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Harbor Seal (Phoca vitulina)

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Harbor seals are part of the “true seal” family, Phocidae. True seals lack external ear flaps and have short forelimbs that result in limited locomotion on land.

Male harbor seals are slightly larger than females, weigh up to 245 pounds (110 kg), and measure about 6 feet (1.8 m) in length. Harbor seals in Alaska and the Pacific Ocean are generally larger than those found in the Atlantic Ocean. Harbor seals’ color varies but they often have a blue-gray back with light and dark speckling. They have short, concave, dog-like snouts, and they tend haul out on land and rest with head and flippers elevated, in a banana like fashion.

Harbor seals eat a variety of prey consisting mainly of fish, shellfish, and crustaceans. Researchers have found that seals complete both shallow and deep dives during hunting depending on the availability of prey (Tollit et al. 1997).

Harbor seals mate at sea and females give birth during the spring and summer; although, the pupping season varies with latitude. Pups are nursed for an average of

This species is classified as LEAST CONCERN according to the IUCN's Red List.
This species is classified as LEAST CONCERN according to the IUCN’s Red List.

24 days and are ready to swim minutes after being born.

Status

MMPA – Harbor seals, like all marine mammals, are protected under the MMPA.

Species Description

Weight:
about 245 pounds (110 kg)
Length:
about 6 feet (~2 m)
Appearance:
generally blue-gray back with light and dark speckling; they lack external ear flaps and have short forelimbs
Lifespan:
about 25-30 years
Diet:
mainly fish, shellfish, and crustaceans
Behavior:
they tend to haul out on land and rest with head and flippers elevated, in a banana-like fashion

Habitat

Harbor seals live in temperate coastal habitats and use rocks, reefs, beach, and drifting glacial ice as haul out and pupping sites. Harbor seals haul out on land for rest, thermal regulation, social interaction, and to give birth. Seals also haul out to avoid predators. Studies have shown that seals in groups spend less time scanning for predators than those that haul out alone.

Distribution

Harbor seals are generally non-migratory and occur on both the U.S east and west coasts. On the east coast, harbor seals are found from the Canadian Arctic to New York and occasionally in the Carolinas. On the west coast, harbor seals are found in the coastal and estuarine waters from British Columbia, Canada to Baja, California. They are found further west through the Gulf of Alaska and in the Bering Sea.

Population Trends

Harbor seal stocks have experienced different population trends over the past 30 years. Along the west coast, stocks are stable and some are even increasing. In New England, the population is also increasing. Most stocks in Alaska are also stable or slightly increasing, but the Gulf of Alaska stock is small compared to its abundance in the 1970s and 1980s and may be continuing to decline. More information on the populations of harbor seal stocks is available in our stock assessment reports.

Threats

  • incidental capture in fishing gear, including
    • gillnets
    • trawls
    • purse seines
    • weirs
  • ship strikes
  • oil spill exposure
  • chemical contaminants
  • power plant entrainment
  • harassment by humans while hauled out on land

Conservation Efforts

The MMPA’s moratorium on taking marine mammals has limited hunting of harbor seals to Alaska Natives for subsistence and handicraft purposes. Therefore, bounty hunting of harbor seals and other marine mammals no longer occurs.

In 2001, a co-management agreement [pdf] was signed between NMFS and the Alaska Native Harbor Seal Commission to promote the health of harbor seals in order to

  • protect the culture of the natives
  • promote scientific research to facilitate management decisions
  • identify management conflicts
  • provide information to the public to promote sustainable use, management, and conservation

In an effort to educate the public about proper wildlife viewing, NMFS and our collaborators created regional guidelines for seal watching.

Regulatory Overview

All marine mammals, including harbor seals, are protected by the Marine Mammal Protection Act of 1972 as amended.

Taxonomy

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

References:

  • Hoover, A.A. 1988. Harbor seal Phoca vitulina. In: Selected Marine Mammals of Alaska: Species Accounts with Research and Management Recommendations (J.W. Lentfer, ed), pp. 125-157. Marine Mammal Commission, Washington, DC.
  • Tollit, DJ., S.PR. Greenstreet, and P.M. Thompson. 1997. Prey Selection by harbor seals, Phoca vitulina, in relation to variation in prey abundance. Canadian Journal of Zoology 75, 1508-1518.
  • NOAA

Cool/Gross/Weird:

-TSF-

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