Mystery as 7 out of 10 common seals vanish

An annual study by St Andrews University has revealed the Orkney population has shrunk by 67 per cent since the late 1990s. In the Firth of Tay, they have declined by 50 per cent, and by 40 per cent in Shetland. Common seal numbers in the Western Isles are down by 35 per cent.

The study provides the latest evidence that common seals are struggling to survive in Scotland – but the cause for the rapid declines remains a mystery.

In contrast, the number of grey seal pups being born is increasing. There are now thought to be about 20,000 common seals compared to 186,000 grey seals in Scotland, according to the special committee on seals report from the Sea Mammal Research Unit at the university.

The seals can be difficult to tell apart, but grey seals have a distinctive hooked nose.

Research is being carried out to try to find what is reducing the populations of common seals. Scientists say it is already clear that shooting and disease alone do not explain the reductions. Killer whale predation is thought to be one factor around the Northern Isles, and competition for food with the larger grey seals is likely to be a cause as a whole.

Environment secretary Richard Lochhead said: "While it's unlikely that any single factor is responsible for this decline in common seals, competition for food supplies with the larger, more numerous grey seal could be a significant factor.

"We need to know more and our research into common seal diet will deliver answers and help shape future policy."

He said Scotland was already taking "decisive actions" to protect the seals. Under the new Scottish Marine Act, passed earlier this year, it is illegal to shoot a seal at any time of year unless a licence has been granted.

Penalties for shooting seals will be strengthened to include possible imprisonment.

Anyone with a licence to shoot a seal will have to report how many have been killed, to build up better numbers of the impact of culling the creatures.

A seal conservation order has been in place since 2007 to protect common seals in the Northern Isles and along the east coast.

The Scottish Seal Forum, which will meet in the summer, will be asked to consider similar additional protection for common seals in the Western Isles.

However, Libby Anderson, political director for campaign group Advocates for Animals, said more needed to be done and called for a ban on killing common seals across Scotland.

She acknowledged that the reasons for the decline in numbers was not known but added: "They are very vulnerable to persecution, so we shouldn't be shooting them at all."