The live red swamp crayfish trapped in Pond 20 at Wolf Lake Hatchery. Despite its dark color, the raised red bumps on its claws and hourglass shape on its back help to identify it as an invasive red swamp crayfish.
(FOX 2) - The discovery of two unusual crayfish at a state hatchery in west Michigan has invasive species specialists on high alert about a new threat to the local environment.
Wildlife officials confirmed the presence of the red swamp crayfish in a pond connected to the Wolf Lake State Fish Hatchery - but aren't sure how it arrived in the first place.
Invasive crayfish in Michigan
Michigan already deals with ample pressure from dozens of invasive species ranging from vegetative and plant-based organisms to insects and beyond.
The latest discovery is a concern for native crayfish, which can't populate as quickly as their invasive cousins - as well as an issue for shoreline stability.
The backstory:
First detected in 2017 in a lake in Kalamazoo and a pond in Pontiac, invasive species monitors have since found isolated infestations of the crustacean in several Southeast Michigan counties, including Wayne, Macomb, Oakland, and Livingston.
Officials believe the crayfish found their way into the wild as live bait, from aquariums, or by being brought to Michigan for crawfish boils.
In the latest discovery, staff with the Wolf Lake State Fish Hatchery in Van Buren County discovered the remains of two of the invasive crayfish in a collection basket from the pond where some types of fish are reared.
Crayfish traps were deployed in the suspect pond, leading to the capture of the invasive crustacean.
Red Swamp Crayfish being collected in a retaining pond off Hagadorn Road in Novi, MI, August 2022. DNR Fisheries technicians come to this pond in the shadow of the Sheraton Hotel every other day to pull the invasive Red Swamp Crayfish from the traps …
Why you should care:
It is illegal to possess red swamp crayfish in Michigan.
Since 2014, importing and owning them in the state has been illegal due to the invasive qualities. They are known to aggressively outcompete native crayfish for food and habitat.
They can also reproduce at a faster rate.
Additionally, the crayfish are known to burrow along the shorelines of inland lakes, which can destabilize the banks, leading to severe erosion.
DNR Fisheries Division staff check red swamp crayfish traps at an infested pond in Novi, Michigan.
Dig deeper:
How the crayfish made their way into the hatchery's facility is a mystery.
According to the Department of Natural Resources, it's highly unlikely the crayfish that were found in the hatchery ponds had arrived from the facility where muskellunge were raised.
The DNR is now looking at the water sources for the hatchery itself. It uses well water and natural spring water that is circulated through the ponds where the fish are reared, before draining into the Paw Paw River on the west side of the state.
Because the system is so open, there are not many barriers preventing invasive crayfish from moving around the area.
In an effort to prevent the crayfish from spreading further, the DNR and the Michigan Invasive Species Program are isolating possibilities of where the invasive species came from.
That includes potential bait or aquarium releases into nearby ponds or Wolf Lake, as well as the accidental transport of forage fish that are used to feed the species that are reared by the state.
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What's Being Done:
There are several steps both teams are taking, including:
- In the last week, 165 traps were set, spanning all 11 earthen bottom ponds at Wolf Lake Hatchery to determine the range of infestation at the site.The DNR is exploring the use of environmental DNA, or eDNA, to help determine the potential source, spread and presence of red swamp crayfish in the hatchery and surrounding waters.
- Suppliers and officials from states where minnows were sourced are fully cooperating with Michigan’s efforts to trace shipments and verify quality control measures to prevent contamination.
- Pending the results of trapping and assessment of risk, the DNR plans to explore potential control options at Wolf Lake Hatchery ponds, such as draining and drying ponds over the winter or adding pesticide, which has been used successfully on an experimental basis in some infested ponds in southeast Michigan.
- MISP and DNR staff are working to evaluate additional biosecurity measures, including improved screening of intake and outlet waters, additional screening methods to prevent bycatch from being transported with stocked fish and the use of only clean well water for fish transport.
- Wolf Lake Hatchery’s lined muskellunge ponds will be offline in 2026 for previously planned construction. Young muskie from this year’s harvest will be reared at Thompson State Fish Hatchery in Manistique, Michigan.
The Source: A press release from the Department of Natural Resources was used for this story.