Seals

Species present in Scotland

Two species, the grey seal Halichoerus grypus and harbour or common seal Phoca vitulina, are present around the coast of Scotland in internationally important numbers

How to tell harbour and grey seals apart

Adult harbour seal males weigh about 85Kg and measure about 145cm in length. Females weigh about 75Kg and are about 135cm long, not much smaller than the males, in fact it is very difficult to tell the male harbour seals from female harbour seals. Grey seals are bigger than harbour seals; adult males weigh up to 300Kg and can be 200cm long while adult females weigh up to 180 Kg and are about 180cm long.  As well as being smaller than grey seals harbour seals have more dog like or 'spaniel' appearance while grey seals have a long sloping 'roman' nose.

Breeding

Grey seals breed on wave-exposed rocky coasts, sometimes on sand or shingle beaches at the foot of cliffs, often on relatively remote islands. Large groups of pregnant females return to traditional breeding sites in the autumn at the Inner and Outer Hebrides, Shetland, Orkney a few places on the north and far north-east coast of Scotland and in the Firth of Forth to give birth. The pups are born with white hair that thins steadily over the first three weeks of life. Female harbour seals haul out to give birth at natal breeding sites within their more restricted range in early summer. Pups are born having already shed their white coat in the womb.

Distribution

Grey seals travel large distances during routine foraging and favour more exposed coasts and islands. Outwith the breeding season they can be found hauled out on the islands or coasts closest to the open sea, perhaps closest to their preferred offshore feeding areas. These areas include the outer fringes of Shetland and Orkney, the west coast of the Out Hebrides, outer islands in the inner Hebrides, outer sandbanks in the Firth of Tay and the Moray Firth.

Harbour seals prefer more sheltered waters and are faithful to a more restricted range routinely travelling 40-50Km from their haul out site to forage for food. The harbour seal strongholds are Shetland, Orkney, the east coast of the Outer Hebrides, most of the Inner Hebrides and the west coast of Scotland (from Skye and Lochcarron down to Arran in the firth of Clyde), the Moray Firth and the Firth of Tay. There are smaller numbers along the north coast, the far north-west coast and in the Firth of Forth.

Threats

The main anthropogenic threats to seals are from:

• Excessive pollution, for example pups are particularly vulnerable to physical contamination from oil spills.
• Toxic chemicals, for example organochlorines or brominated flame retardants can be ingested and accumulate in the blubber.
• Angling and fish farms, for example shooting at salmon rivers or at fish farms.
• Entanglement in fishing nets.
• Marine renewable turbines; the nature and scale of any response of seals to marine turbines, or the impacts of turbines on seals are unknown at present and are being studied at various locations including Orkney and northern Ireland.

The main natural threats are from:

• Disease, in both 1988 and 2002, harbour seals were affected by phocine distemper virus (PDV), approximately half the seals on the east coast of England, mainly around The Wash died in 1988, mortality was considerably lower in Scotland.
• Killer whales, in recent years killer whales have been seen more regularly in Shetland and Orkney and have been observed feeding on both harbour and grey seals.
• Climate change, the most noticeable effect of climate change on seals is likely to be through changes in the distribution and the availability of their prey.

Protection

On the 1st February 2011 it became illegal to kill a seal in Scotland except to alleviate suffering without a licence issued by Marine Scotland under Part 6 of the Marine (Scotland) Act 2010  .

Under European legislation, both seals species are of "community Interest" meaning they are relatively uncommon across Europe as a whole. Under this legislation, known as the Habitats Directive, Scottish Natural Heritage have identified a number of Special Areas of Conservation (SACs) for harbour and grey seals. SACs were selected on the basis of the numbers of seals breeding within each area combined with a reasonably even spread of areas around Scotland.

What do seals eat?

Seals eat fish and are often regarded as undesirable competitors by fishermen. In the open sea, seals are only one group of animals that eat fish. The main consumers of fish around Britain are: humans, cetaceans (whales, dolphins and porpoises), birds, fish, and seals.

Are seals declining in Scotland?

Recent figures show that harbour seal numbers around Scotland as a whole are declining. The decline was first noticed in the Northern Isles and the east coast and the latest results confirm that the harbour seal populations of Orkney, Shetland and the Firth of Tay continue to decrease. So far the Moray Firth population appears to have stabilised and the west coast of Scotland and the Outer Hebrides population does not appear to to be showing the same dramatic decline as the Northern Isles. The reason for the decline is not yet clear and is quite mysterious since harbour seals have declined and grey seals have not. There have been no obvious signs of disease in the harbour seal population and therefore the decline is thought to be due to a number of factors including climate change (particularly the effect on the seals prey such as sandeels and the competition between species for reduced amounts of prey), predation (for example from killer whales), pollution and shooting. The Sea Mammal Research Unit  at the University of St Andrews are currently undertaking a number of studies to determine the reasons for the decline including a study tracking harbour and grey seals to see if they visit the same offshore feeding grounds.