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I I I I I I I I I I I I I I I I I I I curves ~re developed fran the fish collected during the study, an:! then canpnoed to ha.bi tat preferences noted in other Upper Basin studies. The curves included depth, velocity, substrate, tenperature an:! habitat type. The curves pointed out the use of backwaters by young squawtish, and the use of more varied habitats l7f young chubs. STUDY NO 2: Tw3dt, T.M. and P.B. Holden. 1980. The developnent of ha.bitat suitability curves and estimation of available habitat for COlorado squawtish in the San Juan River, Na4 Mexico an:! utah. BIO/WEST pr-46-1, Logan, UT. This study was conducted for the Bureau of Reclamation, Amarillo, TX, and was J:BI"t of an intensive IFIM study BIO/WEST was conducting for that agency on the San Juan River. Habi tat use data was gathered from all available sources, including past BIO/WFST studies, FWS CRFP studies, and COlorado Division of Wildlife studies. Only data with depth, velocity and substrate measurements were used, which included 156 adult COlorado squawfish. Curves for yay an:! juveniles \Ere taken fran Holden (1977) as noted above. Backwaters, areas not handled well l:7f the IFIM hydraulic modeling, an:! areas along shorelines which \Ere considered. cover, were included in the curves and were associated with the substrate curve. For example, the substrate categories for silt included: silt, silt with cover (along a bank), and silt with 1::ackwater. Adult squawfish curves were also broken into three different times of the year when habitat preferences appeared to be different. These were pre-runoff, runoff, and post-runoff, differentiated by time of the year. A discussion on the limitations of the study, especially as related to the use of habitat infonnation collected fran other than the study river, was included . STUDY NO 3: Valdez, R. A., P.G. Mangan, R.P. Smith, and B.C. Nilson. 1982. Upper COlorado River investigations. pp. 101-279 in u.S. fish Wildl. servo an:! Bur. Reclam. Part 2, COlorado River Fishery Project, Final Report. salt Lake City, UT. This study and report SUImlarized the first three years of CRFP information in the upper COlorado River. Sanllling involved the COlorado River fran Lake Pc:well, Utah to Rifle, COlorado. Various types of sampling schanes and gear \Ere represented.. Depth, velocity and substrate was measured at all sampling points or locations of captured fish. SUi tabili ty-of-use cri teria were presented for adult, juvenile an:! yay COlorado squawtish, crlult and juvenile humptBck chub, and adult razorback sucker. The curves \Ere based on 377 YOY, 34 juveniles (60-229 JJIIl), arrl 105 larger COlorado squawtish; 36 juvenile an:! 184 crlult hunpback chub; and 52 crlul t razorback suckers. 6