Madison, Wisconsin: Wisconsin Department of Natural Resources
Summary
In order to better understand the community ecology of southwestern Wisconsin stream fishes, particularly in relation to the smallmouth bass, we performed a series of univariate and multivariate statistical analyses on data collected in the 1970s by Bureau of Research (Wisconsin Department of Natural Resources) personnel during the statewide Fish Distribution Survey. Fish species assemblages in southwestern Wisconsin streams generally overlapped in species composition and habitat use. One group of fishes was primarily restricted to headwater areas and small tributary streams (less than 10 ft maximum width) and another larger assemblage of fishes was usually found only in the largest streams sampled (30-100 ft maximum width). However, most species were encountered over a wide range of stream sizes, several species were found at greater than two-thirds of all stations sampled, and species composition changed gradually rather than abruptly from headwaters to downstream areas. Smallmouth bass were most closely associated with rosyface shiners and stonecats, and to a lesser extent with hornyhead chubs, sand shiners, and golden redhorse. The presence or absence of most of these species at a location appeared to be a good indication of the potential of that location to support smallmouth bass. Stream size (width and depth), amount of rocky substrate, and water temperature were the most important environmental variables associated with the presence/absence of the smallmouth bass and its associates; all 6 species were most frequently found in portions of streams wider than 20 ft that had more than 40% of the bottom as rocky substrate and water temperatures greater than 60 F (in May and June).