The role of cephalopods as forage for the demersal fish community in the southern Bay of Biscay

During annual autumn bottom trawl surveys from 1988 to 1996 (except 1989). 43 907 stomach contents of 27 demersal fish species were analysed. These species represent the community of demersal fish in the southern Bay of Biscay. A small proportion of their stomach contents - 3% by volume and 0.66% by number of prey - comprised cephalopods, both small (e.g. Alloteuthis media, Alloteuthis subulata, Rossia macrossoma and other Sepiolidae) and large species (e.g. Illex coindetii, Todaropsis eblanae and Loligo spp.). In predators with a total length smaller than 50 cm, the percentage of cephalopod prey did not reach 1.5% of total volume. Within this length range, cephalopods occurred, at higher percentages, in stomachs of Lophius piscatorius, Lophius budegassa, Scyliorhinus canicula, Pagellus acarne, Raja montagui, Galeus melastomus and Aspitrigla cuculus. Predators larger than 50 cm total length consumed more cephalopods than smaller ones (8% of total volume), but only lophiids and elasmobranch fish fed on them, with a percentage in terms of volume reaching 17% in large specimens of L. piscatorius. We used annual abundance data on cephalopods from these surveys to look for possible correlations between their annual abundance in the ecosystem and their importance in the diet of the set of predators studied. The correlations between their abundance in the surveys and in the stomachs were not significant, except in the cases of Alloteuthis spp. and the group formed by Octopus spp. and Eledone cirrhosa, whose abundance indices by number and weight in the different surveys correlated positively with their number and volume percentages in the stomachs. (C) 2001 Elsevier Science B.V. All rights reserved.