The white-clawed crayfish is the UK only native crayfish species, now critically endangered due to competition and disease from introduced American signal crayfish.
White-clawed crayfish infected with crayfish plague experience rapid onset neurological failure as the water mould Aphanomyces astaci penetrates the cuticle. Death follows within days of infection onset. The welfare implication of crayfish plague is catastrophic at the population level, with entire river system populations eliminated in weeks. Individual crayfish suffer the neurological effects of the pathogen before death. Signal crayfish that displace white-claws from territories force the latter into suboptimal habitat with reduced food and shelter, causing welfare compromise before eventual displacement. Conservation of white-claws protects individual animals from a particularly rapid and distressing pathogen-caused death.