Assessing potential conflicts between trawl fisheries and Magellanic penguins breeding at a marine protected area in Patagonia, Argentina

YORIO, PABLO; GONZÁLEZ ZEVALLOS, DIEGO; GATTO, ALEJANDRO; SUARÉZ, NICOLÁS; GÓNGORA, MARIA EVA; KASINSKY, TATIANA; MARINAO, CRISTIAN

Cape Town

Conferencia; 2nd World Seabird Conference; 2015

World Seabird Union

Fisheries often overlap with foraging seabird distributions, and may lead to competition for common resources, incidental mortality and the provision of supplementary food in the form of discards. We assessed the interactions between trawl fisheries and Magellanic penguins breeding at the Patagonia Austral Marine Park, Golfo San Jorge, Argentina. Magellanic Penguins instrumented with GPS during the chick stage (n = 32) overlapped with operating vessels (17.9-66.2%). Stomach samples (n = 114) showed that penguins fed on at least 14 species, mostly Anchovy (Engraulis anchoita) (%M = 61.7%), followed by Squid (Illex argentinus) (21.6%) and Hake (Merluccius hubbsi) (9.5%). Stable isotope analysis (n = 120) confirmed that Anchovy was the dominant prey (70-80%) from incubation to chick fledging and molt. Trawlers targeted Hake and Argentine Red Shrimp (Pleoticus muelleri), and caught a mean of 79.5 species per year (n = 1430 hauls) of which only 19 showed FO% of over 5%. Hake was also the most frequent species in the bycatch (94%) and was dominant in over 95% of hauls. Anchovy was present in less than 14% of hauls and was rare (<5%) in over 88% of them. Analysis of Similarity showed significant differences between penguin diet and the fishery´s catch. Prey types designated by SIMPER as contributing most to the observed differences were Anchovy and Hake. Discards appear to be unimportant to breeding penguins, given the relatively frequent but low number of birds associated to vessels (49%; <8.2 birds per haul, n = 129 hauls) and the relatively low contribution of Hake to their diet. Trawl fisheries currently appear to have no significant impact on penguin populations in the study area, although incidental mortality resulting from vessel attraction (0.001-0.31 birds per haul; n = 31686, obtained from 2003 to 2013 by the On-board Observer Program) and plans to develop an Anchovy trawl fishery in the study area raise concerns on the potential impact on penguin populations.