Ecological niche modelling and fisheries interactions in an antarctic population of Southern Giant Petrels Macronectes giganteus

Fisheries and climate change are the main factor threatening seabirds. In this study, we applied ecological niche modeling to estimate the distribution of a Southern Giant Petrel Macronectes giganteus population from an island in Antarctic Peninsula, considering oceanographic variables along with fishing activities. We tracked 17 males and 15 females using geolocators in 2011 and 2014. Respective geographical positions were used in modeling. Models presented an excellent precision (AUC>0.9). During the breeding season, central foraging areas of both sexes were positioned south of the Polar Front, with higher probabilities of occurrence closer to the colony. The ecological niche during this period was similar between sexes. During the non-breeding season, females used waters of the continental shelf off of southern Argentina and less frequently the Polar Frontal Zone. Males presented an opposite pattern to females, occurring mainly in the PFZ during the non-breeding season. The most important variables for the distribution of this population were sea surface temperature and wind speed. Habitat use differed between sexes mainly during the non-breeding season. In this period, females used areas of oceanic fronts with greater density of fishing vessels, while males used areas with higher concentration of chlorophyll-a and greater ice coverage. Habitat use differences among sexes may lead females to use zones of higher fishing activities. The influence of such phenomena upon the population deserves better attention, since this population is most likely feeding on fishing discards.