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Some roles of climate in the population ecology of Some roles of climate in the population ecology of Calanus finmarchicusCalanus finmarchicus (Copepoda) in mid- (Copepoda) in mid-

Norwegian shelf water and in the year-class Norwegian shelf water and in the year-class formation in NE Arctic cod (formation in NE Arctic cod (Gadus morhuaGadus morhua))

Stig Skreslet1, Angel Borja2, Luca Bugliaro3, Georg Hansen4,

Ralf Meerkötter5, Ketil Olsen1 and Jean Verdebout3

1 Bodø Regional University (Norway), 2 AZTI (Spain), 3 EC-JRC Space Applications Institute (Italy), 4NILU (Norway), 5German Aerospace Center.

ICES Symposium The Influence of Climate Change on North Atlantic Fish Stocks

Bergen 11-14 May 2004

UVAC European Commission Contract No EVK3-CT-1999-00012

(Mare Cognitum, TASC)

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NE Arctic Cod abundance NE Arctic Cod abundance forced by natural vernal fershwater forced by natural vernal fershwater

discharge discharge

0

0.2

0.4

0.6

0.8

1

1946

1949

1952

1955

1958

1961

1964

1967

1970

1973

1976

Year of fresh-water discharge

Co

rrel

atio

n c

oef

fici

ent,

r

Estimated 0-group index1 year lag behind discharge

Norwegian landings ofBarents Sea juveniles3 year lag behind discharge

P=0.05

P=0.01

P = 0.01

P = 0.05

P = 0.05

P = 0.05

P = 0.05

P = 0.05

LofotenIslands

Barents Sea

Larvalsurvivallag 1yr

Catchjuvenileslag 3yr

P > 0.05

(Data from Skreslet 1976, 1986)

The few non-regulated rivers in Norway no longer represent the seasonal and interannual variation in freshwater discharge to the sea

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Planktonic components of the Planktonic components of the Vestfjord in late winter and Vestfjord in late winter and

springspring

Advection of cod eggs from spawning grounds in Lofoten.(Ellertsen et al. 1984)

Wintering (black) and reproduction (hatched) habitats of C. finmarchicus(Sømme 1934)

Annual sampling1983-present

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Calanus finmarchicusCalanus finmarchicus generation shift in the generation shift in the

Vestfjord areaVestfjord area

01

.04

.97

28

.04

.97

22

.05

.97

02

.06

.97

20

.06

.97

02

.07

.97

15

.07

.97

29

.07

.97

05

.09

.97

23

.09

.97

09

.10

.97

27

.10

.97

18

.12

.97

21

.01

.98

25

.03

.98

0

10000

20000

30000

40000

50000

60000

N m

-2

CICIICIIICIVCVCVIfCVIm

First generation was produced locally but disappeared in July.

Second generation was imported from the mid-Norwegian shelf in September-October.

Copepodite stage abundance in 0-370 m depth in the Saltfjord basin 1997-98.

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Wintering habitats for Wintering habitats for Calanus finmarchicusCalanus finmarchicusin the eastern Norwegian Seain the eastern Norwegian Sea

Current velocities > 40 cm s-1

(Poulin et al 1996) Accumulated stocks

NCCNAC

0

20000

40000

60000

80000

100000

120000

140000

160000

83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00

Average N m-2 sea surface in Saltfjord in OctoberN=5

Salt-fjord

(Data from Skreslet & Borja 2003)

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NAO Tropo-spheric

AO Strato-spheric

Calanus

sp

Season r p Season r p

finmar-chicus

Mar-Jul 0.717 0.01 Jul-Sep 0.587 0.05

hyper-boreus

- - - Jul-Sep 0.832 0.01

Atmospheric pressure gradients Atmospheric pressure gradients vs copepod abundance in the vs copepod abundance in the

SaltfjordSaltfjord

(Data from Skreslet & Borja 2003)

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H H

• Storms follow northerly tracks• Westerly winds in Norwegian Sea• Increased NAC advection • Much precipitation in Scandinavia

• Storms follow southerly tracks• Northerly winds in Norwegian Sea• Decreased NAC advection• Little precipitation in Scandinavia

H H

Geophysical effects of NAO Geophysical effects of NAO (North Atlantic Oscillation)(North Atlantic Oscillation)

(Greene & Pershing 2000)

NAOpositive

NAOnegative

H H

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SN

Boreal species

Arctic species

NorthAmerica

Eurasia

North-East Atlantic population North-East Atlantic population system of system of Calanus finmarchicusCalanus finmarchicus

Observations•Abundance negatively correlated with NAO in the North Sea (Fromentin & Planque 1996)•Abundance positively correlated with NAO in northern Norway (Skreslet & Borja, 2003)

Norway+

_

Hypothetical causal relationships•Population shifts latitudinal distribution with winds in the NE Atlanticand/or•Population size is a function of precipitation and river discharge

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Summer reproduction of Summer reproduction of C.finmarchicusC.finmarchicus in the Norwegian in the Norwegian

Coastal CurrentCoastal Current

SaltfjordTræna

NCC

SaltfjordTræna

NCC

Argo drifter velocities > 40 cm s-1

(Poulin et al 1996)Lofoten

Summer reproduction habitat

0

10000

20000

30000

40000

17-18June

23-24 July

19-20August

Av

era

ge

N m

-2 Nauplii I-VI 95% Conf.N = 7

0

10000

20000

30000

40000

50000

31 32 33 34 35Salinity

N m

-2

Y = - 10803X + 371383 r = 0.709 p < 0.001

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Abundance of wintering Abundance of wintering C. C. finmarchicusfinmarchicus as function of parental as function of parental

