Understanding of anchovy’s migration cycle of in the Bay of Biscay through individual-based fish movement models
Dimitrios Politikos1, Martin Huret1, Pierre Petitgas2
1 IFREMER, Centre de Brest, STH, BP 70, 29280, Plouzane, France
2 IFREMER, Centre de Nantes, EMH, BP 21105, 44311 Cedex 03, Nantes, France
The life cycle of small pelagic populations is strongly influenced by seasonal processes as reproduction and migration, which are driven by periodic environmental variations. Modelling of fish movement behavior within a heterogeneous marine environment is a challenging but also key issue for understanding the effect of environmental factors and climatic change on fish habitat availability and connectivity occurring at the species level. Towards the building of a full life cycle fish model, the present study provides a better understanding of the mechanisms underlying anchovy annual migration behavior in the Bay of Biscay and evaluates the simulated migration patterns against spring/autumn stock distribution maps and growth histories derived from survey data. To this end, we applied a horizontal two-dimensional Individual Based Model (IBM) coupled to the ECO-MARS3D physical-biogeochemical model. Seasonal sea water temperature and zooplankton fields derived from the ECO-MARS3D were used as external forcing for the fish model. Two movement algorithms (restricted area search and kinesis) were employed to compare the anchovy distribution patterns simulated under different assumptions of fish behavior. The Dynamic Energy Budget model (DEB) was used to represent individual growth and reproduction taking into account seasonally varying food and temperature conditions. Finally, the strengths and the key weaknesses of the adopted modelling tools will be discussed.