Revue des Travaux de l’Institut des Pêches Maritimes
Distribution, Mauritania, Senegal, Sousa teuszii, Atlantic humpback dolphin, Stenella longiristris, Spinner dolphin, orcinus orca, Killer whale, Monk seal, Monachus monachus, Harbour porpoise, Phocoena phocoena
About twenty species of marine mammals are actually known for the fauna of the north-west african coast (Rio de Oro, Mauritanie, Senegal). This large number of species seems to be related to cold waters areas connected with « upwelling» effect. New data, recently collected, mainly during summer cruise (1973) of the « Thalassa », supply new information about the distribution of some species. Souza teuszii shows a northern limit of its range at about 200 N (Bane d’Arguin) and Stenella longirostris at about 16Q 15 N. The Common Porpoise (Phocoena phocoena) seems to be more frequent in Mauritanian waters than in Morrocan ones, and Orcinus orca is commonly observed between Cap Blanc and Cap Timiris. In July and september newborn pups of the Monk seal (Monachus monachus) were found at the Rio de Oro colony. Estimation of the local population there is about fifty, this number showing a certain steadiness for many years.