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s• January 1985 W Z J TIME LAMARRA ET AL.: SQUAWF'ISH Fig. 5. Feeding intensity (expressed as a percentage of ftillness of stomach volume) of all fish compared over time at Yampa River mile 16.5. Fish captured between 1950 and •2140 hours were significantly fiiller than fish captured at other times. Data collected 24-26 July 1981. 135 CRFP (Tyus et al. 1981) survey, at Transect 2, the width of the river was estimated at 70 m compared to 54 m measured for this sur- vey. Both sample periods occurred during postrunoff, with an intervening river stage decrease of approximately 0.6 m and a corre- sponding flow I•eduction of 180 cfs (480 cfs to 300 cfs). The biological community in this study was similar to that documented in previous studies of the Yampa River. The dominant macroinvertebrates (Ephemeroptera: Rhithrogena, Baetis; Pleeoptera: Isogenus; Trichoptera: Hydropsche, given in order of abundance) were also previously reported by Bailey and Alberti (1952) and more recently by Carlson et al. (1979) and Annear (1980). The density of macroinvertebrates also corre- sponded to the levels reported by Annear (1980). The fish species composition of the Yampa River within Dinosaur National Park appears to have changed dramatically in recent years. Carlson et al. (1979) noted that Holden (1973) reported bonytail chub, largemouth bass, bluegill, sunfish, and walleye within this stretch of river. However, in 1979 these spe- TABLE 4. Percentage composition of macroinvertebrates in the diet of fishes (A) and in benthic or drift samples (B) collected in the Yampa River near river mile 16.5 24-26 July 198E (A} Percentage in each fish species diet Redside Red Roundtail Speckled Al] Orders shiner shiner chub dace species Ephemeroptera 92.7 92.6 78.6 87.5 85.8 Pleeoptera -- -- 00.1 -- 00.0 Trichoptera 00.1 -- 05.1 04.2 03.1 Coleoptera -- -- -- 02.3 00.6 Diptera 05.8 01.5 13.2 05.8 07.8 Hymenoptera 01.3 04.3 02.9 -- 02.2 Lepidoptera -- -- -- 00.2 00.1 Hemiptera 00.4 01.6 00.1 00.1 00.4 Hydracrina -- -- 00.1 -- 00.0 (B) Percentage in each sample type Orders Benthic Drift Ephemeroptera 94.26 99.58 Pleeoptera 00.87 00.09 Trichoptera 04.25 00.22 Coleoptera 00.04 00.01 Diptera 00.12 00.08 Odonata -- -- Lepidoptera 00.08 - Hemiptera 00.09 00.00 Homoptera 00.02 00.00 Alachnida -- 00.00 Megalopte.ra -- 00.00 Olit~ochaeta 00.19 -- 163]•1745 1950.1140 0-0175 0910-1030 1475.1630