9561

• UCREFRP Catalog Number: 9561
• Author: Modde, T. and G. B. Haines.
• Title: Adult Fish Use in the Duchesne River Below Myton, 1997-2000.
• USFW Year: 2003.
• USFW - Doc Type: 84-3,
• Copyright Material: NO

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Duchesne River Adult fish monitoring

Conversely, cold water fishes, such as mountain whitefish and brown trout, were less abundant in
summer collections. Colorado pikeminnow were captured during base flow collections in both
1998 and 1999, and between both years pikeminnow were found in each of the three reaches.
The lengths of Colorado pikeminnow captured in the Duchesne River ranged between 345
and 725 nun, however, a large percentage of the pikeminnow captured were subadu1ts or young
adults with 42% of the fish collected less that 500 nun (Appendix Figure 1a). Lengths of
pikeminnow captured between 1997 and 1999 did not show any pattern, although most fish
captured in 1999 were subadu1ts or young adults. Consistency was observed in the length
distribution of blue head sucker (Appendix Figure 1b), but a shift in the length offlanne1mouth
sucker was observed during the three years of data with larger fish (>450 nun) becoming more
abundant in 1998 and 1999 (Appendix Figure 1c). Length frequencies of mountain whitefish
(Appendix Figure 1d) and the most abundant nonnative fishes did not show patterns of change
among the three years of the study (Appendix Figures 2a-d).

Telemetry
Seasonal movement patterns
One razorback sucker and 27 Colorado pikeminnow were implanted with radio
transmitters in the Duchesne River during the spring months between 1997 and 1999 (Table 4).
Transmitters were implanted in five Colorado pikeminnow and one razorback sucker in 1997, six
Colorado pikeminnow in 1998, and 16 Colorado pikeminnow in 1999. The single razorback
sucker was captured near the confluence (rmi 0.1), and Colorado pikeminnow implanted were
captured as far downstream as the confluence (rmi 0.1) and upstream to near the Myton Bridge
(rmi 33.3). However, the majority of Colorado pikeminnow implanted with transmitters were
captured in the lower reach ( 22 or 81.5%).
Information from both data loggers and aerial contacts showed that telemetered fish did
not remain in the Duchesne River throughout the year, but moved into the Green River at various
dates before December (Figure 4). Data from telemetry loggers indicated only two transmitter
implanted fish, 40.323 and 40.374, moved into the Uintah River at any time during the study.
Fish 40.323 was in the lower Uintah River between 11 and 26 September 1998, and 40.3 74 spent
only one day (14 June 1998) in the vicinity in the lower Uintah River. Thus, te1emetered
Colorado pikeminnow did not readily use the Uintah River during the three years ofthe study.

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