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. . Squawfish were also found, although less commonly, in ~es and backwaters. 9ften, when fish were located in these habitats, they were eXhibi ting localized movement wi thin the confines .QL the 9abitat t~, suggesting a foraging behavior. Du~ing periods of lower flows, more backwater habi tat became available and correspondingly more sQUawfish were found in backwaters. It was interestrng to contrast this obserVation on the G,reen River with a situation on the Yampa River, where flows were generally consistent throughout the winter. One squawfish (Carlin tag # 6115), occupied a large backwater on the Yampa River (RM 0.6) from December through mid March. Its eventual movement out of the backwater coincided with slowly rising water levels in the Yampa in late March. . . A considerable degree of diversity existed within each habitat type with respect to physical factors, such as depth, velocity, substrate and cover. Although, differences in combinations of these factors were often difficult to perceive from the surface of the water, the consistency of certain behavior or movements by the fish lends itself to interpretation. Also, this diversity was often confirmed by measurements of depth and velocity. . Razorback Sucker. Approximately 267 hours were spent observing eight radiotagged razorback suckers. The fish were found utilizing only two basic habitat types, including ~and eddies, Between the two habitat types, they were found in runs approximately 56% of the time and in eddies 44% of the time. ~ --- -- . Razorback suckers were found most often in laminar run or eddy type habi tats. The runs they frequented were generally near. shorelines, where velocities were ~ and substrate usually consisted of silt. Razorbacks also showed an affinity for cobble or rubble substrates, and were observed over this relatively large-diameter material approximately 23% of the time. This species appears to be utilizing the microhabitat provlded by the cobble near the bottom. Several times, razorbacks were observed in relatively deep runs (up to 3 m deep) within the thalweg, slowly moving up or down the channel, apparently feeding on material growing on these cobble substrates. . Habi tat SUi tabili ty Index Curves . Colorado squawfish. The results of comparisons between 2-hour and 24-hour monitoring are shown in Table A-l of the Appendix. The distributions of depth C.o~~J.~ and velocity were not significantly different for nose measurements. substrate,1' "',,,5 types, however, were significantly different, possibly reflecting observer bias) ~ in classification. Measurements taken one meter in and out from the fish showed similar patterns for the 2-hourj24-hour comparison except that deptht distributions differed significantly for the measurements taken one meter in. ~ . . Comparisons of habitat measurements taken at the fish (nose) versus one meter ei ther side (in, out) are shown in Table A-2 of the Appendix. Distributions of depth and velocity were not significantly different for any o~ ft"""ef the comparisons, while all differences in substrate were highly significant.) \V\ ~"\t While not significantly different in distribution, mean depth increased from \~ the measurements closest to shore (in) to those furthest from shore (out) as 20 .