Ecology of harp seal (Phoca groenlandica) pups on ices in the White Sea

Abstract

The harp seal ( Phoca groenlandica ) is the most abundant species of the true seals inhabiting the northern hemisphere. Depending on breeding area location, three populations (Newfoundland, White-Sea, and Jan Mayen) of harp seals are distinguished [1, 2]. Owing to the high total abundance, the harp seal remains the key commercial animal whose herds in Russia, Norway, Canada, and Greenland (Denmark) are extensively harvested every year. The current size of the White-Sea population of harp seals is 1.8‐2 million animals [3]. The range of the harp seal is wide: during summer migrations, the seals inhabit the Barents Sea and other Northern Atlantic areas and occur in the Kara Sea [4‐6]. In winter, harp seals congregate in the White Sea for mating and breeding; they live in large herds on ice floes from December to May. The abundance of offspring annually born in spring on ice reaches more than 300 thousand pups [7]. The hydrometeorological conditions of the White Sea ensure gradual drift of ice floes with adult seals and pups from the central areas of the sea to the northeast areas and then to the Barents Sea. Harp seal pups live in the White Sea from February to May. Postnatal development of pups (suckling, moult, and transition to independent nutrition) takes place on drifting ice floes; at this time, young seals adapt to leaving in water. The short breeding (pupping) period, high breeding rate, and sufficient fatness of pups at the end of the suckling period are the key adaptation components. However, published data regarding these issues are scanty. It is known that body weight of pups increases after birth, the suckling period lasts for two weeks, and the postembryonic moult lasts for 25‐ 30 days [8, 9]. In the White Sea, the pupping period of harp seals continues for approximately four weeks [8‐11]. The pupping period of harp seals in 1925‐1935 began