White-Clawed Crayfish: Native UK Species Under Threat

The white-clawed crayfish (Austropotamobius pallipes) is the only native crayfish species in the UK and Ireland, and is now critically endangered due to competition and disease spread by the invasive American signal crayfish.

Key Facts

White-clawed crayfish are listed as Endangered on the IUCN Red List
The UK holds around 75% of the global white-clawed crayfish population, giving it international responsibility
American signal crayfish, introduced in the 1970s for aquaculture, carry crayfish plague which is 100% lethal to white-clawed crayfish
Signal crayfish are now present in most English river catchments and are spreading northward
White-clawed crayfish are protected under Schedule 5 of the Wildlife and Countryside Act 1981
Populations have declined by over 90% in England since the 1970s
Ark sites — isolated headwaters above waterfalls — are a key conservation strategy to protect disease-free populations
Citizen science projects have identified over 200 potential ark sites across England and Wales

Welfare Considerations

The invasive crayfish plague causes rapid mortality in white-clawed crayfish populations — outbreaks can eliminate entire river populations within weeks. The welfare implications are significant given evidence that crustaceans experience nociception and behavioural indicators of pain. Signal crayfish themselves, though ecologically harmful, are also sentient beings: they show associative learning, avoidance behaviour, and anxiety-like states in experimental settings. Management approaches that control invasive crayfish through trapping and culling raise welfare considerations, highlighting the ethical complexity of invasive species management. Ark site conservation protects a remnant population without requiring lethal control.

What You Can Do

Never move fishing equipment between water bodies without disinfecting it to prevent plague spread
Support the Crayfish Conservation Initiative and ARC Trust ark site establishment
Report American signal crayfish sightings to the Environment Agency using the Non-Native Species Secretariat portal
Lobby for stronger controls on import and movement of non-native crayfish species
Participate in local white-clawed crayfish monitoring surveys with county wildlife trusts
Avoid purchasing live signal crayfish for any purpose that risks release into the wild
Support river catchment management plans that include crayfish plague containment measures