Diving behavior of adult female Steller sea lions in the Kuril Islands, Russia

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Satellite-linked time-depth recorders (SLTDR) were attached to eight adult female Steller sea lions (Eumetopias jubatus) at three islands in the Kuril Islands, Russia, during June 1991. The purpose of the study was to enhance our understanding of adult female Steller sea lion dive characteristics and foraging behavior in Russian waters for comparison to similar studies in Alaska during the breeding season. Mean dive depth was 53m (n=7, 143) and mean dive duration was 112 sec (n=7, 775). Steller sea lions had trips to sea lasting about 1 day, but some trips lasted up to 4 days. Virtually all dives were in the late afternoon through early morning, and 99.5% of the dives> 100m occurred between 2100-0300 hrs. Most (94%) locations indicated that the sea lions foraged within 10 km of the capture island, but some traveled as far as 263km. Dive depth and duration varied by individual and by island. Five sea lions from Lovushki Island had statistically longer duration (p<0.05) and deeper (p<0.05) dives than three females from Brat Chirpoyev and Raykoke Islands. The Lovushki Island animals also tended to dive in shallower water over a large reef complex suggesting that they foraged near bottom while sea lions from the other two islands foraged near the surface in deep water. The results support the hypothesis that adult female Steller sea lions in the Kuril Islands have dive characteristics similar to Alaska sea lions.
野生生物保護学会の論文