Note on the group size and behavior of Guiana dolphins (Sotalia guianensis) (Cetacea: Delphinidae) in Marapanim Bay, Pará, Brazil

Abstract

Guiana dolphins (Sotalia guianensis) are found in coastal and estuarine waters of the Caribbean and the South Atlantic from at least Nicaragua and probably Honduras to Santa Catarina, Brazil (Simões-Lopes, 1988; Edwards and Schnell, 2001; da Silva et al., 2010 this volume). An important concentration of this species is found in Marapanim Bay, eastern Pará State, Brazil, but despite its proximity to shore this population is poorly known (Lima et al., 2006). In Cispatá Bay, Colombia, groups consisted of ten or fewer individuals, and their size did not change significantly with season (García and Trujillo, 2004). In Guanabara Bay, southeast Brazil, groups ranged from one to 40 individuals (Azevedo et al., 2005), whereas in the Cananéia region most groups consisted of two to twelve individuals (Geise et al., 1997; Santos and Rosso, 2007). The population of Marapanim Bay, Pará, Brazil, is likely to be resident but its group characteristics have not been reported. The aim of this work was, therefore, to provide information on group size for this population as well as patterns of behavior.