Spatial distribution of foraging in female Antarctic fur seals Arctocephalus gazella in relation to oceanographic variables: a scale-dependent approach using geographic information systems

The distribution of foraging activity for female Antarctic fur seals was in vestigated at Cap Noir (49 degrees 07 'S, 70 degrees 45 'E), Kerguelen Isla nd in February 1998. Eleven females were fitted with a satellite transmitte r and time-depth recorder. The 2 data sets were combined in order to locate diving activity of the seals. The occurrence of fish in the diet of the se als was investigated by the identification of otoliths in 55 scats collecte d at the breeding colony during the study period. Oceanographic variables w ere measured simultaneously by direct sampling and satellite remote sensing . The mesopelagic fish community was sampled at 20 stations along 4 transec ts, where epipelagic trawls were conducted at night at 50 ni depth. We then investigated, using geographic information systems, the relationship betwe en the spatial distribution of diving activity of the seals and oceanograph ic variables (sea surface temperature, surface chlorophyll concentration, p rey distribution and bathymetry) at the same spatio-temporal scale. An inve rse relationship was found between the main fish species preyed on by the f ur seals and those sampled in trawl nets. However, diving activity of the s eals was significantly related to oceanographic conditions, forage fish dis tribution and distance from the colony, although these relationships change d with the spatial scale investigated, A probabilistic model was developed for the distribution of diving activity, which predicted where females,shou ld concentrate their foraging activity according to the oceanographic condi tions of the year, and where breeding colonies should be located.