Aquafacts / Northern Fur Seals

Northern fur seals 

Peruse some of the most frequently asked questions we’ve received about northern fur seals, answered by our biologists and other reputable sources.

Quick info

186 kilograms 

Average adult male weight

40 kilograms 

Average adult female weight

10 days 

Time spent nursing before females mate again


Name for adult male


Name for adult female

What is a fur seal?

Fur seals are a type of pinniped, related to animals like harbour seals and steller sea lions. Despite their name, fur seals are more closely related to sea lions (members of the earred seal or Otariidae family) meaning that they have obvious external ear flaps and large flippers that support their body upright when on land. Like their cousins, fur seals eat fish and are very good swimmers. They are known for having the second densest fur in the animal kingdom (next to sea otters).

What do northern fur seals eat?

Northern fur seals eat herring, sandlance, capelin, anchovy, squid, and salmon just to name a few.

Where are northern fur seals found?

The Northern fur seals can be found in the Pacific Ocean with their range extending from Japan, through the Bering Sea (with breeding colonies on the Commander, Pribolof and Bogoslof Islands which lie west of Alaska) and then down to California.

Are northern fur seal populations endangered?

Yes. The population of Northern fur seals has shown a dramatic decrease since the 1970's. Historically this species was hunted to near extinction for their fur which was highly prized when it was "discovered" by Europeans in the 18th century (the fur seals were relied on by local First Nations peoples as an important resource for many years prior). They have been protected since the early 1900's, but in the 1970's a sharp decline in their population was noticed. Researchers have been trying to understand this change through research both in the field as well as with facilities that house Northern fur seals, like the Vancouver Aquarium.

How does the northern fur seal breeding season work?

Males arrive at the breeding sites (typically on the islands in the Aleutian Island chain) one month before the females do to establish their territory. Once the females arrive in mid June they give birth to their young who were conceieved the previous year. About 11 days after birth, females will mate again. Males manage a harem, a group of females that he protects from other males. In order to make sure he doesn't lose any of his potential mates, the male will not eat throughout the breeding time, and have been observed to lose up to 20% of their overall weight.

After nursing their pups for about 10 days, the females make their way back to the ocean to feed for roughly a week before returning to nurse their pup for a couple of days. This continues for 4 months before the female returns to sea until the following June. The fertilized egg she currently carries experiences a delayed implantation. This ensures that the pup will be born at the right time the next year.

Our experts are doing important research in the field and on site at the Vancouver Aquarium. Learn more about ocean research.