Distribution, status, and biology of the Atlantic Humpback Dolphin, <i>Sousa teuszii</i> (Kükenthal, 1892)

Abstract

The distribution, status, and biology of the Atlantic humpback dolphin (Sousa teuszii) is critically reviewed, and results of recent research are discussed. The species’ known distribution limits are, in the north, Dahkla Bay (23º50’N), Western Sahara, and in the south, Tombua (15º47’S), southern Angola. Its habitat is predominantly inshore coastal and estuarine, over soft-sediment bottoms. There is no evidence that it might occur beyond the brackish waters of estuaries into a riverine, fresh-water habitat. There are no records for the Senegal, Casamance, and Niger Rivers. A total of eight stocks are provisionally discerned for management purposes. Six of these are confirmed-contemporary (based on recent records), including Dahkla Bay, Banc d’Arguin, Saloum-Niumi, Canal do Gêba-Bijagos, South Guinea, and Angola. Two stocks, the Cameroon Estuary and Gabon, are historical, and new fieldwork needs to confirm their current presence. No inference is made on degree of reproductive isolation and biological population status of any named stock. The potential existence of a western Togo stock is currently under study. Nine coastal states, including Morocco (Western Sahara), Mauritania, Senegal, The Gambia, Guinea-Bissau, Guinea- Conakry, Cameroon, Gabon, and Angola are confirmed range states. While historically distribution may have been quasi-continuous over the species’ range, indications of contemporary distribution gaps are emerging. Ongoing monitoring of cetacean takes in coastal fisheries off western Ghana, and experimental whale-watching sorties in Bénin have not yielded a single record. The species has either become rare through human-related pressures or, less likely, it never lived there. For most other areas there is little, if any, information due to the lack of research