Slimy sculpins (Cottus cognatus) in the north central United States are found primarily in three areas: Lake Superior and its tributaries, Lake Michigan, and small cold streams in the "Driftless Area" of southwestern Wisconsin, northeastern Iowa, and southeastern Minnesota. In the region between the Driftless Area and the Great Lakes, populations exist only in a few small streams and two small deep lakes, Trout and Big Green. Slimy sculpins from the north central United States display extensive within-population morphological variation. Males and females appear to differ in morphometry (shape) but not in meristics. Patterns of morphological variation among populations have little correspondence to patterns from other parts of the species' range, and do not match predictions based on the likely degree of reproductive isolation among populations. Some morphometric differences are evident among populations in different habitats, primarily because of the distinctiveness of slimy sculpins from Trout and Big Green lakes. Slight clinal differences exist in meristic variables from Great Lakes to Driftless Area populations, although Big Green Lake deviates from the cline. Hybridization with the mottled sculpin (C. bairdi) may contribute to morphological variation within some populations.
We sampled stream physical habitat, water temperature, and fish and macroinvertebrate communities at multiple paired watersheds before and after BMP installation from 1993 to 1999 to examine the responses of stream quality to watershed-scale BMP implementation. Our results clearly demonstrated that watershed-scale BMP installation significantly (p < 0.10) improved stream habitat quality, bank stability, instream cover for fish, catch of cool-and coldwater fishes, and catch of all fishes. Stream benthic macroinvertebrate community and water temperature showed consistent trends of improvement relative to the reference sites but were not statistically significant. The first catch of naturally reproduced trout in 1999 indicates Spring Creek has gained the ability to partially sustain its trout population because of overall stream quality improvement. Our results collectively demonstrated that watershed and riparian BMP implementation improve overall stream quality and our approach, studying multiple paired watersheds with before-and after-treatment data, proven effective in detecting the response of stream quality to BMP implementation.
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