nor th Ameri cay decreasi ny f r o m Maine t o Ungava ( S c h a f f e r and E l son 1975). The mean age o f f i r s t spawni ng among i nd i v i duals i s pos i t i v e l y c o r r e l a t e d w i t h growth r a t e s a t sea.

Growth i n t h e sea i s f a s t e r t han i n f r eshwa te r ( F i yures 4 and 5 ) . I n 1 y e a r a t sea a salmon may grow 1-3 k g and i n 2 y e a r s , 3-7 kg. Average weights o f anadromous salmon r e t u r n i n y t o va r i ous streams range t r om 2 ana 9 kg a l though weights have been recorded up t o 38 kg . C o m m e r c i a l l y c a u g h t salmon average 4.5 kg. A d u l t land- locked salmon average 1-2 k g ( S c o t t and Crossman 1973).

The growth o f A t l a n t i c salmon i s r e f l e c t e d i n sca les . When about 3U mm long, t h e f r y beg in t o grow scales, f i r s t a l ong t h e l a t e r a l l i n e a t t h e c e n t r a l and p o s t e r i o r p a r t s o f t h e body. D u r i n g r a p i d growth, broad bands fo rm on t h e sca le , s i m i l a r t o growth r i n g s on a t r e e . These banas a r e used t o d e t e r m i n e t h e aye and growth o f i nd i v i duals . Because growth d i f f e r s i n f reshwater and t h e ocean, t h e t i m e t h a t an i n d i v i d u a l has spent

S i ze i s one o f t h e most impo r tan t f a c t o r s de te rm in ing t h e age a t which A t l a n t i c salmon become smol ts ( R e f s t i e e t a l . 1977). F i s h t h a t become smol ts i n one y e a r mature and spawn f o r t h e

1 2 3 4 Year i n sea

F i g u r e 5. Growth o f A t l a n t i c salmon a t sea (A1 l e n e t a1 . 1972).

i n f r e s h w a t e r and t h e ocean can be est imated. Du r i ng upstream m ig ra t i on , t h e salmon p a r t i a l l y absorbs i t s scales; thus, the number o f spawning runs made by an o l d e r f i s h can a l s o be determined ( P r a t t 1946).

P roduc t i on (P) o f j uven i l e A t lan- t i c salmon can be es t imated from t h e mean biomass (B) f o r a l l year -c lasses p resent i n a t y p i c a l Welsh s t ream (Gee e t a l . 1978) w i t h t h e f o l l o w i n g f o r - mula:

The exponent a c t u a l l y ranged f r om 0.73 t o 1.24, and t h e c o e f f i c i e n t ranged f rom -1.91 t o -3.05. The h i g h e r values appeared i n t h e s p r i n g and summer.

Accord ing t o Eggl ishaw and Shack- l e y (1977) t h e s i z e o f O+ salmon i n a S c o t t i s h r i v e r depended on t h e growing season's leng th , which i s determined by emergence t ime, degree days above O°C, and p o p u l a t i o n d e n s i t y (numbers/m2). The r e l a t i o n s h i p o f f o r k l e n g t h (FL) t o p o p u l a t i o n d e n s i t y (N) and degree days (D) i s determined by t h e f o l l o w i n g equat ion :

No s i g n i f i cant r e l a t i o n s h i p between l eng th o f 1+ salmon and t h e i r popula- t i o n d e n s i t y cou ld be es tab l i shed . Egg1 i shaw and Shackley determi ned t h a t t h e annual p roduc t i on r a t e s f o r salmon ranged f r om 5.5 g/m2 t o 12.1 g /m2 and averaged 8.9 g/m2. P roduc t i on i n t h e second y e a r o f a p a r t i c u l a r y e a r c l ass cou ld n o t be s t a t i s t i c a l l y r e l a t e d t o p roduc t i on o f t h a t yea r c l a s s i n i t s f i r s t y e a r o f l i f e . Symons (1979 ) reviewed seve ra l s t u d i e s and noted t h a t smol t p r o d u c t i o n i n streams ranged f r om about 1 t o 10 smol ts /100 rn 2*

COMMERCIAL/SPORT FISHERIES

A t l a n t i c salmon were h e l d i n h i g h esteem by t h e Romans and Gauls. They were an impo r tan t commercial f i s h i n t h e B r i t i s h I s l e s and medieval Europe. They were mentioned i n t h e Magna Car- t a and we re an i m p o r t a n t s o u r c e o f p r o t e i n i n t h e American co lon ies . S e t t l e r s found r i vers teeming w i t h them. Reports o f t h e i r cap ture w i t h p i t c h f o r k s and t h e i r use as f e r t i l i z e r were documented by S tou t (1982). I n t h e l a t e 1800's dams and water p o l l u - t i o n des t royed t h e A t l a n t i c salmon i n U.S. waters except f o r a few streams i n Maine. Popu la t ions i n some Canadi - an streams were d im in i shed by 18bU. A t t h i s t ime Maine had t h e on ly re - main i ng p r o f i t a b l e commercial A t l a n t i c salmon f i s h e r y i n t h e U n i t e d S ta tes . About 70% o f t h e ca tch was f r om t h e Penobscot R i ve r , b u t by 1896, on l y 40 f i s h were landed the re . S ince then, t h e U n i t e d S ta tes has had no s i gni t i - cant commercial ca tch of salmon (Table 1 ) . Th i s i s a b iased value s i n c e com- mer i ca l f i s h i n g i s i l l e g a l i n t h e Uni ted States. A small catch ot

Tab le 1. Commercial catches o f A t - l a n t i c salmon i n m e t r i c t ons o t t h e major A t l a n t i c f i s h e r i e s 1977-lY8U (Food and H g r i c u l t u r a l Organi za- t i o n 1981).

