8022

• UCREFRP Catalog Number: 8022
• Author: Muth, R. T., et al.
• Title: Reproduction and Early Life History of Razorback Sucker in the Green River, Utah and Colorado, 1992-1996.
• USFW Year: 1998.
• USFW - Doc Type: 34,
• Copyright Material: NO

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efficacy of light-trap CPUE data for approximating the density of larvae in nursery
habitats, which would advance the understanding of the causes and biological meaning of
capture variability. These studies may include experiments in artificial (e.g., pools or
ponds) or natural nursery habitats stocked with known numbers of larvae, or estimates of
larval abundance in the wild using capture-recapture methods,
3. