A biophysical model for simulating early life stages of sardine in the Iberian Atlantic stock

The Iberian sardine (Sardina pilchardus) is a traditional fishery in western Iberia that is economically important in Portugal and in Galicia (NW Spain). The International Council for the Exploration of the Seas (ICES) advice for the sardine in regions VIII and IXa in 2013 indicated that the biomass has decreased since 2006 and recruitment has been below the long term average since 2005. Recruitment is very variable, so it is important to understand the underlying processes driving this variation in order to manage the fishery effectively. In this study, a biophysical model was used to simulate the early life (egg and larval) stages of sardine. A high resolution hydrodynamic model for North and Northwest Iberia was used to force a Lagrangian Individually-Based Model (IBM) that simulated advection and dispersion (both horizontal and vertical) and included some biological behaviour. A Lower Trophic Level (LTL) model coupled to the hydrodynamic model was also used to get some insight on recruitment for years 2006-2007. Additionally, since in this area there are two different spawning grounds that could be associated with two eventually different populations, we have tried to show how the model can be used for giving insight on stock connectivity and therefore can contribute to stock delineation.