A fisher. It now has another challenge. U.S. Fish & Wildlife Service hide caption itoggle caption U.S. Fish & Wildlife Service The Two-Way Pot Growers Are Likely Killing Rare Creatures July 17, 2012 The fisher, a weasel-like animal, is already a candidate for protection under the Endangered Species Act. Now, researchers have evidence that the animals have been exposed to lethal poison used by power growers to protect their plants from animals.