c o u n t r y 1977 1978 1979 198U Canada 2,134 1,320 1,084 2,378 Greenland 2,725 2,163 2,467 2,U89 Denmark 1,214 950 1,049 1,133 I r e l a n d 1,184 817 1,528 1,551 U.S.S.R. 344 170 630 966 Sco t l and 450 472 318 896 F i n l a n d 782 568 584 679 Sweden 619 514 57U 602 F a r o e I s . 40 3 7 - 533 I c e l a n d 230 291 225 2 48 N . I r e l a n d 111 150 99 122 Norway 80 8 7 85 7 0 France 0 2 3 23 Germany FR 6 8 5 5 U.S.A. <1 < 1 <1 < 1

Tab le 2. Landings ( l b ) and values (U.S.$) o f commercial catches o f A t l a n t i c salmon i n Massachusetts and Maine i n 1964-1978 ( f r o m annual i ssues o f Cu r ren t F i she ry S t a t i s t i c s , NMFS 1983).

salmon has been r e p o r t e d t o r Massachu- s e t t s and Maine, where s a l e o f salmon caught w i t h s p o r t gear i s p e r m i t t e d (Tab le 2 ) . Spo r t catches p r o v i d e a b e t t e r measure o f t h e A t l a n t i c salmon f i s h e r y (Tab le 3 ) .

Massachusetts Maine

Year Landings va lue Landings va lue 1964 - - 454 385

Co l l apse o f t h e Lake O n t a r i o A t l a n t i c salmon f i s h e r y prompted a s e r i e s o f l e g i s l a t i v e a c t s i n Canada, t o c o n t r o l t h e commerci a1 t i s h e r i es. A 1973 ban on d r i f t - n e t f i s h i n g o f f Newfoundland and on commercial f i s h i n g i n New Brunswick ( bo th l i f t e d i n 1981) was a response t o w o r l d r educ t i ons o f A t l a n t i c salmon ca t ch (Hus t i ns 1981).

I n t h e l a t e 1960 's and e a r l y 19701s, tagged salmon f r o m bo th s i d e s o f t h e A t l a n t i c were caught i n a com- mon area o f f t h e west coas t o f Green- l a n d and o f f t h e Faroe islands (Par- r i s h 1973). Because A t l a n t i c salmon swim c l o s e t o t h e sur face , they a r e easy t o ca tch i n d r i f t and s e t y i 11 ne t s (Dunbar 1973). To reve rse t h e

Tab le 3. The s p o r t ca tch o f anadromous A t l a n t i c salmon i n New England r i v e r s , (Norman R. Dube, Maine A t l a n t i c Salmon Commission, personal communication; Lawrence A . Bandol in , U.S. F i s h and W i l d l i f e Serv ice , persona l communicat ion).

Number o f f i s h caught R i v e r 1978 1979 1980 1981 1982 1983*

Penobscot 360 136 837 725 915 155 Narraguagus 135 58* 119 78 85 89 Machi as 105 65+ 80 53 5 9 15 Dennys 7 5 38+ 190 129 40 27 East Machi as 6 0 25 6 2 8 5 33 8 Pleasant 16 7 5 2 3 19 - Sheepscot 3 5 5 t 3 0 15 12 10 Union 10 3 + 2 9 3 2 1 O 5 Merrimack 1 2 2 2 12 2 3 Connec t i cu t 0 2 4 13 2 5** Others*** - - 20+ - 12 - * th rough September 11, 1983 ** es t ima ted *** i n c l u d e s Kennebec, Duckt rap, S t . C r o i x , Androscoggi n, and Saco H i vers.

H total catch a Greenland'

b-'aDenrnark Norway, Sweden & .~;roes**

,!? 2000

Year * s e t g i 11-net and d r i f t - n e t ** d r i f t n e t ca t ch

F i gure 6. Green1 and and Scandanavi an c a t c h o f A t l a n t i c sa lmon f r o m 1960 t o 1971 (Dunbar 1973).

t r e n d o f i n c reased catches on t h e h i g h seas ( F i g u r e 6 ) , quotas were s e t (B rews te r 1982; L e a v i t t 1982). The Faroe I s l a n d f i s h e r y quo ta was s e t a t 750 m e t r i c t ons i n 1982, and 625 met- r i c t o n s i n 1983. The quo ta f o r Green- l a n d was s e t a t 1,250 m e t r i c t o n s f o r t hese years . The Convent ion f o r t h e Conserva t ion o f Salmon i n t h e No r t h A t l a n t i c Ocean T rea t y , approved Feb- r u a r y 1982, p r o h i b i t e d salmon f i s h i n g w i t h i n 12 mi o f ano the r c o u n t r y ' s c o a s t l i n e , w i t h t h e e x c e p t i o n o f West Greenland, where f i s h i n g o n l y beyond 40 mi was p e r m i t t e d , a n d t h e F a r o e I s l a n d s where f i s h i n g was p e r m i t t e d o n l y beyond 200 mi.

Based on ca t ch by ang le r s and i n t r a p s f o r h a t c h e r i e s t h e t o t a l r e t u r n i n Maine i n 1982 was 4,685 a d u l t A t - l a n t i c salmon, compared t o 4,134 i n 1981 (U.S. F i s h and W i l d l i f e S e r v i c e 1982). Records a r e incomple te , how- ever , f o r some o f t h e s m a l l e r r i v e r s . Of t h e 1982 run, 4,161 were f r o m t h e Penobscot R i v e r . I n sou the rn New England i n 1982, 46 salmon r e t u r n e d t o t h e Merr imack R i v e r , 70 t o t h e Connec-

t i c u t R i v e r (down f r o m t h e 53U i n 1981) and 38 (an e s t i m a t e o f 5U) i n t h e Pawcatuck K i v e r i n Khode I s l a n d , t h e f i r s t t i m e a d u l t A t l a n t i c salmon have r e t u r n e d t o t h i s r i v e r i n n e a r l y 200 years .

