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27 <br />were lost due to the debris-algae clogging problem. In most years, <br />fish samples from Morrow Point and Crystal reservoirs were taken pri- <br />marily with experimental gillnets held at the water surface by means of <br />plastic bottles tied to the float line. The ends of the nets were tied <br />to the bank with ropes of various lengths. Some vertical gillnets were <br />suspended from the middle of.the floated gillnet line in Morrow Point <br />Reservoir. A long Bureau of Reclamation barge was necessary to set the <br />30-ft-wide vertical gillnet used, and, since a similar barge was un- <br />available on Crystal Reservoir, no vertical gillnets were set there. <br />Most fish collected by seines were small specimens and were <br />preserved in 10-percent formaldehyde for later identification. Identi- <br />fications of most species were made using keys and/or characteristics <br />presented by Beckman (1952) and Baxter and Simon (1970). References <br />used for identification of catostomid fishes and their hybrids were <br />Smith (1966); Hubbs and Hubbs (1947); Hubbs, Hubbs, and Johnson (1943); <br />Smith and Koehn (1971); Nelson (1973) and Middleton (1969). The paper <br />of Holden and Stalnaker (1970) was used to discern species of the genus <br />GiZa, while that of Hubbs and Miller (1953) was used for Xyrauchen <br />and related hybrids. <br />Fish collected in gillnets were usually identified in the field <br />by crew members who were capable of identifying catostomid hybrids. <br />Crew proficiency in identification was obtained from our reference col- <br />lections and keys made from earlier collections by the present author <br />and Middleton (1969). The collections of Middleton (1969) from Blue <br />Mesa Reservoir were verified by Dr. Behnke of Colorado State University. <br />Furthermore, author proficiency is suggested since hybrid specimens <br />independently collected and identified by Mike Prewitt (graduate student