Geir Ottersen, Institute of Marine Research, Oslo, Norway

and Centre for Ecological and Evolutionary Synthesis (CEES) University of Oslo, Norway

Manuel Hidalgo, Spanish Institute of Oceanography (IEO), Balearic Oceanographic Centre, Palma de Mallorca, Spain Valerio Bartolino, Swedish University of Agricultural Sciences, Dept. of Aquatic Resources, Lysekil, Sweden

Juan-Carlos Molinero, Helmholtz Centre for Ocean Research, Geomar, Kiel, Germany

Tristan Rouyer, Laboratoire Ressources Halieutiques de Sète, Ifremer, France

Environmental effects on fish populations: Some principles, some examples, and comparisons between large ecosystems from the Mediterranean to the Barents Sea

The wrapping up of the IDEADOS project: Workshop on Environment, Ecosystems and Demersal Resources, and Fisheries, Palma de Mallorca from 14 to 16 November 2012

• Some general principles • Climate effects on regional environment • Environmental effects on early life stages and recruitment • Environmental impacts on fish distribution • Combined effects of fishing and climate • Some comparisons

Overview

Some general principles

Through physiology, (metabolic and reproductive processes)

Direct response to climate

Through biotic environment (predators, prey, species interactions, and disease)

and abiotic environment (habitat type and structure).

Indirect response to climate

4 YEARS OLD COD

3,0 3,2 3,4 3,6 3,8 4,0 4,2 4,4 4,6 4,8 5,0

-1,5 -1 -0,5 0 0,5 1 1,5

Temperature anomaly (C)

Mea

n w

eigt

h (k

g)

R2=0.67

Brander and O’Brien (2000)

Departure from mean weight at age 4

1960 1970 1980 1990 2000 Year Class

0

-1

+1

Temperature anomaly (°C)

Departure from mean weight at age 3

The effect of temperature on weight of North Sea cod

Direct response to climate

Puffin

Joel Durant, CEES

Puffin growth and food availability Early life stages of NSS herring are positively affected by higher temperatures, thus increasing prey availability for puffins:

Indirect response to climate

Age, days

0 10 20 30 40 50 60 70

Bod

y m

ass,

g

0

50

100

150

200

250

300

350

400

96% (423 109)

24% (27 109)

51% (112 109)

Fledgling success

Herring larvae abundance

The relation between the number of herring larvae (prey) and weight and fledgling success in puffin chicks

Herring larva

A

B A

Climate Climate

Interactions with other factors

B

Ecological response to climate fluctuations

Ottersen, Stenseth, Hurrell 2004, OUP

10

12

14

16

18

20

22

1950 1960 1970 1980 1990 2000

Year

Ln

(Rec

ruit

men

t)

Example: Cod at West Greenland

Recruitment

8

9

10

1950 1960 1970 1980 1990 2000

Year

SST

Temperature

9

10

11

12

13

14

15

1950 1960 1970 1980 1990 2000Year

Ln

(SS

B)

Spawning Stock Biomass

M. Stein and V.A. Borovkov

Single climate event causes shift in ecological state

Linear climate signal causes shift in ecological state when climate threshold passed.

Time

Linear ecological response to climate signal

Clim

ate

Ecol

ogic

al

Res

pons

e

Ecological response to climate fluctuations

Climate-ecology links may change with time, non-stationarity

Ecological response to climate fluctuations

NE Arctic Saithe

Year

Example: temporal pattern in recruitment dynamics R

ecru

itmen

t ln

(tho

usan

ds a

ge 3

)

Year

North Sea sole

Rec

ruitm

ent

ln (t

hous

ands

age

1)

NE Arctic Saithe

Year

Year

North Sea sole

Rec

ruitm

ent l

n (th

ousa

nds

age

3)

Rec

ruitm

ent l

n (th

ousa

nds

age

1)

Example: temporal shift in recruitment dynamics

Climate effects on regional environment

Northern Annular Mode (Arctic Oscillation)

