Most Pacific walruses summer north of the Bering Strait, in the Chukchi Sea, around Wrangel Island, the Beaufort Sea, and in waters between these locations. A smaller number of males summer in Anadyr Gulf, on the southern coast of the Chukchi Peninsula, and in Bristol Bay, along the southern coast of Alaska, west of the Alaska Peninsula.
They winter in the Bering Sea, along the eastern coasts of Siberia south of northern Kamchatka and along the southern coasts of Alaska. The much rarer Atlantic walruses are found in the Canadian Arctic, Greenland, Svalbard and western Russian Arctic.
On the basis of the geographical distribution and the movements made, they have been divided into eight subpopulations, five in the west of Greenland and three in the east. In the past, the Atlantic walrus traveled as far as Cape Cod and congregated in large numbers in the Gulf of San Lorenzo.
In April 2006, the Canadian Endangered Species Legislation declared the Atlantic Northwest walrus population as missing from Canada. According to the most recent censuses, there are an estimated 200,000 Pacific walruses today.
The Atlantic walrus was nearly driven to extinction by large-scale commercial exploitation and is consequently much less numerous. Precise estimates are difficult to obtain, but the total population is thought to be probably less than 20,000.
Hunting is certainly one of the risk factors of the species. Another risk factor is the effects of global climate change. In some recent years, sea ice extent and thickness have reached unusually low levels. Walruses stop on this layer of floating ice to give birth and to congregate during the breeding season.
Thinning sea ice in the Bering Sea has reduced the availability of rest areas near prime foraging grounds. This causes lactating females to be separated from the young for a longer period of time, causing increased nutritional stress in the young and a decrease in the reproductive rate.
The reduction of sea ice in coastal regions is also implicated in the increase in deaths from crowding on the coasts of the Chukchi Sea between eastern Russia and western Alaska. However, the climatic data collected so far are still insufficient to make predictions on population trends.
Two of the three walrus subspecies are classified by the IUCN as Least Concern, while the third is classified as Undetermined. The Pacific walrus is not listed as endangered under either the terms of the Marine Mammal Protection Act or the Endangered Species Act.