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 Adultfish monitoring

Executive Summary
Adult fish collected in the lower Duchesne River were well represented by both native and
nonative fishes. The most abundant species was carp followed by flann1emouth sucker. Most
non1isted fishes in the Duchesne River were collected in the tributary throughout the year.
However, both razorback sucker or Colorado pikeminnow occupied the Duchesne River through
only a portion of the year. Razorback sucker tended to use the lower reaches of the tributary close
to the confluence of the Green River during the spring months coinciding with the pre- and
postspawning periods. Colorado pikeminnow were found in all reaches of the Duchesne River
between the confluence with the Green and the Myton Bridge. Pikeminnow occupied the
mainchanne1 of the Green River during the winter and entered the Duchesne River between
February and May. Pikeminnow appeared to leave the Duchesne River as peak spring flows
receded, presumeably to migrate to spawning sites in either the Yampa River spawning site or
Desolation-Gray Canyon spawning site. Several pikeminnow returned into the Duchesne Rive
during the summer and remained in the tributary until most fish left between September and
November. No telemetered pikeminnow were located in the Duchesne River during the winter.
Radio telemetry indicated Colorado pikeminnow actively move within the Duchesne River
both temporally (i.e., diel movements) and spatially (i.e. movement within the tributary), which is
likely assocated with foraging activity. Colorado pikeminnow likely use the Duchesne River in a
similar manner as floodplains in the spring in that they provide thermal, and velocity refuge from
the Green River during peak flood flows. Because some fish remained in the tributary between
the summer and fall during this study, a sufficient prey was available to support those pikeminnow
remaining in the Duchesne River.

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