As a s p o r t f i s h , A t l a n t i c salmon a r e r a t e d as one of t h e bes t . They a r e h a r d f i g h t e r s and h i yh jumpers and a r e cons i de red a p r e s t i g o u s yame f i s h by many ang le r s . I n 1982, Penobscot a n g l e r s r e p o r t e d c a t c h i n g 914 salmon (abou t 1500 were a c t u a l l y caugh t ) dur- i n g 13,384 a n g l e r days on one s h o r t s e c t i o n o f 115 a c r e s o f t h e r i v e r . The a v e r a g e a n g l e r f i s h e d 3 8 h r t o ca t ch one f i s h (U.S. F i s h and W i l d l i f e S e r v i c e 1982).

ECOLOGICAL ROLE

Food H a b i t s

Young A t l a n t i c salmon u s u a l l y remain r e l a t i ve l y s t a t i o n a r y i n t h e s t ream and feed on i n v e r t e b r a t e d r i f t . T h e i r d i e t c o n s i s t s c h i e f l y of l a r v a e o f mayf 1 i es and s tone f 1 i es, c h i rono- mi ds, c a d d i s f 1 i es and b l a c k f li es, aq- u a t i c a n n e l i ds and mol l u sks . L a r g e r j u v e n i l e s feed on a q u a t i c i n s e c t s and t e r r e s t r i a l i n s e c t s t h a t f a l l i n t o t h e wa te r ( S c o t t and Crossman 1973).

I n t h e sea, smo l t and l a r g e r s a l - mon e a t h e r r i n g , lance, a lew ives , cap- e l i n , smel t , smal l rnac k e r e l , cod , haddock, and crustaceans (Le im and S c o t t 1966; S c o t t and Crossman 1973). Salrnon e a t v e r y 1 ittl e o r no th i ng a f t e r r e t u r n i n g t o f reshwater froln t h e sea, b u t some w i l l a t t a c k an a n g l e r ' s l u r e .

P r e d a t i on

Salmon a r e ea ten by a v a r i e t y o f p r e d a t o r s i n f r e s h w a t e r and a t sea (Le im and S c o t t 1966; S c o t t and Cross- man 1973; H a r r i s 1973). Young salmon a r e ea ten by ee l s , n o r t h e r n p i ke , brook t r o u t , l a r g e r salmon, and o t h e r

predaceous f i s h e s ; gu l l s , mergansers, cormorants, herons and k i n g f i s h e r s ; and backswimmers and leeches. A t sea major p reda to r s a r e p o l l ock , tuna, sword f i sh , sharks, o t t e r s , and seal s.

ENVIRONMENTAL REQUIREMENTS

Temperature

Water temperature i s t h e key f ac - t o r i n t h e d e l i n e a t i o n o f t h e geo- g raph i ca l range o f t h e A t l a n t i c s a l - mon. They requ i r e c o o l temperatures a t a l l s tages o f t h e i r l i f e h i s t o r y . Spawni ng occurs between 4.4"-10°C. The optimum tempera tu re o f egg f e r t i - l i z a t i o n and i n c u b a t i o n i s about 6"C, a l though development may occur a t s lower r a t e s a t temperatures as low as 0.5"C (Pe te rson e t a l . 1977). Tem- pe ra tu res o f 7°C a r e t o l e r a t e d , where- as temperatures above 12°C i nc rease egg m o r t a l i ty. Temperatures between 8" and 12°C may i n d i r e c t l y i nc rease m o r t a l i t y , due t o a h i g h e r i n c i d e n c e o f f u n g a l i n f e c t i o n (Gars ide 1973; DeCola 1975). Newly hatched A t l a n t i c salmon a l e v i n s s e l e c t t h e lowes t temperatures a v a i l a b l e . About 250 degree days a f t e r h a t c h i n g t h e a l e v i n s s e l e c t a tempera tu re o f 14°C (Peterson and M e t c a l f e 1979).

Growth and p r o d u c t i o n of juven- i l e s a r e optimum a t wa te r temperatures o f 15"-19°C (DeCola 1970), a l t hough t h e y w i l l t o l e r a t e temperatures up t o 27"C, a t w h i c h p o i n t t h e y move t o c o l d e r water . Huntsman (1942) s t a t e d t h a t salmon cou ld w i t h s t a n d temper- a tu res o f 32°C f o r b r i e f pe r i ods . The l e t h a l tempera tu re f o r j uven i l e s i s about 32°C (Gars ide 1973). Power (1969) suggested t h a t a minimum o f 100 days i n wh ich t h e tempera tu re exceeds 6°C i s needed f o r t h e growing season. S i g i nev i ch (1967) r epo r t ed t h a t growth was optimum a t 16.6"C.

A d u l t s grow i n ocean- temperatures as low as 2°C (DeCola 1975). M o r t a l - i t y can be expected a t wa te r tempera-

t u res h i gher than 28°C. Temperatures o f 20"-27°C reduce r e s i s t a n c e t o d i s - ease and a r e t h e r e f o r e i n d i r e c t l y l e t h a l . A t wa te r temperatures above 20°C a d u l t s a r e r a r e l y ' caught by ang- l i n g .

