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Spanish Bottom (river mile 213) <br />Although gill nets were fished for 459 hours from May 7 to May 21 near <br />Spanish Bottom, no striped bass were captured. Flannelmouth suckers were <br />twice as abundant and razorback suckers four times as abundant in gill nets <br />above the rapids than below (Table 1). Catch per effort for other species <br />was higher and an additional five species of fish were captured below the <br />rapids. <br />Shortly after sampling was initiated, surface water temperature decreased <br />from 14.4°C (58°F) to 11.1°C (52°F), remained cool for several days and then <br />began a slow warming trend (Figure 1). River flow increased as the temperature <br />dropped and began receding as temperature warmed. <br />Three plankton net samples were collected each day of the sampling period <br />except May 11 and 18. No fish eggs or larvae were found in the samples. <br />Adult Colorado squawfish ranging in length from 406 to 734 mm (mean <br />length: 591 mm) were captured in gill nets at Gypsum Canyon as well as <br />Spanish Bottom (Table 5). Thirteen fish were tagged below and two fish above <br />Cataract Canyon. Approximately one half of the squawfish were parasitized <br />by one or more Lernaea. <br />DISCUSSION <br />Striped bass in Lake Powell evidently underwent a spawning migration <br />to the Colorado River during the Spring of 1980. Males were captured as <br />soon as sampling was initiated (April 26) whereas female bass were not <br />captured until May 20. More than twice as many males as females were <br />captured near Gypsum Canyon. Male bass normally arrive on the spawning <br />grounds before females during migrations, and males generally outnumber <br />females at any given time on the spawning grounds (Raney 1952).