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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />fish populations appear explainable by differences in habitat availability, even though <br /> <br />predation was an influence on the Yampa River. <br /> <br /> <br />Riffle habitat is rare at Duffy but abundant at Com Lake and suggests a direct <br /> <br /> <br />relationship between habitat availability and bluehead sucker density at these sites. Also the <br /> <br /> <br />difference in rime habitat availability between the two sites suggests macro invertebrates <br /> <br /> <br />production would also be much different. It was suggested that abundant and stable rime <br /> <br /> <br />habitat at Com Lake provides an abundant macroinvertebrate forage and this helps explain the <br /> <br /> <br />much higher fish density in the 15-Mile Reach compared to Duffy. <br /> <br /> <br />Shanower low velocity pool habitats are very common at Duffy and rare at Com <br /> <br /> <br />Lake. This is reflected in the fish community at these two sites. Duffy is primarily composed <br /> <br /> <br />of non-native species that prefer pools habitats like white suckers and small mouth bass and <br /> <br /> <br />these fish are very rare at Com Lake. The percent of roundtail chub in the population is <br /> <br /> <br />similar to pool habitat availability at Com Lake, but at Duffy in spite of pool habitat <br /> <br /> <br />availability, chub are rare due to obvious predation. <br /> <br /> <br />Run habitats increase with increasing flows at Duffy, but runs decrease as flow <br /> <br />increase at Com Lake. Flannelmouth sucker is a native species associated with deeper runs <br /> <br />and are rare at Duffy but numerous at Com Lake. We believe that future habitat analysis will <br /> <br />confirm that run habitat is also more common at the Lily Park site compared to the other two <br /> <br />Yampa sites. <br />The low flows observed in 2000 provide empirical data in regard to justifying instream <br /> <br /> <br />flow recommendations. One more year of fish sampling will be conducted for this project. <br /> <br /> <br />This will provide an opportunity to see if fish densities remain at the 2000 level, drop lower, <br /> <br /> <br />or return to the 1998 and 1999 levels. A relationship between fish density and habitat <br /> <br /> <br />availability has always been an undocumented assumption of instream flow studies, and this <br /> <br /> <br />data will help dentify this relationship. Given the level of interest in this project, increased <br /> <br /> <br />47 <br />