Alternate name: Alaska Fur Seal

Family: Otariidae, Eared Seals view all from this family

Description Very large flippers. Tiny tail. Small head with short, pointed nose, large eyes, and long whiskers. Bull has greatly enlarged neck; is blackish above, with massive grayish shoulders; reddish below. Female is gray above, reddish below. Male much larger than female, beginning at birth. L male 6' 3"–7' 3" (1.9–2.2 m), female 3' 7"–4' 7" (1.1–1.4 m); Wt male 330–594 lb (150–270 kg), female 84–119 lb (38–54 kg).

Similar Species Sea lions and Northern Elephant Seal are larger. Harbor Seal is spotted.

Breeding Mates mid-June to mid-July; yearlings mate in August. 1 glossy black pup born June–July of following year; birth weight 10–12 lb (4.5–5.4 kg).

Habitat At sea most of year; in summer, breeds on rocky island beaches.

Range In summer, Point Barrow, Alaska, on Arctic Ocean; breeds on Pribilof and Commander islands and vicinity in Bering Sea, and on San Miguel Island, off California. In winter, south to San Diego, California.

Discussion The greatest traveler of the aquatic carnivores, this oceangoing fur seal sometimes migrates up to 6,200 miles (10,000 km), returning to land only during the breeding season. At sea, it is not gregarious and is rarely seen in groups of more than three. By day the animal rests and preens, and may swim slowly with a flipper waving in the air. It rests in a "jug handle" position, lying on its back with the hind flippers bent up over the belly and held there by a fore flipper. Small schooling fish of about 50 species form two-thirds of its diet, with 10 species of cephalopods, mostly squid, forming the other third. In addition, at least 30 species of marine mammals and oceanic birds are eaten occasionally. Feeding at night, when fish swim closer to the surface to eat, this seal forages to depths averaging about 230 feet (70 m); the maximum depth documented was 755 feet (230 m). Dives last for an average of two and a half minutes. This seal’s major rookery on the Pribilof Islands is enormous, with more than 1 million seals within a 30-mile (50-km) radius. Older bulls arrive first, in late May and June, and battle savagely to establish territories in the best places, near the water and with best access to cows. Females arrive from mid-June to mid-July and within two days give birth to a pup conceived the previous summer. The biggest bulls may form harems of 40 or more cows (some of these cows may be stolen by bulls farther from shore). The cow mates 8 to 10 days after the pup is born, usually with the bull in whose territory she has given birth. The bull does not feed during the breeding period and may lose up to 20 percent of his weight. After remaining with the pup one week, the cow goes on feeding forays several times weekly, often more than 100 miles (160 km) out to sea. She returns regularly and stays one or two days to nurse the pup with her rich milk. The pup is weaned by October or November. As many as 12 percent of the young die in their first month, often from hookworm, which causes anemia. In August, female yearlings come ashore and breed with the bachelor bulls too young and small to maintain their own territories; these bulls will join the territory scramble when 9 or 10 years old. Bulls, battle-scarred and thin from their two-month fast during the breeding season, barely have strength to return to the water in August; most winter in the Gulf of Alaska or south of the Aleutians, but some migrate to Asian waters. Females and juveniles leave the beaches by November; a number of them winter as far south as southern California. This seal’s Pribilof breeding grounds were discovered by humans in 1786; by 1834, overhunting had greatly reduced the numbers of seals, which were prized for their fine, soft fur and their meat and blubber. The Northern Fur Seal was afforded some protection as early as 1835, but in 1988 the U.S. National Marine Fisheries Service designated the Pribilof Islands herd a depleted stock, and made it illegal for anyone to harvest these seals except native peoples who rely on them for subsistence.