fur seal, fin-footed marine mammal of the eared seal family (Otaridae), highly valued for its fur. Like the closely related sea lion, the nine species of fur seals are distinguished from the true seal by external ears and the ability to turn their hind flippers forward for walking on land. The northern, or Alaskan, fur seal, Callorhinus ursinus, has an outer coat of long coarse hair known as guard hair and an inner coat of thick soft fur; it is the inner coat that is valued in the fur trade. Males are dark brown and females and young are grayish. The male is about 6 ft (1.8 m) long and weighs up to 600 lb (270 kg), while the smaller female is up to 4 ft (1.2 m) long and seldom weighs more than 110 lbs (50 kg). Herds of northern fur seals, mostly females and juveniles, winter in open ocean along the Pacific coast of North America, migrating in spring to breeding beaches that range from the Pribilof Islands in the Bering Sea to San Miguel Island off California. Adult males, who usually winter separately, arrive at the islands weeks ahead of the females. During the breeding season the most aggressive males establish individual territories and have harems averaging 40 to 50 females, which they defend against other males. Mating occurs after the birth of the young conceived the previous summer; each female bears a single pup after a gestation period of almost a year. The pups nurse for about a month but remain with the mother for another 2 or 3 months. Mothers often leave pups for days to feed on squid and fish. By the early 20th cent. the northern fur seal population was reduced to about 200,000 as the result of wanton slaughter. An international treaty signed in 1911 limited hunting to a fixed number of nonbreeding males per year. By 1976 the world population had increased to almost 2 million; since then it has declined, for reasons still unclear. The United States prohibited the hunting of fur seals in 1985. Southern fur seals, such as Arctocephalus gazella and other species, are similar in size and appearance to the northern fur seal. Although their fur is not considered desirable, they have been hunted almost to extinction. Both southern and northern fur seals migrate, while tropical species remain near their breeding grounds. Fur seals are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Carnivora, suborder Pinnipedia, family Otariidae. See also Bering Sea Fur-Seal Controversy, under Bering Sea.

See W. N. Bonner, Seals and Man (1982); J. E. King, Seals of the World (1983).