At-Sea Movements Of Female Australian Fur Seals Arctocephalus Pusillus Doriferus

Abstract

In May 1999, satellite transmitters were deployed on three lactating female Australian fur seals (Arctocephalus pusillus doriferus) at Kanowna Island (39° 10' S, 146° 18' E) and at-sea movements were recorded for 65 – 174 days. The mean foraging trip and on-shore durations (8 and 2 days, respectively) were not significantly different to that previously reported for the species. The seals all foraged in three separate areas of Bass Strait with each individual repeatedly returning to the same general location. Movements during foraging trips fell into two distinct patterns. In one pattern, displayed by two individuals, the females travelled directly to a presumed foraging area. In this trip type, outward and return travel consisted of relatively constant headings at moderate speed (1.37 ± 0.07 m/s) while the middle phase was characterised by repeated changes in direction within a small area and significantly lower speeds (0.82 ± 0.07 m/s). The second pattern, displayed by the third individual, consisted of a looping path with relatively uniform average speed (1.14 ± 0.06 m/s) throughout the trip. The three foraging areas were: 1) inshore area between Wilsons Promontory and Lakes Entrance; 2) offshore in proximity to The Skerries; and 3) up to 200 km south of Wilsons Promontory in central Bass Strait. The foraging areas used by these seals overlap with regions of commercial fishing effort raising the potential for some conflict.