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(92%) the most ubiquitous, followed by rondtail chub (4.6%), bluehead sucker (2.7%) speclded <br />dace (2.5%), mottled sculpin (<0.1%) and Colorado pikeminnow (<0.1%) (Valdez et a1.1992). <br />Valdez et al. (1992) found strong differences in native fish species composition between river <br />reaches. These reaches were established to account for differences in water quality, <br />geomorphology and flow conditions and are: <br />Reach l: Dolores-Colorado River Confluence (RM 0.0 to the Utah-Colorado Stateline (RM <br />22.7). <br />Reach 2: Utah-Colorado Stateline to Salt Creels (RM 41.3). <br />Reach 3: Salt Creek to Dolores-San Miguel River confluence (RM 64.4) <br />Reach 4: Dolores-San Miguel River Confluence to Paradox Valley at Bedrock (RM 74.8) <br />Reach 5: Paradox valley at Bedrock to Dolores-Disappointment Creek Confluence (RM 128.7) <br />Reach 6: Dolores Disappointment Creek Confluence to Bradfield Bridge (RM 177). <br />Seiiung typically samples slow-shallow habitats dominated by smaller-bodied fish (length < 120 <br />mm) like non-native cyprinids, speclded dace or age-0 of the large bodied native species. Red <br />shiner, sand shiner and fathead minnow dominated seining collections in all habitats except <br />riffles and isolated pools. Native species were only about 2% native fish collected in seines in <br />Reach 1. Native composition by seinng increased in an upstream direction and was about 10% <br />in Reach 2 and 3, about 20% in Reach 4 and about 26% in Reach 5 (Valdez 1992). <br />Gill netting and boat electrofishing sample larger main channel habitats and deep pools. These <br />gear types catch both smaller and larger sized fish and flannelmouth sucker, rondtail chub, <br />bluehead sucker, carp and channel catfish, were the most abundant species, respectively, and <br />collected in 1990 and 1991 using these gear types. <br />In 1990 and 1991, flannelmouth sucker were most prevalent in Reaches 3 and 4 at about 52 to 56 <br />of the catch with the netting and electrofishing gear. Flaiulelmouth sucker were about 40 to <br />45% in Reaches 2 and 5, about 20% in Reach 6 and about 15% in reach 1. <br />Roundtail chub were common in the two upper Reaches (5 & 6) at about 30% of the netting and <br />electrofishing catch. Roundtail chub were uncommon in lower Reaches comprising about 8% in <br />Reach 4 and less than 5% in reaches 1, 2 and 3. <br />Bluehead sucker were more common in lower Reaches 1, 2 and 3 comprising from 11% to 18%, <br />but were about 5% to 8% in upper Reaches 4, 5 and 6. <br />hi 1990 and 1991, speclded dace were rare in lower Reaches 1, 2, 3, 4 and 5 with oiily 1 to 3% of <br />the catch, but were common in reach 6 (23%). <br />14 <br />