Vertebrate species: mammals

1364 Grey seal    Halichoerus grypus   
   Follow link for UK biodiversity information on this species.

Background to selection

Distribution of SACs with species 1364 Halichoerus grypus.  Click image for enlarged map.
Distribution of SACs with species 1364 Halichoerus grypus. Click image for enlarged map.

Description and ecological characteristics


Grey seals Halichoerus grypus spend most of the year at sea, and may range widely in search of prey. They come ashore in autumn to form breeding colonies on rocky shores, beaches, in caves, occasionally on sandbanks, and on small largely uninhabited islands. In such locations they may spread some distance from the shore and ascend to considerable heights.

European status and distribution


Grey seals Halichoerus grypus are among the rarest seals in the world: the UK population represents about 40% of the world population and 95% of the EU population. Globally, there are three reproductively-isolated stocks of grey seal: a west Atlantic (northern North American) stock; a Baltic stock; and an East Atlantic stock. The latter extends from Iceland and northern Norway southwards to northern France, with the majority breeding around Great Britain and Ireland.

UK status and distribution Click to view UK distribution of this species

At the start of the 2000 breeding season, Great Britain held some 124,000 grey seals Halichoerus grypus (SCOS 2000). A further 300-400 in total are found around the Isle of Man and Northern Ireland. There are pupping sites on many coasts between the Isles of Scilly in the south-west, clockwise to Donna Nook in Lincolnshire. These rookeries vary greatly in size with the largest being in the Inner and Outer Hebrides, Orkney, Isle of May, Farne Islands and Donna Nook. Less than 15% of pups are born away from the above areas, but there is an important outlying breeding population on the west Wales coast. Since the late 1970s, no licences have been issued in the UK for commercial hunting or large-scale control measures, and the population has increased markedly since that time.

Site selection rationale


Site selection takes account of the UKs special responsibility to protect this species. The largest breeding colonies, based on pup production, have been selected. Sites have been identified using the most up-to-date population data available, although populations at individual sites may fluctuate. Colonies have also been selected to ensure coverage of the geographical range of breeding in the UK. The sites recommended for selection contain a significant proportion of the UK breeding population of grey seals.


While the SAC series makes a contribution to securing favourable conservation status for this Annex II species, wider measures are also necessary to support its conservation in the UK.

Site accounts

Berwickshire and North Northumberland Coast Northumberland; Scottish Borders
This is an extensive and diverse stretch of coastline in north-east England and south-east Scotland. There is variation in the distribution of features of interest along the coast. The north-east England coastal section is representative of grey seal Halichoerus grypus breeding colonies in the south-east of its breeding range in the UK. It is the most south-easterly site selected for this species, and supports around 2.5% of annual UK pup production.
Faray and Holm of Faray Orkney Islands
These two uninhabited islands in the northern part of Orkney support a well-established grey seal Halichoerus grypus breeding colony. The seals tend to be found in areas where there is easy access from the shore, and freshwater pools on the islands appear to be particularly important. The islands support the second-largest breeding colony in the UK, contributing around 9% of annual UK pup production.
Isle of May Fife
The Isle of May, lying at the entrance to the Firth of Forth on the east coast of Scotland, supports a breeding colony of grey seals Halichoerus grypus. The site is the largest east coast breeding colony of grey seals in Scotland and the fourth-largest breeding colony in the UK, contributing approximately 4.5% of annual UK pup production.
Monach Islands Western Isles / Na h-Eileanan an Iar
The Monach Islands, off the Outer Hebrides, offer a wide area of largely undisturbed habitat for breeding grey seal Halichoerus grypus, and there is easy access to the grassy swards and dune systems of the islands. These islands hold the largest breeding colony in the UK, contributing over 20% of annual UK pup production.
North Rona Western Isles / Na h-Eileanan an Iar
North Rona is a remote and very exposed island in the North Atlantic off the north-west tip of mainland Scotland. The islands are rarely disturbed by human activities in the breeding season. Grey seal Halichoerus grypus are found over much of the island and use many of the submerged sea caves that are found around the coast. North Rona supports the third-largest breeding colony in the UK, representing some 5% of annual UK pup production.
Pembrokeshire Marine/ Sir Benfro Forol Penfro/ Pembrokeshire
Pembrokeshire in south-west Wales is representative of grey seal Halichoerus grypus colonies in the south-western part of the breeding range in the UK. It is the largest breeding colony on the west coast south of the Solway Firth, representing over 2% of annual UK pup production.
Treshnish Isles Argyll and Bute
The Treshnish Isles are a remote chain of uninhabited islands and skerries situated in south-west Scotland. The islands, numerous skerries, islets and reefs support a breeding colony of grey seals Halichoerus grypus, contributing just under 3% of annual UK pup production.

SACs where this Annex II species is a qualifying feature, but not a primary reason for site selection

Cardigan Bay/ Bae Ceredigion Ceredigion; Penfro/ Pembrokeshire
Humber Estuary City of Kingston upon Hull; East Riding of Yorkshire; Lincolnshire; North East Lincolnshire; North Lincolnshire
Isles of Scilly Complex Cornwall; Isles of Scilly
Lundy Devon
Pen Llyn a`r Sarnau/ Lleyn Peninsula and the Sarnau Ceredigion; Gwynedd; Powys
The Maidens

Many designated sites are on private land: the listing of a site in these pages does not imply any right of public access.