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<br />common in the middlc dry section as well as the lower section. Thi-;
<br />species is commonly found in intcrmittant streams and backwaters.
<br />lntroduced fathead minnow (Pimephales promelas) and green sUl1fi~h
<br />(Lcpomis cyancllu5) also did not favor this middle section but \vere
<br />most abundant in the lower and upper sections.
<br />Collection of the sand shincr ir! thc Dolores represents the first pub-
<br />lished record for this species in the upper Colorado basin. It was also
<br />found to be common in the adjoining Colorado River.
<br />The movement of rainbow, brown and cutthroat trout into IO',\"f~r
<br />Yampa Canyon occurs when temperatures are cool enough for their
<br />survival. They presumably move in from thc Green River and perhaps
<br />down the Yampa.
<br />The introduced redside shiner \vas abundant throughout the Yampa
<br />study area. A cool watcr species, the Yampa provides ideal habitat for
<br />this species. The walleye (Stizosledian vitreum), largcmouth bass and
<br />bluegill (Lepomis macrochirus) collected were undoubtedly wander-
<br />ers from some of the small reservoirs on the upper Green HiveI' sys-
<br />tem. Four walleye, one largemouth bass and one bluegill were taken
<br />il! the four years of the study. The abundance of the other species is
<br />typical for a river the size of the Yampa in the upper Grpcn Hiver basin.
<br />The Little Snake Ri~er appears to be a typical small, shallow, sandy
<br />tributary and docs not contain the large river forms. J l is important to
<br />lippeI' Colorado basin rare and endangered species for ifs part in main-
<br />l'lilling flows, thus keeping the Yampa a fairly natural bl'ge river, per-
<br />haps the most natural large river environment left in the Colorado
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<br />1 CONCLUSIONS. From the staEdpoint of preservation of rarc and
<br />t "lIdilllgered fish species, the Dolores HiveI' system appears to have liltle
<br />:q"lrtance. This is primarily lJC'cilusP the upper Colorado Ri\'(~r ('/1-
<br />:.IIIl-wrcd species are large river forms and the Dolores HiveI' docsn '!
<br />., lthis category. Also it should be noted that this system is far frolll
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<br />" " natural state due to irrigation uses and its record of rathC'r sew'!"p
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<br />1 .,lIl1tion. It is doubtful the river has supported Colorado squawfisb.
<br />i :lIl1phack chubs, bony tail chubs or humphack suckers recentl~-. TI1\'
<br />1 ':q.tl!"lance of the Dolores Hiver to native fishes lies primarily ill it:;
<br />'; . .1"\llial capacity to provide the main Colorado HiveI' with watC'r l1ow~
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<br />i ,I maintain a natural large rin~r envirolll11ent. It is not now provid-
<br />4 .~ 'lIeh natural flows and nw~' therefore be considered neutral to the
<br />1 "'I'\'ation of native fishes aud possibly evell detrimcntal.
<br />, I ill' Yampa HiveI' is n'ry important to the prC'serYaliou of r;I!"(' an.1
<br />'.I/Ig('red fishes in the Colorado bilsin primarily because all tlJ('s~
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