Abstract

PORTAL, Caroline; DANILEWICZ, Daniel; OTT, Paulo H  and  SUCUNZA, Federico. DISTRIBUTION PATTERNS OF RISSO’S DOLPHIN, Grampus griseus, IN OFFSHORE WATERS OF SOUTHEAST BRAZIL ASSESSED BY AERIAL SURVEYS. Mastozool. neotrop. [online]. 2022, vol.29, n.1, pp.660-660.  Epub Feb 15, 2022. ISSN 0327-9383.

The Risso’s dolphin, Grampus griseus, is widely distributed in temperate and tropical ocean waters around the world. Despite the known occurrence along the Brazilian coast, information regarding the spatial distribution of the species is scarce. Here we evaluated the distribution pattern of Risso’s dolphins using records obtained through 200 h of dedicated aerial surveys for marine mammals off the slope and outer continental shelf of Southeast Brazil, conducted between March and May 2012. A total of 16 groups of Risso’s dolphins was recorded with a median group size of 35 individuals (range = 1-300). Environmental variables (i.e., depth, slope, distance to the coast and to the shelf break, and sea surface temperature) associated with the Risso’s dolphin groups recorded indicate an oceanic distribution pattern, occurring close to the shelf break, what is probably related with foraging activity. This study provides new information about the distribution of Risso’s dolphins in Brazilian waters, and could be used as basis to plan conservation actions.

Keywords : Aerial surveys; Cetacea; Delphinidae; shelf break; spatial distribution.