Hi all,
I understand why there is a prohibition on keeping most crayfish in the UK, but I should think the chance of the orange morph of Cambarellus patzcuarensis becoming naturalised in the UK is less than nil, it is just a "belt and braces" approach.
It isn't much of a problem for us in the UK, but the same sorts of laws are the reason why New Zealand, Hawaii and Australian members can keep a much more limited range of stuff. You only have to look at those countries for the damage that the imported, Rabbit, Carp, Frog, Deer etc ."wrong animal in the wrong place" can cause.
cheers Darrel