Distribution in the Offshore

Beluga use offshore Beaufort waters during migration and for late summer feeding. There is frequent movement between the offshore and the estuary during July, with progressively more whales in the offshore areas as the month progresses. During August they are widely distributed offshore, often singularly or in small (2-4 animal) groups, which contrasts sharply with their clumped distribution in the estuary during July.

Systematic aerial surveys done in the 1980s and the 2000s recorded beluga throughout the offshore. While the patterns of distribution in the 1980s and 2000s were very similar, the numbers of sightings were significantly higher in the 2000s surveys. About four times as many surfaced whales were seen during the 2000s offshore surveys as during similar surveys in the 1980s. Population growth alone can not explain this increase in numbers. It seems clear that the offshore areas became more attractive to belugas in the 2000s, either because of a decrease in the intensity or extent of industrial activity, climate-change related shifts to the marine ecosystem, or both.

The extent of the offshore range of the Beaufort Sea beluga stock is less well known. Aerial surveys and satellite tracking studies have confirmed that individuals of this stock travel to more distant areas including Amundsen Gulf and Viscount Melville Sound. There is a sexual preference for particular offshore areas. Very large adult males move to Viscount Melvile Sound in August, while the smaller males, females, and females with calves tend to to move into Amundsen Gulf. The return fall migration to Bering Sea wintering areas starts in late August and continues through September. This migration occurs far offshore, seaward of the continental shelf and is along a different route than that used by bowhead whales and ringed seals, which also migrate westward at this time. Little specific information is known of the exact route taken by the beluga.

Papers

L.A. Harwood & M.C.S. Kingsley. 2013. Trend in the Offshore Distribution and Relative Abundance of Beaufort Sea Belugas, 1982-5 vs 2007-09. Arctic 66(3): 247-256. Click here

P. Norton & L.A. Harwood. 2001. Report of the second workshop on Beaufort Sea beluga, April 22-24, 1996, Inuvik, NT., Canada. Can. Manuscr. Rep. Fish. Aquat. Sci. 2578: vi + 28p. Click here

L.A. Harwooc, S. Innes, P. Norton, & M.C.S. Kingsley. 1996. Distribution and abundance of beluga whales in the Mackenzie estuary, southeast Beaufort Sea, and west Amundsen Gulf during late July 1992. Can. J. Fish. Aquat. Sci. 53:2262-2273. Click here

P. Norton & L.A. Harwood. 1985. White whale use of the southeastern Beaufort Sea, July-September 1984. Can. Tech. Rep. Fish. Aquat. Sci. 1401: v + 46p. Click here