Abstract

Eight fresh specimens of Burmeister’s porpoise caught in gillnets in the Necochea area (Buenos Aires Province) were studied for external morphometrics, age, basic reproductive data, organochlorine pollutant levels and parasites. Data from this work and from previous information about the species support the idea that the asymptotic body size of Burmeister’s porpoises from the Uruguayan and northern Argentine waters is larger than that observed in individuals from the Peruvian and Chilean coasts. This provides some support for the hypothesis that at least two stocks of Burmeister’s porpoises exist, one in the Pacific Ocean and another in the temperate South Atlantic. Organochlorine pollution levels in the examined animals were low and appear not to represent a threat to the population. High tDDT/PCB and low DDE/tDDT ratios indicated a preponderance of agricultural pollutants in relation to those of industrial origin. PCB congeners composition was consistent with the high trophic level occupied by the species. The diversity of parasites seems less than that in the Peruvian porpoises. The abundance of Pseudalius inflexus in lungs and Stenurus minor in cranial sinuses is similar to the Peruvian specimens. The presence of Polymorphus (Polymorphus) cetaceum in some stomachs and intestines suggests that the franciscanas, Pontoporia blainvillei, and Burmeister’s porpoises of this area probably feed on the same intermediate host.