Movements and behavior of satellite-tagged spotted seals (Phoca largha) in the Bering and Chukchi Seas

Abstract

In August 1991, satellite-linked platform transmitter terminals (PTTs) were attached to four spotted seals (Phoca largha) captured near a coastal haul out at Utukok Pass in the northeastern Chukchi Sea. The locations and diving behavior of the seals were monitored for periods of 64-259 days. Usable position information was obtained for about 50% of the days that the PTTs were operational. During August-October, seals made long feeding trips southwestward into the southern Chukchi Sea and returned to haul outs at Kasegaluk Lagoon. Durations of at-sea periods ranged from 8 to 902 hours, and the four seals on average spent 7% of their time hauled out. Three seals with still functional PTTs began their southward migration in October; two of them used haul outs in the Kotzebue Sound region and the northern Seward Peninsula. Seals migrated southward through Bering Strait in November and were near St. Lawrence Island in mid-December. The two seals whose PTTs worked into March-April spent the late winter and early spring in the sea ice south and southeast of St. Matthew Island. Haul outs on ice were infrequent, with seals hauled out only 6% of the time, on average. The number of dives to greater than 10 m depth averaged 160 and 284 per day for two of the seals. All dives were to depths less than 100 m, and most lasted for less than 10 minutes.

This study demonstrated the utility of satellite-linked telemetry for studying the biology of spotted seals. Modifications to PTT programming should allow future efforts to gather more detailed information on movements and diving behavior.


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