Prsentation PowerPoint

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Use of Oceanic Observations in Fisheries Science
Climate influence on fish population recruitment
Thomas Brunel Jean Boucher IFREMER Brest -
Ressources Halieutiques
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Basis of fish stocks management
management procedure regulate fishing
activity ( of ships, T.A.C.) to make the best
use of each recruiting year class.
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Improving management by taking account of the
effect of the environment
But this system is also highly influenced by
climatic variability
Management could be improved by a better
knowledge of recruitment oceanic conditions
climate relationships.
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Influence of climate on European fish recruitment
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Influence of climate on European fish recruitment
Main trends in recruitment
Method
PCA
Principal components Linear combinations of the
41 rct time series
Dominant modes of recruitment variations
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Influence of climate on European fish recruitment
synchronous variations among
populations
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Influence of climate on European fish
recruitment Link between recruitment changes and
climate.
Fish recruitment (PC1)
Northern hemisphere temperature
r - 0.71
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How does climate affect fishes ?
Physical factors
Biological communities
Climate
Fish recruitment
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How does climate affect fishes ?
Physical factors
Biological communities
Plankton abundances
Climate
___ Calanus finmarchicus ___ euphausiids
PC 1 phytoplankton
1. direct effect through changes in the physical
environment
Fish recruitment

• Temperature
• Wind mixing and turbulence
• Changing currents and transport

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Climatic forcing of European oceanic
condition Example of SST variability
PC1 (26) influence of global warming
PC2 (22) influence of the North Atlantic
Oscillation
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Fish - climate relationships

• large scale effects of climate variations on
  fish stocks recruitment.
• Climate acts through its effect on oceanic
  physical environment (directly or via trophic
  relationships) .
• - Need to integrate oceanic variability to
  explain the link between climate and fishes.

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The needs of fisheries biologists

• 1 . to understand the present observations on
  fish- climate relationships
• we need to know the link between global climate
  variations and local physical conditions on
  continental shelves
•  Large scale patterns of physical variability
  vs. local heterogeneities of oceanic response to
  climate variations
• 2 . to make previsions on recruitment strength
  
• Short term to forecast next year recruitment ,
  we need to know oceanic conditions in real time,
  and to have short term previsions (month) of the
  physical state of the ocean (e.g. thermocline
  depth, temperature)
• Long term to know how stocks productivity
  will vary during the next decade, we need to know
  how oceanic environment will vary, under
  different climatic scenarios?
•  If global warming goes on, will Bay of Biscay
  water continue to warm too?