SC/65a/SM17 1 How far does it go along the coast? Distribution and first genetic analyses of the boto (Inia geoffrensis) along the coast of Pará, Amazon, Brazil Alexandra F. Costa 1 , Renata Emin-Lima 1 , Larissa R. Oliveira 2 , Victor Valiati 2 , José de Sousa e Silva Júnior 1 and Salvatore Siciliano 3 1 Museu Paraense Emílio Goeldi, Coordenação de Zoologia, Setor de Mastozoologia, Grupo de Estudos de Mamíferos Aquáticos da Amazônia (GEMAM), Av. Perimetral, 1901. Terra Firme, Belém, Pará, Brazil, 66077-530. 2 Universidade do Vale do Rio dos Sinos – UNISINOS. Av. Unisinos nº 950, Centro 2, bloco D, sala 2 D221, São Leopoldo, RS, 93022-000, Brazil. 3 Escola Nacional de Saúde Pública/FIOCRUZ. Rua Leopoldo Bulhões, 1.480 – sala 611, 6º. andar, Manguinhos. Rio de Janeiro, RJ Brazil 21041-210 and Instituto Megafauna Marinha, Cabo Frio, Brazil. Introduction The boto or Amazon river dolphin (Inia geoffrensis) has been subject to intensive ecological studies during the last decade. Several authors consider the boto the best studied and most well known of the river dolphins. Despite such increase in knowledge in many parts of its range throughout the Amazon and Orinoco drainages, there is no information available on its distribution and ecology in the Amazon delta, including the south Amazon river channel, Marajó bay and Belém area, Pará state, Northern Brazil. In fact, the distribution of I. geoffrensis in the Marajó bay and near Belém has remained obscure for long time. Since November 2005 intensive surveys along the coast of Pará were conducted in search of stranded aquatic mammals. Two areas were selected for regular surveys: east coast of Marajó Island and Maiandeua Island. Additional surveys included several other locations, such as the northeast coast of Marajó Island and Curuçá, in the east coast of Pará state, which lacked any aquatic mammal survey and collection. Since then, several new records of I. geoffrensis have been confirmed. Concomitantly, there was an increase of biological material collected, resulting from the detection and recovery of carcasses during beach surveys. This material has been deposited in the mammal collection of Museu Paraense Emílio Goeldi. In order to analyze the existence of genetic variation for Amazon River dolphin, analysis of control region and cytochrome b were made to infer about subspecies of Inia geoffrensis for the east coast of Marajó Island and Curuçá Bay. Results of genetic analyses suggests that one specimen from the east coast of Pará state represent a different and isolated geographic form of boto, highly distant in terms of genes from the remaining subspecies proposed. The results of this study points to a common and regular presence of I. geoffrensis in the Marajó bay and the surrounding coastline of Marajó Island, to the east coast of Pará state. Material and Methods Study area and field work Monthly beach surveys were regularly conducted since November 2005 in two separate areas along the coast of Pará (Figure 1). These areas are: (a) the east coast of Marajó Island and (b) around Maiandeua Island, Maracanã County, Pará state. The east coast of Marajó Island is formed by Marajó bay, which is ecologically a part of Amazon Basin (Goulding et al., 2003), where important rivers flow as Tocantins, Mojú, Acará and Guamá. These rivers form the whole complex of Guajará Bay, and part of the discharge of the Amazon River (Isaac and Barthem, 1995; França and Souza Filho, 2003). Maiandeua Island is surrounded by Marapanim Bay to the west and Maracanã Bay to the east. Marapanim bay is formed by the estuary of Marapanim River, located in the northeastern of Pará state. The surveys were conducted along 68 km of beaches, including 58 km along the east coast of Marajó and 10 km around Maiandeua