8182

• UCREFRP Catalog Number: 8182
• Author: Bestgen, K. R. and L. W. Crist.
• Title: Response of the Green River Fish Community to Construction and Re-regulation of Flaming Gorge Dam. 1962-1996\
• USFW Year: 2000.
• Copyright Material: NO

May 1993 and was 572 mm TL and 1.6 kg. When we recaptured it on 12 September 1995 at RK
576.4, it was 661 mm TL and 3.05 kg. We assumed this fish had about three growing seasons
between recapture intervals, and a growth rate of about 30 mm/year (89 mm TL increase/3 yr =
29.7 mm TL/yr).
Roundtail chub.-Chubs were rare in the regulated reach of the Green River and were

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restricted to Lodore Canyon. Roundtail chubs were captured in Lodore Canyon seine samples in
reaches 2 (N = 2) and 4 (N = 28); 20 reach 4 fish were taken in a single sample in a backwater
just upstream of the Yampa River. Roundtail chub were only slightly more abundant in the
Green River in Island and Rainbow parks seine samples (N = 39) and in the lower Yampa River
(N = 63). Adult Gila were captured in all reaches of Lodore Canyon. Only single specimens
were captured in reaches 1 and 2, while three and nine individuals were captured in reaches 3 and
4, respectively. Adult chubs were generally large; mean TL was 374 mm (255 - 451 mm TL).
With the exception of one individual, adult chubs had nine dorsal and anal fin rays and lacked the
distinct nuchal hump characteristic of humpback chub so were classified as roundtail chubs. The
exception was a 409 mm TL individual captured in lower Lodore Canyon. This individual had
nine dorsal and ten anal fin rays and a slight nuchal hump.
Razorback sucker.-The single razorback sucker (459 mm TL, 0.95 kg) captured during
this study was from lower Lodore Canyon. It had 14 dorsal fin rays, 85 lateral line scales, a
moderately raised nuchal hump, and scale pattern, coloration, and lip morphology typical of a
pure razorback sucker. The fish was in good condition and, based on its unmarred physical
appearance, it appeared relatively young. A single hybrid specimen 485 mm TL was also
captured in lower Lodore Canyon. It had 13 dorsal fin rays, 941ateral series scales, a very slight
nuchal hump, coloration typical of a razorback sucker, but lip morphology typical of a
flannelmouth sucker.
Non-native predators.-The thirteen northern pike captured during this study were
restricted to the lowermost 8 km of Lodore Canyon. Pike averaged 633 mm TL (305 - 800 mm
TL), and all were in good physical condition. Most were captured from deep eddies and pools;
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