It is generally agreed that the genus Odobenus includes only one species, O. rosmarus. At least two subspecies are widely recognized: O. r. rosmarus, the Atlantic walrus, and O. r. divergens, the Pacific walrus. A third nominal subspecies, O. r. laptevi, the Laptev walrus, is designated by some Soviet researchers; and the taxonomic status of the Kara Sea walrus is undetermined. The range and abundance of nearly all walrus stocks have been seriously reduced by intensive human exploitation.

The Atlantic walrus, the principal subject of this study, remains plentiful in only three known areas of concentration: northern Hudson Bay and northern Foxe Basin in the eastern Canadian Arctic, and the Thule district of northwest Greenland. This animal is no longer the object of large-scale commercial hunting, but is still subject to heavy subsistence hunting by native groups in some areas.

The status of the walrus population in Canada was investigated in the 1950's and is believed to have changed little since that time. There are probably no more than about 10,000 walruses in Canadian waters, virtually all of them in the eastern arctic. The biology, ecology, and exploitation of walruses in the Thule district were studied during the 1940's, and some information is available concerning recent catch levels and hunting practices. The Polar Eskimos of north Greenland continue to organize much of their cultural and economic life around the hunting of walruses, and the species remains abundant in their area, numbering at least a few thousand. The walrus stocks off west Greenland and in the Greenland, Barents, and Kara seas are the most critically depleted. No systematic field investigations of walruses east of Greenland have been made since the Kara Sea and Franz Josef Land populations were studied in the mid-1930's. Opportunistic sighting records and compilations of historical catch information indicate that the herds of many tens of thousands that once inhabited Svalbard, Bear Island, Franz Josef Land, Novaya Zemlya, and other parts of the Eurasian Arctic have been very nearly extirpated.

Measures to curb the international trade in walrus ivory and skins may benefit the Atlantic subspecies in Canada and north Greenland. Enforcement of existing regulations pertaining to hunting by aborigines, and perhaps the imposition of further restrictions on such activities, are necessary if the subspecies is to approach full recovery. Field studies in the northeast Atlantic and off west Greenland would help determine the current status of walruses and provide a better understanding of the requirements for their recovery in these areas.

The Laptev walrus seems to have been reduced by overexploitation, but available information, most of it translated from Russian, is inconclusive. This subspecies was thought to number around 4,000 to 5,000 in 1975, and Soviet scientists have remarked on the need for a reduction in hunting pressure and protection of its habitat.