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

YORIO, P.; GONZÁLEZ ZEVALLOS, D.; GATTO, A.; SUÁREZ, N.; GÓNGORA, M.E.; KASINSKY, T.; MARINAO, C.

Ciudad del Cabo

Congreso; II World Seabird Conference; 2015

Fisheries often overlap with foragingseabird distributions, and may lead to competition for common resources,incidental mortality and the provision of supplementary food in the form ofdiscards. We assessed the interactions between trawl fisheries and Magellanicpenguins 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 andArgentine Red Shrimp (Pleoticus muelleri),and caught a mean of 79.5 species per year (n = 1430 hauls) of which only 19 showedFO% 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% ofhauls and was rare (<5%) in over 88% of them. Analysis of Similarity showedsignificant differences between penguin diet and the fishery's catch. Preytypes designated by SIMPER as contributing most to the observed differenceswere 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 lowcontribution of Hake to their diet. Trawl fisheries currently appear to have nosignificant impact on penguin populations in the study area, althoughincidental mortality resulting from vessel attraction (0.001-0.31 birds perhaul; 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 concernson the potential impact on penguin populations.