FOR the first time in UK history captive-bred freshwater mussels have produced their own offspring, a feat which was achieved on the shores of Windermere.

A population of the molluscs has been housed by the Freshwater Biological Association (FBA) at its Far Sawrey ‘Ark’ site since 2007.

Freshwater mussels play an important role in rivers by filtering water and removing contaminants such as algal particles and bacteria. In turn, this improves the habitat and water quality for wildlife.

They can only be found in a few areas of the UK, with Cumbria’s rivers being a stronghold. Habitat degradation and loss has seen numbers fall dramatically in the last century.

In most rivers, juvenile freshwater mussels are not surviving to adulthood, resulting in ageing populations which are threatened by extinction.

A spokesperson for the FBA said: “This is a great achievement for the staff working at the Ark, demonstrating that mussels can successfully breed and produce viable offspring in captivity in our hatchery.

“It will also mean that when these juveniles are released into their native river next year, they will help contribute to the recovery of the wild population.”

Freshwater mussels have a complex and interesting life cycle. After brooding their eggs, the females release glochidia (a form of larva) which attach themselves to the gills of young Atlantic salmon or brown trout. The glochidia remain there over winter as they develop into juveniles until, in spring, they drop off. They must land in clean, well-oxygenated gravel beds, where they grow into adults.

An FBA spokesperson said people could help mussel populations by taking part in activities such as tree planting and gravel cleaning with local wildlife or river conservation groups, and by properly disposing of household chemicals to preserve an area’s water quality.