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. INTROOOCTI~ . . This document is the Annual Summary Report for 1986-87 subrndtted to the Bureau of Reclamation (BOR) for Contract No. 6-CS-40-04490, entitled "Winter Habitat study of Endangered Fish - Green River". Three progress reports were submitted during the course of the investigation, one following the complet}on of phase one of the procj19ct which involved implanting radiotransmitters in~i r~orback suckers ~ 10,Colorado s~awfish, and two during the radiotracking phase. ~/ Objectives . The objectives of this investigation were to: . 1. Determine if adult Colorado squawfish and razorback suckers remain in specific river segments from ~ t~ early sprinq iJl the ~ River from the ~ay Refuge to Browns Park. ~ ''I.' - it", ,,,r 2. Determine microhabitat (dwtb, ve1.ggj.ty, s~ate, c~r and t~mperature) u~ by adult Colorado squawfish and razorback sucker during the winter months (November through March). ------ ---- -- ----- . 3. Develop winter habitat utilization curves based on microhabitat data collected during the study (Bovee, 1986). 4. ~luate Physical Habitat Simulation (~HABSUI) data output derived from t e utilization curves developed in item 3 above relative .9L a~l Colorado sIDJ,awfish use patterns observed in the field and areas evaluated by the ~Rsti9"m F10"" Iacremel"ltal Motlleeelogy (IrIHf( Bovee, 1982). This includes computer analysis of the PHABSIM effort following calibration of each instream flow station by the u.S. Fish and Wildlife Service (FWS). This objective is ~ accomplished after the ~COIld year of field investigations, 1987-88. . Background . This investigation was conducted as part of the BOR's ongoing program on endangered fishes of the upper Colorado River basin. That program is part of the responsibility of federal agencies as prescribed by the Endangered Species Act of 1973, as amended in 1978, to protect and, where possible, to promote the recovery of these fishes. . . Since 1978, the FWS has been collecting biological information on the endangered fishes of the Green and Colorado river systems. These investigations, principally funded by the BOR, have been undertaken to develop a better understanding of the physical and biological needs of the endangered Colorado squawfish (Ptychocheilus lucius), humpback chub (Gila cypha) and bony tail chub (Gila elegans), as well as the federal candidate species razorback sucker (Xyrauchen texanus). A major portion of this effort by BOR has been to fund the ongoing Colorado River Fisheries project (CRFP) being . 1 .