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Saving Freshwater Mussels from Extinction! the aim of breeding mussels in captivity until the rivers have been restored and the juveniles were old enough to be reintroduced. The first mussel populations were brought to our Ark in Windermere in 2007, and the first juveniles from the adult mussels were collected in the summer of 2008. These juveniles are now 11 years old and they have recently released larvae (called glochidia). Captive Bred Mussels Produce Their Own Offspring for the First Time in UK History Since 2007, scientists at the Freshwater Biological Association (FBA) have been breeding the critically endangered freshwater mussel (Margaritifera) to help save it from extinction. 12 years on and these captive bred young mussels have produced offspring of their own for the first time! “This is an amazing achievement for the mussel team at the FBA which will help conserve this critically endangered species. Great to see the hard work and dedication over the last 12 years is paying off and that these juveniles will contribute to their population over the next 100 years or more!” Dr Bill Brierley, Chief Executive of the FBA. Freshwater mussels are classified as critically endangered across Europe, and only a few populations remain in England and Wales, with Cumbrian rivers being a stronghold. In most English rivers, no juveniles are surviving to adulthood; resulting in aging, relict populations, which are at high risk of extinction. Habitat degradation and loss has seen this species decline by over 90% in the last century. These mussels play a vital role in the rivers as they can filter 50 litres of water per day, removing particles like algae and bacteria from the water column. By doing so, they improve the habitat and water quality for fish, invertebrates, birds and aquatic mammals. To help save this species from extinction in England, the FBA, with support from Natural England and the Environment Agency, set up a Mussel Ark, with
Freshwater mussels have a complex but fascinating lifecycle (Image 1). They can live to around 130 years old; however, the oldest one ever found was estimated to be 257 years old! Males release sperm to fertilise the female’s eggs in late spring. The females brood their eggs on their gills for approximately 6 weeks before releasing the glochidia in late summer. These glochidia look like mini mussels that “snap” as they are looking for a fish for the next stage of their development (Image 2) (Video - www.facebook.com/freshwaterbio/ videos/659841514494581/ ) They attach themselves to the gills of young Atlantic salmon (Salmo salar) or brown trout (Salmo trutta), where they remain over winter and develop into juvenile mussels. In spring, they will drop off the gills and must land in clean, well-oxygenated gravel beds, where they grow into adults. They become sexually mature between 11-15 years old. Our juveniles from 2008 have now completed this full cycle and this is the first time in the UK that captive bred freshwater mussels have been confirmed as mature and able to produce their own offspring. The glochidia that were released have now successfully attached themselves onto the gills of Atlantic salmon (Image 3) and will start growing into juvenile mussels. This 2nd generation of captive bred mussels will be collected next June. 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.
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