£820,000 project aims to save Cumbria’s freshwater pearl mussels
A major project to protect one of Cumbria’s rarest river species has received £820,000 in government funding.
West Cumbria Rivers Trust secured the grant through Natural England’s Species Recovery Programme. The money will support river restoration and work to rebuild freshwater pearl mussel populations across the county.
Around 9,000 young mussels to be released
One of the main aims is to release around 9,000 young freshwater pearl mussels into the River Irt and River Ehen.
The juveniles are being raised by the Freshwater Biological Association at its facilities near Windermere. Releasing them into the rivers should strengthen ageing populations and reduce the risk of local extinction.
Freshwater pearl mussels have an unusual life cycle. Their young spend part of their early development attached to the gills of salmon or trout.
They later leave the fish and settle into clean sand or gravel on the riverbed. The fish are not harmed during the process.
What work will take place?
The scheme will cover the River Ehen, River Irt and other nearby catchments.
Planned work includes:
- Restoring floodplains
- Lowering some river embankments
- Improving riverbanks
- Reducing the amount of soil and sediment entering rivers
- Carrying out surveys and population checks
These changes should create cleaner and cooler rivers. They may also help waterways cope with floods, drought and other pressures linked to climate change.
The project will bring together West Cumbria Rivers Trust, Eden Rivers Trust, South Cumbria Rivers Trust and the Freshwater Biological Association.
Farmers and landowners will also be involved in making practical improvements to rivers and surrounding land.
Why are the mussels in danger?
Freshwater pearl mussels need clean, fast-flowing water and a riverbed made from sand and gravel.
They are harmed when rivers become polluted or when too much fine soil and silt covers the riverbed. Young mussels can suffocate if they cannot reach clean, oxygen-rich gravel.
Other threats include falling salmon and trout numbers, damage to river habitats and climate change.
The UK population has fallen by around 90 per cent over the past century, according to West Cumbria Rivers Trust. The species is classed as critically endangered in Europe.
River Ehen supports England’s largest population
Cumbria is one of the most important areas in England for the species.
The River Ehen supports England’s largest freshwater pearl mussel population. It is protected as both a Special Area of Conservation and a Site of Special Scientific Interest.
The River Irt has a much smaller and older population. There is currently no clear evidence that the mussels there are successfully breeding in the wild.
Surveys will search six rivers
The project will also improve knowledge of where the mussels still survive.
Teams plan to study 176 environmental DNA samples taken from six Cumbrian rivers. Environmental DNA, often called eDNA, allows experts to search for traces left by animals in the water.
This could help identify small or previously unknown populations. Habitat surveys and further population checks will also take place.
Other wildlife should benefit
Although the project is centred on freshwater pearl mussels, the work should help many other species.
Cleaner rivers and better riverbanks can support Atlantic salmon, trout, insects, birds and other wildlife.
Adult pearl mussels also help the river themselves. One mussel can filter around 50 litres of water each day while feeding on small organic particles.
Chris West, project manager at West Cumbria Rivers Trust, said the funding would improve habitats, water quality and the long-term health of rivers across Cumbria.
The £820,000 award forms part of a wider £60 million government programme supporting 130 projects and 364 threatened species across England over the next three years.
