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~i III reach, although brown trout and rainbow trout were also common. A wide range of sizes was reported for whitefish and brown trout; however, older fish dominated the rainbow trout population. It was suggested that whirling disease might be responsible for the unbalanced structure of the rainbow trout population. 1 Nehring, R B. and I{. G. Thompson. 1997. Stream Fisheries Investigations. Colorado Division of Wildlife. Federal Aid Project F-237R-4. Fort Collins, Colorado. Fryingpan River The purpose of this study was to monitor trout populations, species composition and determine potential impacts from whirling disease. The results of sampling during the fall of 1996 indicated that populations of brown trout, rainbow trout and brook trout had varied only slightly since 1995. It was suggested that predation by brown trout was still ' the primary cause for the decrease in brook trout density and biomass. Unlike most other Colorado streams the presence of whirling disease had not had a noticeable impact on the density, size or age structure of the rainbow trout population in the Fryingpan River at ' this time. Roaring Fork River The Roaring Fork River was not sam led durin 1996. p g ' Nehrin R B. 1998. Stream g~ Fisheries Investigations. Colorado Div~ston of Wildlife. Federal Aid Project F-237R-5. Fort Collins, Colorado. ' F 'n an River ~ ~ The purpose of this study was to monitor trout populations, species composition and determine potential impacts from whirling disease. The results of sampling during the fall of 1997 indicated that populations of brown trout, rainbow trout and brook trout had varied only slightly at all stations since 1995. Most of the data indicated that trout populations m the Fryingpan River had been relatively unaffected by whirling disease; ' however, rainbow trout recruitment near the confluence of Taylor Creek was lower during 1996 and 1997 than it had been prior to 1996. It was suggested that large rainbow and brown trout might be foraging on small brook trout in the reach below the dam. ' Roaring Fork River ' The reach of the Roaring Fork River extending from the confluence with the Fryingpan River downstream for approximately 4 km was sampled by boat electro-fishing during the fall of 1997. These results were compared to the data collected from the same reach during 1995. On both occasions whitefish were the most abundant species, although Fryingpan-Roaring Fork Literature Review February Z7, 2002 Miller Ecological Consultants, Inc. Page 21