The marbled crayfish is a mutant species that clones itself
One way to get rid of this problem is if they taste good, market them to Asian restaurants.Right now spicy crawfish boils are fashionable in China, and I'm pretty sure the other East/Southeast Asian countries like crawfish also.Just like with jellyfish. Chinese people already eat jellyfish, so if there's an infestation of jellyfish in the ocean, figure out a way to eat that species. A billion people can really put a dent in any wild population.