Harbor Seal

The Alaska Zoo has one seal species, the harbor seal. Back to animal directory.


LIFE SPAN: 30 years in captivity. Maximum age estimates for wild seals are 26 years for a male and 35 years for a female based on the annual growth rings in their teeth.

RANGE: Harbor seals inhabit the North Atlantic and Pacific Oceans from southern California up to the Bering Sea. In Alaska, they live in coastal waters from the Kuskokwim region through the Aleutians and along the coasts of the Gulf of Alaska into Canada. Juveniles move greater distances, but almost all harbor seals stay within a 100 miles of known locations or birth places.

SIZE: Harbor seal pups weigh close to 20 pounds at birth. Adult males have been noted to reach 285 pounds and are larger than females, who stay closer to 200 pounds or less. An adult harbor seal is between 5 and 6 feet long.

PHYSICAL FEATURES: Harbor seals are True (earless) seals. They are the only northern true seals that breeds on land rather than ice.  Their short, bristly hair is shed (molted) each year after breeding season. They are well-adapted for life at sea, but never far from land or ice. While mostly solitary while in water, they will haul out in groups and females will band together to pup in glacial bays together in larger groups. Harbor seals move slowly on land in an undulating motion as they cannot rotate their hind flippers forward. They use their front flippers and body motion to move on land, they rest or haul out on land and give birth on land. They have good hearing and eyesight, especially while underwater. Harbor seals can dive down over 1,600 feet and stay under water for 20 minutes.

FOOD: Harbor seals commonly eat pollock, cod, herring, octopus and squid.

BEHAVIOR: Seals have what is called embryonic diapause (i.e. delayed implantation). This means that the female's fertized egg stops development very early in the embryo stage and doesn't implant continue developing until the female's body condition and metabolism are at a sustainable level for embryo development. If she is food stressed and not in good health, the embryo may not develop any further and would be absorbed by her body. In Alaska, pups are born between May and mid-July in various haul-out locations including those in glacial fjords. Pups can swim almost immediately after birth, but females do carry them on their backs in rough seas. Seal teeth grow by the addition of layers, so age can be determined by cutting across a tooth and then counting the annual growth rings.

CONSERVATION: Slow population declines have been noted in the Gulf of Alaska and Bering Sea areas, but harbor seal populations are stable overall in Alaska. Gillnets and crab pots sometimes injure seals as they search for fish. Harbor seals are marine mammals are therefore protected by the Marine Mammal Protection Act through the US Fish and Wildlife Service. Only Alaska Natives are allowed to hunt them for cultural purposes.