Harbor Seal (Phoca vitulina)

	Harbor Seal (Phoca vitulina) Photo: NOAA

	Did You Know? · Harbor seal pups can swim at birth and can dive for up to 2 minutes when they are only 2-3 days old. · Harbor seals are the most common seal seen along the U.S. east coast.

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

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

Species Description
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 anywhere from about 5.6-6.3 feet (1.7 to 1.9 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 tend to haul out on land in a banana-like fashion with their head and rear flippers elevated. 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 24 days and are ready to swim minutes after being born.

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.

Harbor Seal Range Map
(click for larger view PDF)

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 southern New England, New York and occasionally end up in the Carolinas. On the west coast, harbor seals are found in the coastal and estuarine waters off Baja, California, north to British Columbia, west through the Gulf of Alaska and in the Bering Sea. NMFS manages seven stocks of harbor seals throughout the United States: Bering Sea, California, Gulf of Alaska, Oregon -Washington coastal, Southeast Alaska, Washington Inland, and Western North Atlantic. Based on recent genetic findings, NMFS is reevaluating the structure of the Southeast Alaska, Gulf of Alaska, and Bering Sea stocks.

Population Trends
Harbor seal stocks have experienced different population trends over the past 30 years. Along the west coast, stocks have increased since the passage of the MMPA in 1972. Harbor seal populations in Oregon and Washington are at or approaching their "carrying capacity" with a population of roughly 22,380 seals. The California coast stock is beginning to stabilize at 34, 233 seals. In New England, the population is increasing is and currently estimated to be 91,000 seals. The Southeast Alaska and Bering Sea stocks are stable or slightly increasing. The Gulf of Alaska stock is small compared to its abundance in the 1970s and 1980s and may be continuing to decline. The current population estimate for Alaska is 180,017 seals.

Threats
Harbor seals are incidentally captured in fishing gear including gillnets, trawls, purse seines, and weirs. They are also victims of boat strikes, oil spill exposure, chemical contaminants, and power plant entrainment. On land, humans may "harass" and disturb hauled out harbor seals while the seals are resting.

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 1999, 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, to promote scientific research to facilitate management decisions, to identify management conflicts, and to provide information to the public to promote the sustainable use, management, and conservation of harbor seals. MMPA section 118 governs interactions between commercial fishing and marine mammals to ensure mortality and serious injury of harbor seals does not exceed sustainable levels. Taking of harbor seals and other marine mammals incidental to activities other than commercial fishing is limited by regulations, which include monitoring, reporting, and mitigation. In an effort to educate the public about proper wildlife viewing NMFS and collaborators have 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.

Key Documents
(All documents are in PDF format.)

Title	Federal Register	Date
Co-Management Action Plan	n/a	01/2001
Stock Assessment Reports	n/a	various

More Information

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.