The Winisk River enters Hudson Bay near the midpoint of the northern Ontario Hudson Bay coastline. The site includes the Winisk River estuary and the shores and associated marshes extending about 15 km east and 20 km west of the river. The river mouth contains a number of islands and interconnected river channels, while the shores along the coast have wide intertidal marshes and submerged shoals that extend for 1 km or more offshore. Supertidal marshes extend as far as 10 km inland among drier low raised beach ridges with heath lichen. This habitat extends for about 10 to 15 km in each direction of the river mouth. Farther from the river, raised beach ridge systems become more prominent, with numerous small lakes and ponds being located between tundra covered strips.
Large congregations of geese occur along the Winisk River coastline during both the spring and fall migration. A one-day count of 8,200 Canada Geese was recorded in the late1970s, representing from 1% to 2% of the estimated Mississippi Valley wintering population. Large numbers of Lesser Snow Geese (ssp. caerulescens) have also been recorded at this site during both the spring and fall migrations. In the late 1970s, about 75,000 birds were recorded during the spring migration, and during the fall, a one-day total of 56,500 geese was recorded. Both of these totals represent well over 1% of the estimated Hudson Bay population.Other birds found at this site include up to 100 staging Tundra Swans, nesting Arctic Terns and Yellow Rails (nationally vulnerable) and thousands of nesting and moulting ducks.
Conservation responses/actions for key biodiversity
Most of this site is protected within the boundaries of Polar Bear Provincial Park. Because of the remoteness of this site, the park is not heavily visited, although some individuals are starting to promote ecotourism in the area. The Winisk River may potentially be dammed to provide electricity to Peawanuck. The location of the proposed dam, however, is far enough upstream that it would not likely affect water flow and levels at the mouth of the river.