Feeding behaviour and trophic environment of Engraulis encrasicolus (L.) in the Bay of Biscay

The main environmental abiotic and biotic factors and the feeding activity of adult anchovy were analysed in the Bay of Biscay during the spawning per iod (spring) in neritic and oceanic areas characterized by high anchovy den sities. In the neritic area located in the water plume of the Gironde estuary ('GIR ') chlorophyll concentrations and zooplankton biomass, above and below the thermocline, were higher than in the oceanic area ('FAC'). Copepods constit uted the dominant group of zooplankton (greater than or equal to 85%); the main species were, decreasingly: Clausocalanus sp., Paracalanus parvus, Onc ea sp., Corycaeus sp., Temora longicornis and Oithona sp. in GIR and Clauso calanus sp.,P. parvus, Oithona sp., Centropages chierchiae and Acartia clau si in FAC area. Anchovy feeding activity mainly occurred during the day and was higher in t he FAC area than in the GIR area. Food ingested constituted exclusively of zooplankton, in particular copepods that made up about 98%; T. longicornis, Oncea sp. and Corycaeus sp, were the main species in the 'GIR' area and C. chierchiae in the FAC area. Considering anchovy distribution and feeding characteristics, (fullness ind ex, preponderance index especially) the results showed that, in both areas, biting (anchovy taking of prey) is the dominant or exclusive pattern of an chovy feeding behaviour. Feeding efficiency appears to be most related to z ooplankton specific composition than to zooplankton abundance. (C) 1999 Aca demic Press.