Post-breeding distribution and diving behavior of adult male southern elephant seals from Patagonia

Seven post-breeding adult male southern elephant seals, Mirounga leonina, were tracked using satellite-relay data loggers (SRDL) in 1994-1996. Two animals also were instrumented with a time depth recorder(TDR). Animals were monitored for 31-112 days at the end of the breeding season as they left Peninsula Valdes, Argentina. Males travelled less than or equal to1,300 km from the breeding rookery but remained in temperate waters of the SW Atlantic Ocean, between 42degreesS and 55degreesS. The maximum travel distance recorded for the entire trip for any one seal was >4,500 km. Five males swam across the continental-shelf in 3-11 days and stayed along the shelf margin or break where travel rates decreased markedly and remained low, suggesting that they may have reached foraging grounds. The other two males remained on the continental shelf during the entire time that they were tracked at sea. One of them was tracked for 66 days and concentrated his activity only 6-10 km off the coast of Patagonia in two areas located 700-800 km S of Peninsula Valdes. He never dived deeper than 94 m. The diving behavior sampled by one working TDR and several SRDL were similar. Dives over the continental shelf were mostly down to the seabed. Some dives over the shelf break were to the seabed (down to 1,500 m) but most were mid-water (300600 m) and were deeper during the day. Previously studied post-breeding and post-molt adult females from the same colony spent virtually all their time over deep water off the shelf in the latitudinal range of 36-50degreesS. Their movements were less localized than those of males and dives did not take them to near the ocean bottom.