Invasive red swamp crayfish have been found in southwest Michigan's Cass County for the first time, the Michigan Department of Natural Resources said.
Two carcasses were found in a private pond near Niles in mid-September during a survey for invasive aquatic plants, according to the DNR. Staff identified the specimens as invasive red swamp crayfish.
Though native to the southern United States, red swamp crayfish have been prohibited in Michigan since 2014. They are considered invasive because of their high reproductive rate and ability to outcompete native crayfish, amphibians, invertebrates and juvenile fish for food and habitat, the DNR said. The species can be particularly destructive to aquatic plants, the loss of which degrades water quality and clarity.
The crayfish's destructive burrowing along shorelines can destabilize banks and infrastructure, according to the agency. Populations were first detected in Michigan in 2017. To date, isolated infestations have been confirmed in Kalamazoo, Livingston, Macomb, Oakland, Van Buren and Wayne counties.
Infestations are believed to result from released or escaped aquarium pets, live bait or live crayfish brought to Michigan for crawfish boils, the DNR said. It is illegal to knowingly possess, introduce, import, sell or offer the species for sale.
The DNR is asking anyone in the greater Niles area to report sightings. Red swamp crayfish are generally 2 to 6 inches long, brown to red, with raised bumps on the body and claws. They may also appear in colors including blue, orange and white when from the pet trade.