Relevance of forage fish in the diet of Magellanic penguins breeding in northern Patagonia, Argentina

YORIO, P.; GONZÁLEZ ZEVALLOS, D.; GATTO, A.; BIAGIONI, O.E.; CASTILLO, J.

MARINE BIOLOGY RESEARCH

TAYLOR & FRANCIS AS

Lugar: Londres; Año: 2017 vol. 13 p. 603 - 617

1745-1000

We quantified the trophic niche ofMagellanic penguins (Spheniscus magellanicus) breeding and moulting in Golfo SanJorge, Argentina, through conventional stomach content and stable isotopeanalysis. A total of 112 adults were flushed during the early and late chickstages of 2011 and 2012 at Isla Vernacci Norte, and at least 15 prey taxa werefound, including fishes, cephalopods, crustaceans and polychaetes. Overall,Argentine anchovy (Engraulis anchoita) showed the highest contribution interms of importance by mass (68.1?85.3%, depending on chick stage and year), except forthe old chick stage in 2011 when the shortfin squid (Illex argentinus) was the main preyconsumed (56.0%). Based on carbon and nitrogen isotopic values from a total of256 blood samples corresponding to young and old chicks and to adults of bothsexes sampled throughout the incubation, chick and moult stages at the abovementioned colony and years, Bayesian mixing model outputs showed that Argentineanchovy was always the main prey (48?86%). Bayesian mixing model outputs obtained from adultsof both sexes and their chicks during the late chick stage of 2013 at IslaVernacci Norte, Isla Tova and Isla Leones also showed that Argentine anchovywas the main prey consumed. This is the first comprehensive assessment ofMagellanic penguin diet composition in northern Patagonia, quantifying therelative contribution of prey in the diet of adults and chicks in differentstages of the annual cycle and years, and confirms the relevance of a foragefish such as the Argentine anchovy in its trophic ecology.