ICES Symposium
This presentation is the property of its rightful owner.
Sponsored Links
1 / 14

Stig Skreslet 1 , Angel Borja 2 , Luca Bugliaro 3 , Georg Hansen 4 , PowerPoint PPT Presentation


  • 72 Views
  • Uploaded on
  • Presentation posted in: General

ICES Symposium The Influence of Climate Change on North Atlantic Fish Stocks Bergen 11-14 May 2004. Some roles of climate in the population ecology of Calanus finmarchicus (Copepoda) in mid-Norwegian shelf water and in the year-class formation in NE Arctic cod ( Gadus morhua ).

Download Presentation

Stig Skreslet 1 , Angel Borja 2 , Luca Bugliaro 3 , Georg Hansen 4 ,

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Stig skreslet 1 angel borja 2 luca bugliaro 3 georg hansen 4

ICES Symposium

The Influence of Climate Change on North Atlantic Fish Stocks

Bergen 11-14 May 2004

Some roles of climate in the population ecology of Calanus finmarchicus (Copepoda) in mid-Norwegian shelf water and in the year-class formation in NE Arctic cod (Gadus 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.

UVAC

European Commission Contract No EVK3-CT-1999-00012

(Mare Cognitum, TASC)


Ne arctic cod abundance forced by natural vernal fershwater discharge

Barents

Sea

Estimated 0-group index

1 year lag behind discharge

Catch

juveniles

lag 3yr

P=0.01

P > 0.05

Larval

survival

lag 1yr

P = 0.05

Lofoten

Islands

P= 0.05

P=0.05

P = 0.05

Norwegian landings of

Barents Sea juveniles

3 year lag behind discharge

P = 0.01

P = 0.05

P = 0.05

(Data from Skreslet 1976, 1986)

NE Arctic Cod abundance forced by natural vernal fershwater discharge

The few non-regulated rivers in Norway no longer represent the seasonal and interannual variation in freshwater discharge to the sea


Planktonic components of the vestfjord in late winter and spring

Planktonic components of the Vestfjord in late winter and spring

Advection of cod eggs from spawning grounds in Lofoten.

(Ellertsen et al.

1984)

Annual sampling

1983-present

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

(Sømme 1934)


Calanus finmarchicus generation shift in the vestfjord area

Calanus finmarchicusgeneration shift in the Vestfjord area

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

  • First generation was produced locally but disappeared in July.

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


Stig skreslet 1 angel borja 2 luca bugliaro 3 georg hansen 4

Wintering habitats for Calanus finmarchicus

in the eastern Norwegian Sea

Average N m-2 sea surface in Saltfjord in October

N=5

Accumulated stocks

Salt-

fjord

NCC

NAC

(Data from Skreslet & Borja 2003)

Current velocities > 40 cm s-1

(Poulin et al 1996)


Stig skreslet 1 angel borja 2 luca bugliaro 3 georg hansen 4

Atmospheric pressure gradients vs copepod abundance in the Saltfjord

(Data from Skreslet & Borja 2003)


Stig skreslet 1 angel borja 2 luca bugliaro 3 georg hansen 4

Geophysical effects of NAO

(North Atlantic Oscillation)

NAO

positive

NAO

negative

H

H

(Greene & Pershing 2000)

H

H

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


Stig skreslet 1 angel borja 2 luca bugliaro 3 georg hansen 4

North-East Atlantic population system of Calanus 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)

Eurasia

North

America

Arctic species

  • Hypothetical causal relationships

  • Population shifts latitudinal distribution

  • with winds in the NE Atlantic

  • and/or

  • Population size is a function of

  • precipitation and river discharge

+

N

S

Norway

_

Boreal species


Summer reproduction of c finmarchicus in the norwegian coastal current

Nauplii I-VI 95% Conf.

N = 7

Y = - 10803X + 371383

r = 0.709

p < 0.001

Summer reproduction of C.finmarchicus in the Norwegian Coastal Current

Argo drifter velocities > 40 cm s-1

(Poulin et al 1996)

Lofoten

Summer reproduction habitat


Abundance of wintering c finmarchicus as function of parental uvr exposure in may

Biologically weighted doses of lethal UVR on eggs in the G1 reproduction habitat, calculated from satellite data on ozone and cloudiness in May

October 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) ontogeny

b) sexual maturation

c) ovulation

d) mating

Abundance of wintering C. finmarchicus as function of parental UVR exposure in May

P < 0.01


Ices 0 group abundance of ne arctic cod as function of average uvr in lofoten in march may

O-gr index

UVR

r = 0.53, p < 0.01

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

  • Speculation: UVR disinfects the aquatic environment of eggs and larvae

    • Kills bacteria

    • Trigger viral attacks on bacteria


Summary

Summary

  • 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


Future challenges

Future challenges

  • 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


Stig skreslet 1 angel borja 2 luca bugliaro 3 georg hansen 4

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

(UVR)

+

(UVR)

-

(Modified from Skreslet, 1997)


  • Login