Grey seal (eastern Atlantic population) (Halichoerus grypus)

Spanish: FOCA GRIS
GenusHalichoerus (1)
SizeMale body length: up to 2.3 m (2)
Female body length: 2 m (2)
Male weight: up to 350 kg (2)
Female weight: 250 kg (2)
Top facts

Classified as Least Concern (LC) on the IUCN Red List (1). Protected in Europe under Annex II and V of the EC Habitats Directive, and Appendix III of the Bern Convention (3). In Britain it is protected under the Conservation of Seals Act 1970 (closed season from 1 September until 31st December) (4), and listed under Schedule 3 of the Conservation Regulations (1994) (5).

The grey seal (Halichoerus grypus) is the larger of Britain's two species of breeding seal (2). The coat colour varies from grey to brown to silver, often with blotches (4). Males (bulls) can be distinguished from females by the pattern of darker and lighter fur colour. In males, the continuous background colour is dark, but in females is it light. Juveniles are born with a creamy white natal coat (6). The nostrils are parallel (4), and the 'Roman' nose is characteristic, especially in males (7); the scientific name derives from the Greek for 'hooked-nose sea-pig' (8).

The grey seal is found on both sides of the north Atlantic in temperate and sub arctic waters (6). Three distinct populations occur; the western Atlantic population, the north-eastern or Baltic population which is endangered, and the eastern Atlantic population (3) which is centred around British coasts, particularly around Scotland (2).

Grey seals usually haul out on uninhabited offshore islands, but occasionally on quiet mainland beaches (6).

Grey seals feed on a wide range of fish species, and also take crustaceans, cephalopods and the occasional seabird. When feeding they typically dive to depths of 30 to 70 metres (3). In autumn females congregate at traditional pupping sites, called rookeries. At birth the pups weigh 14 kilograms, but as the mother's milk contains 60 percent fat, they rapidly put on weight and develop the blubber layer essential for maintaining body temperature when at sea (4). Males come ashore at the pupping sites to mate; they compete for sole access to a group of females (3), and successful dominant males can secure access to up to as many as ten females (3). After mating the seals disperse. The pups stay in the rookery surviving on their blubber reserves until after the moult, they then go to sea and may disperse over large distances (3).

In 1914 the UK grey seal population was thought to number just 500, and the Grey Seals Protection Act was introduced that year (9). The Sea Mammal Research unit estimated that the British grey seal population numbered 124,300 in the year 2000, representing 40% of the world population (2). The population is increasing, which has led to highly controversial (7) concerns by fishermen that they pose a threat to fish stocks (9). Although protected between 1 September and 31st December by the Conservation of Seals Act (1970), they can still legally be shot during this time if they are damaging fishnets (4), furthermore illegal shooting continues (3). Grey seals are sensitive to disturbance by people and dogs, particularly when lactating. They are also susceptible to oil and chemical pollution and often become tangled up in fishing nets, which may be fatal (3).

Several important grey seal sites in EC member countries have been proposed as Special Areas of Conservation. In August 1999 the location of the world's third largest island-based grey seal breeding colony, the uninhabited island of Linga Holm in the Orkney Islands was purchased by the Scottish Wildlife Trust as a sanctuary for grey seals (3). It has been suggested that human access to breeding sites could be restricted. This has occurred at Berry Head in Devon, where video monitors have been used to show the breeding seals to visitors, so pressures on the breeding site are reduced (9).

For more information on the grey seal see:

Authenticated (2002) by Dr Pat Morris.

  1. IUCN Red List (November, 2008)
  2. Sea Mammal Research Unit. (2007) Scientific Advice on Matters Related to the Management of Seal Populations. University of St Andrews, Scotland. Available at:
  3. Seal Conservation Society (January, 2002)
  4. Mammal Society fact sheet. (July, 2010)
  5. Office of Public Sector Information (January, 2008)
  6. King, J.E. (1983) Seals of the World. Oxford University Press, Oxford.
  7. Morris, P. (2002) Pers. comm.
  8. Gotch, A.F. (1979) Mammals, their Latin Names Explained. Blandford Press Ltd, Dorset.
  9. Westcott, S. (1996) The Grey Seals of the West Country. Stephen Westcott and Cornwall Wildlife Trust, Truro.