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<br />Density estimates for tlannelmouth sucker, white sucker and channel catfish were not
<br />significantly different between 2003 and 2001,
<br />
<br />The density estimates were significantly different for most species between 2003 and
<br />2000. The density estimates for ilannelmouth sucker, white sucker, carp and channel catfish
<br />were higher in 2003 than 2000, The bluehead sucker estimate was significantly lower in
<br />2003 than in 2000, Roundtai] chub was the only species not significantly ditTerent between
<br />2000 and 2003,
<br />
<br />Table 17. Density estimates at the IS-Mite Reach, Colorado 2000 to 2003,
<br />
<br />COLORADO RIVER Density estimate in fish per hectare
<br />IS-Mile Reach No/ha No/ha No/ha
<br />Species 2000 2001 2003
<br />Total fish 583.7 718,9 710.4
<br />Flannelmouth sucker 220.2 268,6 258,6
<br />Bluehead sucker 187,0 203,5 159,5
<br />Colorado pikeminnow 0,4 0.3 0
<br />Roundtail chub 59.9 43,0 61,1
<br />White S, + hybrids 25.6 53.4 59,2
<br />Channel catfish 61,3 77,5 87,8
<br />Carp 93.4 84,5 129.6
<br />
<br />Table 18. Biomass estimates at the lS-Mile Reach, Colorado River 2000 to 2003,
<br />
<br />COLORADO RIVER
<br />IS-l'-liIe Reach Kg/ha Kg/ha Kg/ha
<br />Species 2000 2001 2003
<br />Total fish 433.8 490,1 543,6
<br />Flannelmouth sucker 160,9 194,6 197.4
<br />Bluehead sucker 76,7 91.4 67,3
<br />Colorado pikeminnow 0,6 0,7 0
<br />Roundtail chub 12,8 11,1 14,5
<br />White S, + crosses 8.9 18.4 19,5
<br />Channel catfish 45.4 64,2 77,2
<br />Carp 129,0 110.4 167.7
<br />
<br />Mean lengths of fish in 2003 were not noticeably different from prior years (Table
<br />19). Low numbers of Age-l fish in the 2003 sample, however, indicated that native species
<br />did not have good reproductive success in 2002, Flannelmouth sucker had very few Age-O (S
<br />to 10 cm) and yearling fish (11 to 20 cm) in the catch in 2003 (Figure AI-II & -12), but fish
<br />of these sizes were common in 2000 and 2001. The 2003 bluehead sucker histograms
<br />(Figures AI-4 & -5) were very similar for the three years, thus little was indicated about the
<br />2002 flows impact on reproduction of this species.
<br />
<br />29
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