DAVEY CURTIS: Rock Lobster

Dear Jon,

Here are some photo's of a fresh water crayfish that Tatyana spotted (our new Belarusian C.F.Z rep?) whilst we were out for a walk in the woods at Barnard Castle County Durham. We hope the pics maybe able to identify it as a native.

Regards
see you soon

Dave, Joanne, Rosie and eagle eyed Tatyana.

Max Writes:

I can't confidently identify the crayfish, the ultimate 'silver bullet' for identifying the two species found up north (the colour on the underside of the claws) is invisible in the photos, though I cannot blame anyone for not wanting to pick them up to check! Just incase you got a hint of the underside colour, white-clawed crays (the British native) is white to pink on the underside, but the American signal/red-claw is, guess what, red underneath. I have first hand experience with both species (signals at uni, and white-claws at Bristol Zoo) and the red underside is by far the easiest aid to identification.

Have a look here: http://www.environment-agency.gov.uk/static/documents/Leisure/Crayfish_Identify.pdf

Ignore the shape of the claws on the signal in the photo they use: it is an old male which typically grow huge claws. Yours looks smaller (say, 10-12cm) which puts it in the size range of both species.

If I was to have to take a stab, I would say it was an American signal crayfish. There are hints in the second photograph that there is red on the underside of the claws. This is probably the most common species in your area, so I would stick with that as the identification.