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

Previous research on the distribution of Neosho madtoms, which are Federally-listed as threatened, indicated a positive relationship between density of Neosho madtoms and cumulative density of other riffle-dwelling benthic fishes. This suggested that interspecific competition was not limiting Neosho madtom populations. We provide further evidence that interspecific competition is not limiting Neosho madtom populations. Densities of fishes with habitat preferences similar to those of the Neosho madtom were positively correlated with Neosho madtom densities, whereas densities of fishes with different habitat preferences were negatively correlated. Slenderhead darter, suckermouth minnow, and juvenile channel catfish densities were positively correlated with Neosho madtom densities. Like the Neosho madtom, these species are found most often over gravel substrate with moderate flows; the suckermouth minnow is tolerant of high turbidities. Bluntnose minnow, western slim minnow, and bullhead minnow densities were negatively correlated with Neosho madtom densities. In contrast to the Neosho madtom, these species are found most often in pools or sluggish backwaters.