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COSEWIC Assessment and Update Status Report on the Atlantic Walrus in Canada

Habitat

Habitat Requirements

Atlantic walruses require large areas of shallow water (80 m or less) with bottom substrates that support a productive bivalve community, open water over these feeding areas, and suitable ice or land nearby upon which to haul out (Davis et al. 1980). This is a relatively narrow ecological niche (Born et al. 1995).

Walruses often gather in large herds. They are associated with moving pack ice for much of the year. When ice is lacking in summer and fall, they tend to congregate and haul out on land in a few predictable locations (Mansfield 1973). Uglit are often situated on low, rocky shores with steep or shelving subtidal zones where animals have easy access to the water for feeding and quick escape (Mansfield 1959; Salter 1979a, b; Miller and Boness 1983). The animals generally move to more sheltered areas when there are strong onshore winds and heavy seas (Mansfield 1959).


Trends

Suitable walrus habitat is decreasing as human activities in the north expand. Hunting and noise disturbance caused by motorized transportation have caused herds to abandon uglit near communities in favour of less accessible islands and shores (Born et al. 1995). Whether these animals would eventually habituate to disturbance and reoccupy abandoned uglit if hunting ceased is unknown.

Post-glacial rebound is slowly raising existing uglit relative to sea level over much of the eastern Canadian Arctic. In southern Hudson Bay, near Cape Henrietta Maria, the rate of rebound is about 1.2 m per century (Webber et al. 1970). Some uglit that were once islands in the Winisk area have become part of the mainland, reducing their use by walruses (Fleming and Newton 2003). Declining use of habitat in the Attawapiskat area has also been attributed to coastal changes, which could, however, be offset by the emergence of new shoals with consequent shifts in walrus distributions.


Habitat Protection/Ownership

Existing National Parks, National Wildlife Areas, Migratory Bird Sanctuaries, Indian Reservations, and other lands owned and managed by the Government of Canada afford little protection to walrus habitat. Walruses haul out in the Polar Bear Pass National Wildlife Area (Davis et al. 1978) but this area only protects a few of their uglit along the east coast of Bathurst Island. They also haul out on Coburg Island in the Nirjutiqavvik National Wildlife Area and on the Wollaston Islands, which lie partly within the Bylot Island Migratory Birds Sanctuary (Born et al. 1995). Walruses may occasionally haul out at the East Bay Bird Sanctuary on Southampton Island and the Bowman Bay Wildlife Sanctuary on Baffin Island. They may also haul out along the northeast coast of Bathurst Island on lands reserved for a proposed national park. Their use of other National Parks and Bird Sanctuaries is very limited at best. Overall, federal lands only offer temporary protection to a few walruses from the Baffin Bay Population. In itself, this level of habitat protection is certainly insufficient to ensure the long-term survival of the species.