Strandings of the shortfin mako and the pelagic stingray on the coast of São Paulo State, Southeastern Brazil: report of cases

Abstract

Strandings of oceanic-pelagic elasmobranchs in the southeastern Brazil are reported. Data come from animals observed in the coast of São Paulo state between 1999 and 2012. Nine individuals of two species were recorded: Pteroplatytrygon violacea (n = 5; mostly during the winter) and Isurus oxyrinchus (n = 4; two in the winter and two in the summer). For P. violacea, the strandings restricted to the austral winter suggest that the species follows the intrusion of high temperatures water masses recorded in southeastern Brazil during this season, bringing some individuals to shallow waters. For I. oxyrinchus it is possible that individuals escaped from hooks of the commercial pelagic longline fishery and suffered injuries in the esophagus and in the gastric wall, stranding due to difficulties in locomotion and feeding. As these stranded sharks were not necropsied and only two animals were observed during the austral summer, it can not to be excluded other causes of beaching such diseases or the intrusion of cold water masses in the continental shelf during this season.