Walruses are subdivided into two subspecies: the Atlantic walrus (O. r. rosmarus) and the Pacific walrus (O. r. divergens). The Pacific walrus is distributed along the continental shelf of the Bering and Chukchi Seas. In winter, they mostly occur in polynyas and open leads in two major concentrations, one south of St. Lawrence Island and the other in Bristol Bay. In the summer, most follow the retreating pack ice, migrating north into the Chukchi Sea. However, many adult males remain in the Bering Sea to rest and molt at terrestrial haul-out sites. Alaskan and Russian natives hunt Pacific walruses for subsistence purposes. These harvests are an important means of maintaining cultural traditions in native villages while providing a source of food, skins, and ivory for local subsistence lifestyles and economies.
Because of their large size (they can weigh more than 3,500 lbs.) and prominent tusks, they are one of the most recognizable pinnipeds. Walruses do not use their tusks to dig for food as is commonly believed. Rather, they use them for fighting and displays of dominance with other walruses, for defense against predators, as picks to pull themselves out of the water onto ice floes, and to kill and tear apart seals.