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

bluehead sucker was similar between both stations (Figures A5 and A6) and there were no

breaks in the histogram between 10 and 44 em.

Table 6. Species composition for fish Over and Under 15 cm at the Big Gypsum site on the
Dolores River, 2000.

Big Gypsum Big Gypsum Reach 5 Reach 6
2000 2000 Valdez. Valdez.
Species >15 em <15 em All fish All fisb
Flannelmouth Sucker 16.0% 5.2% 45.2 21.7
Bluehead Sucker 2.2% 0.0% 7.8 3.5
Roundtail Chub 54.9% 48.0% 29.5 27.0
Channel Catfish 15.8% 1.4% 7.3 4.3
Carp 3.4% 0.2% 5.9 4.3
Green Sunfish 2.0% 5.7% 0.5 3.5
Brown trout 0.6% 0.0% 5.2
Rainbow trout 1.7
Black Bullhead 5.2% 0.2% 0.3
Speckled Dace 0.0% 33.8% 3.1 23.5
Mottled Sculpin 0.9
Red Shiner 0.0% 5.2% 0.4 2.6
Sand Shiner 0.0% 0.2%
Fathead minnow 0.0% 0.2% 1.7
Native species 73.1% 87.0%
Sample size 577 501 ? ?
Recaptures

*Valdez, et al. (1992), Table 31 on page 56, data collected in 1990 & 1991, Reach 5 is
Bedrock (74.8) to Disappointment Creek (128.7), Reach 6 is disappointment Creek to
Bradfield bridge (RM 177). Big Gypsum is RM 109.

Each river and each station on the Yampa had dissimilar bluehead histograms. The

Colorado River appears to represent a bluehead sucker length distribution where habitat is

abundant and predation or competition is not regulating size structure. The lack of large

bluehead on the Dolores River is apparently due to low quality and quantity habitat (deep

rimes) since there are no predators and competitors of significance. The station with the most

rime habitat on the Yampa River is at Lily Park. All Yampa sites have large predators, which

are believed to explain the lack of small bluehead in the Yampa. The Duffy station also has

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