Endangered pearl mussels discovered in Scottish lochs

FRESHWATER pearl mussels have been found in two of Scotland’s lochs, according to researchers.

Up until now, freshwater pearl mussels were thought to live only in Scotland’s rivers, but researchers – who used remotely-operated underwater drones and snorkelling equipment – discovered a small number of the crticially-endangered mussels in Sutherland and the Trossachs.

The survey, carried out by NatureScot, said the mussels are likely to have entered the lochs by clinging to the gills of a host fish, either a young trout or salmon, adding that they spend the first year of their lives harmlessly attached to the fish, before falling off to live independently.

NatureScot’s Iain Sime, who led the latest project, said other mussel species — including the much more widespread swan and duck mussels — are known to live and breed in Scottish lochs, “but up until now we’ve had no evidence to suggest that pearl mussels routinely do this too”.

He said: “This project was an exciting first step in exploring our lochs and we’re keen to do further surveys to better understand more about this critically-endangered species.

“We don’t yet know whether they can breed in lochs and we want to learn more about a loch pearl mussel’s relationship with their host fish.”

He added that Scotland’s nature agency will extend conservation management advice for freshwater pearl mussels to include lochs and rivers.

NatureScot said pearl mussels are rare in Scotland due to illegal pearl fishing, poor water quality, habitat damage and over exploitation.

With the species on the brink of extinction in some rivers, NatureScot says it is leading efforts to conserve pearl mussels.

Read more stories on Scottish Field’s wildlife pages.

Plus, don’t miss Andy Dobson’s article about wildcats in the May issue of Scottish Field magazine.