8204

• UCREFRP Catalog Number: 8204
• Author: Tyus, H. M.
• Title: Razorback Sucker ‎(Xyrauchen texanus)‎ Recovery Plan.
• USFW Year: 1998.
• USFW - Doc Type: Boulder, Colorado.
• Copyright Material: NO

may cause mortality of razorback sucker larvae (Bruce Waddell, USFWS, pers.
comm. 1993). Although predaceous game fish occur in this reach the States of
Colorado and Utah have removed bag and possession limits to encourage their
removal.
RZ3: Green River section from Sand Wash to the Colorado River.
The lower portion of the Green River, which now contains a small population of
razorback suckers, may provide important nursery habitat when water levels are
high enough to flood bottomland. However, flow regulation by upstream
reservoirs has prevented inundation of nursery habitat and may restrict
movements of razorback sucker from main river channels to flooded areas. This
reach may facilitate genetic exchange between razorback sucker populations in
the Colorado River and the Green River. This reach is under close evaluation as
a recovery area due to the presence of newly hatched razorback sucker larvae.
RZ4: Lower 18 miles of the White River.
This reach contains seasonally flooded habitat and may be used by razorback
suckers from the adjoining Green River. Historic flow patterns of White River
below Rangely, Colorado, were altered by construction of the Taylor Draw Dam,
which poses a complete barrier to fish migration. Water quantity is acceptable
for razorback suckers, but the potential for degradation of water quality by
various industries along the river should be investigated. Although predaceous
game fish occur in this reach the State of Utah has removed bag and
possession limits to encourage their removal.
RZ5: Lower 2.5 miles of the Duchesne River.
This reach is presently used by razorback suckers and is presumably an
important staging area for fish spawning in the mainstream Green River (Tyus
and Karp 1990). Water diversions, which have eliminated habitat upstream,
continue to threaten the remaining habitat in this reach. Several proposed
diversion projects would further threaten flows.
RZ6: Gunnison River from Redlands Diversion to Uncompahgre River.
Upstream reservoirs (Taylor Park Dam and the Aspinall Unit) have changed the
timing of runoff flows, but water use is mainly nonconsumptive and most of the
water still flows down the Gunnison River. The Fish and Wildlife Service and the
Bureau of Reclamation have been working to manage reservoir releases to
mimic the shape of the natural hydrograph. A formal agreement is expected in
1998 with completion of a Biological Opinion. Adequate flows are maintained in
most of the reach because the Redlands Diversion Dam has a senior water right.
However, the 2.3 miles of river below the dam have been completely dewatered
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