The Northern Fur Seal, the only fur seal of the Arctic, is a member of the eared seal family (Otariidae).
Length 2.1 m (males), 1.4 m (females). Weight 250 kg (males), 40 kg (females). Male calves also weigh more than females (5.4 kg versus 4.5 kg at birth). Adult males are heavy-bodied and have a mane. Females are much smaller and more slender. Head is small, with a pointed snout. Flippers are very large. Males have dark brown or black fur, with gray guard hairs on their neck. Females have a greyish colour, paler on the belly tan on the back. Young calves are black.
Feeds on a variety of fish (anchovy, herring, capelin, hake, walleye pollock) and squid. Lives in large rookeries. Males are polygynous and defend their breeding territories against other males. Females give birth in June and breed again 8 to 10 days after giving birth. Pups are lactated for 4 months. Young animals can be killed by Killer Whales or Steller's Sea Lions. Both females and males are sexually mature at the age of 4 to 5 years, but males rarely mate until the age of 8. May live for 25 years.
Largest breeding rookeries are in the Bering Sea, on Pribilof Islands (Alaska) and Commander Islands (Russia). Also breeds in smaller numbers in the Sea of Okhotsk, on Kuril Islands, in the Aleutians and on the Channel Islands (California). Outside breeding season, animals may wander great distances; seals from the Bering Sea may reach Japan and California.
Northern Fur Seals have a long and bloody history of commercial exploitation. Now, inhabitants of the Pribilof Islands kill about 2000 animals a year, and Russian hunters also kill a small number of them. Thousands of seals are killed accidentally in fishing nets. The total number of Northern Fur Seals is about 1.1 million, but they have been constantly declining since the 1970s, and now the species is considered as vulnerable.