The white-clawed crayfish, Britain’s only native species, has seen a dramatic reduction in its distribution and population in recent decades following the introduction of non-native species such as the American signal crayfish, which outcompete our native species and transmit a lethal fungal infection (crayfish plague).
The white-clawed crayfish is protected under both European and UK law. Under UK legislation the white-clawed crayfish is protected under Schedule 5 of the Wildlife and Countryside Act 1981 (as amended), making it an offence to take them from the wild or sell them. They are also fully protected under Annex II and V of the European Habitats Directive (1992), requiring the designation of Special Areas of Conservation (SAC) for their protection and prohibiting the taking (capture or handling) or disturbance of the species in the wild. The European Bern Convention lists white-clawed crayfish in Appendix III as a protected species.
White-clawed crayfish occupy a variety of freshwater habitats, and are additionally threatened by activities (such as dredging) that modify these environments or pollute or otherwise degrade them.
White-clawed crayfish surveys are required where their known distribution and historical records suggest they may be present and/or there is suitable habitat, and proposed works (whether a development requiring planning consent, or routine repair or maintenance) may harm the population.
An initial site appraisal and desktop survey can identify the potential for white-clawed crayfish to be present. Surrogate signs such as burrows, sloughs, remains in spraints and droppings and anecdotal evidence can indicate presence, but further survey work may be required to confirm presence/absence. This may entail:
- Combined manual searching and hand-netting
- Night-viewing using powerful torches
- Trapping using plastic baited mesh baskets or refuge traps