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

with some pools and long runs through the Marble and Grand canyons. The
dam controls the quality and quantity of water in the reach, and habitat
conditions can change drastically due to reservoir operation. In contrast, Lake
Mead provides deep water, shallow bays, and cove habitats. These low velocity
areas have suitable temperatures for all life stages and physical habitat for
adults. However, the reach, and especially Lake Mead, also contains many
nonnative predators. The USFWS is presently consulting with the Bureau of
Reclamation to potentially change management of Glen Canyon to improve
downstream conditions for razorback sucker.
RZ11: Colorado River from Hoover Dam to Davis Dam.
The largest known population of razorback suckers (about 25,000) occurs in
Lake Mojave. Flows into Lake Mojave are controlled by the releases from
Hoover Dam. This population of razorback suckers provides almost all hatchery
stocks and has been the focus of extensive research on population genetics,
parasites, disease, and many other aspects of razorback life history. A
reintroduction program is presently underway.
RZ12: Colorado River from Parker Dam to Imperial Dam.
Extensive construction-for water development projects and other physical habitat
alteration has occurred along this reach. Several diversion dams impose partial
and seasonal barriers to fish migration. Water quality has been altered by
increased salinity due to water re-usage and lower temperatures from
hypolimnetic release. However, water temperatures below Parker Dam are
higher than tailrace temperatures below Glen Canyon or Hoover Dam. Portions
of the channel have been stabilized or channelized, but suitable habitat (i.e.,
unmodified channel, backwaters, and gravel bars) is still available for all life
stages of the razorback sucker and the presence of 11- to 12-inch juveniles in
canals and drainage ditches provides evidence of successful spawning within
this reach. Recruitment to the population is probably suppressed due to
predation by nonnative fishes.
RZ13: Gila River from Arizona/New Mexico state line to Coolidge Dam.
Razorback suckers were extirpated from this reach by the 1950s. Water quantity
and quality appears acceptable for razorback suckers from Safford, Arizona, to
the confluence with the San Francisco River. However, hatchery-reared
juveniles have been stocked into the Gila River and tributaries since 1981, but
apparently with little success. Water depletion in this reach is extreme, and
reservoirs may nearly dry up during periods of drought but pools in the main
channel and tributaries can provide some habitat during low flow periods.
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