The Project “Botos Costeiros” (coastal dolphins) is one of the oldest GEMARS projects. The project began in 1991 with the monitoring and photographic record of Lahille's bottlenose dolphins from the estuaries of the Tramandaí and Mampituba rivers, on the northern coast of Rio Grande do Sul, southern Brazil.
Bottlenose dolphins, like many other species of marine mammals, can have their individuals recognized, through photographs, from natural marks (e.g. small cuts and scratches) existing, especially on the dorsal fin.
The individual recognition of each dolphin allows us to follow them over time and discover important information about their behavior, including the patterns of movements and levels of association between individuals.
Studies carried out by GEMARS have made it possible to discover, for example, that dolphins have a high degree of residence and site fidelity to the estuaries of the region. One of the dolphins, known as Geraldona by artisanal fishermen, has regularly used the Tramandaí River estuary since 1991. Currently, GEMARS has concentrated its studies on the region of the Mampituba River and adjacent coastal areas.
The data obtained by the project reveal that more than 20 dolphins use the coastal region of Torres and Passo de Torres, although only a small number frequent the inner waters of the Mampituba River. In this area, as well as in the Tramandaí and Laguna estuaries, there is a unique association between dolphins and artisanal fishermen, known as cooperative fishing. Due to the uniqueness of this association and its social and economic importance, the project also aims to value and strengthen artisanal fishing in the region.
It is worth mentioning that the Lahille´s bottlenose dolphins are considered threatened with extinction, being included in the Official List of Endangered Species of Wild Fauna in Rio Grande do Sul. The information obtained by the project, therefore, also seeks to assist in the adoption of management measures that guarantee the long-term conservation of these dolphins in the region.
