Center for Biological Diversity

For Immediate Release, April 26, 2023


Will Harlan, (828) 230-6818,

Two Missouri Crayfish Receive Endangered Species Protection

2,000 Miles of Streams Protected As Lifesaving Habitat

ST. LOUIS, Mo.— Following litigation by the Center for Biological Diversity, the U.S. Fish and Wildlife Service today protected the Big Creek and St. Francis River crayfish as threatened under the Endangered Species Act. The Service also designated 2,112 river miles of critical habitat in the Missouri Ozarks for the two crayfish.

“These crayfish are clinging to survival in contaminated streams, but protection under the Endangered Species Act gives them a fighting chance,” said 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 Center sued the Service in March for failing to protect the animals.

Both crayfish species are suffering steep population declines due to heavy metal mining pollution. Mining in Southeast Missouri has resulted in high concentrations of lead and cadmium in the crayfish, and that is known to affect their metabolism, respiration and survival.

Big Creek and St. Francis River crayfish downstream of mining sites have dangerously elevated levels of lead and cadmium and significantly reduced abundance. Mine tailings also contaminate and clog the river bottoms where these crayfish dwell.

Both species of crayfish are also declining because of the invasive woodland crayfish, which has displaced the Big Creek and St. Francis River crayfish across much of its range. More than half of these crayfishes’ streams are expected to be invaded by the woodland crayfish in the next 50 years.

The Big Creek crayfish is a two-inch, olive-tan crayfish with black blotches across its pincers, carapace and abdomen. The St. Francis River crayfish is also a two-inch crayfish with black blotches across a dark brown body. Both occur in the headwaters, tributaries and main stem of the Upper St. Francis River watershed, but their river habitats generally do not overlap.

The Big Creek crayfish received 1,069 miles of critical habitat in Big Creek and Twelvemile Creek, and the St. Francis River crayfish received 1,043 miles of critical habitat across Iron, Madison, St. Francois, Washington and Wayne counties above the Wappapello Dam.

“The habitats of these crayfish also shelter a stunning diversity of other aquatic species, including fish, mussels and turtles,” said Harlan. “Protecting these areas will help a lot of other vulnerable animals.”

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 1.7 million members and online activists dedicated to the protection of endangered species and wild places.

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