Movements of adult male southern elephant seals from King George Island observed by satellite telemetry
The migratory behaviour of adult male southern elephant seals, Mirounga leonina, from King George Island was studied in relation to sea ice coverage. Fourteen animals were immobilzed and fitted with satellite linked transmitters (Telonics/Wildlife Computers, USA) after the annual moult at their southernmost breeding colony at Stranger Point, King George Island, South Shetland Islands, from March to May 2000. The seals were tracked by Service ARGOS (Toulouse/France) for up to 12 months until March 2001. Daily data of sea ice coverage were derived from the Special Sensor Microwave/Imager (SSM/I) of the Defence Meteorological Satellite Program (DMSP).The bulls moved south-eastward along the shelf margin east of the Antarctic Peninsula reaching their southernmost locations in the interior pack ice of the Weddell Sea in May 2000.Here they concentrated their foraging close to the northern sill of the Filchner Trough. This region corresponds to a divergence of the Antarctic Coastal Current which forms the southern limb of the Weddell Gyre. Upwelling in this area might cause vertical transport of organic material which correlates with increased prey availability for top predators through food web linkages. In August 2000 the remaining bulls with functional transmitters returned northwards to their breeding sites, mainly King George Island.The migration routes of the bulls differ considerably from those of cows and weaned pups of both sexes which moved westward from King George Island into the Pacific sector of the Antarctic Ocean as revealed in a previous tracking study. It needs to be verified whether such separation is maintained within and between years.