Police have launched a crackdown on illegal fishing in a bid to protect Scotland's endangered freshwater pearl mussels.

The shellfish, which are protected by law, are targeted for their natural pearls by illegal fishers who are endangering the species' future survival.

But on Sunday police and Scottish Natural Heritage (SNH) launched Operation Necklace 2000 and appealed for the public's help to catch the pearl fishers.

Martin Gaywood, of SNH, said: "The freshwater pearl mussel is an important part of Scotland's and Europe's biodiversity.

Damage

"Persecution by way of pearl fishing is by far the biggest cause of decline in, or extinction of, many colonies.

"The message to illegal pearl fishers is clear. This is a rare species which needs protection, not persecution."

People caught attempting to take the pearls can be fined up to �5,000 for every one of the bivalves which are harmed or killed.

Mr Gaywood warned the illegal fishers their chances of finding a valuable pearl were remote.

A survey by the heritage body found 99% of colonies which face decline or even extinction were damaged by illegal pearl fishing.

'On the lookout'

And Scotland is seen as Europe's main stronghold for the species, with most colonies found in rivers in the Highlands and on Tayside, whose two police forces are backing the initiative.

"Many people are on the lookout for illegal fishers and will be reporting them to the police," said Mr Gaywood.

"We are working closely with the police, who will respond to all reports, and every opportunity will be taken to press charges, with penalties of up to �5,000 for every mussel harmed."