Cetacean occurrence near an offshore oil platform in southern Brazil

Abstract

Information about cetaceans in offshore Brazilian waters is scarce, and oil-rigs could provide an important opportunity to obtain new data. The present work was conducted on the P-XIV oil-rig (Petrobrás) (26o46’02.2”S; 46o47’02.15”W), located on the border of the continental slope, in an area of 200m depth. In the period between July 2000 and August 2002, 75 sightings of cetaceans were recorded during 38 days of effort. Among the species identified, Tursiops truncatus was the most common, corresponding to 53.3% of the records. Among the misticets, only Balaenoptera acutorostrata was identified with accuracy, with 4 records (5.3%). These were the only species that approached and stayed close to the oil-rig. Many records were made at night, when the gas burner illuminated the area around the oil-rig. We recorded an aggressive interaction involving T. truncatus and B. acutorostrata.