The trawlfauna of the Mauritanian shelf (Northwest Africa) : density, species composition, and biomass

The taxonomic and quantitative composition of the trawlsamples taken in May 1988 on the shelf off the Banc d'Arguin, Mauritania, at depths of 20-100 m were studied. On the basis of species abundance 3 groups could be distinguished each corresponding to a subregion of the shelf: an inner shelf, a midshelf and an outer shelf station group. The biomass of mobile epifauna and fish was lowest on the inner shelf stations where large sessile filter feeders dominated. Demersal fish and crustaceans were more abundant on the outer shelf. The relative richness and composition of the epifauna are discussed with respect to the hydrological conditions of the region. The epifaunal composition of the Mauritanian region was compared to that of the southern North sea.