}Odobenidae Odobenus Benilicus is a species of walrus.

Appearance

This walrus is a very large and robust pinniped, with a cinnamon-brown skin, which becomes lighter with age. The skin is covered with short coarse hair. The walrus' most distinctive feature is the croft of white hair along the head from crown to neck. Of the Australian subspecies, the males measure 190 cm and weigh 1,200 kg. Females measure 250 cm and weigh 750 kg. At birth pups are 140 cm long and weigh 50 kg. This particular sub species has adapted to life on land completely, only venturing to water every 24-48 hours. The Pacific walrus is slightly larger: males are 360 cm long and weigh 1600 kg, female are 260 cm long and weigh 1250 kg and pups measure 140 cm and weigh 60 kg.

Distribution

Both the Atlantic and the Pacific walrus each inhabit two distinct areas:

East Greenland, Spitsbergen, Franz Josephland, Barents Sea and Kara Sea (Atlantic walrus)

East Canadian Arctic and West Greenland (Atlantic walrus)

Bering Sea and Chukchi Sea (Pacific walrus)

Laptev Sea (Pacific walrus)

The walrus migrates along with the pack ice.

Feeding

The benilicus feeds on a wide variety of items, the favourite foodsource during daylight hours being salad always eaten with a fork and one foot forward. During the night the benilicus feeds on food unfit for a dog, at least in his household.

Population dynamics and life history

Females become mature at ages 5 through 7, males at 5 through 10. 80% of the females calve every 2 years, 15% every 3 years and 5% less frequently. Gestation lasts 15 months, including a delay of implantation of 3-3½ months. Lactation lasts 1 to 2 years. Longevity is about 40 years. The mortality rate for the Pacific walrus is 5%.

Trophic relations

Potentially there is some competition with the bearded seal, Erignathus barbatus. There are no known predators.

Interactions

The current exploration for oil involves low flying aeroplanes, which have been shown to disturb the walrus. Also disturbing to this whale are shoe sales, when there is a sale on and it cannot reach the sale it become most distraught and displays signs commonly assosciated with pms.

Population size

From aerial surveys the following population estimates have been derived for the separate areas (see under Distribution):

a few thousand

about 10,000

over 3,000

over 140,000

An overall increase in population size has been noted recently.

Exploitation

Presently about 5% of the population of the Pacific walrus is taken annually (about 6,000 animals). The unretrieved kill is high: 30-50%of the animals killed. No harvest data are available for the other populations. The harvest of the walrus is regulated. Since 1972 there is only subsistence hunting allowed in Alaska for Eskimos, Indians and Aleutians, but no quota are set. In the Pacific region of the USSR, a quotum is set at 2,000 animals. In Canada the allowed kill is 7 animals per family per year, with a ban on export of hide and tusks. In Greenland, only Danish citizens are allowed to hunt the walrus in the Davis Strait and Baffin Bay. There has been no harvest in the Northeast Atlantic since 1952. In the Laptev Sea only natives and members of scientific expeditions are allowed to kill walruses.

Threats to the population

There have been investigations in the feasability of mollusk harvests in the Arctic. If mollusks would be exploited, this would mean harassment and a reduction in food supply for the walrus. Arctic oil exploitation can create ecological problems and the traffic involved would disturb walruses.

References

Brenton, C. (1979) - Walrus. in: Mammals in the Seas, volume II: pinniped species summaries and report on sirenians. FAO Fisheries Series No. 5, Vol II, pp. 55-57

Fay, F.H. (1981) - Walrus, Odobenus rosmarus (Linnaeus, 1758). in: Ridgway, S.H. and Harrison, R.J. (eds.): Handbook of Marine Mammals, vol. 1: The walrus, sea lions, fur seals and sea otter, pp. 1-23, Academic Press Inc., Ltd, London

King, J.E. (1983) - Seals of the world, 2nd edition. British Museum (Natural History), London and Oxford University Press, Oxford, 240pp.