Direct and Indirect Effects of the Highseas Fisheries on the Marine Mammal Populations in the Northern and Central Patagonian Coast

• DOI: 10.2960/j.v22.a15
• Publication Date: 2008-12-18T13:41:35Z
• Authors: E A Crespo; S N Pedraza; S L Dans; M Koen Alonso; L M Reyes; N A García; M Coscarella; A C M Schiavini
• Keywords: Marine mammal

Since 1989, interactions between marine mammals and fisheries have been monitored along the Atlantic Patagonian coast.The Argentinian national fishing fleet in area is composed of approximately 208 vessels (75% trawlers; 16% jiggins; 9% longliners).The operates year-round from eight harbours Escondida Island San Jorge Gulf (80 000 naut. miles 2 ).The important target species are: hake (Merluccius hubbsi), shortfin squid (IIlex argentinus) shrimp (Pleoticus muelleri), while several tons other fish are discarded.The dusky dolphin (Lagenorhynchus obscurus), Commerson's (Cephalorhynchus commersonii) southern sea lion (Otaria flavescens) incidentally caught.The dolphins become entangled mainly mid-water trawls at night, lions any kind trawl.Annual mortality rates obtained 170-480 (mostly males; figure estimated to be 1-2% population size area), 70-200 (70% females) 25-170 dolphins.Feeding habits top predators, catch bycatch fishery were also studied.Dusky prey on anchovy squid, was most food item for male lions.Squid overlaps with taken by commercial fishery.Fishing areas jigging overlap part those foraging lions.Even though 30 cm or larger, smaller hakes largely discarded fishery.A combination operational specific detected.At present, seem low there insufficient evidence competition species.However, concern about large amounts (particularly hake) fishery.