D i sso l ved Oxygen

F o r optimum growth and develop- ment, d i s s o l v e d oxygen concen t ra t i ons shou ld be a t o r near s a t u r a t i o n ; good development r e q u i r e s a t l e a s t 6 mg/l (E l son 1975). Streams w i t h d i s s o l v e d oxygen concen t ra t i ons below 5 mg/l a r e n o t u s u a l l y i n h a b i t e d by salmon. M i - g r a t i ng a d u l t salmon requ i r e a mi nimum of 5 my/ l f o r exposure l e s s t h a n 6 h r and 6 mg/l f o r exposure more t h a n 6 h r (DeCol a 1970 \.

The r e s p i r a t i o n o f a d u l t A t l a n - t i c salmon i s depressed a t oxygen concen t ra t i ons below 4.5-5.U mg/l (Kazakov and K h a l y a p i n a 1981 ) . A t concent r a t i o n s from 1.5-1.7 mg/l , most f i s h d i e f r om a l ack o f oxygen. Le- t h a l concen t ra t i ons f o r j u v e n i l e A t - l a n t i c salmon a r e about 1.1 my/l f o r age 0+ p a r r and 2.3 mg/l f o r age I+ p a r r t e s t e d a t t h e same wa te r temper- a tu res as t h e a d u l t s . Embryos r e q u i r e even h i g h e r oxygen l e v e l s o f 6-7 mg/l (DeCol a 1970). Oxygen consumpti on d i f f e r s among f i s h o f d i f f e r e n t sex, age, and weight . The r a t e of oxyyen consumption i n a d u l t s decreases w i t h age and body we igh t .

F l u c t u a t i o n s i n pH of wa te r a r e impo r tan t i n t h e f r eshwa te r en- v i ronment o f t h e A t l a n t i c salmon (Peterson e t a l . 198U). To le rance t o l o w pH v a r i e s among d i f f e r e n t l i f e s tages and ages. H igh m o r t a l i t y o f eggs and a l e v i n has been a t t r i b u t e d t o low pH, which i s c h a c t e r i s t i c o f snowmelt and heavy f a l l r a i n s . Eggs develop no rma l l y a t pH 6.6-6.8. A pH o f 4.0-5.5 delays o r p reven t s hatch- i ng , y e t r e t u r n i n g t hese eggs t o pH 6.6 induces ha tch ing . The lower

l e t h a l pH f o r embryos i s about 3.5 du r ing e a r l y cleavage and about 3.1 j u s t be fore hatching.

Death by low pH i s a t t r i buted t o dys func t ion o f i o n r e g u l a t i on, asphyx- i a t i o n , and e l e v a t i o n o f metal concen- t r a t i o n s . Exposure t o low pH causes edema between ou te r g i l l l a m e l l a r c e l l s and o ther g i l l t i s sue , d i s r u p t - i n g r e s p i r a t i o n and excre t ion . A pH o f 5.0 o r lower a f f e c t s eggs by de- g radat ion o f t h e enzymes respons ib le f o r movement o f t h e embryo w i t h i n t h e egg, w i thou t which hatch ing i s impos- s i b l e (Haines 1981). At pH 5.0-5.5 reproduct ion f a i 1s. A lev ins sub jec ted t o low pH a t 7 days and p a r r a t 28 days a f t e r ha tch ing had a lower l e t h a l l i m i t o f about 4.0 (Daye and Garside 1977; 1980). R ivers i n Nova Sco t i a w i t h a mean pH less than 4.7 have l o s t salmon runs; between 4.7 and 5.0 runs decl ined; and above 5.0 runs were un- a f f e c t e d (Watt e t a l . 1983). Juven i les i n these Nova S c o t i a streams were most numerous a t mean annual pH above 5.4, much reduced between 4.7 and 5.0, and absent below 4.7.

Depth and V e l o c i t y

The optimum s t r e a m h a b i t a t f o r spawning i s a grave l t a i l of a pool w i t h a h y d r a u l i c head produced by a r i f f l e o r a steeper grad ien t below t h e pool . The gravel has an average area o f 3.8 m2-

Water depth over a redd averages 0.4 rn i n Maine r i vers (Beland e t a1 . 1982) and 0.2 m i n New Brunswick r i v - e rs (Peterson 1978). Water v e l o c i t y a t 12 cm above t h e subs t ra te averaged 49 cm/sec i n Maine, and a t 2.5 cm above t h e subst ra te , 52 cm/sec i n New Brunswick (Elson 1975). The average water depth i n a Maine salmon stream was 38 cm ( r a n g e 17-76 cm) w i t h a water v e l o c i t y o f 53 cm/sec, measured 12 cm above t h e subs t ra te (Beland e t a l . 1982).

A t l a n t i c salmon f r y l ess than 60

mm l ong tend t o s tay i n depths less than 20 cm (Kennedy and Strange 1982). The f r y may n o t be a b l e t o compete w i t h o l d e r p a r r i n deeper waters be- cause o f p reda t i on and/or chasing, o r they may simply p r e f e r shal lower wa- t e r . Compet i t ion f o r space among f i s h o f d i f f e r e n t ages may be t h e c r i t i c a l r e g u l a t i n g f a c t o r a f f e c t i n g t h e sur- v i v a l o f f i r s t - y e a r (U+) f r y . I n one study (Knight e t a l . 1981), t h e pre- f e r r e d f r y h a b i t a t had a mean depth of 25 cm (range 9-39 cm). The aepth o f 62 s i t e s where salmon f r y were found i n New Brunswick streams ranged f rom 10 t o 31 cm (Franc is 198U).

P a r r , 1+ y e a r and o lder , seem t o p r e f e r w a t e r s 10-40 cm deep. Mean depth o f p r e f e r r e d areas i n New Eny- l and streams was 29 cm (Knight e t a l . 1981), and 10-15 cm i n Canadian streams (Symons and Heland 1978).

