Fur Seal, Northern

(Callorhinus ursinus), a mammal of the family Otariidae of the order Pinnipedia. The adult male is up to 2.25 m long and weighs up to 380 kg; the female attains a length of up to 1.6 m and a weight of up to 71 kg. The animals are divided by age into black fur seals (ranging from newborn animals to those three months old), gray fur seals (from three months to two years, with a silvery gray underfur), bachelors (males from two to five years, with a gray-brown underfur), subadult bulls (six-year-old males), and adult bulls (males over six years). Females are divided only into the first two age groups. Fur seals have a double coat consisting of a layer of coarse outer hair and a soft, thick undercoat (this layer is gray in young seals and brown in adults). The animals have well-developed ear pinnae. The hind flippers are bent under the body and serve as support when the animal moves on dry land.

Fur seals are found in the Northern Pacific, where they winter on the open sea at 32°-38°N lat. and migrate north during the summer. There are three distinct herds of fur seals, with separate breeding grounds. The first herd is found on the Komandorskie Islands and the second is found on Tiulen’ Island (USSR); both herds winter in the Sea of Japan and the Pacific waters near Japan. The third herd is found on the Pribilof Islands and San Miguel Island (USA) and winters near the coast of North America. The adult bulls arrive at the breeding grounds first (in May), and the females and young follow later. Fur seals are polygamous, each adult bull having from 30 to 50 females in his harem. The young seals (the gray ones and the bachelors) sleep on beaches apart from the breeding grounds. The cows give birth two to three days after arriving at the rookery and mate several days later. The gestation period is one year. The pups are born with vision and are suckled for about three months. Females reach sexual maturity at the age of three and males at the age of five or six.

Fur seals molt at the end of the summer, and in autumn they abandon their rookeries until the following year. The animals feed on fish and cephalopods. They are fattest in spring and leanest in autumn. The animals’ fur is highly valued, but only bachelor bulls are slaughtered. In 1957 the USSR, the United States, Canada, and Japan concluded a treaty for the protection of fur seals in the North Pacific. The agreement provides for joint scientific study and regulates hunting. A related genus, Arctocephalus, comprising five species, inhabits the southern hemisphere.