Hi!
I'm Zen Faulkes, biologist who curates the Marbled Crayfish research site. (Not the commercial site. I don't sell crayfish.)
I am here to ask -- no, beg on bended knee that anyone who suspects they might have found marbled crayfish in the wild, please contact me.
There has never been a confirmed case of Marmorkrebs found in natural waters in North America. (There have been suspected cases, but never 100% sure.) Finding even one would be an important landmark for management of this potentially problematic crayfish. My colleagues would also want to do genetic tests to see how a North American animal compares with populations overseas.
Please help science! My name is distinct enough that you should be able to find me with a Google search easily.