The behavior of Sotalia guianensis (Van Bénéden) in Pernambuco coastal waters, Brazil, and a further analysis of its reaction to boat traffic

Abstract

There is still little knowledge about the behavior of the estuarine dolphins and also the way they react to the presence of different types of vessels. The aim of the present study was twofold: to investigate the behavior of estuarine dolphins in four locations in Pernambuco, Brazil, and also their reaction to the presence of common types of nautical crafts. The data of this study resulted from 48 fieldtrips to each of the four localities studied (ports of Recife and Suape, and beaches of Bairro Novo and Piedade), thus totaling 192 days of observations, with approximately 380 hours of actual sampling. Ten types of behavioral activities were counted for Bairro Novo beach and the port areas, but only four for Piedade beach. The greatest flows of boats were recorded in the port of Recife. Fishing boats were the commonest type in the port area of Recife and Bairro Novo beach, while tourist vessels predominated in the port of Suape and Piedade beach. During the observations of encounters between these boats and the estuarine dolphins, neutral reactions predominated for all the vessel types studied. The same type of reaction predominated when the distances at which the interactions between the animals and vessels occurred were correlated.