Potential effects of interspecific competition on Neosho madtom (Noturus placidus) populations

Previous research on the distribution of Neosho madtoms, which are Federall y-listed as threatened, indicated a positive relationship between density o f Neosho madtoms and cumulative density of other riffle-dwelling benthic fi shes. This suggested that interspecific competition was not limiting Neosho madtom populations. We provide further evidence that interspecific competi tion is not limiting Neosho madtom populations. Densities of fishes with ha bitat preferences similar to those of the Neosho madtom were positively cor related with Neosho madtom densities, whereas densities of fishes with diff erent habitat preferences were negatively correlated. Slenderhead darter, s uckermouth minnow, and juvenile channel catfish densities were positively c orrelated with Neosho madtom densities. Like the Neosho madtom, these speci es are found most often over gravel substrate with moderate flows; the suck ermouth minnow is tolerant of high turbidities. Bluntnose minnow, western s lim minnow, and bullhead minnow densities were negatively correlated with N eosho madtom densities. In contrast to the Neosho madtom, these species are found most often in pools or sluggish backwaters.