Winter Habitat Use by Orangethroat Darter, Etheostoma spectabile, at Multiple Spatial Scales

Abstract

ABSTRACT We determined densities of orangethroat darter (Etheostoma spectabile) from different channel units during winter, the relation between fish size and channel unit used, and the microhabitat conditions related to the densities of this species. A quadrat sampler and backpack electrofishing were combined to sample darters from different channel units in an Ozark border region stream in central Missouri, USA. Analysis of variance revealed significant differences between mean densities of orangethroat darters in channel units. Densities were highest in pool and lowest in riffle habitats. Darter length was significantly greater in riffles than runs or pools. Variables significant to our model were velocity (negative correlation), percent cobble (positive correlation), and percent boulder (negative correlation). We found darters used all channel units during winter, though disproportionately. Identifying microhabitat conditions (low-velocity microhabitats) used by darters without channel unit use could have been misleading because riffles, whereas used less than other channel units, were important habitat for adult darters. We suggest an appropriate conservation strategy for this species must account for all channel unit types in order to benefit darter fitness parameters.