Invasive signal crayfish threaten UK native species

Invasive signal crayfish, originally introduced to the United Kingdom for commercial aquaculture, have escaped into natural waterways and spread across rivers in England, Wales, and Scotland. These North American species are outcompeting native white-clawed crayfish for food and habitat due to their larger size and aggressive nature.

Beyond competition, signal crayfish carry crayfish plague, a disease that is often harmless to the invasive species but lethal to native populations. The UK Environment Agency has warned that native white-clawed crayfish are now facing the threat of extinction in many areas. Additionally, the species causes environmental damage by burrowing into riverbanks, which increases soil instability and erosion, and by disrupting local food chains through the consumption of fish eggs and other aquatic life.

To mitigate these effects, authorities are working to create isolated habitats and relocate native crayfish to secure water sources to establish new, protected populations.