Red swamp crayfish

The invasive red swamp crayfish can reduce populations of amphibians and other crayfish. The Wisconsin Department of Natural Resources is asking for the public's help in investigating who dumped the crayfish in a parking lot near the Wisconsin River in Sauk Prairie.

Red swamp crayfish, which are illegal to possess or transport in Wisconsin because of their potential to threaten other wildlife, were dumped in the parking lot of a Sauk Prairie canoe landing on the Wisconsin River at the end of June.

The Wisconsin Department of Natural Resources is asking for the public’s help in investigating the incident.

The DNR does not believe any of the crayfish made it into the Wisconsin River or any other bodies of water. Within 24 hours of the June 21 dumping, DNR staff collected as many crayfish as possible and put up fencing and trenches to contain the crayfish.

Red swamp crayfish can host parasites and often carry the crayfish fungus plague, which can lead to a decline in other crayfish species, according to the DNR.

The crayfish are listed on the DNR’s list of invasive species in Wisconsin. Red swamp crayfish were last found in Wisconsin in 2009.

“If they establish, they can impact the ecosystem by aggressively competing with native crayfish and other species for food and habitat,” the DNR said.

In California and Spain, red swamp crayfish have been found to reduce amphibian populations, according to the DNR.

Sometimes called the Louisiana lobster or the American crayfish, the creatures are 2 to 5 inches long and have raised bright red spots covering their red claws and bodies. The DNR said they are likely introduced to new areas because they are a popular food.

Anyone with information about who may have dumped the invasive crayfish in Sauk Prairie is asked to call the DNR tipline at 1-800-847-9367 or submit a violation report online.

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Emily Hamer is a general assignment reporter for the Wisconsin State Journal. She joined the paper in April 2019 and was formerly an investigative reporting intern at the Wisconsin Center for Investigative Journalism.