Harbour seal population has 'east-west' divide

Some conservationists blame the decline of the harbour seal on increasing competition with grey seals

The population of harbour seals on the east coast of Scotland and Northern Isles has declined by up to 90% in the past 15 years, according to a report.

But Scottish Natural Heritage (SNH), said there was an "east-west" divide with numbers of the mammals at an all-time high on the west coast.

Last year only 29 were counted in the Firth of Tay and Eden Estuary.

Numbers have also dropped dramatically around Orkney and declined in the Moray Firth and Dornoch Firth.

The research was carried out by the Sea Mammal Research Unit (SMRU) at the University of St Andrews. Scientists there have been documenting the decline of harbour seals on the east coast since 2000.

'Real concern'

In the Firth of Tay and Eden Estuary Special Area of Conservation, which was set up in part to protect the harbour seal, the population has fallen 90% in 15 years, with a decline of 75% around Orkney over the same period.

In contrast, the population of seals has risen by 60% or more in some parts of the west coast in the last six years.

John Baxter, principle marine adviser with Scottish Natural Heritage, said: "It's great to hear that harbour seal numbers on the west coast are doing so well but it's of real concern that numbers on the east coast continue to drop so dramatically.

"It's still not clear what's causing the decline but we're continuing to work with colleagues at Marine Scotland and SMRU to try to get a better understanding of what is going on."

There are two species of seal in Scotland - the harbour seal and the grey seal, but only harbour seal numbers are declining. Some conservationists blame their falling numbers on increasing competition with the larger and more numerous grey seal.

Harbour seals - also known as common seals - are found in cold and temperate waters throughout much of the northern hemisphere. Scotland is home to 36% of the European population.

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 180kg 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.

Source: Scottish Natural Heritage