Spatial variation: correlations between the NAO and SST

Stige, Ottersen.., Stenseth MEPS 2006

The Mediterranean Sea Under the influence of numerous climatic processes acting at

global scales – Northern Annular Mode (AO/NAO) – Indian and African monsoon – Subtropical Jets – Atlantic depression – Hadley Cells

Northern Annular Mode regional scales Complex orography

Regional winds (Mistral, Bora, …) Mediterranean depressions

Latitudinal and longitudinal gradients

Bolle, 2003

A

B C

r = 0.79; p < 0.001 Gulf of Lions

r = 0.75; p < 0.001 Ligurian Sea

r = 0.67; p < 0.001 Balearic Sea A B C

Links between North Atlantic and regional climate 1950-2005

-0.4 -0.2 0 0.2 0.4 0.6 0.8 10

50

100

150

200

250

300

350

400

r

frequ

ency

r = 0.53; p < 0.01 1950 - 1977

r = 0.73; p < 0.0001

1978 - 2000

-0.4 -0.2 0 0.2 0.4 0.6 0.8 10

50

100

150

200

250

300

350

400

r

frequ

ency

r = 0.27; p < 0.05 1950 - 1977

r = 0.62; p < 0.001

1978 - 2000

Links between North Atlantic and regional climate change over time

Balearic Sea NW Med

Image: Glynn Gorick for ICES WG Cod and Climate Change

Environmental effects on early life stages and recruitment

SR relationships improvement with environmental information

Massutí et al. 2008 J Mar Syst

IDEA index improves the SR relationship of hake off the Balearic Islands

Modelling the Spawning Stock-Recruitment

relationship for North Sea cod North Sea cod

Modelling the Spawning Stock-Recruitment

relationship for North Sea cod by a linear relation?

?

?

North Sea cod

Modelling the Spawning Stock-Recruitment

relationship for North Sea cod by a Ricker type relation?? North Sea cod

Modelling the Spawning Stock-Recruitment relationship

for North Sea cod by a Beverton-Holt type relation?? North Sea cod

Enhancing the S-R relation by including environmental effects in a combined Beverton-Holt and Ricker model Apply a family of recruitment curves depending on initial larval- and zooplankton densities Beverton-Holt type relation at high food levels Overcompensation (Ricker) at limited food levels: At low food levels the time to metamorphosis is delayed to the extent that larval mortality accumulates and makes the recruitment curve overcompensatory

Proc. R soc. B.2011

Model Structure 1 log(R/S) = a + log(exp(-b•S)) log(R)-log(S)=a-bS 2 log(R/S) = a – log(1 + exp(c)•S/maxS) 3 log(R/S = a + log(exp(-b•S)•(1-Z) + 1/(1 + exp(c)•S/maxS)•Z) 4 log(R/S) = a – (a1•T) + log(exp(-b·S)•(1-Z) + 1/(1 + exp(c)•S/maxS)•Z)

1 Traditional Ricker model 2 Traditional Beverton-Holt model 3 Combined Ricker-Beverton-Holt model including a Z effect only 4 Combined Ricker-Beverton-Holt model including Z and T effects

A-priori set of stock (S) and recruitment (R) models

T is sea temperature and Z the zooplankton index developed by Beaugrand et al. (2002) Sea temperature and Zooplankton are standardized

North Sea cod

Combined Ricker and Beverton-Holt, dependent on zooplankton (based upon the data)

REC

RU

ITM

ENT

North Sea cod

Model # Parameters AIC Support* 1 2 80.4 0 2 2 80.6 0 3 3 64.6 0.24 4 4 62.3 0.76

Model selection

*normalised Akaike weights (Burnham and Anderson 1998)

Model 4 is the most parsimoneus: Combined Ricker-Beverton-Holt model including zooplankton (Z) and temperature (T) effects

NSS herring

North Sea sole

Temperature-recruitment correlations 15-year moving windows

Barents Sea cod M

ovin

g 15

-yea

r win

dow

cor

rela

tions

[ l

n(R

), te

mpe

ratu

re]

Environmental impacts on fish distribution

Temperature change affects fish distribution: Example, cod at West Greenland

Air temperature

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 30N

40N

50N

60N

70N

80N

90N

Latit

ude

Greenland

Warming Cold

Cod stock in West Greenland

Today

Marked changes in distribution of Northeast-Arctic cod with historical temperature shift

