Residence patterns of the Guiana dolphin Sotalia guianensis in Babitonga bay, south coast of Brazil

F A S Hardt,A J Tonello,P C A Simões-Lopes,M J Cremer

doi:10.5597/lajam00160

Abstract

Photo-identification and video-identification techniques were applied to study the residence of Sotalia guianensis in the Babitonga Bay, north coast of Santa Catarina State. From November 2000 to February 2003 a photo-identification effort was conducted trough 21 months, with additional video-identification conducted from August 2003 to August 2004, totalling 34 months of identification effort. Fifty-one different animals were identified with residence rates varying from 2.9% (n = 1 sighting) to 67.6% (n = 23 sightings). During the four years it was found that more than 30% (n = 16) of identified individuals were observed during three years, and 25% (n = 13) only were seen within one year. Considering previous studies, the longest period of residence reached eight years for one individual. Due to the high rates of resightings observed for most of the animals and the small percentage of animals only seen once, it is clear that S. guianensis is resident year-round in the studied area.

Highlights

It is known that residence and habitat use patterns in dolphins may vary from one region to another (Ballance, 1990)
Considering the high number of animals seen in the Babitonga Bay and the small percentage of animals observed only once, it became clear that S. guianensis has a regular occurrence throughout the year in the study area
In Guanabara Bay, Pizzorno (1999) observed that 32 animals were resident for a period of three years, and Santos et al (2001) observed that 16 animals lived throughout two years in Cananéia Estuary

Summary

Introduction

It is known that residence and habitat use patterns in dolphins may vary from one region to another (Ballance, 1990). Sotalia guianensis has a continuous distribution, from Nicaragua, Central America to Florianópolis, Santa Catarina State, Brazil (Simões-Lopes, 1988; Carr and Bonde, 2000; da Silva et al, 2010 this volume). This species is classified as ‘Data Deficient’, according to the IUCN (Reeves et al, 2003), which calls attention to the relevance of long-term studies. Variable degrees of residence have been observed for some individuals (Pizzorno, 1999; Santos et al, 2001; Flores, 2003). Previous studies showed that Babitonga Bay is an important shelter area for the species, where the population shows evidence of residence (Cremer, 2000)

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