Help us to Save Our White-Clawed Crayfish
The rare and protected white-clawed crayfish (Austropotamobius pallipes) is native to many of the rivers and becks in the Eden catchment. Specifically found in hard water, limestone rivers, such as the Upper River Eden, the River Lyvennet, the River Leith and the Scandal Beck.
It is under threat of crayfish plague, a wide spread and virulent disease, caused by the fungus Aphanomyces astaci. It is believed that it was introduced, and is spread, by the North American Signal Crayfish (Pacifastacus leniusculus).
The plague produces free-swimming zoospores that are specific to crayfish and can be carried in water and mud, and on damp equipment. The risk of picking up these spores is greatest when there is an outbreak of crayfish plague as the number of zoospores is high.
Much of the UK’s population of white-clawed crayfish has now been lost. The Eden catchment is one of the few remaining habitats where they are surviving but we need your help to ensure that this continues.
How you can help us
Crayfish plague is not only spread by the signal crayfish itself, but spores of the fungus can also be transmitted in water, on damp equipment and mud, and attached to the mucus or scales of fish.
To try and prevent the spread of this disease, we ask all river users to:
1. Wash mud etc off equipment on site, preferably with a scrubbing brush. This will reduce the risk of the crayfish plague spores being transferred elsewhere.
2. Dry equipment thoroughly. This is an effective way of killing the spores as they only remain viable when damp.
3. Disinfect the equipment. This will again reduce the risk of any spores being transferred to new waters. A hypochlorite solution, such as domestic bleach, or an iodine based disinfectant can be used. Iodine based disinfectants are usually available from farm or dairy suppliers; please follow the manufacturers instructions carefully.
4. When visiting a number of rivers in quick succession, visit those without signal crayfish first, followed by those with them. If coming to Cumbria, all our rivers are signal-free except the Derwent river system, so please visit signal-free rivers before going eslewhere.
For more information, please see the following leaflets:
White Clawed Crayfish - Wildlife Trust leaflet
Life Cycle of the Crayfish leaflet
Stop the spread of alien crayfish and crayfish plague - Environment Agency leaflet for the general public.
Stop the spread of alien crayfish and crayfish plague - Environment Agency leaflet for restaurant owners.
Signal crayfish - an unwelcome addition to Scottish Streams - Fisheries Research Services leaflet.
Freshwater crayfish in Britain and Ireland (includes Identifying freshwater crayfish in Britain & Ireland key) - only available from the Environment Agency.
Thank you for you help and consideration; your action will not only protect the white-clawed crayfish but also prevent the spread of other fish diseases.
Eden Rivers Trust have run a number of projects on Crayfish - see the Projects Page
Volunteering with Eden Rivers Trust as a crayfish surveyor offers a fantastic opportunity to see this protected species up close in its native habitat, learn more about crayfish ecology and gain experience of survey techniques. Surveys will take place between July and September. For more information, and details of up and coming training days contact
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Projects are supported by SITA Trust, which makes awards through the Landfill Communities Fund. SITA Trust provides funding to improve biodiversity and the environment around landfill sites throughout England. SITA Trust receives its funding from the waste management company, SITA UK.
A volunteer's view
"Having started aiding the Eden Rivers Trust as merely an attempt to complete the service aspect of my Duke of Edinburgh’s award it came as almost a surprise that I begun to enjoy my weekly commitment of crayfish surveying, filling the otherwise empty void of my summer holidays. The best site we surveyed contained about 40 crayfish under 50 rocks. Unfortunately however there was one week where I couldn’t make any of the crayfish surveying dates and so I tried my hand at electro fishing and to my surprise we caught approximately 60 trout and 40 salmon fry. Overall I found that Volunteering for the Eden Rivers Trust is a fun, useful and interesting way for anyone fill any spare days." John Rothwell
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white clawed crayfish - wildlife