ST. LOUIS, Mo.— Two species of Missouri crayfish are listed as threatened under the Endangered Species Act. The U.S. Fish and Wildlife Service says that the Big Creek and St. Francis River crayfish are suffering steep population declines because of competition with other species and pollution from former lead mines in the area.

The Big Creek crayfish - Image from the U.S. Fish & Wildlife Service
The Big Creek crayfish – Image from the U.S. Fish & Wildlife Service

The Big Creek Crayfish is olive and the St. Francis River crayfish is dark brown. They can only be found in southeast Missouri, in the Upper St. Francis River watershed. 

The woodland crayfish has displaced the native species along much of the Big Creek and St. Francis River. The streams may be taken over by invasive species if nothing is done over the next 50 years.

The runoff from the old lead mines is also a contributing factor to the native species decline. The pollution can affect their metabolism, and respiration.

The “threatened” status comes after litigation by the Center for Biological Diversity. They issued this statement on the crayfish protection status.

St. Francis River crayfish

“These crayfish are clinging to survival in contaminated streams, but protection under the Endangered Species Act gives them a fighting chance,” writes Will Harlan, a scientist at the Center. “By protecting the river habitats of these crayfish, we’re also safeguarding drinking water and creating a healthier future for humans.”

The designation may have benefits for other species living in the same environment. The U.S. Fish & Wildlife Service designated over 2,000 miles of rivers in critical habitat areas. That includes all streams occupied by the Big Creek and St. Francis River crayfish. This includes many streams in Iron, Madison, St. Francois, Washington, and Wayne counties. Learn more about this ruling here.