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- r. <br />41 <br />Growth <br />The effect;,ofi..ration level on growth, _ though <br />difficult to interpret ,because both"limited" and," <br />geared to be in excess.."Limited" ration resulted. <br />changes in mean weight for fish held at 15, 20, <br />Figure 8). It is possible that excess rations left <br />.significant, was <br />excess" rations ap- <br />in greater. dotal <br />and 25 C (Table 4, <br />so much uneaten <br />food at the three lower temperatures that it irritated the gills of <br />the fish,_.caused stress and a decreased growth rate, but no outward <br />signs of stress were observed. <br />Temperature effects on growth were. significant, ,with the. best <br />growth at the estimated final preferendum, 25 C (Table 6). Bulkley et <br />al. (1981) found Ghat swimming stamina was greater for squawfish ac- <br />climated to 20 .:and 26 C than to 12 C, and concluded that 20-26 C was <br />in the optimum temperature range for swimming stamina of Colorado <br />squawfish. Brett (1971a) estimated the final preferendum of sockeye <br />salmon (Oncorhyncus nerka) at 15 C, and found that several physiologi- <br />cal responses were optimal at this temperature. The only exceptions <br />to the 15 C optimum were a better appetite at 17 G, and, where ration <br />-was restricted, a downward shift of the optimum to-11.5 C. Colorado <br />squawfish should be tested further to determine if other physiological <br />reponses besides growth are optimal at 25 C. <br />In this study, rations were in excess; whereas in`the wild, food <br />is often a limiting factor., Accordingly, as-,food becomes more limit- <br />ing, maximum growth would be expected to occur at progressively; lower <br />temperatures ,(McCormick -and Kleiner 1976). Hence maximal growth for <br />~~i <br />