Barents Sea

”Warm” Cold

Drinkwater 2011

Marked changes in spawning distribution of capelin expected under climate change

Barents Sea

Huse and Ellingsen 2008, Drinkwater 2011

Present day spawning sites Potential new spawning sites

Climate response from Northeast-Arctic cod

In cooling phases: - Spawning sites displaced southward - decreasing spawning stock

In warming phases: - Spawning sites displaced northward - Increasing spawning stock

2,5

3,0

3,5

4,0

4,5

5,0

1900 1920 1940 1960 1980 2000

Year

Tem

pera

ture

Sundby and Nakken (2008) IJMS

JUVENILE HAKE DISTRIBUTION IN THE TYRRHENIAN SEA: Horizontal

Recruits are aggregated in nurseries along the shelf-break, not continuous, but in specific areas. Concentration may be very high, up to >25.000 n/km2 ! Distribution of these areas (nurseries) may be explained by: -the current pattern -the patchy distribution of unique biocenoses (i.e., crinoids sea-bed)

Colloca et al. 2009, MEPS

Hake recruits distribution in early Autumn

Hake recruits and juveniles are well segregated in space. Juveniles move on the shelf for feeding and maturing

JUVENILE HAKE DISTRIBUTION IN THE TYRRHENIAN SEA: Vertical

Bartolino et al. 2008, FishRes

White color shows high depth preference as function of fish length

Two distinct depth-length clusters throughout 1998-2004: - Small hake over the slope - Larger hake over the shelf in shallower waters

Combined effects of fishing and climate

Balearic Sea

Combined effects fishing – climate

Increasing sensitivity of hake to climate variability due to the accumulated fishing effect

Hake influenced by the IDEA index after early 1980s

Hidalgo et al. 2011 MEPS

Balearic Sea Combined effects fishing – climate

Increasing sensitivity to climate variability…

Fishing-climate effects synchronize CPUE variability of many demersal species

… of the whole demersal community

Quetglas et al. in press ICES J. Mar. Sci

Finally, a few comparisons between the different regions

Some rather obvious, but important differences

Temperature Salinity Open/closed Species richness Barents Cold Intermediate Open Poor Norwegian Cold Saline Open Poor North Intermediate Intermediate Open (towards N) Intermediate Med Temperate Saline Semi-enclosed Rich

Expected Climate Change Effects on European Marine Regions

Warmer waters will lead to northward movements of species in open systems. Examples North Sea, Norwegian Sea

In semi-enclosed seas some species may have nowhere to move. For instance northwestern, colder parts of the Med. Particularly in semi-enclosed seas a loss of endemic species due to the invasion of non-indigenous species, which may adapt better to new area with climate change. For example Black Sea, Southeastern Med (Red Sea invasion through Suez canal)

1965

1970

1975

1980

1985

1990

1995

2000

years

0

4

8

12D

2

16

12

8

4

0

D2

1965

1970

1975

1980

1985

1990

1995

2000

years

0

4

8

12

16

16

12

8

4

0

Ligurian Sea

NAC

North Sea

NAC

North Atlantic climate triggers synchronic shifts in North and Ligurian Seas

Correlations between N. Atlantic climate and North Sea: r=0.80 (p<0.001) Correlations between N. Atlantic climate and Ligurian S: r=0.79 (p<0.01) Correlations between North and Ligurian Seas: r=0.40 (p<0.02)

Major environmental variability patterns in the North and Ligurian Seas are synchronous

Conclusions stock-recruitment

The results suggest that the stock-recruitment relationships of both hake off the Balearic Islands and North Sea cod are not stationary, but that they depend on environmental conditions, respectively the IDEA pattern or sea temperature

Cod Gadus morhua abundance Barents Sea…………………………Many Norwegian Sea……………………..Coastal only North Sea……………………………Less than before

FINAL COMPARISON

Morey et al. 2012 MEPS

Mediterranean……………………...1, the Mallorca cod

Thanks for your attention!

Geir Ottersen

IMR