The Northern Fur Seal (callorhinus ursinus) is a member of the family of eared seals, or Otariidae. Northern Fur Seals are a common brown color, and when wet they are black, although older males develop a lightly colored mane at about 6 years of age. Fur Seals have greatly valued furs, which contain over 300,000 hairs per square inch, and are great insulators. Mature males can weigh up to 600 lbs., but are rarely below 450 lbs. Mature females weigh about 90 to 110 lbs.

Fur Seals are carnivores, feeding on Pollock, Herring, Capelin and Squid at depths of 600 feet underwater. Seals feed mainly at night.

Fur Seals leave their summer habitats - the Pribilof Is., W. Bering Sea, Sea of Okhotsk and Kuril Is. - somewhere between October and December. While the females and young males travel south to the coast of California, keeping 10 to 100 miles offshore, not touching the shore unless they are injured or sickly. Adult males are thought to spend their winters in Southern Alaska. No eared seals have ever taken up existence in freshwater rivers or lakes, for reasons unknown.