Identification - the white clawed crayfish is the only native freshwater crayfish in the British Isles. They are up to 12 cm from the tip of head to the tail. The head tip sides are smooth and converge towards the base of the small triangular apex. There is a fine mat of hair covering the top surface. The body is smooth and generally brown to olive coloured. The claws are rough on the top side and dirty-white to pink on the underside.
General ecology - it is fairly docile and is generally found in clean, calcareous streams, rivers and lakes and also water filled quarries.
They are present in the rivers Blackwater, Pant, Stour and Stebbing and Robins Brooks. They are very vulnerable to river management and water quality. They are at threat from non-native Signal and Turkish crayfish through competition and are present in some of the Essex rivers. They are also affected by crayfish plague.
Surveying tips - please contact Essex Biodiversity project or the Environment Agency if you know where this species occurs.