Pinniped - fisheries interactions in the Southwestern Atlantic Ocean off Argentina

CRESPO, ENRIQUE ALBERTO; KOEN ALONSO, MARIANO; PEDRAZA, SUSANA NOEMÍ; DANS, SILVANA LAURA; REYES, LAURA MARINA; SCHIAVINI, ADRIÁN CARLOS MIGUEL; GARCÍA, NÉSTOR ANÍBAL; COSCARELLA, MARIANO ALBERTO

Washington DC

Simposio; International Symposium and Workshop on Otariid Reproductive Strategies and Conservation; 1996

Smithsonian Institution

Interactions between otariids and fisheries in the southwestern Atlantic Ocean concern two species: southern sea lion (SSL) and southern fur seal (SFS). Regarding operational interactions the SSL interacts with all types of gillnet and trawling fisheries while SFS interactions remain unknown or undetected. The SSL interacts with coastal gillnets set for sharks in Buenos Aires Province, where single individuals damage caught sharks decreasing the economic value of the fishery. This damage has not been evaluated yet and no mortality of sea lions in gillnets has been reported. Along the Patagonian Shelf, bottom and midwater trawling fisheries predominate. In central Patagonia an estimated 1-2% of the SSL population has been reported becoming entangled in trawls. Regarding the specific interactions, the SSl overlaps in part with trawling fisheries in the use of food resources. Females seem to be more coastal than males which move far from the coast. In addition the rate of increase of SSL in well monitored areas is around 3%. The feeding pattern of the SFS is unknown in Argentine waters; current studies come from Uruguay and southern Brazil, where currents are warmer. Pelagic and demersal fish predominate between the food items. Demographic information of SFS in Argentina is fragmentary and although important rockeries on islands in central Patagonia have recently been discovered the population trend is unknown. The information available to date on specific interactions between pinnipeds and fisheries, and population trends of the species involved, do not suggest important effects of fisheries on Patagonian otariids even when fisheries themselves are not considered to be properly managed.