Occurrence of the Guiana dolphin Sotalia guianensis (Delphinidae) in Camamu Bay, Bahia, Brazil

Much data is still lacking to conduct a rigorous assessment of the status of the Guiana dolphin, Sotalia guianensis, a coastal-estuarine dolphin of eastern Central America and north-eastern South America, considered vulnerable to extinction in Brazil, relevant information is still lacking to evaluate its global population trends. This article presents the first description of the occurrence of the Guiana dolphin in Camamu Bay in Brazil. From November 2016 to October 2017, we conducted 68 on-board monitoring in two zigzags transects, totalling 272 h of sampling effort. Seven groups composed of up to 5 individuals were sighted between November 2016 and June 2017, and five of these groups were encountered in the main channel of the bay. Sightings were independent of the monitoring period and of the phase of the semidiurnal tide but occurred within three days from a spring tide. Guiana dolphins are less frequent in Camamu Bay than in other geographically neighbouring estuaries, even the smaller ones. We hypothesize that the shallowness of the bay and boat traffic may explain this result.