Harp Seal (Pagophilus groenlandicus)
Did You Know?
· Although harp seals live in the Arctic, they are born with no protective fat. As pups, their white coats absorb sunlight, and their fur traps heat, keeping the pups warm.
MMPA - Harp seals, like all marine mammals, are protected under the MMPA.
Harp seals are part of the family Phocidae, known as the "true" or "earless" seals because they lack external ear flaps. They have a robust body, a relatively small, broad, flat head, and a narrow snout that contains eight pairs of teeth in both the upper and lower jaws. Their front flippers have thick, strong claws. On their hindflippers, the inner and outer digits are longer and have small, narrow claws. Phocids are unable to rotate these back flippers underneath them to walk, and instead use their front flippers to pull themselves along on land. Adults are approximately 5-6 ft (1.7 m) long, and weigh around 300 lbs (135 kg). They have light gray fur, with a black face and a horseshoe-shaped black saddle on their back. Their common name refers to this pattern, which looks like a harp.
Harp seals are modest divers by pinniped standards. The average maximum dive is to about 1,200 feet (370 m), with a duration of approximately 16 minutes. They eat a variety of fish and invertebrates, but mainly focus on smaller fish such as capelin, arctic and polar cod, and invertebrates including krill.
Females give birth to pups near the southern limits of their range from late February to mid-March. Pups nurse on high-fat milk for approximately 12 days, during which they gain about 5 lbs (2.2 kg) per day and develop a thick blubber layer. At birth, harp seals are just under 3 feet (1 m) long, and weigh about 25 lbs (11 kg). Called "whitecoats," newborns have long, wooly, white fur known as "lanugo", and undergo a complicated series of "molts" before reaching adult coloration. Harp seal pups are abruptly weaned from their mothers when they weigh approximately 80 lbs (36 kg). Adult females leave their pups on the ice where they remain without eating for approximately 6 weeks. Pups can lose up to half of their body weight before they enter the water and begin feeding on their own.
After pups are weaned and left alone, adult harp seals begin mating. Adult females undergo a period of suspended development known as "delayed implantation" during which embryos do not attach to the uterine wall for three months or more. This allows all females to give birth during the limited period of time when pack ice is available.
During breeding in February and March, and when molting in late spring, harp seals aggregate in large numbers of up to several thousand seals on the pack ice. During extensive seasonal migrations, large groups may feed and travel together.
Harp seals are prey for polar bears, killer whales, and sharks.
Harp Seal Range Map
(click for larger view PDF)
The harp seal population is divided into three separate stocks, and each uses a specific breeding site. The first and largest, the Western North Atlantic stock, is located off eastern Canada and is divided into two herds based on breeding location. The Front herd breeds off the coast of Newfoundland and Labrador, and the Gulf herd breeds near the Magdalen Islands in the middle of the Gulf of St. Lawrence. The second stock breeds on the "West Ice" off eastern Greenland, and the third stock breeds on the "East Ice" in the White Sea off the coast of Russia. Breeding occurs between mid-February and April, at varying times for each stock.
Harp seals are highly migratory. Following the breeding season, adults assemble north of their "whelping" sites to undergo an annual molt before continuing to migrate north to Arctic summer feeding grounds. In late September, after feeding all summer, most adults and some immature seals of the Western North Atlantic stock migrate south along the Labrador coast to the entrance to the Gulf of St. Lawrence, generally arriving by early winter. There they split into two groups, one moving into the Gulf and the other remaining off the coast of Newfoundland.
In recent years, the number of sightings and strandings from January to May have increased off the east coast of the United States from Maine to New Jersey. During this time, the Western North Atlantic stock of harp seals is at the most southern point of their migration.
Abundance estimates, which use a variety of methods including aerial surveys and mark-recapture, are available for the Western North Atlantic stock. These methods involve surveying whelping concentrations and estimating total population adult numbers from pup production. The best estimate of abundance for Western North Atlantic harp seals is 5.9 million animals. The minimum population estimate based on results of a 2004 pup survey is 5.3 million seals. According to NMFS 2007 Stock Assessment Report, there is not enough information to calculate a minimum population estimate for U.S. waters, but this population appears to be increasing based on the increased number of stranded harp seals.
Humans are the main threat to harp seals, and have hunted all three stocks for centuries. Other human-caused m ortalities have been documented from various sources, including boat strikes, fishing gear interactions, power plant entrainment, oil spills, harassment, and shooting. Loss of sea ice is a potential threat to their habitat.
Harp seals are not considered a strategic stock because the level of human-caused mortality and serious injury in the U.S. Atlantic "Exclusive Economic Zone (EEZ") is believed to be very low relative to the total stock size.
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