Encounters with pelagic and continental slope cetacean species near the northern shore of the Gulf of Taranto, Italy

Abstract

Little is known about the distribution and species composition of cetaceans in the Gulf of Taranto, central Mediterranean Sea. Available information is limited to stranding reports and to scant preliminary observations at sea. Cetacean sightings were recorded between April 2007 and October 2009 during 23 daily boat surveys, totalling 1728 km of navigation. Three cetacean species were encountered: striped dolphins (n = 41), Risso's dolphins (n = 5) and fin whales (n = 3). An additional sighting of a sperm whale group is reported. Encounter rates of striped dolphins were the highest, suggesting a regular occurrence in the study area. Risso's dolphins seemed to be predictably present in continental slope waters off the coast of Basilicata. Fin whales and striped dolphins, normally inhabiting deep pelagic waters offshore, were found in continental slope waters relatively close to the coast, possibly due to the particular bathymetry of the Gulf of Taranto and to oceanographic conditions that enhance local productivity. High human impact and worsening environmental conditions in the northern Gulf of Taranto raise concerns over the future of cetaceans living in these waters. This study expands previous knowledge and aims to stimulate research on whales and dolphins in what seems to be an important portion of their Mediterranean range.