Identifying gray whale (Eschrichtius robustus) foraging grounds along the Chukotka Peninsula, Russia, using satellite telemetry

Abstract

The purpose of this study was to evaluate sum- mer and fall residency and habitat selection by gray whales, Eschrichtius robustus, together with the biomass of benthic amphipod prey on the coastal feeding grounds along the Chukotka Peninsula. Thirteen gray whales were instru- mented with satellite transmitters in September 2006 near the Chukotka Peninsula, Russia. Nine transmitters provided positions from whales for up to 81 days. The whales trav- elled within 5 km of the Chukotka coast for most of the period they were tracked with only occasional movements oVshore. The average daily travel speeds were 23 km day i1 (range 9-53 km day i1 ). Four of the whales had daily aver- age travel speeds <1 km day i1 suggesting strong Wdelity to the study area. The area containing 95% of the locations for individual whales during biweekly periods was on average 13,027 km 2 (range 7,097-15,896 km 2 ). More than 65% of all locations were in water <30 m, and between 45 and 70% of biweekly kernel home ranges were located in depths between 31 and 50 m. Benthic density of amphipods within the Bering Strait at depths <50 m was on average »54 g wet wt m i2 in 2006. It is likely that the abundant benthic biomass is more than suYcient forage to support the current gray whale population. The use of satellite telemetry in this study quantiWes space use and movement patterns of gray whales along the Chukotka coast and identiWes key feeding areas.