Narrow-clawed crayfish

The Narrow-clawed crayfish (or Turkish crayfish) Astacus leptodactylus originates in Eastern Europe and Western Asia. The species is classified as a non-native invasive species in Britain; dispersed throughout the south of England. It has yet to be recorded in Ireland.

The Turkish crayfish is easily distinguished by its long narrow claws, and the rough upper surface of its claws. The Turkish crayfish commonly grow to approximately 15cm; however, some have been recorded at 30cm. Colours vary from pale to dark green, sandy yellow and sometimes blue. Leg joints are normally orange. The Turkish crayfish is capable of walking across land to access waterways.

The Turkish crayfish diet on macrophytes and invertebrates; their introduction to Irish waters would trigger competition between the non-native species and native White-clawed crayfish for food and survival. The UK Biological Record Centre maintains ‘that Turkish crayfish would outcompete white-clawed crayfish if ranges overlapped’. The Turkish crayfish is not a vector of ‘crayfish plague’ and therefore poses less of a threat than the Signal crayfish. They are susceptible to the ‘crayfish plague’ however, some are immune which allows populations to recover. The Turkish crayfish have a high tolerant for salinity.

Females produce between 200 – 400 eggs with the young hatching in spring. The species becomes sexually mature after 3 years. There is a high mortality rate among Turkish crayfish due to the species susceptibility to ‘crayfish plague’ which is contracted by their increased overlapping with the Signal crayfish in Britain.

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