9549

• UCREFRP Catalog Number: 9549
• Author: Bestgen, K. R., K. A. Zelasko, R. I. Compton and T. Chart.
• Title: Response of the Green River Fish Community to Changes in Flow Temperature Regimes from Flaming Gorge Dam since 1996 based on sampling conducted from 2002 to 2004.
• USFW Year: 2006.
• USFW - Doc Type: 115,
• Copyright Material: NO

Chubs were more common in Lodore Canyon in 1994 to 1996 than in 2002 to 2004.
Fourteen adult roundtail chubs were captured in the earlier period, with at least one from each
Lodore Canyon reach. Roundtail chubs were in Lodore Canyon seine samples in 1994 to 1996
in reaches 2 (N = 2) and 4 (N = 28); 20 of the LD4 reach fish were taken in a single sample in a
backwater just upstream of the Yampa River. Roundtail chub was only slightly more abundant
in the Green River in Island-Rainbow Park seine samples (n = 39). Adult chubs captured in
1994 to 1996 in Lodore Canyon were generally large; mean TL was 374 mm (255 - 451 mm
TL).
Limited trammel net sampling in Lodore Canyon did not detect roundtail chub.
Trammel net sampling in Whirlpool Canyon captured 290 adult roundtail chub. Dorsal/anal fin
ray counts of large juvenile and adult roundtail chub from all reaches and captured by all gears
were as follows: 7/9 (N = 2), 8/8 (N = 1), 8/9 (N = 8), 8/10 (N = 5), 9/6 (N = 1, damaged anal
fin), 9/8 (N = 12), 9/9 = (N = 232), 9/10 (N = 27).
Adult roundtail chub captured in electrofishing and trammel net samples ranged in size
from 220 to 439-mm TL, modal size class was 251 to 275-mm TL. Chubs smaller than 200-mm
TL were either rare or not susceptible to electrofishing and trammel nets. Most adult roundtail
chub captured in 2002 to 2004 from Lodore Canyon were large; mean TL was 367 mm (range
236 to 439).
In September and October 2003 sampling of Whirlpool Canyon, the three sampling
passes yielded 84, 88, and 96 roundtail chubs of which 12 were recaptures. Using model M. in
program MARK, abundance of roundtail chubs was estimated at 1956 (SE = 529, 1214 to 3546,
95% profile likelihood interval, CV= 27%, probability of capture = 0.046). Of the 12 recaptures
made during the sampling passes, eight chubs remained in place, two moved upstream about 1.5
RK from just downstream of Rain Camp (RK 357.1), and two fish moved from upstream of Rain
Camp downstream to State Line, a distance of about 5.3 RK. One roundtail chub, first captured
and tagged at Stateline in October 2003, moved 2.5 km downstream to Compromise Camp and
was recaptured in September 2004.
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