There are 2 subspecies of grey seal - Halichoerus grypus grypus
and Halichoerus grypus macrorhynchus
.They live in the north Atlantic and Baltic seas respectively.The grey seal lives in coastal waters, where it dives for food and comes ashore onto ‘haul out sites’ to rest, mate and give birth.Female seals feed their young for only 3 weeks, but their milk is rich in fat. In this short time, the seal pup can quadruple in size.In some parts of the world, grey seal numbers are increasing. This is because one of its major predators, an Atlantic shark species, is over-exploited by humans. But the seal still faces threats from hunters, pollutants and viruses.