Beluga whale (Delphinapterus leucas) COSEWIC assessment and status report: chapter 6

• Previous page
• Table of contents
• Next page

Habitat

The habitat used by beluga whales varies seasonally. As the fast ice breaks up in late spring, beluga whales mass along the ice edges and penetrate the leads, which provide access into the ice-covered areas (Stirling 1980). Belugas will often appear in their traditional river estuaries, which have become ice-free, several weeks before the large areas of sea ice, outside these bays, have completely broken up.

During the summer when the fast ice has broken up or completely disappeared, belugas are found along the coastlines and in relatively shallow waters (Sergeant 1973, Brodie 1971, Ognetov 1981, Michaud et al. 1990, Smith and Martin 1994). It is during this period that belugas frequent specific river estuaries (Sergeant 1973, Smith and Martin 1994), and glacier fronts (Lydersen et al. 2001).

There remains some uncertainty about whether belugas are moulting (St. Aubin et al 1990), feeding or calving (Stewart and Stewart 1989) in these areas of summer aggregation. All three are possible and activity might vary from one geographical location to the other.

Beginning in mid-August, belugas commence to move away from the estuarine areas. Some populations, such as those of the High Arctic – Baffin Bay and the Eastern Beaufort Sea, appear to make long journeys to deep-water areas away from land (Smith and Martin 1994, Richard et al. 2001b) where they spend several weeks diving to the sea floor and engage in what appears to be intensive feeding activity. In mid-to late September, belugas begin to actively move towards their winter areas.

Aerial surveys in March indicate that belugas are found in loose pack ice or polynyas, preferring ice cover of 4/10 to 8/10 (Jonkel 1969, Finley and Renaud 1980, Koski and Davis 1979). Because satellite tag retention has been limited, their specific areas of feeding and possible interactions with other beluga populations sharing these same areas, during the winter, are not yet known. Many of the prey species of belugas have been described from stomach content collections obtained from shallow coastal waters during the summer (Vladykov 1946, Kleinenberg et al. 1964, Watts and Draper 1986). Nothing is yet known of their feeding strategies, or prey availability, as related to specific habitat features during the long winter season.

Barber et al. (2001) examined beluga habitat relationships using telemetry. They found a bimodal distribution with respect to depth, animals preferring either shallow waters or those about 500m deep. Ice-free waters were proportionally more used than those with cover, and ice cover of 10/10 was avoided.