Figure 3. Bowhead whale, 20 August 2012. Photo by Cynthia Christman.
Western Arctic Bowhead Whales
The distribution of bowhead whales (Fig. 3) during the 2012 fall migration remained consistent with historical data collected from 1982 to 2011, with a few exceptions. Since 1987, broad-scale aerial survey coverage in the western Beaufort Sea has been mainly limited to the months of September and October to cover the fall migration of bowhead whales. Information on the summertime use of the western Beaufort Sea by bowheads was lacking until recently, and it was presumed that most bowheads spent their summers feeding in the eastern Beaufort Sea. The Alaska Department of Fish and Game’s (ADF&G) satellite-tagging program (funded by BOEM) to track bowhead whale movements has documented the bowhead whale migration from their Bering Sea wintering grounds to summering grounds in the eastern Beaufort Sea. This tracking program has also documented bowhead whales moving throughout the Chukchi and Beaufort Seas more than previously thought, including documentation of bowhead whales in the western Beaufort Sea during the summer. In July 2011, the ADF&G tracked a tagged bowhead to the western Beaufort Sea, and the ASAMM team from Barrow then found 16 bowhead whales in the area of the tagged whale. Based on this information, the ASAMM survey season in the western Beaufort Sea was extended to mid-July in 2012. Bowhead whales were found during 13 of 23 ASAMM aerial surveys conducted from 19 July to 29 August 2012. Bowheads were distributed primarily along the outer continental shelf of the western Beaufort Sea, including 58 sightings totaling 115 whales (including 11 calves). The bowhead whale fall migration in the northeastern Chukchi Sea may have been somewhat earlier in 2012, as bowheads were also sighted in this area more frequently and in greater numbers in September 2012 than in past years.
Gray Whales
Figure 4. Gray whale mother and calf pair, 14 July 2012. Photo by Cynthia Christman.
The distribution of gray whales in 2012 also remained consistent with historical data collected from 1982 to 2011. Gray whales have continued to use Chukchi Sea foraging grounds between Point Barrow and Point Lay, but they were consistently sighted further offshore in 2011-12. In 1982-91, gray whales were sighted feeding in the Hanna Shoal region, but few gray whales have been sighted there in recent years (2008-12). In 2012, more gray whale calves were sighted in the Chukchi Sea than in any previous survey year in this region (Fig. 4). Calf distribution in 2012 was primarily in nearshore, shallow water, which may provide protection from predators; killer whales were sighted by ASAMM observers in multiple locations in the northeastern Chukchi Sea in 2012 and have been documented in this region by others in previous years. During the 2012 survey of the gray whale northward migration along the California coast (conducted by the Southwest Fisheries Science Center), calf counts were also high compared to surveys in previous years. It is possible that conditions were favorable for foraging in 2011 and many females were able to accumulate sufficient energy reserves to reproduce in 2012. Another possibility is that other habitats where gray whale cow-calf pairs have been documented in the past, such as just west of Point Hope, Alaska, and along the Chukotka Peninsula in Russia, may not have been as favorable for cow-calf pairs in 2012. (continued)
