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28 <br />about the same time [Personal communication, B. D. Burdick, Utah <br />Division of Wildlife Resources, Vernal]. No razorback suckers were <br />collected at Ouray either, but ineffective sampling rather than a <br />lack of razorback suckers was probably the reason. This species is <br />believed to occupy the Green River from its confluence with the <br />Colorado River upstream to its confluence with the Yampa River <br />(Figure 4). <br />Age and Growth <br />Length-weight relationship <br />The length-weight relationships were not significantly different <br />for males and females (p<0.1) so they were combined for both the Yampa <br />and Colorado Rivers. There was no significant difference (p<0.1) <br />between the length-weight relationships for fish from the two river <br />systems either, but the two groups were analyzed separately, since <br />the characteristics of the two rivers are different. However, the <br />fish from the Colorado River (Figure 5) were generally larger in <br />both length and weight than the fish from the Yampa River (Figure 6), <br />and females were larger than males. <br />Back-calculation of growth <br />Back-calculation of growth from scale analysis is an important <br />technique used to obtain life history information for fish. It <br />involves the assumption that scale growth is proportional to body <br />growth [Teach, 1971], which does not appear to be true for razorback <br />suckers. The relationship between body length and scale radius was <br />not significant for fish from either river. Scales from the key