Vertebrate species: mammals


1365 Harbour seal    Phoca vitulina   
   Follow link for UK biodiversity information on this species.

Background to selection

Distribution of SACs with species 1365 Phoca vitulina.  Click image for enlarged map.
Distribution of SACs with species 1365 Phoca vitulina. Click image for enlarged map.

Description and ecological characteristics

 

Harbour seals Phoca vitulina are the characteristic seal of sandflats and estuaries, but are also found on rocky shores in Scotland. As pups swim almost immediately after birth, seals can breed on sheltered tidal areas where banks allow access to deep water. Seals may range widely in search of prey, but individuals often return to favoured haul-out sites.

European status and distribution

 

Harbour seals Phoca vitulina have a near-circumpolar distribution, with at least four subspecies recognised, from the eastern and western Pacific and eastern and western Atlantic. Only the eastern Atlantic subspecies P. vitulina vitulina occurs in Europe, where its range extends from Iceland and northern Norway southwards to northern France, including the Kattegat/Skagerrak and south-western Baltic. The UK population represents about 5% of the world population of P. vitulina, approximately 50% of the EU population, and 45% of the European subspecies. The European population has shown a marked recovery after being reduced by a viral epidemic in the late 1980s.

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

 

The Harbour seal Phoca vitulina is widespread around the shores of the UK, but population density varies greatly from place to place, with low numbers at many sites. Harbour seal are found from Northern Ireland and the southern Firth of Clyde clockwise round the coast to the Thames estuary. The vast majority of common seal haul-outs are found on the coasts of Scotland, but with an additional important concentration on The Wash, and a smaller number in Strangford Lough, Northern Ireland.

 

The UK holds at least 33,400 common seals. This is a minimum figure, counted at coastal haul-outs during the moulting period in August. The relationship between this number and total population size has not yet been fully established. Studies in Scotland and the Netherlands suggest that this number represents 60-70% of animals aged one year or older. Applying this correction factor indicates that the total population lies between 48,000 and 56,000.

Site selection rationale

 

Site selection has favoured sites that are important both as general haul-out sites and for moulting and pupping. The largest breeding colony has been selected, in the south of the species’ range in the UK. The geographic range of breeding has been covered by the selection of a representative sample of relatively large colonies in the north. Sites have been selected using the most up-to-date population data available, but populations at individual sites may fluctuate, with low numbers at many sites, meaning it can be difficult to define the boundaries of specific sites.

 

Haul-out areas are thought to be very important for the conservation of the species, as are the most important breeding colonies. As well as their importance in maintaining overall population size, larger breeding sites are significant as sources of emigration to smaller or newly-established colonies.

 

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

Ascrib, Isay and Dunvegan Highland
The complex of skerries, islets, undisturbed mainland shores and offshore islands in north-west Skye consistently support a breeding colony of the Harbour seal Phoca vitulina. The site represents one of the larger discrete colonies of common seals in the UK, holding around 2% of the UK population.
Dornoch Firth and Morrich More Highland
The Dornoch Firth is the most northerly large estuary in Britain and supports a significant proportion of the inner Moray Firth population of the Harbour seal Phoca vitulina. The seals, which utilise sand-bars and shores at the mouth of the estuary as haul-out and breeding sites, are the most northerly population to utilise sandbanks. Their numbers represent almost 2% of the UK population.
Eileanan agus Sgeiran Lios mór Argyll and Bute
The island of Lismore on the west coast of Scotland provides the most sheltered and enclosed site for the Harbour seal Phoca vitulina. Lismore is a composite site comprising five groups of small offshore islands and skerries which are extensively used as haul-out sites by the colony. Seal numbers represent just over 1% of the UK population.
Firth of Tay & Eden Estuary Angus; City of Dundee; Fife; Perth & Kinross
The Firth of Tay & Eden Estuary supports a nationally important breeding colony of Harbour seal Phoca vitulina, part of the east coast population of common seals that typically utilise sandbanks. Around 600 adults haul-out at the site to rest, pup and moult, representing around 2% of the UK population of this species.
Mousa Shetland Islands
The exposed rocky island of Mousa, off the east coast of Shetland Mainland, supports one of the largest groups of Harbour seal Phoca vitulina in Shetland and is one of the most northerly groups in the UK. The large rocky tidal pools on the island are of particular importance, as they are frequently used by the seals for pupping, breeding and moulting, and provide shelter from the exposed conditions on the open coast. The site supports just over 1% of the UK population.
Sanday Orkney Islands
Sanday is situated in the north-east of the Orkney archipelago and supports the largest group of Harbour seal Phoca vitulina at any discrete site in Scotland. The breeding groups, found on intertidal haul-out sites that are unevenly distributed around the Sanday coast, represent over 4% of the UK population. Nearshore kelp beds that surround Sanday are important foraging areas for the seals, and the colony is linked to a very large surrounding population in the Orkney archipelago.
South-East Islay Skerries Argyll and Bute
The skerries, islands and rugged coastline of the Inner Hebridean island of Islay hold a nationally-important population of the Harbour seal Phoca vitulina. The south-east coastline areas are extensively used as pupping, moulting and haul-out sites by the seals, which represent between 1.5% and 2% of the UK population.
The Wash and North Norfolk Coast Lincolnshire; Norfolk
The Wash, on the east coast of England, is the largest embayment in the UK. The extensive intertidal flats here and on the North Norfolk Coast provide ideal conditions for Harbour seal Phoca vitulina breeding and hauling-out. This site is the largest colony of common seals in the UK, with some 7% of the total UK population.
Yell Sound Coast Shetland Islands
Yell Sound Coast in the Shetland Islands is the most northerly UK site selected for the Harbour seal Phoca vitulina. The rocky shores and uninhabited islands and skerries within Yell Sound support a colony representing over 1% of the UK population.

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

Murlough Down
Sound of Barra Western Isles / Na h-Eileanan an Iar
Strangford Lough Down
 

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