WSP01392

• File Number: 8240.200.10.B
• Description: UCRBRIP - Riverine Fish Flow Investigations
• Basin: Colorado Mainstem
• Date: 6/1/2000
• Author: CDOW
• Title: Riverine Fish Flow Investigations 2000
• Water Supply Pro - Doc Type: Publication

Fish density was significantly higher on the Colorado River station than for the Yampa

sites. Total fish density was estimated at 3,962 per Ian at the IS-Mile Reach station (Table 6).

Total fish density on the Colorado River (3.92 per 100 m2) was 2.3 times higher than at

Sevens (1.72 fish/I 00 m2) and 6.4 times higher than Duffy (0.62 fish/IOO m2). Native sucker

density was very low at the Yampa Duffy site, where the estimate was only 25 bJuehead and

20 flannel mouth per kilometer, especially when compared to the Colorado River where both

native sucker estimates were over 1,500 per Ian (Table 6). The density of native sucker per

100 m2 at the IS-Mile Reach was over three times higher than at Sevens and over 46 times

higher that at Duffy (Table 6).

Channel catfish was the only nonnative predator collected in the IS-Mile reach and its

density (1.95 fish/IOO m2) was comparable to that on Yampa River at the Sevens (2.01

fish/IOO m2) and at Duffy (1.55 fish/IOO m2) (Table 6). Small mouth bass and northern pike

density was 2.2 times greater at Duffy than at the Sevens.

Table 6: Population estimates with 95% C.l. and density estimates (No/1000m) for the 15-
Mile-Reach, Sevens and Duffy stations, faJlI999.

SEVENS 15 Mile Reach. CO. R. Sevens, Yampa Duffy, Yampa
No/kmi95%C.1. No.l1000m2 No/kmt95%C.1. No/'OOOrn' No/kmt95%C.1.I No.l1000mz
Total 3962:1:11 % 39.62 1137:1:16% 17.07 409:1:7% 6.14
Bluehead 1573:1:20% 15.73 238:1:43% 3.57 25:1:33% 0.38
Flannelmouth 1550:1:17% 15.50 376:1:19% 5.65 20:1:30% 0.30
Roundlail Chub 192:1:83% 1.92 41:1:84% 0.62 27:1:71% 0.41
Colo. Pikeminnow 5:1:NR 0.05 3:1:NR 0.05 8:1:NR 0.12
Carp 309:1:36% 3.09 89:1:196% 1.34 8:1:96% 0.12
Channel Catfish 195:1:54% 1.95 134:1:192% 2.01 110:1:108% 1.65
Small Moulh Bass - - 29:1:123% 0.44 83:1:60% 1.25
Northern pike - - 22:1:120% 0.33 31:1:104% 0.47
Wh~e Sucker 62:1:65% 0.62 110:1:51% 1.65 113:1:11% 1.70
Wh~e-Bluehead 50:1:103% 0.50 1:I:NR 0.02 22:1:51% 0.33
WhITe-Flannel. 27:1:196% 0.27 85:1:104% 1.28 110:1:11% 1.65
Brown Iroul 18:1:196% 0.18 - -

On the Colorado River the same reach that was e1ectrofished was also surveyed for

habitat composition. However on the Yampa River the surveyed reach was shorter. Because

36

I
I
I
I
I
I
I
I
I
I
t
I
I
I