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where CA is competitive ability of Colorado squawfish, when grown with fathead <br />minnow, 6 ~ and Gff are relative growth of Colorado squawfish and fathead <br />minnow in single-species assemblages, and G~f and Gf~ are relative growth of <br />Colorado squawfish and fathead minnow in mixed-species assemblages. Positive <br />values of CA suggest that Colorado squawfish were more competitive than <br />fathead minnow; negative values, that fathead minnow were more competitive <br />than Colorado squawfish. <br />Diet overlap of Colorado squawfish and fathead minnow in mixed-species <br />assemblages was calculated using Schoener's (1970) measure: <br />percent similarity = 100(1 - ZE I PX•; - P~ I ), <br />where PX•; is the proportion of the i`h prey in species x, and Pte; is the <br />proportion of the i`h prey in species y. Abrams (1980, 1982) argued that <br />Schoener's measure has several advantages over other indices for comparing <br />similarity of resource use between species. Because of a relatively large <br />number of-empty guts (32 90 of Colorado squawfish and 20 % of fathead minnow), <br />results from replicate aquaria were pooled and diet overlap was calculated <br />based on the mean frequency of each prey type in an experimental treatment. <br />For comparison, diet overlap of Colorado squawfish and fathead minnow in <br />single-species assemblages was also calculated for each feeding regime. Diet <br />overlap of fish in mixed-species assemblages and single-species assemblages <br />was compared by inspection. <br />12 <br />