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Harbor Seal (Phoca vitulina)

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Harbor Seal Image / Jennifer Kennedy

Harbor seal, Gulf of Maine

© Jennifer Kennedy, Blue Ocean Society for Marine Conservation

Harbor seals, or common seals (Phoca vitulina) are a type of "true" (or earless) seals. These seals do have ears, but they aren't marked by external ear flaps, as in sea lions.

Description:

Harbor seals grow to about 5-6 feet in length, and weigh between 200-300 pounds. Females are smaller than males. Harbor seals have a coat that varies in color on the back from brown to gray, with light undersides. They also may have light and dark spots scattered throughout their coat.

If you see a harbor seal swimming, it might look like a dog, with its round head, long whiskers and large eyes peeking above the water surface.

Classification:

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Carnivora
  • Family: Phocidae
  • Genus: Phoca
  • Species: vitulina

Feeding:

Harbor seals feed on fish, crustaceans, and invertebrates. Their predators include sharks, orcas and polar bears.

Habitat and Distribution:

Harbor seals spend about half their lives in the water (where they feed and mate) and half on land (where they haul-out to rest, give birth, and nurse their young).

Harbor seals are found in both the Atlantic and Pacific Oceans. In the Atlantic, they are found from arctic Canada, down through New England to New York, and occasionally as far south as the Carolinas. In the Pacific, they are found from the Gulf of Alaska and Bering Sea down to Baja, California.

Reproduction:

Males and females mate at sea. After mating, the embryo may take 1.5-3 months before it implants into the uterine wall and begins growing (this is called delayed implantation, and allows the mother to recover from her last birth and have her pup during an optimum time). A study in 2010 reported that good access to food may lead to sooner implantation and births earlier than usual.

The gestation period is 11 months, after which a single pup is born. Pups are about 2.5-3 feet long and weigh 20-30 pounds at birth. Unlike some seals (e.g., monk seals) who spend their initial weeks on land, harbor seal pups can swim just minutes after birth and can accompany their mother when she is foraging at sea. The pups nurse for about 24 days. After weaning, the mother pays no attention to the pup, and the pup learns to catch its own food.

The live span of a harbor seal is estimated to be about 25-35 years.

What to Do If You See a Seal on Shore:

In coastal areas within harbor seal habitat, harbor seals may be seen on shore. In most cases, if left alone, the seal will be fine - they are comfortable on the beach and out of the water. They may be hauled-out to rest, or a pup may be resting on shore while its mother is in the ocean foraging. Going near the pup or trying to take care of it will do more harm than good.

What to do if you see a seal:

  • Remember that they are wild animals. They are also protected by the Marine Mammal Protection Act, which has strict prohibitions on disturbance or harassment.
  • If you choose to observe the seal, do it from at least 150 feet away.
  • If the seal appears injured, sick or dead, do not approach it, but call local stranding authorities (your local police department or town/city hall will likely know who to call if you don't have a number handy).
  • Keep pets away from the seal, whether it is dead or alive.
  • Do not cover the seal, pour water on it, try to feed it, or try to get it to move. It will likely go back into the water soon on its own.

Status:

The harbor seal is listed as of “least concern” on the IUCN Red List because of its large, increasing/stable population.

Threats to harbor seals include capture in fishing gear, boat strikes, marine pollution, and human disturbance at haul-out sites.

Sources:

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