Nothern Fur Seal - Callorhinus ursinus - Video, Facts

Northern fur seals are classified as pinnipeds, a word which is derived from the Latin and means "flap-footed." Native to the northern Pacific Ocean, northern fur seals have the second thickest fur of any animal, second only to the sea otter. The coat of the adult female fur seal is a reddish brown on the front and underside with a silver patch on the chest and silver gray on their top. Adult males can range in color anywhere from brownish gray to black.

Diet

The primary diet of the fur seal consists mainly of squid, pollack, herring, salmon, mackerel, and anchovies.

Population

There are an estimated 1.2 million northern fur seals in the world today. The majority of fur seals, an estimated 60 - 70%, breed at Pribilof Islands located in the Bering Sea. Smaller rookeries are located on Bogoslof Island in the Aleutians and the Kuril Islands and Commander Islands near mainland Russia in the western North Pacific. Unfortunately over the last decade there has been a steady decline of northern seal pup births.

Range

Northern fur seals are found throughout the Northern Pacific Ocean from Japan to southern California all the way up to the Bering Sea. See a nothern fur seal range map >>

Behavior

Northern fur seal males are territorial and upon arriving to the mating sites during mating season, will begin to assert their dominance and establish territories by threatening and fighting other males. These territories may contain at least 40 females. Adult males do not feed during mating season and can lose up to 20% of their total weight.

Northern fur seals tend to live alone or in pairs, and rarely come to land, except to breed. About half of each year is spent out at sea. Sharks, killer whales, and Steller sea lions will all hunt northern fur seals if they get the opportunity.

Reproduction
Mating Season: Summer, with peak in late June
Gestation: 11-12 months
Litter size: One pup

Global Warming and Other Threats

A 2008 survey of the main breeding ground on the Pribilof Islands found the lowest level of northern fur seal pup production since 1916. Climate change may be disrupting patterns of prey abundance in the ocean. As temperatures in the ocean rise, the fish on which northern fur seals depend have begun moving further out to sea, where the water is cooler. If fish numbers are reduced or more plentiful further offshore, seals will need to spend more time foraging, thereby expending more time and energy on feeding and less on reproduction and raising young, which reduces survival rate of pups, leading to a reduction in the overall fur seal population.

Over-fishing is also depleting fish stocks that the northern fur seals depend on for food, especially after the mothers give birth and need a ready supply of food to keep up their strength while she is nursing her newborns. Fur seals are also continually entangled in squid driftnets used by the Japanese fisheries and Alaskan gillnet and trawler fisheries.

Northern fur seals are very sensitive to warmer waters. Marine mammal rehabilitators report dramatically higher fur seal cases during El Niño years when the water is unusually warm. Fur seals are also susceptible to infection from a hookworm that causes anemia, which can be deadly to pups. Hookworm populations increase when temperature and humidity are higher.

Reasons For Hope

Because of such vigorous hunting of fur seals in the 1800's, in 1911 the North Pacific Fur Seal Convention was founded making it illegal to hunt seals at sea and restricting fur seal hunts to immature male seals on land. Despite the 1911 convention elapsing in 1984 all commercial hunting was stopped of fur seals. However subsistence hunting by natives is still allowed in some areas.

Legal Status/Protection

• IUCN Red List: Due to population decline, the northern fur seal is listed as vulnerable.
• Northern Fur Seals are a depleted species under the Marine Mammal Protection Act.
• Learn more about legal status and protection of northern fur seals >>

How You Can Help

• Help fur seals and other wildlife by adopting an imperiled animal from our Wildlife Adoption Center.
• Take Action for habitat and Wildlife at our Wildlife Action Center.

For additional information

• Learn more about Defenders of Wildlife's work on Global Warming.