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EXECUTIVE SUMMARY The Colorado River Fishery Report consists of a Summary Report • (Part 1) which synthesizes and analyzes Field Investigations (Part 2) and hatchery/laboratory Contracted Studies (Part 3). Those interested in ,methodology and details of each study should review Parts 2 and 3. s Findings Colorado squawfish are widespread throughout the Upper Colorado River Basin and do not appear to be concentrated in large numbers in any one location. Numbers of Colorado squawfish appear to be less today than 10 to 20 years ago and may still be declining. Archer (1982) has calcu- lated a 66 percent decline in juvenile and adult Colorado squawfish from 1960 to 1980. The decline in young-of-the-year is even greater with a projected decline of 94 percent between 1960 and 1980. Spawning areas seem to be limited and the life stages of greatest concern are those from spawning through the first year. If adequate spawning and rearing areas cannot be found, protected, and managed, then a species management program with stocking would be required to ensure the continued existence of the Colorado squawfish. Extensive movement of Colorado squawfish was documented with total movement of some individuals over 200 miles. Spawning, migration, and homing behavior was observed and one definite Colorado squawfish spawning site was confirmed in the Yampa River. Movement of Colorado squawfish between mainstem rivers and tributary streams was documented. Blockage of migration routes may be a signifi- cant factor in the decline of the species. Humpback chubs are not wide ranging and are found primarily in four locations (Black Rocks, Westwater Canyon, and Gray Canyon in the Upper Colorado River Basin and the Little Colorado River in the Lower Colorado River Basin). Habitats differ slightly from area to area; however, the chubs appear stable in three of the four locations. Only the Gray Canyon population seems unstable and possibly decreasing at this time. Given the deep and narrow canyon configuration of the Colorado River at Black Rocks and Westwater Canyon, it does not appear that present flow depletions and regulations are limiting factors to the chub in the Upper Colorado River. However, some hybridization with roundtail chub has been documented which may be related to changes in flow and/or temperature. The humpback chubs are very sensitive to temperature and demonstrated a need for temperatures of at least 16-18° C in the spring to successfully spawn and have eggs hatch. Barring significant changes in their habitat humpback chubs should be considered relatively secure at their present population level at Black Rocks and Westwater Canyon in the Upper Basin « and in the Little Colorado River in the Lower Basin. The Gray Canyon population, found in the Green River, seems to be decreasing rapidly and will require management programs in the near future if this population is to be maintained. Few, if any, bonytail chubs still exist in the Upper Basin. A few individual bonytail were found in the Green River in Gray Canyon. I