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The harp seal ( Pagophilus groenlandicus), also known as the saddleback seal or Greenland seal, is a species of Phocidae, or true seal, native to the northernmost Atlantic Ocean and Arctic Ocean. Originally in the genus Phoca with a number of other species, it was reclassified into the Monotypic taxon genus Pagophilus in 1844. In Greek, its scientific name translates to "Pagophily from Greenland," and its taxonomic synonym, Phoca groenlandica translates to "Greenlandic seal." This is the only species in the genus Pagophilus.
Lactating female harp seals spend about 80% of the time in the water and 20% of the time on the fast ice, weaning or staying near their pups. However, almost half of the time spent in the water is at the surface, well beyond what is expected to recover from dives. This behavior allows the mother harp seal to conserve energy and avoid the harsh conditions of the fast-ice while remaining near her pup. As with most phocids, she requires vast amounts of energy to ensure sufficient mass transfer to her growing, weaning pup. Harp seals remain within their aerobic dive limit for 99% of dives.
Harp seals combine anatomical and Ethology approaches to managing their , instead of elevating their metabolic rate and subsequently their energy requirements. Their lower critical temperature is believed to be under in air. A thick coat of blubber insulates its body and provides energy when food is scarce or during fasting. Blubber also its body for more efficient swimming. Brown fat warms blood as it returns from the body surface as well as providing energy, most importantly for newly weaned pups. This blubber insulates the harp seal's core but does not insulate the flippers to the same extent. Instead, the flippers have circulatory adaptations to help prevent heat loss. Flippers act as heat exchangers, warming or cooling the seal as needed. On ice, the seal can press its fore flippers to its body and its hind flippers together to reduce heat loss.
They can also redirect blood flow from the periphery to minimize heat loss; the nostrils and eyes of harp seals are adapted to conserve heat, possessing a countercurrent heat exchange system and Rete mirabile, respectively.
On ice, the mother identifies her offspring by Olfaction. This sense may also warn of an approaching predator. Underwater, the seal closes its nostrils, disabling its sense of smell.
Its whiskers, or vibrissae, lie in horizontal rows on either side of its snout. They can sense to low-frequency , and may be able to detect movement of nearby animals during dives.
Western North Atlantic harp seals forage both near and offshore of Newfoundland, most preferring such prey as Arctic cod ( Boreogadus saida), capelin, Greenland halibut ( Reinhardtius hippoglossoides) and American plaice ( Hippoglossoides platessoides). As in other populations and foraging areas, diet varies with distance from shore, with arctic cod comprising more of it Nearshore waters and capelin more of it Pelagic zone. However, capelin is the preferred prey in both locales.
Females become sexually mature between ages five to six. Annually thereafter, they may bear one pup, usually in late February. The gestation period lasts about 11.5 months, with a fetal development phase of 8 months. There have been reported cases of , but singletons are vastly more common. The fertilized egg grows into an embryo which remains suspended in the womb for up to three months before implantation, to delay birth until sufficient pack ice is available.
Harp seal are rapid, with recorded lengths as short as 15 seconds in duration. In order to cope with the shock of a rapid change in environmental temperature and undeveloped blubber layers, the pup relies on solar heating, and behavioral responses such as shivering or seeking warmth in the shade or even water.
Newborn pups weigh on average and are long. After birth, the mother feeds only her own pup. During the approximately 12-day long nursing period, the mother does not hunt, and loses up to per day. Harp seal milk initially contains 25% fat (this number increases to 40% by weaning as the mother fasts) and pups gain over per day while Lactation, quickly thickening their Blubber. During this time, the juvenile's "greycoat" grows in beneath the white neonatal coat, and the pup increases its weight to . Weaning is abrupt; the mother swiftly turns from nursing to promiscuous mating, leaving the pup behind on the ice. In the post-weaning phase (after abandonment), the pup becomes sedentary to conserve body fat. Within a few days, it Moulting its white coat, reaching the "beater" stage. This name comes from the sound a beater's tail makes as the seal learns to swim. Pups begin to feed at 4 weeks of age, but still draw on internal sources of energy, relying first on energy stored in the body core rather than blubber. This fast can reduce their weight up to 50%. As many as 30% of pups die during their first year, due in part to their early immobility on land. During this time the ice begins to melt, leaving them vulnerable to and marine predators such as and .
