Belugas observed in the study area in late summer and early fall are from the eastern Chukchi Sea stock and the Beaufort Sea stock. The distribution of belugas in 2012, particularly in the western Beaufort Sea and Barrow Canyon, remained consistent with historical data collected from 1982 to 2011. In the northeastern Chukchi Sea, relatively few belugas were sighted in 1982-91 and 2008-10, particularly in the summer months. Conversely, in 2011, belugas were distributed throughout the northeastern Chukchi Sea in all months, with more beluga sightings in 2011 (299) than in 2007-10 combined (157). In late June and early July 2012, more than 8,600 km were flown on coastal and offshore transects in the northeastern Chukchi Sea. Despite this effort, very few belugas were seen offshore; groups ranging in size from 1 to 300 belugas were observed within a few kilometers of shore. Large groups of belugas were observed feeding near entrances to Kasegaluk Lagoon on 4 days in late June and early July. Beluga distribution and habitat preference (belugas per km per depth zone) in the western Beaufort Sea heavily favored the continental slope and Barrow Canyon in 2012.
Other Cetaceans
Figure 5. Killer whales and calf, 20 August 2012. Photo by Cynthia Christman.
In addition to cetacean species typically seen during our aerial surveys in this area, several species not commonly encountered were documented during the 2012 survey, including humpback, fin, minke, and killer whales. These four species were primarily sighted in two areas: nearshore between Icy Cape and Point Barrow, and west and south of Point Hope. None were seen in the western Beaufort Sea. Humpback, minke, and killer whales were seen in both areas, whereas, fin whales were seen only in the southern area. Most of the humpback whales were seen in the southern area, a region where gray whales have been consistently seen in past years. Humpback, minke, and fin whales exhibited feeding behavior, and both fin and killer whale calves (Fig. 5) were observed. The killer whales were not observed feeding; however, several large whale carcasses were observed in the study area, one of which appeared to be missing its lower jaw, suggesting possible killer whale predation. None of these species were sighted during historical surveys in 1982-91. Since broad-scale aerial surveys recommenced in the northeastern Chukchi Sea in 2008, only one fin whale (July 2008), one humpback whale (July 2009), and six minke whales (2011) have been sighted. Although all of these species have been detected acoustically in the northeastern Chukchi Sea, particularly in the southern area, the historical scarcity of sightings from broad-scale aerial surveys is likely indicative of their relative rarity in this region. The 2012 ASAMM sightings may represent a continuing trend towards greater cetacean species diversity and abundance in the northeastern Chukchi Sea. (continued)
