| Status
of Razorback Suckers in Senator Wash Reservoir |
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 Background:
The razorback sucker, Xyrauchen texanus, is an endangered southwestern
fish that has suffered severe population declines due to habitat alteration
and destruction, decline in water quality, and direct competition and
predation by non-native fishes. Consequently, the razorback sucker
is currently listed
as Endangered by the U. S. Fish and Wildlife Service (since 1991;
56 FR 54957) and population numbers are presently located above Lake
Powell in the upper Colorado River basin and in Lakes Mead, Mohave,
and Havasu in the lower Colorado River basin (see
distribution map). Historically, razorback suckers were found throughout
the Gila River basin in Arizona and the Colorado River basin in Wyoming,
Colorado, Utah, Nevada, Arizona, and New Mexico.
Razorback recovery efforts have been in effect for over 20 years, but information
regarding life history and biological requirements and preferences is limited.
While there is some evidence of reproduction of razorback suckers in the
wild, recruitment of razorback suckers has not been documented.
Location:
Senator Wash Reservoir is located near Yuma,
Arizona, on the California side of the Colorado
River two miles upstream from Imperial Dam.
Senator Wash Reservoir was completed in 1966
and currently has a surface area of approximately
470 acres. Senator Wash is home to the endangered
razorback sucker as well as a variety of non-native
fishes including flathead catfish, channel
catfish, largemouth and stripped bass, carp,
and various sunfish species. Adult razorback
suckers were first documented in Senator Wash
in the 1980s and larval razorback suckers have
been collected in the reservoir since the 1980s.
However, there has been no documentation of
recruitment of razorback suckers in Senator
Wash.
Approach:
 This
study is designed to verify the presence of
adult razorback suckers in Senator Wash, identify
distinct size classes (indicating recruitment),
document spawning through larval fish sampling,
and determine what aspects of the Senator Wash
system facilitate razorback spawning and/or
recruitment. This study began in October of
2002 and will be completed in September of
2005. This recovery project is part of a Cooperative
Agreement between United
States Bureau of Reclamation and Arizona
Game & Fish Department.
Benefits:
Since most remnant razorback populations are concentrated in reservoirs,
information from this type of study is directly applicable to larger reservoir
systems (i.e., Lakes Mead, Mohave, and Havasu). Additionally, information
gained could be directly applicable to off-channel backwater areas of main-stem
rivers, which have been shown to be preferred habitat for razorback suckers.
For more information
contact:
Laura L. Leslie, Arizona Game and Fish Department, 2221 West Greenway Road,
AZ 85023.
Phone (623) 236-7368 E-mail: lleslie@gf.state.az.us |
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