White-clawed crayfish were once common in Britain’s waterways. But thanks to a restaurant craze in the 1970’s, that brought the American signal crayfish to our shores, our only native freshwater crayfish is under threat from this invasive species. 

White-clawed crayfish are eco system engineers keeping rivers and streams clean and they also have amazing limb re growing superpowers. But they’re being outcompeted for food and habitat by the American signal crayfish and succumbing to a killer plague being spread by them. But, with a little help from Ranger Nick Allen and the team at Walling...