FOREVAR - Mesoscale environmental forcing and variability of pelagic populations in the Bay of Biscay

FOREVAR - FORcage Environnemental a meso-echelle et VARiabilite des
populations pelagiques dans le golfe de Gascogne (Mesoscale
environmental forcing and variability of pelagic populations in the
Bay of Biscay)

This project is based on the correspondence between the hydrodynamical
concept of mesoscale structures and the biological concept of habitat.
The project concentrates on the investigation of the relationships
between mesoscale hydrodynamical structures and a populations' life
cycle. A particular population is described as an ensemble of
mesoscale spatial units and the global response of the population to
environmental forcing is then analysed as the result of the multiple
mesoscale responses. The project particularly concentrates on two
types of population response: recruitment and spatial organization.

The target population is the anchovy in the Bay of Biscay. The
spatial distribution of this population is relatively limited (in
comparison with highly migratory species in the same area), its life
duration is short, it is highly dependent on hydroclimatic variations
and it is an economically important stock. The Bay of Biscay is
constituted by a collection of mesoscale features which can be
activated or not, depending on meteorological conditions. 3D
hydrodynamical models, such as the one developed at IFREMER allow for
realistic reconstruction of the key mesoscale structures so that it is
possible to study the details of the bio-hydrodynamical coupling
between anchovy habitats during successive life stages (e.g. spawning,
larval stages) and the activation/de-activation of physical
structures).

The current results from the programme include the determination of:
- spatial distribution of spawning areas
- the influence of wind regimes
- regional variations in larval growth and food web structures
- spatial structures of fish schools
- a recruitment forecast index
- evaluation of the anchovy stock and cartography of adult
distribution and spawning areas are currently produced annually
and used for management advice