Evidência de uma tentativa mal-sucedida de predação pelo tubarão-cabeça-chata, Charcharinus leucas, sobre o botocinza, Sotalia guianensis, em águas brasileiras

Abstract

Even though shark-cetacean interactions have been the subject of numerous studies worldwide, several ecological aspects such as competition, predation risk and co-evolution remain unclear. On February 16th, 2008, during a photo-identifi cation survey to investigate population parameters of Guiana dolphins, Sotalia guianensis, in estuarine waters of Paraná State (25o S; 48o W), Brazil, an adult dolphin was photographed without its dorsal fi n. A detailed analysis of the healed area on the injured dolphin showed that the circular, crescent-shaped outlined wound was provoked by the bite of a bull shark, Carcharhinus leucas. Wound shape, prey-predator distributional patterns (sympatry) and feeding habits of the shark species here considered were indicative of the species’ identity. The wound is likely to be the result of a failed predation attempt. Interactions between C. leucas and S. guianensis should be expected, since they are sympatric along almost all of their distribution range in the tropical and subtropical western South Atlantic. The presented observation adds S. guianensis to the list of cetacean species involved in interactions with large coastal predatory sharks.