Around 13–14 months old, the pups molt again, becoming "bedlamers". Juveniles molt several times, producing a "spotted harp", before the male adults' harp-marked pelt fully emerges after several years. In females, it may not emerge.
Seals congregate annually on the ice to molt, pup and breed before migrating to summer feeding grounds. Their lifespan can be over 30 years.
The number of pups born in the traditional pupping area of the southern Gulf of St. Lawrence was greatly reduced, with an estimated pup production of only 18,300 (95% CI, 15,400-21,200 rounded to the nearest hundred). Another 13,600 (95% CI, 7,700-19,500) pups were born in the northern Gulf. An estimated 714,600 (95% CI, 538,800-890,400) pups were born off the northeastern coast of Newfoundland (Front); accounting for 96% of all pupping in 2017. Combining the estimates from all areas resulted in an estimated total pup production of 746,500 (95% CI, 570,300-922,700).
There are two recognised subspecies:
| Eastern Canada to Norway |
| White Sea and Barents Sea seas |
More recently, they reached Lindisfarne in Northumberland in September 1995, and the Shetland Islands in 1987. The latter was linked to a mass movement of harp seals into Norwegian waters; by mid-February 1987, 24,000 were reported drowned in fishing nets and perhaps 30,000 (about 10% of the world population) had invaded as far south as Oslo. The animals were emaciated, likely due to commercial fishing causing competition for the seals' prey.
Harp seals can strand on Atlantic coasts, often in warmer months, due to dehydration and parasite load. In March 2020, a harp seal was spotted near Salvo, North Carolina. Harp seals often consume snow to stay hydrated, but in mild winters may not have enough available. Several centers are active in seal rescue and rehabilitation, including IFAW, NOAA, and the New England Aquarium. Harp seals are protected by the Marine Mammal Protection Act in the United States.
In Canada, commercial hunting season is from November 15 to May 15. Most sealing occurs in late March in the Gulf of St. Lawrence, and during the first or second week of April off Newfoundland, in an area known as "the Front". This peak spring period is generally what is referred to as the "Canadian seal hunt". Hunting Canadian whitecoats has been banned since 1987. Since 2000, harp seals that are targeted during the hunt are often found to be less than a year old, known as "beaters". In 2006, the St. Lawrence hunt officially started on March 25 due to thin ice caused by the year's milder temperatures. Inuit living in the region hunt mainly for food and, to a lesser extent, commerce.
In 2019, the Department of Fisheries and Oceans estimated sustainable harvest levels for the next five years. The identified annual Canadian Total Allowable Catch (TAC) levels were 425,000 assuming harvest age structures of 95% young of the year (YOY). In 2016, 66,800 harp seals and 1,612 grey seals were harvested in Atlantic Canada.
In 2005, the Independent Veterinarians' Working Group (IVWG) recommended a three-step process for hunters to kill the seals with little or no pain for the seals, as long as the process is completed in rapid succession. The process is as follows:
In 2009, this process was included in both the 'Conditions of License' for the Canadian hunt as well as the Canadian Marine Mammal Regulations.
The Canadian seal hunt is monitored by the Canadian government. Although approximately 70% of the hunt occurs on "the Front", most private monitors focus on the St. Lawrence hunt, due to its more convenient location.
The annual quota off the coast of Greenland for 2017–2019 was set at 26,000 1+ animals, where two pups are equivalent to removing one 1+ animal. The total catches of harp seals were 2000 (including 1934 pups) in 2017, 2703 (including 1218 pups) in 2018, and 5813 (including 2168 pups) in 2019.
The 2004 West Ice total allowable catch (TAC) was 15,000, almost double the sustainable catch of 8,200. Actual catches were 9,895 in 2004 and 5,808 in 2005. The 2004 White Sea TAC was 45,000. The catch was 22,474.
The White Sea and West Ice populations:
Impact on populations
Hunting has tremendously affected the population size of harp seals. Over the past 150 years, the harp seal population has fluctuated from over 9 million to as little as 1 million. The current population is estimated to be around 4.5 million or less. The Northwest Atlantic populations was found to have decreased by at least 50 percent from 1952 to 1970 but nowadays, seal populations all are hunted under quotas and other restrictions.
See also
Further reading
The Northwest population:
External links
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