Field Guide
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Grey Seal

Halichoerus grypus

Not yet photographed by the community

Large Atlantic seal; UK hosts half the world population.

Species Profile

Least Concern (IUCN); UK populations are recovering and have been removed from protected species lists in some regions due to population growth.
Lifespan
25–40 years in the wild
Size & Weight
1.6–2.0 m in length; males 150–310 kg, females 100–180 kg
Habitat
Coastal rocky islands, skerries, and haul-out sites in cold temperate and subarctic waters around the British Isles.
UK Distribution
Found around Scotland (especially Orkney, Shetland, and the Hebrides), Wales, Cornwall, and Northern Ireland. Resident year-round with seasonal movements; populations have expanded southward in recent decades.
Diet
Primarily fish species including cod, pollack, whiting, and flatfish; also takes crustaceans and cephalopods. Diet varies by region and season.
Prey
Fish (cod, pollack, whiting, flatfish); crustaceans; cephalopods
Predators
Adults have few natural predators in UK waters; pups may be vulnerable to large sharks and occasionally killer whales; historical hunting by humans was significant.
Mating Season
September to November
Breeding
Single pup born per female after gestation of ~11.5 months; pups are weaned after 3–4 weeks. Breeding occurs in large terrestrial haul-outs.
Behaviour
Highly social, forming large haul-outs on rocky islands. Males are territorial during breeding season and engage in aggressive displays. Grey seals are excellent divers, capable of reaching depths over 400 m and remaining submerged for up to 30 minutes while foraging.
Did You Know?
  • Grey seals are the largest carnivore in British waters, with males being substantially larger than females.
  • They have a distinctive large head and elongated snout; males often have a more prominent 'Roman nose' profile than females.
  • UK grey seal populations have increased dramatically from fewer than 500 individuals in the 1960s to over 100,000 today.
  • Their scientific name, Halichoerus grypus, means 'hook-nosed sea pig' in Greek and Latin.
  • Grey seals are known to be intelligent and curious, sometimes investigating boats and divers, though they are generally wary of humans on land.

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