Potential spawning habitat of sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) in the Bay of Biscay

No abstracts are to be cited without prior reference to the author.

Large amplitude variations in the recruitment in small pelagic fish results from interaction between a fluctuating environment and population dynamics processes such as spawning. The spatial extent and location of spawning, which is critical to the fate of eggs and larvae, can vary strongly from year-to-year, as a result of changing population structure and environmental conditions. Spawning habitat can be divided in 'potential spawning habitat', defined as habitat where the hydrological conditions are suitable for spawning, 'realised spawning habitat', defined as habitat where spawning actually occurs, and 'successful spawning habitat', defined as habitat where fish have spawned and from where successful recruitment has resulted. Using biological data collected during the period 2000-2004, as well as hydrological data, we investigate the role of environmental parameters in controlling the potential spawning habitat of anchovy and sardine in the Bay of Biscay. Modelled relationships between anchovy and sardine spawning are used to predict potential spawning habitat from hydrodynamical simulations. The results show that the seasonal patterns in spawning if the two species are well reproduced by the model, indicating that hydrological changes may explain a large fraction of spawning spatial dynamics. Such model may prove useful in the context of forecasting potential impacts of future environmental changes on sardine and anchovy reproductive strategy in the north-east Atlantic.