The conflict between invasive signal crayfish and native white-clawed crayfish creates welfare dilemmas about how to manage two sentient species with conflicting conservation needs.
Freshwater crayfish welfare presents a particularly acute version of the invasive species welfare dilemma, involving two species that are now both recognised as potentially sentient under the UK Animal Welfare (Sentience) Act 2022. White-clawed crayfish face welfare harm through competitive displacement and crayfish plague, a disease that causes rapid mortality; signal crayfish killed in management trapping face acute welfare harm from trapping methods. The precautionary approach to decapod sentience established in UK law means that both species deserve welfare consideration in management decisions. Trap design affects signal crayfish welfare: baited cage traps allow crayfish to enter but not escape, where they may be held for extended periods before collection. Overcrowding in traps and extended confinement cause stress in animals that show pain avoidance behaviour. More humane trapping practices including more frequent trap checking and prompt dispatch reduce the welfare burden of management operations. The conservation case for managing signal crayfish to protect white-clawed populations is strong, but the implementation of that management should incorporate welfare considerations for both species.