CONSERVATIONISTS are working in a remote North Yorkshire river to preserve a rare and endangered species of fresh water pearl mussel.
Experts from the University of York and the Environment Agency are working in the River Esk near the North York Moors.
By introducing a series of microscopic glochidia (the mussels’ young) into the water, it is hoped they will latch on to the native fish and migrate to areas where they can mature.
Freshwater pearl mussels are an important indicator of water pollution and quality, and are threatened by a variety of pollutant factors such as cattle manure, over-sedimentation, decline of salmon and trout numbers and historical pearl fishing. This mixture of threats means they are believed to be threatened with possible extinction in less than 40 years.
Even despite this work, the outlook according to York Biology Student Sam Jones, is quite grim. “The river Esk is a big place and, as we have so few mussels remaining, the likelihood of the glochidia attaching to the gills of the fish – a process known as encystment - is exceedingly low.”
The conservationists are working to ensure the future of the freshwater pearl mussel. This includes catching trout and salmon from the river through harmless electro-fishing and holding them in containers near the river banks with the fertile female mussels to increase the chances of glochidia encystment.
According to Allison Pierre, a technical officer of the Environment agency “With work such as this and improvements to the river habitat we hope to start finding some young mussels in the river over the next few years”.
Freshwater mussels were once common across the UK, but now they only live in small enclaves, the River Esk being the only one in Yorkshire. They can live for over 100 years, with most in the Esk averaging 60.
The National Park Authority has also worked with 50 farms, installing fences, planting trees and providing crossing points and alternative stock watering to help benefit the local habitats and wildlife. It will also go on to benefit kingfishers, otters, dippers and water invertebrates as well.