Distribution of Threatened Endemic Crayfishes of the St. Francis River drainage, MO, and Spread of the Invasive Woodland Crayfish

Principle Investigator: Dr. Jacob Westhoff

Students and Staff: Anna Raney

Objectives:

1. Determine the current distribution of the invasive Woodland Crayfish in the St. Francis River drainage

2. Refine and update distributional knowledge of the endemic Big Creek Crayfish and St. Francis River Crayfish, including verifying and updating past distributional models

3. Use updated distributional data with past distributional data to estimate rate of spread of invasive Woodland Crayfish and provide a temporal foundation for recovery and management plans

Overview:

The St. Francis River Crayfish (Faxonius quadruncus) and the Big Creek Crayfish (Faxonius peruncus) have been proposed for listing as federally threatened and a final listing rule formalizing the proposed status is expected during 2022. Both species are stream-dwelling crayfish endemic to portions of the upper St. Francis River drainage in Missouri and their primary threat is displacement by the invasive Woodland Crayfish (Faxonius hylas). These two crayfishes may be the 7th and 8th crayfish species listed under the Endangered Species Act (ESA).

We plan to sample over 100 locations throughout the upper St. Francis River drainage to determine the current distribution of all three species. Using those data, we will create a species distribution model to predict the probability of species presence in un-sampled stream segments. We will also intensively sample the leading edges of the invasion to estimate the spread of the invasive.

Study results will provide current and comprehensive distributional records for the invasive and two native crayfishes proposed for federal listing, define the leading edges of the invasion in all known invaded streams, and produce more accurate estimates of invasion rates and native declines. This information is essential to recovery planning to identify potential refugia where natives occur and the invasive has not yet reached.

Partners:

Robert DiStefano (MO Dept. Conservation Project Lead), Trisha Crabill (U.S. Fish and Wildlife Service Missouri Ecological Services Field Office), MO Department of Conservation Staff (Kelly Rezac, Kevin Brunke, Dave Knuth, Kara Tvedt, Craig Scroggins, Sherry Gao)

Funding:

U.S. Fish and Wildlife Service and Missouri Department of Conservation

Duration:

Winter 2022 - Summer 2024 (2.5 years)