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Signal Crayfish, Pacifastacus leniusculus


Short description of Pacifastacus leniusculus, Signal Crayfish

The signal crayfish is lobster-like in appearance and reaches a maximum size of 16-18cm. It is much larger than the native white-clawed crayfish and its claws have red undersides with a small turquoise/white blotch on the upper surface at the claw hinge.

Description of Pacifastacus leniusculus, Signal Crayfish status in GB

The signal crayfish is well established in England and Wales, especially in the south-east of England. Not as prevalent in Scotland but several well-established populations have been recorded.

Habitat summary: Pacifastacus leniusculus, Signal Crayfish

Signal crayfish are found in streams, canals, rivers, lakes and ponds, and are also able to survive in brackish water.

Overview table

Environment: Freshwater
Species status: Non-Native
Native range: Northern America, British Columbia
Functional type: Omnivore
Status in England: Non-Native
Status in Scotland: Non-Native
Status in Wales: Non-Native
Date of first record: 1975

Distribution map

Map of the UK with areas shaded to show the UK distribution of Signal Crayfish

GB Distribution from NBN Atlas

Author's name:

David Aldridge

Last updated:

October 2nd 2019

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