Neosho madtom and other ictalurid populations in relation to hydrologic characteristics of an impounded Midwestern warmwater stream: Update

The Neosho madtom, Noturus placidus, is a small (less than 75 millimeters in total length) ictalurid that is native to the main stems of the Neosho and Cottonwood Rivers in Kansas and Oklahoma and the Spring River in Kansas and Missouri. The Neosho madtom was federally listed as threatened by the U.S. Fish and Wildlife Service in May 1990. The U.S. Fish and Wildlife Service has been monitoring Neosho madtoms since 1991, and questioned whether or not Neosho madtom densities were affected by other catfish species, reservoirs, and hydrologic characteristics. Using the first 8 years of U.S. Fish and Wildlife Service monitoring data, Wildhaber and others (2000) analyzed whether or not Neosho madtom densities were related to these environmental characteristics. The goal of this report is to update these results with data from 1999 to 2008. The trends of Neosho madtom densities in respect to John Redmond Reservoir and other catfish species remains consistent with the previous report. In both the Neosho and Spring Rivers, Neosho madtoms had a significant positive association with all catfish species. Of those species tested, only in the population of Neosho madtoms were significantly different in density above verses below the John Redmond Reservoir after accounting for the yearly variation. The average density of Neosho madtoms at the streamgage immediately below the reservoir had the second lowest density compared to the other streamgages. The positive associations with Neosho madtoms that remained consistent from the previous report included the 1-, 3-, and 7-day minima discharges and the annual minimum discharge from the previous water year (water year prior to when the fish were sampled) and the 1-, 3-, 7-, and 30-day minima discharges from the current water year (same water year fish were sampled).