Following a significant native white-clawed crayfish kill on the By Brook, Wiltshire in August/September, it has been confirmed that the crayfish sampled were infected with Aphanomyces astaci, which is the water mould (fungus) that causes crayfish plague.
Crayfish plague is a deadly disease that infects and kills our native white-clawed crayfish. The invasive non-native signal crayfish can carry the disease, but is not affected by it. The fungal spores can easily be transported to other watercourses on damp equipment, by other animals or by water transfer. As the spores cannot be seen with the naked eye, it is easy to transfer the disease without knowing it.
It can take the disease several weeks to spread among a crayfish population, so you may see dead or dying crayfish in the river for some time. As a result, the spores could still be present and could easily be transferred to other watercourses that could have susceptible native crayfish present. The disease is specific to crayfish, therefore there are no implications to human or other animal health.
We are therefore urging people that are visiting, or working in or near the river, to follow strict biosecurity measures to reduce the risk of the plague being transferred to other watercourses in the area. The best methods are to follow the ‘Check, clean, dry’ campaign, and/or use an approved chemical disinfectant to kill any fungal spores.
More information on good biosecurity measures and non-native species can be found on the GB Non-native Species Secretariat (NNSS) website.
If you see dead or dying crayfish or need to report another environmental incident, please call the Environment Agency’s incident hotline on 0800 80 70 60.
If you need further advice or information, please contact the Environment Agency at wessexenquiries@environment-ag
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Fisheries, Biodiversity & Geomorphology