Cooperative Fish and Wildlife Research Units Program: Missouri
Education, Research and Technical Assistance for Managing Our Natural Resources

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). 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. This is a cooperative project between the US Fish and Wildlife Service, Missouri Department of Conservation, and the USGS Missouri Coop Unit.