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population found in the Green River and its tributaries (Tyus 1991); the most tenuous population c<< "~ S <br />in the the San Juan. Colorado squawfish population size was recently estimated for the Colorado <br />River (Osmundson et a1 1997), where it was determined that 600-650 adults and sub-adults <br />inhabit the river from the confluence with the Green River upstream to Palisade, Colorado. As <br />reviewed in the Colorado Squawfish Recovery Plan (I7SFWS 1990 Colorado squawfish aze <br />suspected to spawn in two reaches in the Colorado River :~betwee~-~lack Rocks and Loma, and Ll <br />between Grand Junction and C~li$o~ $pawning occurs in the upper portions of the San Juan <br />.~ ;-< <w ~ r e r r a l'' I <br />River in New Mexi /fn the Green River sub-basin ~u~r ~,~ , i d ~l ~ ~ <br />:the lower 20 miles of Yampa Canyon and Gray Canyon of the Green River, while ,:< < <br />spa ' g has bee suspected (Tyus et al. 1987) in the lower portion of the Green River upstream <br />of the confluence. This supposition was supported by the collection of protolaryae downstream ~ <br />((~~ ~ <br />of this area (V dez 1990). , The debris fan /cobble bar at the mouth of Millazd wettld-appea~ a <br />likely locatios awnin ~o in the lower Green River. To forth r ' <br />P g ~ ~ a u~vestigat~ <br />suspected Colorado squawfish spawning in this ar WR developed obje~ctive~t~, etermine: <br />a. if Colorado squawfish spawn neaz the mouth of l~~d Canyon and the surroundin az and ~ ~, <br />g ~, ~-f~~ <br />b. presence /absence of larval squawfish in the Iower 50 km of the Green River. <br />Other agencies have been conducting similaz sampling for these species in the lower and upper <br />Green River concurrent with the subject study, and prior to it in some azeas. Data collected as <br />part of this study must be incorportated with this larger data base to truly understand the <br />importance of the lower Green River to these populations offish. <br />DRAFT 2 <br />