Noble crayfish

The Noble crayfish (Broad-fingered crayfish) Astacus astacus is native to European and Western Russian freshwater rivers and streams. Once abundant in European freshwater rivers and streams the species is now in decline; introduction of the Signal crayfish to Europe brought ‘crayfish plague’, which instigated a sharp decline in the number of Noble crayfish. Unlike the Signal crayfish, the Noble crayfish is highly susceptible to crayfish plague. The introduction of non-native invasive species, crayfish plague, habitat loss and over harvesting have caused a decline in species population, and the Noble crayfish is listed on the IUCN Red List.

The Noble Crayfish is present in the River Chew in south-west England and an ornamental pond in Bristol, and would not be seen as highly invasive. Introduction of the Noble crayfish to Irish waterways would spark a direct competition for food between the White-clawed crayfish and the Invasive Noble crayfish. It is worth noting that no mixed population of native and non-native crayfish have survived more than five years in Britain.

Noble crayfish grow to approximately 16cm. The Noble crayfish vary in colour from green/blue to brown and sometimes black. The broad claws led themselves to the species alternative name the ‘Broad-fingered crayfish’, the underside of the claws are dark red.

The Noble crayfish reaches sexual maturity after 3 to 4 years (a slow development rate). The species breed in October and November. The female carries the eggs until May when the young hatch. Females produce 60 – 100 eggs at a time. Adult and hatchling alike are preyed upon by otter mink eel and perch.

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