Distribution and Habitat
The walrus resides in North Pacific, North Atlantic, and Arctic waters. There are three subspecies: the nominate subspecies rosmarus in the North Atlantic, Barents, eastern Canadian Arctic and western Kara Seas; divergens in the Chukchi and Bering Seas and North Pacific south to Kamchatka and Bristol Bay; and laptevi in the Russian Arctic from the western reaches of the East Siberian Sea, the Laptev Sea and western Kara Sea. Now largely restricted to northern latitudes it was once much more widely distributed, particularly the Atlantic walrus which ranged as far south as Cape Cod in North America before hunting wiped out southern populations. Primarily associated with pack ice in winter, walruses will also haul out on land.
Atlantic walrus males average 3.0 m in length and weigh approximately 800-900 kg. Pacific walrus males are somewhat larger, averaging 3.2 m and approximately 1200 kg. Females are generally smaller. Laptev walruses are intermediate between the other subspecies (but more similar to Pacific walruses of which some consider them to be a population). Although they appear to be naked, the brown skin is covered with short, coarse hair. Both sexes have enlarged upper canine teeth which appear as external tusks, and are larger in males. Males are sexually mature at approximately 15. Some females may mature by age 4, but age 7 - 8 is usual. Gestation lasts 15 months and lactation 1 to 2 years. Females may produce a pup every other year, but every third year is considered usual. Molluscs are the main food, constituting 95% of the diet by numbers and mass. Other benthic invertebrates and fish are also taken. Some individuals are known to prey on seals, particularly ringed seals. Walruses may live up to 40 years.
The Pacific walrus is most numerous, with the present population estimated to be between 200,000 and 300,000. It is thought that the Laptev walrus population numbers 5,000 - 10,000. The Atlantic walrus is believed to number approximately 15,000, although estimates for Russian populations are out of date. The Laptev walrus is entered in the IUCN Red List as Insufficiently Known.
Threats to the Species
Pacific walruses are legally hunted in Russia, and the USA and Atlantic walruses are legally hunted in Canada and Greenland. The IUCN Seal Specialist Group has stated that "overexploitation of local stocks is one of the major threats in some areas." Poaching is known to occur on all subspecies and is thought to be at unsustainable levels for some populations. Proposed mineral and petroleum exploitation pose threats both directly, and through the increased risk of disturbance and poaching that attend increased human activity. Harvesting of Arctic molluscs on which walruses feed has been proposed in some areas and may constitute a risk to the forage base of affected populations.
Reijnders, P. et al. 1993. Seals, Fur Seals, Sea Lions, and Walrus. Status Survey and Conservation Action Plan. IUCN Seal Specialist Group. Gland, Switzerland. 87pp.
Rice, D.W. 1998. Marine mammals of the world: systematics and distribution. The Society for Marine Mammalogy Special Publication Number 4. 231 pp.
Links to other sites about walruses