Michigan DNR taking steps to halt invasive red swamp crayfish at hatchery pond
Red swamp crayfish – a species that is native to the southern United States but prohibited in Michigan – was found in a state hatchery pond in Van Buren County, Michigan.
The Michigan Department of Natural Resources reported Thursday that the invasive species was found in a muskellunge rearing pond at Wolf Lake State Fish Hatchery in Mattawan. The source of this crayfish appearance is not yet known, but isolated cases have been documented in Michigan since 2017. It's been banned in Michigan since 2014.
, also known as Louisiana crayfish, are about 2 to 7 inches in length. They have an hourglass shape, along with claws that are typically red. The feed on snails, invertebrates, amphibians and aquatic plants.
While they are native to the Mississippi River drainage area and Gulf Coast, their presence in Michigan is considered invasive as they push out and become destructive to local species. The Red swamp crayfish also will burrow into shorelines, contributing to erosion.
Known and suspected ways the species has appeared in Michigan include the release or escape of aquarium pets, live bait that is dumped as leftovers, and live crayfish that were brought into the state for crawfish boil preparations.
Another possibility is that because the hatchery pond is open and outdoors, the species could have migrated from another location. There is a known population about 15 miles away.
The Van Buren County incident was discovered after hatchery staff unexpectedly noticed the carcasses of two crayfish in a Wolf Lake pond used to raise muskellunge, the DNR explained. The muskellunge had been just been stocked at Thornapple Lake in Barry County and Lake Hudson of Lenawee County.
Upon seeing the carcasses, the hatchery staff set crayfish traps both in that pond and two adjacent ponds. They captured one live, positively identified, red swamp crayfish.
DNR staff do not believe any of the red swamp crayfish went to Thornapple Lake or Lake Hudson, as the muskie selected for transfer were noticeably larger at 12 to 13 inches in length. But a monitoring plan has been developed for both sites.
In the meantime, over 150 traps have been set at Wolf Lake Hatchery to determine the extent of the invasive species population. The DNR is also tracing shipments and quality control efforts, taking additional steps to screen the intake water.
As it turns out, Wolf Lake's muskellunge ponds are scheduled to be out of service in 2025 because of a construction project. The young muskie collected thie year will be reared at Thompson State Fish Hatchery in Manistique.
The DNR asks that Michigan residents and anglers who notice red swap crayfish in the wild are asked to collect and freeze a sample, or take photos with the location noted, and send their reports to Kathleen Quebedeaux, DNR Fisheries Division, QuebedeauxK@Michigan.gov.
