Larval dynamics and recruitment modelling of the Moroccan Atlantic coast sardine (Sardina pilchardus)

An age structured population dynamics model of the Moroccan Atlantic coast sardine is presented. The model focuses essentially on the larval phase which is composed of two stages: endogenous and exogenous stages called, respectively, S1 and S2. The entrance in stage S2, here called pre-recruitment, is characterized by yolk resorption and mouth opening. At the beginning of stage S2, there is a short but critical period when larvae have consumed their vitelline reserves but are not yet able to move enough in quest of food.The recruitment in the juvenile phase occurs when the larva reaches a threshold size related to a certain amount of food it has to ingest during the whole stage S2.Larval mortality and feeding are density-dependent. A function ω(t,X)ω(t,X) is introduced to take implicitly into account the impact of environmental and hydrographic conditions variability (upwelling, enrichment, retention, ……, etc.) on pre-recruitment.