Global Range: Arctic and subarctic circumpolar; south to Hokkaido (Japan), Alaska, Hudson Bay, and Newfoundland (now largely or entirely extirpated). Most of the Bering Sea-Chukchi Sea population probably migrates through Bering Strait and winters in the Bering Sea; in winter, the largest concentrations are near St. Lawrence Island, in the ice 60-100 km north of the ice's frontal zone, west of St. Matthew Island, and in the southern Gulf of Anadyr; in summer, scattered acros the broken margin of the multiyear ice that covers much of the continental shelf in the Chukchi and western Beaufort seas (Reeves et al. 1992). In Canada, occurs at high densities in western Hudson Bay and in northern Foxe Basin; relatively abundant in Ungava Bay and Roes Welcome Sound; scattered throughout many of the High Arctic inlets and fiords from July to October; in some years, overwinters in the North Water of Baffin Bay, over deep water; in the Beaufort Sea, high densities occur from Sachs Harbour to Norway Island (Reeves et al. 1992).