This causes sediment pollution by increasing the sediment load of the river. They burrow interconnecting tunnels up to 2m into the riverbanks, which destabilises the sediment and erodes the riverbank. Signal Crayfish are not only detrimental to our aquatic ecology but also to river stabilisation. Signal crayfish are also more tolerant to varied conditions and reproduce more quickly, so have become widely distributed across our waterways. Signal crayfish also outcompete the White-Clawed crayfish for habitat and food, as they feed on just about anything – fish, tadpoles, juvenile fish, invertebrates, amphibian eggs and even their own species ! This impacts other native species and can disturb the natural food web of our aquatic ecosystems. The spores can be killed by disinfecting or drying equipment that has come in contact with the waterway. The disease spreads by waterborne spores which can last up to 2 weeks in our waterways. Signal crayfish carry a crayfish plague which is fatal to the White-Clawed crayfish. Our White-Clawed crayfish have had a population decline of 50-80% across Europe in the last 10 years, classifying them now as endangered. The decimation of our native White-Clawed crayfish population is possibly the most devastating impact Signal crayfish have caused. They were farmed for food and exported to the Scandinavian market, but soon escaped the fishing farms and entered our waterways, causing havoc with our native ecosystems. Signal crayfish are a non-native, invasive species that were introduced from North America by the British Government in the 1970s. What are Signal Crayfish and why are they such a problem? Written by Jodie Rochford, a volunteer for Unlocking the Severn and Severn Rivers Trust. These blogs have been written by Unlocking the Severn volunteers and apprentices, so we figured we’d share them here too! See the original blog on the Severn Rivers website HERE. We love the ‘All About’ series, published on the Severn Rivers Trust website. Meet the Diglis Island Guides: Heather’s Story.Endangered UK fish reach ancient spawning ground after two centuries.43 fledglings: a successful first year for the Diglis Island sand martin box.Unlocking the Severn’s 7 successes of 2022.
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