F i r s t - y e a r f i s h (age U+) p re fe r water v e l o c i t i e s o f 50-65 cm/sec (Sym- ons and Heland 1978). Kni ght e t a1 . (1981 ) repo r ted t h a t p r e f e r r e d h a b i t a t o f 0+ f i s h had a mean v e l o c i t y o f 14 cm/sec (range 1.8-32 cm/sec) , whereas I + p a r r were i n h a b i t a t w i t h a mean v e l o c i t y o f 20 cm/sec (range 14-32). Stream grad ien ts t h a t salmon p r e f e r range f rom 2 t o 12 m/km (Elson 1975).

R e s t i n g p o o l s f o r ups t ream m i - grants a r e impor tan t as temporary re- fuge f rom s w i f t cur ren ts . Large boul- ders and o the r stream obst ruc t ions prov ide eddies and s lack water i n which a d u l t salmon may r e s t .

L i g h t

A t s u r f ace i 1 1 umi n a t i ons between 0.4 and 160 foot-candles ( f c ) , salmon were photoposi t i ve, whi l e a t i 1 lumin- a t i ons above 300 f c they were photo- negat ive when t h e l i g h t e d area had an unbroken subs t ra te (Gibson and Keen- l e y s i de 1966). With submerged cover i n t h e l i g h t e d area, t h e salmon were pho topos i t i ve . The amount of shade over a stream i n d i r e c t l y af fects t he

s u r v i v a l o f salmon by p r e v e n t i n g s o l a r r a d i a t i o n f r om warming t h e wate r above t h e upper l e t h a l tempera tu re (McCrim- mon 1954).

S a l i n i t y

To le rance o f A t l a n t i c salmon t o sudden changes i n s a l i n i t y d i f f e r s among i t s l i f e s tages (Pa r r y 1960). Smolts g r e a t e r t han 120 mm can s u r v i v e an ins tan taneous change f r o m f r e s h - wate r (0.1 p p t ) t o 100% seawater (30 p p t ) f o r 84 h r , and a r e c o m p l e t e l y t o l e r a n t when i n t r o d u c e d i n t o 27 p p t seawater. P a r r 7 t o 100 mm can t o l e r - a t e 30 p p t seawater f o r 10 h r a f t e r d i r e c t i n t r o d u c t i on, and su r v i ve i n- d e f i n i t e l y i n waters o f 22 pp t . P a r r 30 - 40 mm a r e a b l e t o s u r v i v e f o r on ly 2.5 h r i n 30 p p t seawater b u t a r e t o l e r a n t o f a b o u t 18 p p t s e a w a t e r . F r y 15 - 20 mm p e r i s h w i t h i n 2 h r a f t e r sudden i n t r o d u c t i o n i n t o 30 p p t seawater b u t can t o l e r a t e a l e v e l o f 8 p p t i n d e f i n i t e l y . . S i x-week-old a l e - v i ns s u r v i v e f o r o n l y 0.5 h r i n 30 p p t seawater bu t s u r v i v e w e l l a t s a l i n - i t i e s near 20 pp t . One-week-old a l e - v ins , however, a r e a b l e t o s u r v i v e up t o 9 h r i n 100% sea water , even though 3% i s op t ima l . Pa r r y (1960) suggests t h a t t h e ep i t he1 i um o f these a l e v i n s i s a b l e t o m a i n t a i n some de- gree o f impe rmeab i l i t y , which i s l a c k - i n g i n somewhat o l d e r f i s h , and may a c c o u n t f o r t h e l o n g e r s u r v i v a l o f younger f i s h a t h i g h s a l i n i t i e s (F i g - u r e 7 ) .

A t l a n t i c salmon p a r r , though adapted f o r l i f e i n f r eshwa te r , can r e a d i l y s u r v i v e w i t h i n a w ide s a l i n i t y g rad ien t f r om 0 t o 20 p p t (Shaw e t a l . 1975). Ins tan taneous growth r a t e s and f ood convers ion e f f i c i e n c i e s o f salmon i n d i f f e r e n t s a l i n i t i e s were s i m i l a r .

3 0 15 (ppt ) Sea wa te r

F i g u r e 7. S u r v i v a l t i m e o f d i f f e r e n t l i f e s tages o f A t l a n t i c salmon i n var- i ous seawater concen t ra t i ons (Pa r r y 1960 ) .

Subs t ra te , Sediment, and T u r b i d i t y

The spawning h a b i t a t has a p a r t i - c l e s i z e compos i t ion c o n s i s t i n g o f 0%-3% f i n e sand (0.06-0.50 m); 10%- 15% coarse sand (0.5-2.2 mm); 40%-50% pebb le (2.2-22 mm); and 4U%-6U% cobb le (22-256 mm) (Pe te rson 1978). F i r s t y e a r f i s h (O+) p r e f e r a s u b s t r a t e o f g rave l 1.6-6.4 cm i n d iameter w h i l e p a r r o f age 1+ p r e f e r a bou lde r and r u b b l e s u b s t r a t e g r e a t e r t han 26 cm i n d iameter (Symons and Heland 1978). Bot tom sed imen ta t i on p l a y s an i m p o r t - a n t r o l e i n t h e s u r v i v a l and d i s t r i bu- t i on of j u v e n i l e salmon (McCrimmon 1954 ) . Spaces be tween p e b b l e s and cobb le a r e used as s h e l t e r by t r y and p a r r . D e p o s i t i o n o f sediments t h a t c l o g t hese spaces decrease s u r v i v a l o f salmon f r y and p a r r (McCrimmon 1954). T u r b i d i t i e s i n excess o f 115U s tandard u n i t s , caused by autumn f r e s h e t s , d i d n o t i n j u r e o r k i l l sa lmon t r y and p a r r . McCrimmon (1954) suggested t h a t t u r b i d wate r i n s p r i n g may p r o t e c t mi- g r a t i n g smo l ts f r om p reda t i on .

