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Invasive species threatens local crayfish

Missouri Department of Conservation offers two access points on the St. Francis River from Highway 72.

Woodland crayfish affecting native crayfish species in Iron, Washington, Madison, St. Francois counties.


The future viability of the Big Creek crayfish and the St. Francis River crayfish, two native species in the Parkland region, is threatened by several factors, according to a recent report in the Federal Register, the official newspaper of the federal government.

Part of the National Archives and Records Administration, the Federal Register states that the primary concern is the displacement of these species by an invasive crayfish known as the woodland crayfish.

Noted by their reddish tent and brown spots, this invasive species has been seen mating with the native crayfish, leading to genetic hybridization and the eventual decline and destruction of the native populations.

The woodland crayfish was first documented outside its native range located in Jefferson County in 1984. Since then, it has invaded a significant portion of the river, impacting the distribution and abundance of the Big Creek and St. Francis River crayfish.

In invaded areas, the woodland crayfish has become the dominant species, comprising up to 86% of the crayfish community. Hybridization occurring between the woodland crayfish and the native species has overall favored the woodland crayfish in that most of the attributes of the hybrid species share the traits and appearance of the woodland crayfish, leaving the Big Creek crayfish and St Francis River crayfish displaced through lack of suitable dens to lay eggs in.

The Woodland Crayfish is the main threat to the local St. Francis Crayfish and Big Creek crayfish, having been observed mating with the local species causing major population displacement.

Apart from the non-native crayfish, contamination from heavy metal mining and sedimentation buildup also contributes to the decline of the St. Francis River crayfish and the Big Creek crayfish.

Southeastern Missouri’s rich history of lead production has resulted in ongoing contamination of the soil and water due to the presence of mining waste.

According to the Federal Register, the crayfish are exposed to high concentrations of heavy metals in the water, affecting their health and population density. Additionally, sedimentation resulting from changes in land use and erosion reduces the availability of suitable habitat for crayfish.

To combat the spread of non-native crayfish species in Missouri, the Missouri Department of Conservation implemented amendments to the Missouri Wildlife Code in 2011-2012. These amendments prohibit the sale and purchase of live crayfish for bait, the import and sale of live crayfish in pet stores, and the purchase and import of live crayfish for classroom study, all of which contribute to crayfish invasions. Additionally, the release of baitfish or crayfish into public waters is illegal without specific permits from the Missouri Department of Conservation.

Along with this, the Environmental Protection Agency (EPA) has been actively involved in remediating areas impacted by lead mining, including the Upper St. Francis River, with ongoing efforts planned for the future.

Considerably smaller than the other native crayfish, the Big Creek crayfish is much more elusive than the St. Francis River crayfish, but still faces the same displacement.

Additionally, the U.S. Fish and Wildlife Service and Missouri Department of Natural Resources are working together to restore natural resources affected by mining waste from historic mining operations. According to the Federal Register, these restoration projects aim to mitigate the ecological damage caused by mining activities and enhance the overall health of the affected habitats.

According to Trisha Crabille from the U.S. Fish and Wildlife Service, kids playing with crayfish, or “crawdads” as they’re colloquially called is still okay, so long as those crawdads are not moved out of wherever they were found.

Originally, this was how the invasion of the woodland crayfish began.

“The main thing is to avoid moving crayfish from where you find them. Once they are out of their watershed, it is hard to keep them from expanding,” Crabille said. “This is a problem all over the world for this kind of animal, it’s just how they operate. Once it starts, you can’t stop it.”

Crabille also explained that keeping rivers clean and reducing sediment buildup on rivers running through local properties can help contribute to the conservation of the native crayfish.

For more information, contact the U.S. Fish and Wildlife Service’s Columbia, Missouri Field Office at:

One of the native species at risk, the St. Francis River Crayfish, is categorized by its brown carapace, bearing white specks and blotches along its claws and back.

John Weber, Field Supervisor

Missouri Ecological Services Field Office

101 Park DeVille Drive, Suite A

Columbia, Missouri 65203

Phone: 573–234–2132

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