Effects of Habitat and Spatial Factors on Age-0 Smallmouth Bass in the Ozark Highlands

Understanding the habitat characteristics that influence the abundance of age-0 Smallmouth Bass Micropterus dolomieu is important for effectively managing populations. Factors operating across multiple spatial and temporal scales influence Smallmouth Bass, though these analyses are rarely done with sub-yearling bass in streams. This research aims to determine the role of local abiotic and broader-scale watershed features on densities of age-0 Smallmouth Bass in the Ozark Highlands relative to stream-reach location. Paired upstream and downstream reaches were sampled in 11 watersheds across eastern Oklahoma and southwest Missouri. We used snorkeling surveys to determine densities of age-0 bass and collected habitat variables at the mesohabitat, reach, and watershed scale using field surveys and GIS. Surveys from August-November 2015 suggest that spawning was successful in nearly all reaches, though densities of age-0 fish varied considerably. Although relationships with local habitat were not detected, results suggest that spatial factors explained variation in young of year densities. For example, densities were greatest in reaches of intermediate drainage area. Understanding influences on age-0 bass across spatial scales will help determine appropriate management actions for maintaining Smallmouth Bass populations. Spatial context-dependence of habitat effects may further explain differences in population-level responses to broad-scale environmental conditions.