Distribution of the Antillean manatee, Trichechus manatus manatus, on the northern coast of Brazil

Abstract

The Antillean manatee, Trichechus manatus manatus, is now considered the most endangered aquatic mammal of Brazil. In 1992 and 1993 a coastal survey off the Maranhão, Pará and Amapá states was performed aiming to identify the distribution on the species on the northern Brazilian coast. The Maranhão State was considered as a part of the northern region on environmental grounds. The survey covered 3,000 km in 145 localities and 262 interviews with people involved in fishing activities were carried out. Discontinuous areas of the species were found, but that was not to be expected, owing to the conservation and environmental characteristics of area. The Amazon Gulf displays more favourable conditions to the Amazonian manatee, Trichechus inunguis, and the occurrence of the Antillean manatee was registered in few localities where the sea waters penetrate into Pará River. enablinf the occurrence of two sirenian species in simpatry. According to early local inhabitants poaching probably led the local species to extinction. The discontinuity of the occurrence area bears out the hypothesis that the Antillean manatee does not perform great migrations along the Brazilian coast and suggests the isolation of small remaining groups. The presence of both species in the Amazon Gulf suggests simpatry and the existence of hybrids. Biological and genetic studies are called for in order to confirm this hypothesis.