The importance of the Banc d’Arguin (Mauritania) for juvenile fish has been investigated in September 1988. Fish have been sampled with a 2 m beam trawl at 50 locations in the coastal zone between Cap Sainte Anne and Cap Timiris. Water depth varied between 1 and 16 metres. Temperature and salinity at each station have been measured, as well as the weight of the catch and total length of the individual fish. The largest catches — in numbers as well as in weight — were obtained around the shallows of Tidra and Arel. This region has a large diversity in species, and contains large numbers of juvenile fish and cephalopods. The deeper areas seem to be much poorer in species, but average length and weight of the sampled fish are higher than around Tidra and Arel.