Environmental niche overlap between common and dusky dolphins in North Patagonia, Argentina

Data of common and dusky dolphins groups recorded during both systematic and occasional survey in San Matías Gulf, Patagonia, Argentina. Sistematic surveys consisted of transects onboard large vessels (30 to 70 m long) at an average speed of 10 kn and with one or two observers. These surveys covered areas further than 60 km from the coast. Study period: 2006 – 2011. Occasional sightings comprisaed a) research surveys of demersal fish that covered the entire extent of the SMG onboard fishing vessels 30 to 40 m long, b) research surveys of bivalve mollusks and benthic fauna that covered the northwest coast of the SMG onboard research and fishing vessels 7 to 20 m long and c) regular surveys by the Fishery Observer Program (FOP) of the trawl demersal fishery of Río Negro Province (a survey area from 42° south latitude to the north of the gulf).Study period: 1983 - 2010.