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<br />Table 16, Species composition at the IS-Mile Reach, Colorado River 1999 to 2003,
<br />
<br />COLORADO RIVER CORN L. CORN L. CORN L, CORN L.
<br />Species 1999 2000 2001 2003
<br />Flannelmouth sucker 38% 31,0% 39,8% 32,1
<br />Bluehead sucker 35% 36.3% 37,3% 30,7
<br />Roundtail chub 3% 4,3% 2,9% 4,6
<br />Colo. pikeminnow 0.10% 0,04% 0,03% 0,02
<br />Razorback sucker 0,20% 0,3% 0,05% 0,2
<br />White S. + hybrids 6% 4,5% 5,8% 10.4
<br />Channel catfish 4% 6,3% 4,7% 6,5
<br />Carp 11% 14,1% 6,7% 11,6
<br />Sunfish (all species) 0,9% 1.5% 1,2% 2.7
<br />Trout (all species) 0,0% 0,1% 0,25% 0,1
<br />Bullhead 1,3% 0.6% 1,3 0,7
<br /> 0,1 0,1 0 0,4
<br />Sample size 3499 2784 3667 4279
<br />COLORADO RIVER CLIFTON CLIFTON CLIFTON BOTH BOTH BOTH
<br />Species 2000 2001 2003 2000 2001 2003
<br />Flannelmouth sucker 32,5% 42.0% 32,5% 31,7 41,0 32.3
<br />Bluehead sucker 40,5% 26,8% 25,2% 38,6 31,5 28,2
<br />Roundtail chub 5.1% 5,9% 6.0% 4,7 4.5 5.2
<br />Cola, pikeminnow 0,03% 0,09% 0,1% 0,03 0,06 0.04
<br />Razorback sucker 0 0,04% 0,00% ,15 0,02 0,1
<br />White S. + hybrids 3,7% 4.1% 8,0% 4.4 4,8 9,3
<br />Channel catfish 5,1% 5,7% 10.5% 5,6 5,2 8.3
<br />Carp 11.7% 13,8% 12.1% 12,8 10,6 11,8
<br />Sunfish (all species) 1,2% 1,1% 4,0% 1,3 1,1 3,3
<br />Trout (all species) 0.1% 0,3% 0,3% 0,1 0,3 0.2
<br />Bullhead 0,2% 0.4% 1,0% 0.4 0,8 0,8
<br />Blue-fiannelmouth hvbrid 0,2 0 0,5 0,2 0,0 0.4
<br />Sample size 3276 4485 3558 6060 8152 7864
<br />
<br />Species composition and density data collected in 2000 was less consistent with the 1999 and 2001
<br />data. That was attributed to variability in sampling efforts and efficiency between years
<br />(Anderson 2002), Only six passes at both sites were made in 2000 instead of seven or more
<br />for 1999 and 2001. The author felt that the true species composition was consistent for 1999,
<br />2000 and 200 I, and the discrepancy in 2000 was due to sampling bias (Anderson 2002),
<br />
<br />Density and biomass estimates were not dramatically different in 2003 compared to
<br />earlier years (Tables 17 and 18). Significant differences in density estimates (alpha = 0.05)
<br />were identified in 2003 for bluehead sucker, roundtail chub and common carp compared
<br />against 200 I. Bluehead sucker density was 22% less and biomass was 26% less in 2003
<br />compared to 200 I. Roundtail chub density and biomass was increased 42% and 31 %
<br />respectively, Carp density and biomass was 53% and 52% higher in 2003 compared to 2001,
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