LITERATURE CITED

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A l l e n , K.R., and J.A. R i t t e r . 1977. Salmoni d t e r m i n o l o J. Cons. I n t . E x p l o r . Mer 378;): 293-299.

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Baum, E.T., and A.L. Me is te r . 1971. Fecund i t y o f A t l a n t i c salmon (Salmo s a l a r ) f r o m two Maine -. - r i v e r s . J. F i sh . Res. Board Can. 28: 764-767.

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B ige low, H.B., and W.C. Schroeder. 1953. F ishes o f t h e G u l f o f Maine. U.S. F i s h W i l d l . Serv. F i sh . B u l l . 53(74):1-577.

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Brews te r , W.S. 1982. A re t h e Faroese r u i n i n g t h e salmon f i s h i n g ? A t l . Salmon J . 30(3):8-11.

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C la r ke , L.A. 1981. M i g r a t i o n and o r - i e n t a t i o n o f two s t ocks o f A t l a n - t i c salmon (Salmo s a l a r L.) -- ~ m o l t s . Ph.D. d i s s e r t a t i o n , Univ . o f New Brunswick, F r e d e r i c t o n , N.B. Canada.

Daye, P., and E. Gars ide. 1977. L o w e r l e t h a l l e v e l s o t pH t o r embryos and a l e v i n s o f A t l a n t i c sa lmon, Salmo s a l a r L . Can. J. Zoo1 . 55: 1504-1508.

Daye, P., and E. Gars ide. 198U. De- velopment, s u r v i v a l , and s t r u c - t u r a l a l t e r a t i o n s o f embryos and a l e v i n s o f A t l a n t i c salmon, Salmo s a l a r L., c o n t i n u o u s l y exposed t o a l k a l i n e l e v e l s of uH f rom t e r t i - l i z a t i o n . Can. J . Z o o l . 5 8 ( 3 ) : 369-377.

DeCola, J.N. 1970. Water q u a l i t y r e - q u i rements f o r A t l a n t i c salmon, USDI. Federa l Water Q u a l i t y Ad- m i n i s t r a t i o n , N.E., Region, bos- t on , Mass. 42 pp.

DeCola, J .N. 1975. A t l a n t i c salmon r e s t o r a t i o n and t h e q u e s t i o n o f wa te r q u a l i t y . I n t . A t l . Salmon Found. Spec. Publ . Ser . b:24-28.

Dunbar , M.J. 1973. On t h e West G r e e n l a n d sea l i f e a r e a o f t h e A t l a n t i c salmon. A r c t i c 2b(1 ) : 3-6.

Eggl ishaw, H.J., and P.E. Shackley. 1977. Growth, s u r v i v a l and p ro - d u c t i o n o f j u v e n i l e sa lmon a n d t r o u t i n a S c o t t i s h stream, 1966-75. J . F i s h B i o l . 11:647- 672.

E lson, P.F. 1975. A t l a n t i c sa ln~on r i v e r s smo l t p r o d u c t i o n and o p t i - mal spawning: an overv iew o f na t - u r a l p roduc t i on . I n t . H t l . Sa l - mon Found. Spec. P u b l . S e r . 6. 6:96-119.

F isknes , B., and K.B. Doving. 1 9 8 2 . O l f a c t o r y s e n s i t i v i t y t o group s o e c i f i c substances i n A t l a n t i c salmon (Salmo s a l a r L.) . J . Chem. Eco l . 8 (B l08-2 .

FAO. 1981. 1980 yearbook o f f i s h e r y s t a t i s t i c s . V o l 50. Food and A g r i c u l t u r e O r g a n i z a t i o n o f t h e U n i t e d Nat ions Rome. 387 pp.

F r a n c i s , A.A. 1980. D e n s i t i e s o f j u v e n i 1e A t l a n t i c salmon and o t h e r species, and r e l a t e d da ta from e l e c t r o s e i n i n g s t u d i e s i n t h e S a i n t John R i v e r system, 1968-78. Can. Data Rep. F i s h . Aq. Sc i . No. 178: 95 pp.

F r i ed , S.M., J.D. McCleave, and G.W. LaBar. 1978. Seaward m i g r a t i o n o f ha tchery - reared A t l a n t i c s a l - mon, Salmo s a l a r , smo l ts i n t h e Penobscot R i v e r E s t u a r y , Maine: r i v e r i ne movements. J. F ish . Res. Board Can. 35: 76-87.

G a r s i d e , E . 1973. U l t i m a t e u p p e r l e t h a l t e m e r a t u r e o f A t l a n t i c salmon, ~ a l m o s a l a r . Can. J. Zool . 5:8-.

Gee, A.S., N.J. M i l n e r , and R.J. Hems- w o r t h . 1978. The p r o d u c t i o n o f j u v e n i l e A t l a n t i c salmon, Salmo s a l a r i n t h e u p p e r Wye, Wales.

J . F i s h B i 01. 13: 439-451.

J. F i sh . Res. Board Can. 23: 1977- 1980.

Gibson, R.J., and M.H.A. Keenleys ide. 1966. Responses t o l i g h t o f Youns A t l a n t i c salmon (Salmo sa- h) -and brook t r o u t ($a1 v e l i nus f o n t i n a l u s ) . J. F i sh . Res. Board Can. 23:1007-1024.

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H a r r i s , 6.S. 1973. Rea r i ng smo l ts i n mounta in l akes t o supplement s a l - mon s t o c k s . I n t . A t l . Salmon Found. Spec. Publ . 4. 4 (1 ) : 237-252.

