Grey seal
- Class: Mammals (Mammalia)
- Order: Carnivores (Carnivora)
- Family: Seals (Phocidae)
- Genus: Halichoerus
- Art: Species: Halichoerus grypus
Size
The grey seal is the largest seal species in Sweden. A fully-grown grey seal male weighs approximately 300 kg, and the female 150 kg.
Ecology
The Baltic Sea grey seal population is isolated from two other, significantly larger, grey seal populations in the Atlantic. Grey seals live in colonies on archipelagos and rockbound coasts, and males are usually polygamous. During February and March, the pack ice that forms around the areas that they generally inhabit, becomes the site where female seals give birth to their pups. Three weeks later the females rejoin the males in their activities in readiness to breed again, leaving the pups to fend for themselves.
Food habits
The grey seal feeds predominantly on fish, and can often be seen at river-mouths where it hunts migrating salmon.
Longevity
Grey seals live for 35 to 40 years.
Reproduction
Following mating, grey seal females undergo a delay in the implantation of her fertilised egg, and then gestation lasts 11.5 months. At birth grey seal pups weigh approximately 16 kg and have long, white fur, which sheds after the first three weeks of life. The pup gains weight quickly on its mother’s rich milk, and by moulting age will have almost quadrupled in body mass.
Conservation status
Despite grey seals’ protection in 1974, the population continued to decrease due to high toxin levels (especially PCBs, i.e. polychlorinated biphenyls) in the waters of the Baltic Sea. An estimated half of the female seal population were maturing with deformed reproductive organs, their cervix, hence being unable to conceive. Their sterility severely threatened reproduction rates.
Recently, toxin levels have diminished due to strict legislation, improving this situation considerably, and today grey seal population numbers are on the increase.
Reproduction
Following mating, grey seal females undergo a delay in the implantation of her fertilised egg, and then gestation lasts 11.5 months. At birth grey seal pups weigh approximately 16 kg and have long, white fur, which sheds after the first three weeks of life. The pup gains weight quickly on its mother’s rich milk, and by moulting age will have almost quadrupled in body mass.
Conservation status
Despite grey seals’ protection in 1974, the population continued to decrease due to high toxin levels (especially PCBs, i.e. polychlorinated biphenyls) in the waters of the Baltic Sea. An estimated half of the female seal population were maturing with deformed reproductive organs, their cervix, hence being unable to conceive. Their sterility severely threatened reproduction rates.
Recently, toxin levels have diminished due to strict legislation, improving this situation considerably, and today grey seal population numbers are on the increase.