UVR exposure in MayUVR exposure in May

1 5 0 0

1 6 0 0

1 7 0 0

1 8 0 0

1 9 0 0

2 0 0 0

2 1 0 0

1984

1986

1988

1990

1992

1994

1996

1998

2000

Calan

us dos

es Ma

y

0

2 0 0 0 0

4 0 0 0 0

6 0 0 0 0

8 0 0 0 0

1 0 0 0 0 0

1 2 0 0 0 0

1 4 0 0 0 0

1 6 0 0 0 0

CFSO

abund

ance

M a y d o s e s

C F S O

y = - 0 . 0 0 6 9 x + 2 1 3 3 . 1

R 2 = 0 . 6 9 2 3

1 4 0 0

1 5 0 0

1 6 0 0

1 7 0 0

1 8 0 0

1 9 0 0

2 0 0 0

2 1 0 0

C F S O A b u n d a n c e

Calan

us dos

es Ma

y

2 0 0 0 0 4 0 0 0 0 6 0 0 0 0 8 0 0 0 0

1 5 0 0

1 6 0 0

1 7 0 0

1 8 0 0

1 9 0 0

2 0 0 0

2 1 0 0

1984

1986

1988

1990

1992

1994

1996

1998

2000

Calan

us dos

es Ma

y

0

2 0 0 0 0

4 0 0 0 0

6 0 0 0 0

8 0 0 0 0

1 0 0 0 0 0

1 2 0 0 0 0

1 4 0 0 0 0

1 6 0 0 0 0

CFSO

abund

ance

M a y d o s e s

C F S O

y = - 0 . 0 0 6 9 x + 2 1 3 3 . 1

R 2 = 0 . 6 9 2 3

1 4 0 0

1 5 0 0

1 6 0 0

1 7 0 0

1 8 0 0

1 9 0 0

2 0 0 0

2 1 0 0

C F S O A b u n d a n c e

Calan

us dos

es Ma

y

2 0 0 0 0 4 0 0 0 0 6 0 0 0 0 8 0 0 0 0

P < 0.01

Biologically weighted doses of lethal UVR on eggs in the G1 reproduction habitat, calculated from satellite data on ozone and cloudiness in MayOctober abundance of G2 copepods in the Saltfjord (CFSO)

Significant negative correlation before the summer reproduction in June-August may indicate potential effects on 1st generation:

a) ontogenyb) sexual maturationc) ovulationd) mating

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600

700

800

900

1000

1100

1200

1300

1973

1975

1977

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

ME

AN

(3

mo

nth

s) M

AX

DO

SE

S

0

50

100

150

200

250

300

350

RE

CR

UIT

ME

NT

mean

Recruit

r = 0.53, p < 0.01

O-gr index

UVR

ICES 0-group abundance of NE Arctic Cod ICES 0-group abundance of NE Arctic Cod as function of average UVR in Lofoten in as function of average UVR in Lofoten in

March-MayMarch-May

Speculation: UVR disinfects the aquatic environment of eggs and larvae• Kills bacteria• Trigger viral attacks on bacteria

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SummarySummary

Freshwater outflow from Norway probably forces recruitment to the NE Arctic cod stock via food-web interactions that are not clear.

The population system of Calanus finmarchicus plays a key role in the transfer of the troposphere’s hydrological forcing of cod recruitment.

The 1st generation of C. finmarchicus reproduce during summer in the NCC, under influence of meltwater outflow and solar radiation of UV.

The 2nd generation of C. finmarchicus and a generation of C. hyperboreus invade north Norwegian fjords in October.

The stock abundance of C. finmarchicus in October is negatively correlated with UVR in May, but positively correlated with NAO in March-July, and AO in July-September.

UVR is not detrimental for juvenile cod biology but may interact with the microbial environment of cod eggs and larvae in Lofoten in favourable ways

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Future Future challengeschallenges

The complex forcing of climate on cod population systems cannot be solved by only disciplinary field-work, and time-series analyses

Modern models for numerical marine ecosystem analyses allow for simulation of zooplankton production, but fail to assimilate the relevant forcing of river discharge

The lack of functions that couple zooplankton production and fish population models is an obstacle for understanding how climate forces fish production

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Carni-vores

CalanusCV

Fresh-water

CodSSB

Fuel

Fishing

NI-NVI

CI-CV

CVI

NI-CV

CIV-CV

CVI

Codlarvae

0 grcod

I-IIIgr cod

I-IVgr cod

II-Vgr cod

Springbloom

Summerbloom

0

1

2

3

Wind

Solarradia-tion

Tides

Atlanticheat

Summerbloom

Autumnbloom

Norway

Heat sink

Storage

Producer

Consumer

Physical forces

NE Arctic cod(Gadus morhua)

C. finmarchicus

Zooplanktivores

Phytoplankton

Source

Interaction

Carni-vores

CalanusCV

Fresh-water

CodSSB

Fuel

Fishing

NI-NVI

CI-CV

CVI

NI-CV

CIV-CV

CVI

Codlarvae

0 grcod

I-IIIgr cod

I-IVgr cod

II-Vgr cod

Springbloom

Summerbloom

0

1

2

3

Wind

Solarradia-tion

Tides

Atlanticheat

Summerbloom

Autumnbloom

Norway

Heat sink

Storage

Producer

Consumer

Physical forces

NE Arctic cod(Gadus morhua)

C. finmarchicus

Zooplanktivores

Phytoplankton

Source

Interaction

Forcing of trophic energy flow in the Forcing of trophic energy flow in the food-web of juvenile NE Arctic Codfood-web of juvenile NE Arctic Cod

(Modified from Skreslet, 1997)

+(UVR)

(UVR)

-