The name Harp Seal is given to Pagophilus groenlandicus due to a large harp-shaped marking or saddle, on the back of its coat. Its latin name means ‘ice-lover from Greenland’. Despite declining sea ice and annual culling of P. groenlandicus pups in several countries, the species is still classified as Least Concern by the IUCN due to a large population size and increasing trend in multiple areas. Estimated population size = 9,000,000.
P. groenlandicus are a medium sized true seal(males ♂ up to 1.9 m long/ 140 kg, females ♀ up to 1.8 m/ 130 kg). Their flippers are relatively short and their heads relatively small, with round, broad faces, flattened crowns and slightly pointed muzzles. They also have jet black eyes and cream coloured whiskers. Colour-wise they are usually whitish, silvery or grey with black patterning for the back saddle and hood. Females may be spotted and have more muted patterning than males, appearing more grey than vividly marked.
P. groenlandicus diet is comprised chiefly of fish and invertebrates. During the late spring they migrate north and this is reflected in changing prey choice throughout the different locations. They tend to specialise in Polar species of cod, herring and capelin, feeding intensively during summer and winter, and reducing their intake during travelling in spring and autumn. Juveniles often take a lot of invertebrates such as low trophic level crustaceans. The species are competent divers and will routinely dive up to 100 m depth to forage.
Sexual maturity – males ♂ 4-8 years old/ females ♀ 4-8 years old. Though neither sex usually routinely or successfully breeds until 8-10 years old.
P. groenlandicus are a highly social species of seal with a promiscuous mating strategy. Courtship starts on the ice with copulation in the water and gestation lasts around 11.5 months, including a delayed implantation period of 3-4 months. The females haul out in large densities on pack ice to birth during February and March, and the young are born as ‘whitecoats’ with the iconic white lanugo so often depicted in media. This insulating fur coat may often be stained yellowish from placental fluid for the first few days. The pups are fairly helpless at this age and will hardly move for the 12 days of nursing to conserve energy. Weaning takes place fairly abruptly and the young are left to fend for themselves, often losing up to 50% of their body weight whilst remaining on the ice for up to 6 weeks to complete the moult into juvenile pelage, before they learn to swim and hunt. Oestrus and mating follows weaning for the adults, and then a period of intense feeding before the onset of the moult in April/ May. The lifespan of P. groenlandicus is around 30 years.
Though there are generally recognised to be two to three distinct populations of P. groenlandicus, in the western North Atlantic, the Greenland Sea, and the White/ Barents Sea, the IUCN does not endorse any official subspecies given that there is no conclusive genetic evidence of similarities and differences between individuals of the populations.