The illegal fishing of these bi-valve mussels, Margaritifera margaretifera, is threatening the species.
They are protected under the Wildlife and Countryside Act and are often found on the bed of salmon rivers where they can live for up to 80 years.
Seventy two of Scotland’s rivers support reproducing populations and represent some of the world’s most important sites for the survival of the mollusc.
But the population is now critically low, particularly as they are threatened by pearl fishers hoping to find the precious white pearls, for which they are famous, inside the shells.
The Scotsman (1 Aug 2013)