Гренландский тюлень: биология и особенности вида.

Species of mammal

The harp seal (Pagophilus groenlandicus), also known as Saddleback Seal or Greenland Seal, is a species of earless seal, 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 genus Pagophilus in 1844. In Greek, its scientific name translates to "ice lover from Greenland," and its taxonomic synonym, Phoca groenlandica translates to "Greenlandic seal." This is the only species in the genus Pagophilus.

The mature harp seal has pure black eyes. It has a silver gray fur covering its body, with black harp or wishbone shaped markings dorsally. Adult harp seals grow to be long and weigh from Dive duration ranges from less than two minutes to just over 20 minutes. 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. The insulating quality of this fur depends on its ability to keep a layer of air trapped inside or between the hairs. It takes a year for their blubber to develop and for their first year pelage to grow. This transition from thick lanugo fur to blubber is important because lanugo fur does not insulate well in water. Their lower critical temperature is believed to be under −10 degrees Celsius in air. 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. A thick coat of blubber insulates its body and provides energy when food is scarce or during fasting. Blubber also streamlines 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. They have a diverse diet including several dozen fish and invertebrate species. The White Sea population migrates northward in the summer to forage extensively in the Barents Sea. Where common prey items include krill, capelin (Mallotus villosus), herring (Clupea harengus), flat fish and Gadiform fish. Harp seals prefer some prey, though their diet depends largely on prey abundance. Diet and abundance analysis of the Svalbard population found that this population predominantly eats krill, followed closely by polar cod (Arctogladus glacialis). As in other populations and foraging areas, diet varies with distance from shore, with arctic cod comprising more of it nearshore and capelin more of it offshore. Harp seals can live over 30 years in the wild. Breeding occurs between mid February and April. Females, who remain on the ice, will resist copulation unless underwater. 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. 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). Due to their dependence on pack ice for breeding, the harp seal range is restricted to areas where pack ice forms seasonally. There are two recognised subspecies: one individual was located off the north Norwegian coast, east northeast of its tagging location. Their navigational accuracy is high, with good eyesight an important factor. They are occasionally found as vagrants, south of their normal range. In Great Britain, a total of 31 vagrants were recorded between 1800 and 1988. 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 fjords 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.

All three populations are hunted commercially, mainly by Canada, Norway, Russia and Greenland. 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 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 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. As of 2019, the current population is estimated to be 7.6 million. 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.