Freshwater white-clawed crayfish  (Austropotamobius pallipes)

Perhaps the most devastating factor affecting freshwater white-clawed crayfish at present is crayfish plague, a virulent fungal disease carried by the aggressive introduced species, the American signal crayfish (Pacifastacus leniusculus)(4). Spores of this disease can be spread in the water, on wet equipment and on fish (2). Competition with introduced crayfish species has also affected our native crayfish (3); signal crayfish were first introduced to the UK in the 1970s and are now naturalised and breeding (2). Two other introduced species have become established (3); the narrow-clawed (or Turkish) crayfish (Astacus leptodactylus) and the noble crayfish (Astacus astacus) (2). Pollution and river works are also likely to have affected the species (2).

The freshwater white-clawed crayfish has been targeted as a priority for conservation under the UK Biodiversity Action Plan (UK BAP). The Species Action Plan aims to maintain the current distribution of the species through a combination of restricting the spread of non-native crayfish and crayfish plague, as well as providing suitable habitat features (3). The Environment Agency has carried out research into potential methods of controlling the signal crayfish, and is currently investigating the use of pheromones to lure this introduced species into traps (5). It is an offence under Schedule 9 of the Wildlife and Countryside Act to release the three introduced species of crayfish into the wild (3).