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Water Resources Region 6, memo to Keith Rose, Project Leader, Endangered <br />Species, Grand Junction, 3 December 1987). Some changes in alluvial <br />reaches of the Island Park area (RM 330.6 to 329.4) were noteet, such that <br />some previous side channels had been filled with sedimentation and <br />vegetation resulting in a loss of island habitat. In general, however, <br />the Ruple Ranch study site, located within Dinosaur National Monument, was <br />considered stable and protected from industrial and agricultural <br />development. <br />1. Species Distribution <br />Species distribution for the Green River has been determined from <br />radiotelemetry, catch data, and other information (Tvus et. al 1987). This <br />information concludes that adult Colorado squawfish occupy a variety of <br />habitats including eddies and runs throughout this reach year round. <br />During the prespawning period when water temperatures range between 16 and <br />20 C, adult squawfish move through this area to specific spawning grounds. <br />Young squawfish are abundant soon after the spawning period in backwater <br />habitats. Little is known about the life history of the razorback sucker, <br />however collections of ripe males in this area has resulted in <br />classification of this reach as a suspected spawning area. <br />The biological importance of this reach is as follows: 1) Colorado <br />sguawfish: adult habitat year round; young-of-year nursery habitat from <br />mid-July to November 1; spawning habitat from mid-June to September; and <br />migration routes from mid-May to October (one month before and after <br />spawning), and 2) Razorback sucker: spawning habitat fran April to July <br />(FWS 1987; Tables 5 and 6). <br />22 <br />~~~ <br />