PRECIOUS, threatened and previously unknown – conservation chiefs are working to protect a newly-discovered colony of freshwater pearl mussels from criminals.

Almost half of the global population of the endangered species is found in Scotland.

The molluscs grow larger than other varieties and can live for more than 100 years, bearing a pearl only occasionally.

Despite high levels of legal protection, demand for the iridescent spheres means illicit fishing is a continuing threat to the survival of the species.

Now experts from Scottish Natural Heritage (SNH) are working to safeguard a never-before-recorded colony of the shellfish which has been uncovered in the Highlands.

The discovery was made during survey work related to culvert replacement undertaken by specialist firm Alba Ecology.

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SNH told The National the exact location of the find, in the north of the region, will not be disclosed to “prevent unscrupulous persons from trying to hunt them down”.

However, it is hoped that habitat improvement work, including the planning of 8000 broadleaf trees along a 6.5km water course, will boost the area for the species.

Suzanne Dolby of Forestry and Land Scotland, which is managing the project, said: “Species conservation is a huge part of what we do and that includes looking after over a quarter of all of Scotland’s pearl mussel watercourses.

“This is a significant responsibility for a species that has declined by 95% in central Europe and is classified by the International Union for Conservation of Nature as being critically endangered in Europe.

“Discoveries like this highlight the importance of sustainable forest management and the type of work that we continue to build on to improve in-stream habitat for fish and pearl mussels.”

Iain Sime of SNH said the work will ensure that “this rare species will have more than a fighting chance”.