SEASONAL-VARIATION IN HABITAT USE BY THE NEOSHO MADTOM (TELEOSTEL, ICTALURIDAE, NOTURUS-PLACIDUS)

We sampled a series of riffles and pools on the Cottonwood River, Kansas, for one year to determine seasonal densities, habitat use, and the extent of inter-riffle movements of the Neosho madtom (Noturus placidus), a federally threatened catfish. The species exhibited limited seasonal variability in habitat use and appeared to be a year-round riffle inhabitant. Neosho madtoms inhabited shallower riffle areas in spring and summer, sites with greater water velocities in spring, and slower velocities in winter. Madtoms used sites with greater percentage rock substratum in winter, and substratum embeddedness was consistently low at sites of madtom presence. Current speed at the substrate surface, low variance of current speed, shallow water, and loosely embedded substratum were variables most useful in predicting madtom presence. Only one inter-riffle movement was documented, suggesting little dispersion among riffles throughout the year. Two age classes were obvious in length-frequency histograms; young-of-year appeared in july, suggesting a June spawn. Neosho madtom populations were assessed by mark-recapture (47 madtoms/100 m2), depletion removal (22 +/- 4/100 m2), species-specific (15.5/100 m2), and overall (3.3/100 m2) density calculations.