Freshwater pearl mussels Margaritifera margaritifera

Freshwater pearl mussels (FWPM) are large, long-lived mussels that live in the bottom of clean, fast-flowing rivers. They are now very rare and Scotland is one of the global strongholds for the species. The River Spey is one of the most important rivers for FWPM’s in Scotland, supporting a population of several million. The significance of the Spey FWPM population has resulted in its designation as a Special Area of conservation for its FWPM population ( ). In parts of the River Spey, extremely dense mussel colonies have been recorded (225 m2). As the population also shows evidence of recent recruitment and a high proportion of juveniles, the River Spey is considered to support a pearl mussel population of great international significance.

In many rivers in Scotland pearl mussels are no longer breeding and the populations consist only old specimens. We are fortunate on the Spey to have such a healthy population, the presence of which provides good evidence of the high water quality generally found throughout the catchment. Like all mussels FWPM are filter feeders with each adult capable of filtering the same amount of water daily as we use when showering.

Why are they rare?
Freshwater pearl mussels have been killed for the pearls they occasionally contain. They are also very vulnerable to disturbance from engineering work in rivers and water pollution. These threats continue and have resulted in many rivers no longer supporting pearl mussel populations.

What does the law say?
The law is very clear. It is an offence to intentionally or recklessly kill, injure, take or disturb freshwater pearl mussels or their habitat.

What can I do?
If you see any suspicious activity, please report it to the police as soon as possible. Contact your local police station and ask for the Wildlife Crime Officer.

For further information see