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immeediately downstream, and the lower 2.2 miles of the Gunnison River <br />between the Redlands Diversion Dam and the confluence. <br />Distribution and relative abundance of young-of-the-year (YOY) Colorado <br />squawfish were estimated by seining backwaters with 3-mm-mesh beach seines <br />during late September and early October. Two samples were collected from <br />each of two backwaters in each 5-mile reach. Collected fish were preserved <br />in the field and identified in the laboratory under a dissecting microscope. <br />To determine relative abundance, the surface area seined was measured and <br />the number of squawfish collected per 100 square meters was calculated. The <br />study area sampled for YOY included the 15-mile reach and the adjacent 18- <br />mile segment of the Colorado River immediately downstream. <br />Microhabitat use of adult Colorado squawfish and razorback sucker was <br />estimated by measuring depth, velocity, substrate and temperature at the <br />locations of radio-tagged fish. Possible spawning sites were identified by <br />the aggregation of ripe adults during the spawning season and, for <br />squawfish, by the subsequent collection of larvae. Unfortunately, <br />techniques for identifying razorback sucker larvae have not yet been <br />developed. Post-hatching age of collected squawfish larvae was calculated <br />using total lengths of individual larvae in age-length equations developed <br />by Haynes and Muth (1985). Spawning date was then estimated by subtracting <br />four days from the estimated hatching date. Four days was considered the <br />mean egg incubation time, based on the 3.8-5.0-day range reported by Haman <br />(1981) for fertilized eggs of hatchery-reared squawfish incubated at <br />20-24 C. <br />4