Havey, K.A., and K. Warner. 197U. The l and locked salmon {Salmo sa la r ] : i t s l i f e h i s t o r ~ y and manaoement i n Maine. s p o r t F ish . i ns t . , Washington, D.C. 129 pp.

Huntsman, A.G. 1942. Death o f salmon and t r o u t w i t h h i g h temperature. J. F ish . Res. Board Can. 5:485- 501.

Hus t i ns , D.G. 1981. The f i g h t f o r s u r v i v a l o f Salmo s a l a r . A t l . Salmon J. 30(4):12-14.

Jordan, R.M., and K.F. Beland. 1981. A t l a n t i c salmon spawning and e v a l u a t i o n o f n a t u r a l spawning success. A t l a n t i c Sea-Kun Salmon Commission, Augusta, Maine. 25 PP*

Gibson, R.J. 1966. Some f a c t o r s i n - Kazakov, K.V. 1981. The e f f e c t o f f l u e n c i n g t h e d i s t r i b u t i o n of t h e s i z e o f A t l a n t i c salmon, brook t r o u t and A t l a n t i c salmon. Salmo s a l a r , eggs on embryos and

a l e v i n s . J. F i s h B i o l . l Y ( 3 ) : 353-360.

Kazakov, R.V., and L.M. Khalyapina. 1981. Oxygen consumpti on of a d u l t A t l a n t i c salmon, Salmo sa- l a r , ma les and f e m a l e s i n f i s h c u l t u r e . Aquacu l tu re 25(2-3) : 289-292.

Kennedy, G.J.A., and C.U. Strange. 1982. The d i s t r i b u t i o n of s a l - monids i n upland streams i n re - l a t i o n t o depth and g rad ien t . J.

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Kn igh t , A.E., and J.C. Greenwood. 1982. Spec ia l r e p o r t - h a b i t a t c r i t e r i a f o r A t l a n t i c salmon and Amer i can shad. Pages DF1-DF16 i n S p e c i a l r e p o r t - anadromous f i s h : w a t e r and l a n d r e s o u r c e s o f t h e Merrimack R i v e r Basin. U.S. F i s h and W i l d l i f e Serv ice , Laconi a, N .H.

Kn igh t , A.E., G. Marancik, and J.C. Greenwood. 1981. A t l a n t i c salmon p roduc t i on p o t e n t i a l o f t h e Mad R i ve r , New Hampshire 1975-1980. Unpubl. Prog. Rep. U.S. F i s h and W i l d l i f e Serv ice , Laconia, N.H.

Leavi tt , B. 1982. Mi t c h e l l t a r g e t s : woodcock, salmon. Bangor Dai l y News. F r i . Aug. 13. 1982.

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Lundqvis t , H., and G. F r i dbe rg . 1982. Sexual ma tu ra t i on versus immatur- i t y : d i f f e r e n t t a c t i c s w i t h adap- t i v e values i n B a l t i c salmon

(salmo s a l a r L.) male smol ts . -- Can. J . Zool . 60: 1822-1827.

McCrimmon, H .R . 1954. Stream s tud ies on p l a n t e d A t l a n t i c salmon. J. F i sh . Res. Board Can. 11:362-403.

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Me i s te r , A.L. 1962. A t l a n t i c salmon p r o d u c t i o n i n Cove Brook, Maine. Trans. Am. F i sh . Soc. 91:208-212.

Na t i ona l Mar ine F i s h e r i e s Se rv i ce (NMFS). 1983. F i s h e r i e s o t t h e U n i t e d S ta tes . 1982. Uep. Comm., Cur ren t F i s h e r i e s S t a t i s t i c s No. 83UU. 117 pp.

Netboy, A. 1974. The salmon: t h e i r f i g h t f o r s u r v i v a l . Houghton M i f - f l i n Company, Boston, Mass. 594 PP*

Ottaway, E.M., and A. C la rke . 1981. A p r e l i m i n a r y i n v e s t i g a t i on i n t o t h e v u l n e r a b i l i t y of young t r o u t (Salmo t r u t t a L . ) and A t l a n t i c s-lar L . ) t o down- s t ream di5l-t by h i g h water v e l o c i t i e s . J. F i s h B i o l . 19: 135-145.

P a r r i s h , B.B. 1973. A rev iew o f t h e work o f t h e ICES/ICNAF ~ o i r i t wo rk i ng p a r t y No r th A t l a n t i c sa lmon. I n t . A t l . S a l . Found. Spec. Pub. Ser. 4(1):383-396.

Parry , G. 1960. The development o t s a l i n i t y t o l e r a n c e i n t h e salmon, Salmo s a l a r L., and some r e l a t e d species. J. Exp. B i o l . 37: 425-434.

Peterson, K .H . 1978. Phys ica l c h a r a c t e r i s t i c s o f A t l a n t i c sa lmon spawn ing g r a v e l i n some New Brunswick, Canada, streams. Can. F i sh . Mar. Serv. Tech. Key. No. 785: l-28.

Peterson, R.H., and J.L. Metca l fe . 1979. Responses o f A t l a n t i c salmon, a l e v i n s t o t e m p e r a t u r e g rad ien ts . Can. J. Zoo1 . 57 ( 7 ) : 1424-14311.

Peterson, R.H., H.C.E. Spinney, and A. Sreedharan. 1977. Oevelopment of A t l a n t i c salmon (Salmo s a l a r ) eggs and a l e v i n s under v a r i e d temperature regimes. J. F ish . Res. Board Can. 34(1):31-43.

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Pope, J.A., D.H. M i l l s , and W.M.. Shearer. 1961. The f e c u n d i t y o f A t l a n t i c salmon (Salmo s a l a r L.). Dep. o f A g r i c . o f m . f o r S c o t - land. Freshw. Salmon F i sh . Res. No. 26. 12 pp.

