The feeding habits of Scyliorhinus canicula and Galeus melastomus were investigated by analysing the stomach contents from 6 036 individuals collected on research surveys in the southern region of the Bay of Biscay during the autumns of 1988-2001. These catshark species are the most abundant scyliorhinids on the Cantabrian shelf. Their depth ranges partly overlap, although they occur in different habitats. Both catshark species are opportunistic scavengers, with their main prey being fish and crustaceans. Diets of the two species overlap; they are most similar in individuals <30 cm total length (TL) where euphausiids are important prey, but, for individuals ≥30 cm TL, fish (mainly discarded from trawlers) are important prey. Lesser-spotted catshark are mostly benthic feeders and they feed on a greater diversity of prey than blackmouth catshark, which are more suprabenthic. Resource partitioning between the two species appears to depend on the better vision of the blackmouth catshark, which feeds more in the water column whereas the better developed olfactory sense of the lesser-spotted catshark is an adaptation to benthic feeding. The broad diets of these catshark species and their consumption of fish discarded from trawlers may make them good indicators of fishinginduced change in the Cantabrian Sea ecosystem.

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N. 1998. Importance of discarded blue whiting (Micromesistius poutassou) in the diet of lesser spotted dogfish (Scyliorhinus canicula) in the Cantabrian Sea. -ICES Journal of Marine Science, 55: 331-341.The blue whiting is the most important demersal species caught by the Spanish trawler fleet in the southern Bay of Biscay. Lesser spotted dogfish are not a commercial by-catch, and are discarded immediately after sorting. During 1994 the contents of 1094 dogfish stomachs were analysed. The results show that lesser spotted dogfish with a total length of >17 cm eat blue whiting throughout the year. The length range of blue whiting found in lesser spotted dogfish stomachs was similar to the length range discarded by the fishery. Blue whiting account for 20% of the stomach volume in lesser spotted dogfish 30-50 cm long. From the state of digestion of blue whiting prey, and the comparative analysis of the size distributions of blue whiting in lesser spotted dogfish stomachs and in the fishery, it appears that many of these blue whiting are discards, consumed when already dead or damaged. The impact of this supplementary food on lesser spotted dogfish abundance is discussed.1998 International Council for the Exploration of the Sea

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