Relationships between anchovy (Engraulis encrasicolus L.) recruitment and the environment in the Bay of Biscay

Abstract

SUMMARY: Oceanographic conditions in spring and summer, caused by northerly-easterly winds of medium and low intensity, in the Bay of Biscay seem to induce good levels of recruitment to the anchovy population. This wind regime produces upwelling conditions with, generally, low degrees of turbulence. Indices of upwelling and turbulence were built and proved significantly correlated with an index of annual recruitment of anchovy (p<0.0001). Both physical parameters explain about 70% of the variance in the index of recruitment of the Bay of Biscay anchovy. The likely explanations for this relationship are outlined and discussed in the light of the current hypotheses about the processes determining recruitment of marine populations. Enhancement of the productivity and increased availability of food to the early life history stages of anchovy seem to be the main consequence of the prevalence of weak upwelling conditions in this area during spring.