CONSERVATIONISTS have called for fresh action over illegal fishing that is threatening to push the freshwater pearl mussel into extinction after it emerged there has been no prosecutions over the past ten years.

The mussels, whose pearls feature in the Scottish crown jewels, are an endangered species found in rivers in the north of Scotland, which has become the last stronghold of them in the world.

The pearl mussels are listed as one of the most critically endangered molluscs globally and have been a protected species for nearly 40 years.

Yet is still being exploited in the search for pearls and between 1999 and 2015 became extinct in 11 watercourses in Scotland that it occupied a century ago.

Wildlife Crime Tasking and Coordinating Group, which includes Police Scotland and the National Wildlife Crime Unit have identified the illegal fishing as one of six wildlife crime priority areas.

According to Police Scotland, the penalties for this crime can be severe. For every mussel killed, taken or injured, a fine not exceeding £5,000 or 6 months in custody may apply.

It is also an offence to intentionally or recklessly damage or destroy a place which mussels use for shelter or protection.

Shoddy or unauthorised river engineering, mini hydro-electric schemes or fishing proprietors can all result in alterations to the river bed or bank that can lead to large scale killing or injuring.

A Scottish Natural Heritage video that highlights the work done to help secure the future of the freshwater pearl mussel.

But the latest Scottish Government-produced Wildlife Crime report listed just two recorded offences in 2016/17 - but no prosecutions, or any reports to the Crown Office.

Now conservation groups are calling for fresh impetus to stop the illegal fishing and are suggesting that new environmental protection laws in Scotland after the UK leaves the EU might help.

READ MORE: Brexit threatens to wipe out Scotland's rarest animals and put at risk iconic landscapes

Scottish Environment LINK a coalition of more than 30 leading Scottish environment charities made a call for new laws seven months ago after warning that Scotland's rarest species face being obliterated in the fall-out from Brexit unless action is taken to ensure vital environmental protections are provided in Scotland.

It wants legally binding measures to ensure that the nation’s natural environment, wildlife and air and water quality are safeguarded through an Environment Act. It says the UK’s planned departure from the EU “threatens to unravel critical environmental protections”.

Buglife, the invertebrate conservation charity says the only case involving wildlife crime involving pearl mussels in the last decade was six years ago.

HeraldScotland:

Then, a court heard, a green energy scheme caused pollution that would last hundreds of years and wiped out one of the world’s most important populations of the highly endangered species in Perthshire.

The hydro scheme – designed to produce electricity for 600 homes – destroyed a colony of protected freshwater pearl mussels and devastated the River Lyon in Perthshire.

Company directors Alan Smith, 48, and Charles Kippen, 52 with the now liquidated A&C Construction (Scotland) Ltd, were fined a combined total of £11,000 at Perth Sheriff Court for water pollution offences which led to freshwater pearl mussels being killed.

READ MORE: Firm directors admit killing endangered pearl mussels

English firm Shawater Ltd had previously been fined £4,000 fo offences relating to the pollution in the Inverinain Burn and the River Lyon.

Craig Macadam, Scotland conservation director of Buglife, said: "People look for pearls in the mussel. They take them out the water, open them up and see if there is a pearl and discard them on the bank. It is a massive issue.

"There have been cases on Harris, Angus, on the Spey, the Dee, so it is a widespread problem but there are very few if any prosecutions."

In June, last year, police appealed for information after 80 freshwater pearl mussels were killed in a poaching incident on the River Spey in the Cairngorms.

HeraldScotland:

The previous month, several dozen freshwater pearl mussels were killed by poachers in Assynt in the north west Highlands. Assynt Field Club said the shellfish were forced open in the "off chance" one or more might contain a pearl.

Mr Macadam said: "It is difficult to catch people in the act, it is often in the remote areas, the police are under-resourced for wildlife crime, and the evidence required is often too big a burden to bring a case.

"The fact there is a number of recorded crimes suggests there are more that we are not seeing.

"This is a big issue we are trying to tackle."

READ MORE: Pearl fishers threat to mussels 

He said a Riverwatch scheme launched a couple of years ago supported partly by LIFE, the EU's funding instrument for environment and climate action, had scaled down after a cash injection ended.

"The reports we do get from the Wildlife Crime report are just the tip of the iceberg, they are just the ones seen by the police."

He added: "We need a Scottish Environment Act that retains and builds upon EU environmental protections, to help save unique species like the Freshwater pearl mussel from extinction."

Footage of pearl fishing in Perthshire from 1961

Charles Dundas, chairman of Scottish Environment LINK, added: “Freshwater pearl mussels help clean Scotland’s rivers, making the water safer for other species. These amazing creatures can live for more than 100 years, making them among the longest-lived animals on the planet. And Scotland has up to half of the world’s population.

"But they’re also critically endangered, and illegal pearl fishing is the number one threat to their survival. Freshwater pearl mussels are protected by European nature laws, and European funding for conservation has given a huge boost to efforts to protect them and to crack down on illegal fishing.

"We need a Scottish Environment Act that retains and builds upon EU environmental protections, to help save unique species like the Freshwater pearl mussel from extinction.”

READ MORE: Ministers criticised for failure to act on new Scottish environment laws

Scottish Natural Heritage said it had awarded almost half a million pounds of the new £1.8m Biodiversity Challenge Fund to projects specifically aiming to help freshwater pearl mussels at five sites across Scotland, from Dumfries & Galloway to Caithness.

An SNH spokesman said: "Police Scotland continue to run proactive operations against illegal fishers."

A Crown Office spokesman said: “The Crown Office is committed to the rigorous, fair and independent prosecution of crime.

“Careful consideration is given to any reports of alleged criminal conduct which are submitted by the police, or any specialist reporting agency. Prosecutorial action will be taken if the reports contain sufficient evidence of a crime and if it is appropriate and in the public interest to do so.”

A Police Scotland spokesperson said: "If an incident is reported to us we will fully investigate along with partner agencies."