[I]n May a culmination of 10 years work by the Freshwater Biological Association (FBA) will result in the release of 100 native captive-reared freshwater mussels back into the wild, at an undisclosed location of suitable habitat in a river in Cumbria. An exciting and important milestone in the history of the Ark which will inform the future priorities for the project.
The Freshwater Pearl Mussel Ark project has been running at the FBA since 2007, and supported in part by Natural England and the Environment Agency. The Ark holds adult mussels to protect populations against local extinction, and the FBA breed from these adults to provide juvenile mussels for reintroduction. Because this species is so slow growing (taking around 12 years to become sexually mature) we are only now thinking about releasing some of our oldest captive-reared juveniles.
A handful of Cumbrian rivers are among a very few places in England where it’s still possible to find the freshwater pearl mussel. The creature’s future is so uncertain that it has been listed as critically endangered, meaning that it faces an extremely high risk of extinction in the wild. To try to stop the mussel from disappearing from our rivers, experts at the Freshwater Biological Association, based on the shores of Windermere, are leading a project to conserve and boost its dwindling numbers.
“We reared these native mussels at the FBA’s Ark in Windermere, the only facility of its kind in England,” said Dr Ceri Gibson, the FBA’s Mussel project manager.
This month the FBA will painstakingly place 60 mussels at 3 locations in an undisclosed river in Cumbria. Following monitoring and observation the FBA intend to release the final 40 mussels later this year. The goal is to boost natural populations of these animals, which play vital, irreplaceable roles in the overall health of aquatic habitats by serving as water filters.
“Freshwater mussels are what we call a ‘keystone species,”’ Dr Gibson explained. “They may be small, but they have enormous beneficial effects on the lives of other organisms. If we can get the water quality and river habitat conditions right for them it will also help other species such as kingfishers and otters.”
Mussels are filter feeders which take in large amounts of water, filtering out bacteria, algae, or decaying plant or animal matter before passing the clean water back into the river. Just one adult mussel can filter more than 50 litres of water in one day.
Freshwater mussels make up the most imperilled group of wildlife in the UK. Over a century of manmade changes to rivers have damaged mussels’ preferred sand-gravel habitats. The mussel thrives in nutrient-poor rivers which have clean and well oxygenated gravel. Its decline is thought to be due to a number of factors, including rivers becoming nutrient-rich because of fertilisers used in agriculture, runoff surges due to forestry management and other industrial threats. Other threats include changes to its habitat such as increased sediment or altered river courses. As a result, of the 6 known species of native freshwater mussels in the U.K., 2 are listed as endangered, threatened or species of special concern at national or international levels.
The release of mussels into the river has been made possible through a recent 3 year project ‘Restoring Freshwater Mussel Rivers in England, funded by Biffa Award and supported by Natural England and the Environment Agency, to improve conditions in the river gravels where the juveniles dwell for the first 3-4 years of life, to improve river habitat for the host fish which are essential to the freshwater mussel lifecycle and to ensure that we have juveniles fit for release.
“We are thrilled to fund efforts to augment native freshwater mussel populations in Cumbrian waterways as one of our rebuilding biodiversity themes. It is important that we protect and strengthen our natural environment so that it can adapt to threats such as climate change, and is protected for future generations to enjoy,” said Andrew Moffat, Chairman of the Biffa Award Board.
If you’d like the chance to experience a behind the scenes tour of the Ark please apply to pearlmussel@fba.org.uk by Friday 26th May. The exclusive tour with limited places will take place on Saturday 8th July 2017.
To volunteer for conservation work on the restoring freshwater mussel rivers project contact Ceri Gibson on email: pearlmussel@fba.org.uk or tel: 015394 87713.
The Lakes Aquarium at Newby Bridge has an interactive exhibition about the species and the project, see www.lakesaquarium.co.uk.
To keep up-to-date with the project visit fba.org.uk, where you can also link to the FBA’s e-newsletter, Facebook and Twitter @freshwaterbio pages.
