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<br />7 <br /> <br />RESULTS <br /> <br />Fish Distribution and Abundance <br /> <br />Over 330 individual samples of fish were taken during the study. <br />These included 125 samples in runs, 121 samples in backwaters, 59 sam- <br />ples i~ eddies, and 19 samples in riffles. This is approximately pro- <br />portionate to the availability of these habitat types in the study area. <br />Nineteen species of fish were collected totaling over 19,500 <br />specimens (Table 1). Length/frequency information from measured speci- <br />mens provided an estimate of the lengths of most year classes (Appendix <br />I). The introduced red shiner (Notropis lutrensis) was by far the most <br />abundant fish, whereas the flannelmouth sucker (Catostomus latipinnis) <br />was the most abundant native species. The bony tail chub (Gila elegans) <br />was the rarest native fish cqllecteq, with only two indi~iduals ~eing <br />caught. The introduced white sucker (Catostomus commersoni), redside <br />shiner (Richardsoni~ balteatus) and creek chub (Semotilus atromaculatus) <br />were found in very small numbers and only in the upper portion of the <br />study area. They are more abundant upstream from the study area where <br />the river is cooler (Holden and Stalnaker, 1975; Seethaler, McAda and <br />Wydoski, 1976). <br />Young-of-the-year Colorado squawfish (35-64 mm) were found only in <br />the lower portion of the study area (Table 2). Juvenile squawfish (65- <br />200 mm) were concentrated in the upper and lower portions of the study <br />area, with fewer in the middle portion. Subadult squawfish were found <br />