Report of the Working Group on Distribution, Habitat Characteristics and Preferences, and Group Size

Abstract

INTRODUÇÃO: The genus Sotalia includes two species: Sotalia guianensis distributed along the coast of Brazil, northern South America, and throughout the Caribbean Sea up to Honduras in Central America (Flores and da Silva, 2009), and Sotalia fluviatilis, confined to the rivers of the Amazon River basin. Although widely distributed in the Amazon basin and familiar wherever it occurs, S. fluviatilis (known as tucuxi in the Brazilian Amazon) is poorly studied. Due to its speed and small size as well as the turbidity or opacity of most Amazonian rivers, studies of the tucuxi are rare and few attempts have been made to quantify its habitat preference and ecology (da Silva and Best, 1994; Martin et al., 2004). On the other hand, due to its costal distribution, occurrence in bays and estuaries, larger body size and behaviour, and a high level of fisheries interaction, S. guianensis is better known than its fluvial congener. However, the available information on the distribution, habitat characteristics and habitat use, as well as group size and group structure of these dolphins is not well known and most of studies are concentrated where the species is more abundant and of easy access.