Power, G. 1969. The salmon of Ungava Bay. A r c t . I n s t . N. Am. Tech. Rep. 22. 72 pp.

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- 16. Abstract (Limit: 200 words)

50172 -101 1 REPORT NO. REPORT DOCUMENTATION i. .- 3. Recipient's Accession NO.

PAGE i FWS/OBS-82/11.22* 1 '' -- -- -

4. Title and Subtitle I- 5. Report Date

Species P r o f i l e s : L i f e H i s t o r i e s and Environmental Requirements ( J U ~ Y 1984 of Coastal Fishes and Inver tebra tes (Nor th A t l a n t i c ) - - A t l a n t i c - -- - .

Sa 1 mon ~ . ~ "-- ~ .

7. Author(%) 8. Perlorming Organizatidn Rept. No.

Dwight S. Danie, Joan G. T r i a l , and Jon G. Stanley

Species p r o f i l es are 1 i t e r a t u r e summaries on t h e taxonomy, morphology, range, 1 i f e h i s t o r y and environmental requirements o f coasta l aqua t i c species. They are in tended t o a s s i s t i n environmental impact assessment. A t l a n t i c salmon a re a h i g h l y p r i z e d s p o r t f i s h and t h e i r f l e s h i s gourmet t a b l e fa re . Once abundant i n New England's coas ta l r i v e r s , they are on l y now being res to red t o po r t i ons o f t h e i r o r i g i n a l h a b l t a t . Popul a t i ons dec l i ned f o l lowing deve- lopment o f i n d u s t r i e s a long r i v e r s and comerc i a1 f i s h e r i e s i n es tuar ies . A t l a n t i c salmon are anadromous. Spawning, embryo development and growth o f young f i s h occur i n f reshwater streams and r i v e r s . Juven i le s u r v i v a l i s h ighes t i n c lear , cool ( <27O~) , w e l l oxygenated (d i sso l ved oxygen 2 5 mg/l) streams. Fo l low ing s m o l t i f i c a t i o n , a phys io l og i ca l change enabl ing e n t r y i n t o s a l t water, f i s h mig ra te downstream and then t o oceanic feed ing grounds near Greenland, where they grow r a p i d l y . Sexual ly mature f i s h r e t u r n t o t h e i r n a t a l r i v e r s t o spawn. M ig ra t i on i n t o es tua r i es and lower reaches o f r i v e r s begins 7 months be fo re t he October-November spawning per iod . M i g r a t i n g adu l ts r equ i r e d i sso l ved oxygen concentrat ions g rea te r than 6 mg/l f o r successfu l upstream movement. Because j uveni 1 es m i g ra te through

t o t h e consequences o f coasta l development .

I t h e coastal zone i n s p r i n g and adu l t s i n summer and f a l l t h e species i s e s p e c i a l l y vu lnerab le

-. --- . --- 9. Perlorming Organization Name and Address

Maine Cooperative F ishery Research Un i t 313 Murray Hal 1, U n i v e r s i t y o f Maine Orono, ME 04469

-. - 12. Sponsoring Organization Name and Address

Nat ional ' Coastal Ecosystems Team U.S. Army Corps of Engineers Fish and W i l d l i f e Serv ice Waterways Experiment S t a t i o n U.S. Dept. o f t h e I n t e r i o r P.O. Box 631 Washington, DC 20240

-- - Vicksburq, MS 39180

17. Document Analysis a . Descriptors

Salmon Fishes Rivers Ili g ra t i on

- - - . - lo. Proiect/Task/Work Unit No.

- ~- --- -- 11. Contractcc) 01 Grant(G) NO.

(c)

(GI

~ ~- - . - 13. Type of Report d. Period Covered

. - - - - - . . - -. .~. - 14.

b. Identitien/Open.Ended Terms I

15. Supplementary Notes

*U.S. Army Corps o f Engineers Report No. TR EL-82-4

A t l a n t i c s a l m n ~ a b i t a t requ l rements S a l m s a l a r -- Spawning Temperature req u i remen t s L i f e h i s t o r y

c. COSATI Field/Group

18. Availability Statement 1 19. Secur!ry Class (This Report) 1 21. No o' Paces 1 I I Un l im i ted

19 j 22. p,,:,

l ~ n c l a s s i f i e d I I (See ANSI-239.18) OPTIONAL FORM ?72 , $ - i i ,

(Formerly NTIF-35, Department of C::wmercr

REGION 1 Regional Director U.S. Fish and Wildlife Service Lloyd Five Hundred Building, Suite 1692 500 N.E. Multnornah Street Portland, Oregon 97232

REGION 4 Regional Director U.S. Fish and Wildlife Service Richard B. Russell Building 75 Spring Street, S.W. Atlanta, Georgia 30303

REGION 2 REGION 3 Regional Director Regional Director U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service P.O. Box 1306 Federal Building, Fort Snelling Albuquerque, New Mexico 87 103 Twin Cities, Minnesota 55 1 1 1

REGION 5 REGION 6 Regional Director Regional Director U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service One Gateway Center P.O. Box 25486 Newton Corner, Massachusetts 02158 Denver Federal Center

Denver, Colorado 80225

REGION 7 Regional Director U.S. Fish and Wildlife Service 101 1 E. Tudor Road Anchorage, Alaska 99503

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As the Nation's principal conservation agency, the Department of the Interior has respon- sibility for most of our.nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, preserving theenvironmental and cultural values of our national parks and historical places, and providing for the enjoyment of life through outdoor recreation. The Department as- sesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also has a major responsibility for American Indian reservation communities and for people who live in island territories under U.S. administration.