Intraspecific habitat segregation by smallmouth bass in the Buffalo River, Arkansas

We recorded habitat variables including macrohabitat type (run or pool), substrate, cover type, stream depth, and light level periods for focal point observations of smallmouth bass Micropterus dolomieu while snorkeling along transects in the Buffalo River, Arkansas. We used logistic regression analysis to determine which habitat variables were important in discriminating between the presence of age-0 (<100 mm) and older fish as an indication of microhabitat segregation. Runs and pools were occupied by both groups of smallmouth bass, though a higher proportion of age-0 fish were observed in pools. Age-0 smallmouth bass were not restricted to stream edges and runs as in some eastern United States streams. A fitted model for run microhabitats indicated that bedrock, silt, sand, gravel, aquatic macrophytes, boulders, and light period were significant predictors of an age-0 smallmouth bass observation. Significant predictors in pool microhabitats included cobble, undercut banks, depth, and light. Thus, we found evidence of intraspecific microhabitat segregation in the Buffalo River. We conclude that Buffalo River smallmouth bass are habitat generalists and may not be a good indicator species of the effects of habitat alterations. Our evidence of intraspecific habitat segregation indicates the need to identify relations between habitat use and survival of age-0 fish.