Patterns of social association in the franciscana, Pontoporia blainvillei

Abstract

Little is known from living animals about the social patterns of the franciscana, Pontoporia blainvillei , a small dolphin inhabiting a narrow strip of coastal waters off Argentina, Uruguay, and Brazil. These dolphins tend to be found in small groups, typically composed of two or three individuals (Bordino et al. 1999). Throughout much of the species' range, franciscanas encounter artisanal gill nets (Praderi 1989, Corcuera et al. 1994, Bertozzi and Zerbini 2002, Bordino et al. 2002, Secchi et al. 2003). Entanglement in these nets results in the deaths of thousands of individuals each year, at levels that are likely unsustainable (Bordino and Albareda 2004, Cappozzo et al. 2007).