Michigan DNR Finds Invasive Red Swamp Crayfish at Wolf Lake Hatchery

The Michigan Department of Natural Resources (DNR) confirmed the presence of invasive red swamp crayfish at the Wolf Lake State Fish Hatchery in Mattawan, raising concerns about this species' impact on native ecosystems. These crayfish, native to the southern U.S. and banned in Michigan since 2014, are known for outcompeting native crayfish, reproducing rapidly, and causing shoreline erosion through burrowing. The infestation was discovered after staff drained a rearing pond used for muskellunge, with traps capturing live specimens and carcasses found in collection baskets. While the exact pathway of introduction remains unclear, possibilities include contaminated water, aquarium or bait release, or transport with forage fish. The DNR considers the risk of spreading the crayfish to lakes where hatchery fish were stocked as low but is implementing monitoring plans and exploring control measures such as pond drying or pesticide application. Officials urge the public to report any sightings to help manage and contain this invasive threat.