WSP07697

• File Number: 8240.200.10.B
• Description: UCRBRIP - Riverine Fish Flow Investigations
• Basin: Colorado Mainstem
• Date: 7/1/2001
• Author: CDOW
• Title: Riverine Fish Flow Investigations 2001
• Water Supply Pro - Doc Type: Publication

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composition increased from 63 to 78% from 1999 to 2000. Fewer channel catfish caught at

Clifton in 2000 is the reason for the higher native composition.

Table 4. Species composition for fish> 15 cm in the 15-MILE Reach Colorado River in
October 1999, and in August 2000 for two stations, Corn Lake and Clifton.

Corn Lake Corn Lake Clifton Clifton
Species 1999 2000 1999 2000
Flannelmouth Sucker 38.4% 31.1% 32.8% 32.5%
Bluehead Sucker 34.5% 36.3% 22.6% 40.5%
Roundtail Chub 3.1% 4.3% 7.2% 5.1%
Colo. Pikeminnow 0.1% 0.04% 0.5% 0.03%
White sucker 3.7% 2.9% 3.8% 1.7%
White X Flannelmouth 1.2% 1.6% 0.6%
White X Bluehead 0.7% 0.8% 1.2% 1.4%
Channel Catfish 4.2% 6.3% 14.2% 5.1%
Carp 11.3% 14.1% 15.9% 11.7%
Smallmouth Bass 0.1% 0.5%
Largemouth bass 0.7% 1.1% 0.2% 1.1%
Green Sunfish 0.1% 0.4% 0.2% 0.1%
Brown trout 0.4% 0.1% 0.5% 0.1%
Rainbow trout 0.03% 0.04%
Black Bullhead 1.3% 0.6% 0.5% 0.2%
Razorback Sucker 0.2% 0.3%
Sample size 3499 2784 575 3276
Recaptures 248 212 0 246

In last years progress report, species composition was separated for fish captured from

the main channel and fish collected in backwaters. In this report, Tables 4 and 5 are for total

fish collected at the stations without distinguishing main channel from backwater samples.

Small (<15 em) flannelmouth sucker, bluehead sucker and roundtail chub were collected at

both sites in both years (Table 5). Speckled dace and mottled scuplin were only sampled

qualitatively. Therefore dace and scuplin composition is biased low, because special effort

was not made to collect these species, since they are common and occupy swift habitats in the

main channel. Efforts were made to net all sunfish sighted, and most originated in backwater

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