THE GREY SEAL Halichoerus grypus



Grey and brown fur, sometimes with pattern of blotches; no ears visible; long muzzle; nostrils parallel.
Head/body length: average for males 207cm; for females 180cm; flippers about 25cm.
Weight: males 233kg; females 155kg.

General Ecology:

Grey seals in Britain are found mainly around exposed rocky northern and western coasts. They also occur in the south west and off the east coast, around the Isle of May and the Farne Islands off Northumberland. Between the tides they haul themselves out on to rocks, usually on uninhabited offshore islands; though some haul-outs are on secluded mainland beaches. Grey seals are gregarious at these haul-outs, sometimes forming large groups of several hundred animals, especially when they are moulting their fur in the spring. They are not, however, very sociable and keep a distance between one another.

About two-thirds of greys seals' time is spent at sea where they hunt and feed. Sand eels and cod are their most important foods, but grey seals are opportunistic feeders and probably take whatever fish are most abundant.

In the autumn grey seals congregate at traditional sites on land to breed. The timing of births varies around the coast, beginning in September in West Wales, in October in western Scotland, and as late as November in the Farne Islands.

Grey seal pups weigh about 14kg at birth and have soft white fur. They remain on land where they suck from their mother for 18-21 days. A female's milk contains up to 60% fat, so pups grow very quickly, gaining about 2kg in weight each day. This weight gain consists mainly of a layer of blubber below their skin, which is vital insulation when they go to sea. During the pupping season, male grey seals also come ashore to mate. The largest males, usually more than 10 years old, compete for a position within groups of breeding females. Occasionally males fight, and may sustain deep scars on their necks as a result. Female grey seals may live for 35 years, but males seldom survive to more than 25 years old.


Grey seals were the first mammals to be protected by modern legislation - the Grey Seals Protection Act of 1914. Today, the Conservation of Seals Act (1970) protects them during a closed season from 1st September to 31st December, although seals causing damage at fish nets can still be killed. The law also allows complete protection to be given. For instance, grey seals in England and Wales, though not Scotland, were fully protected following the outbreak of phocine distemper in 1988.

The numbers of grey seals in British waters have doubled since 1960 to over 80,000 animals. As this amounts to half the world population, the protection of British grey seals is of international conservation importance.
However, such a dramatic increase in numbers led to claims that seals were causing much damage to fisheries. Seals try to take salmon from fish farm nets in sea lochs and either damage the fish or tear the nets and release valuable fish in the process. They may also compete with commercial fisheries for valuable wild fish stocks, and an increase in cod and herring parasites has been blamed on seals which can carry the same parasites.
Increased numbers of grey seals breeding on the Farne Islands caused much soil erosion and concern for other island wildlife. Several grey seal culls have been undertaken, the most recent in Scotland in 1977. This resulted in a public outcry and the cull was abandoned in 1978 to await the results of more research into seals and fisheries.

Recent research indicates that grey seals eat large quantities of sand eels, which are caught for use in fish meal but not for human consumption. Salmon does not appear to be an important part of the seal's diet, although other commercially important fish like cod are taken.

The relationship between numbers of seals and the incidence of fish parasite infestations, is a complex issue. Problems of soil erosion on the Farne Islands have been relieved simply by discouraging seals from breeding on the most vulnerable islands.

Frequent Questions:

Were grey seals affected by the seal plague?
Seal plague, or phocine distemper virus, mostly affected common seals. Of 3,000 seals known to have died from the virus in British waters, only 300 were grey seals. However, blood tests show that most grey seals had been exposed to the virus.

What do I do if I find an injured or diseased seal?
In England or Wales telephone the RSPCA (0345 888999) and in Scotland telephone the local SSPCA office. Do not go too close to the seal - it may bite! Avoid disturbing seal pups as this could result in the mother to abandoning them.

Further Information: