Northern Fur Seal

This is the largest of the fur seal family and was once widely hunted for its coat. This is the only fur seal in the northern hemisphere. Its well-documented migration takes it from the Bering Sea between Alaska and Siberia, where it spends the summer, to its winter destination of the northern Pacific. Populations are spread down the coasts of the Pacific, reaching Japan to the west and the extreme south of California to the east.

Male northern fur seals are much larger than females, being up to six times heavier and about 50 per cent longer. While the females tend to be grey, the males' fur is red and black.

Northern fur seals prefer cold water and spend a lot of time far out at sea, only returning to land to breed. Most of their breeding grounds are on islands in the northern Pacific. As with most seal species, the male northern fur seals arrive at the breeding grounds first and occupy a territory on the shore. The largest bulls take the best locations, usually in the middle of the beach. Females arriving to give birth move into the territory of a male. They seem to choose according to the location of the territory and the number of other females it contains, rather than by the bull’s size. At this stage, the males — called bulls - will not feed for up to two months as they battle to mate with the cows, and will lose a considerable amount of body weight. Dominant northern fur seal bulls may establish harems numbering 40 to 50 cows. The dense underfur of this species, insulating the seals from the cold, consists of 60,000 individual hairs per square centimetre (350,000 per square inch).

Distribution: Found in the northern Pacific Ocean, with its main breeding areas, called rookeries, on the Commander Pribilof and Tyuleni Islands in the Bering Sea.

Habitat: Rocky beaches.

Weight: 30 - 275 kg (66 - 606 lb); males are heavier.

Length: 140 - 210 cm (55 - 83 in).

Maturity: Females 3 - 5 years; males 5 - 6 years, but rarely mate before 10.

Gestation Period: 248 days; embryonic development starts about 4 months after mating.

Breeding: 1; weaning occurs at 26 weeks.

Diet: Piscivorous, hunting a variety of fish and squid.

Lifespan: Males up to 17 years; females up to 26 years.

Status: Vulnerable.


Both sexes have a short muzzle, with the nose extending beyond the jaws in bulls.


Whiskers are very long — white in adults, but black in youngsters.

Front flippers

There is no fur on the upper surface, extending back up to the wrist joint.

Male physique

Males have a thick, wide, powerful neck with a mane of longer, coarser guard hairs.


A male northern fur seal seeks to intimidate a rival first, but if fighting follows, they can bite using long, sharp canine teeth.

Females have a significantly longer lifespan than males.