Use of fishing discards by breeding Kelp Gulls in northern Golfo San Jorge

YORIO, P.; KASINSKY, T.; SUÁREZ, N.

Puerto Iguazú

Congreso; Ornithological Congress of the Americas (XVII RAO/XXIV CBO/XCV AFO); 2017

Association of Field Ornithologists, Sociedade Brasileira de Ornitologia y Aves Argentinas

The Kelp Gull (Larus dominicanus) is a generalist species thatincludes in its diet food derived from human activities. The ParqueInterjurisdiccional Marino Costero Patagonia Austral in northern Golfo SanJorge, Chubut, constitutes one of its most relevant breeding areas, and trawlfisheries operate in its adjacent waters to which it associates to takeadvantage of fishing discards. The main discarded component is the Common Hake(Merluccius hubbsi), a demersal species that is not normally availableto surface feeding seabirds. In order to assess the interaction between theKelp Gull and fishing activities, we analyzed the spatial association withoperating vessels and diet of breeding individuals from Isla Vernacci Esteduring the incubation stage of 2015. We tracked 11 breeders using globalpositioning system loggers, recording 56 foraging trips which showed a meanmaximum distance from the colony of 26.4 ± 11.9 km. Ten of the instrumentedindividuals mainly made offshore foraging trips and only one made tripsexclusively to intertidal zones. The spatial overlap with fishing operationswas 76%. The analysis of stomach samples (n=29) showed that 96% comprised fish,being Common Hake (FO=50%) and Anchovy (Engraulis anchoita) (FO=42%) thetwo most frequent prey. Results confirm that Kelp Gulls breeding in the MarinePark take advantage of food provided by fisheries and suggest the need tocoordinate management actions within and outside the protected area.