They are the mussels whose pearls feature in the Scottish crown jewels.

Julius Caesar’s admiration of the mollusc is cited by his biographer as a motive for the first Roman invasion of Britain in 55BC.

But they are now being pushed into extinction due to illegal fishing.

Now  it has emerged that plans to save the freshwater pearl mussel are to benefit from a new fund aimed at protecting and growing Scotland’s vulnerable marine life.

Some 12 successful projects across Scotland will share an additional £2m committed in the Biodiversity Challenge Fund.

One of the projects benefitting the Kyle of Sutherland Fisheries Trust’s bid to save the pearl mussels.

The project aims to restore river habitats to protect the vulnerable population within a tributary of Loch Shin in the the north west Highlands.

The mussels 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 similar in shape to common marine mussels, but can grow larger and live for up to 130 years in fast-flowing rivers.

The movement of Atlantic salmon and brown/sea trout is essential to the freshwater mussel population to support the larval stages of their life cycle.

They harmlessly live on the gill filaments and grow until they detach themselves the following spring.

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

Pearl mussels are also valuable as a water filter - keeping water clear for other species.

But conservationists have been concerned over illegal fishing which is threatening the mollusc and have called for firm action.

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.

But official data shows that there had been no prosecutions over a ten year period.

There were just two recorded offences in 2016/17 - but no prosecutions, or any reports to the Crown Office.

In June, 2018, police appealed for information after 80 freshwater pearl mussels were killed in a poaching incident on the River Spey in the Cairngorms.

Also benefitting from the extra spend is a Heriot-Watt University project which aims to boost the threatened wild oyster population.

The money will also support plans for nature parks and green corridors in Glasgow, Edinburgh, St Andrews and Orkney.

Environment minister Màiri McAllan said: “The Scottish Government is committed to tackling the twin crises of climate change and biodiversity loss.

“Protecting Scotland’s biodiversity is not just essential for the environment, it is central to our green recovery from the pandemic. Initiatives like these can boost local resilience and provide great opportunities for people to gain vital skills.”

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 they are 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.

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.

Scottish Environment LINK a coalition of more than 30 leading Scottish environment charities made a call for new laws in 2018 after warning that Scotland’s rarest species, including the mollusc, face being obliterated in the fall-out from Brexit unless action is taken to ensure vital environmental protections are provided in Scotland.

It continued to push for legally binding measures to ensure that the nation’s natural environment, wildlife and air and water quality are properly safeguarded in law. Last year, a new colony of the freshwater pearl mussels were discovered in the north Highlands but the exact location was being kept a secret to prevent illegal fishing.

The rare species was uncovered during a watercourse survey being carried out before culvert replacement work.