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57 <br />Fish Distribution and Population Trends <br />Colorado squawfish. - Most of the adult squawfish were caught in or near <br />Black Rocks Four were captured further downstream near Moab (RM 80- <br />111) in an effort to capture brood stock. Twenty-one juveniles were <br />caught just above the Colorado - Green River confluence (RM 47), and <br />five in the section near Moab (RM 47-80). Nearly all of the young-of- <br />the-year squawfish occurred just above the confluence. As many as 106 <br />young were caught in one haul with a 1/4-inch mesh seine. <br />i <br />'Humpback chub.- The majority ofd the humpback chub were encountered in a <br />uniquely deep section of the Coloradw'River - Black Rocks (RM 125-154) or.- <br />i - <br />near the rapids of Westwater Canyon (IM 111-125). Every adult of this species <br />captured was found in or near deep, swift water in a rocky channel. The <br />young-of-the-year and juveniles were all found in shallow, calm water with <br />sand-silt substrate such as backwaters. <br />Habitat Preferences i <br />Colorado squawfish. - Using the habitat information gathered from the <br />F <br />3 <br />capture of 36 adults, 30 juveniles, and 256 young-of-the-year, probability <br />of use criteria were developed for Colorado squawfish (Figure 8). <br />These data show that adults occupied a greater variety of depths, velocities, <br />and substrates than other ages, but most were found in water less than-- <br />10 feet deep, velocities of less than 2 feet per second, and over boulder <br />substrates.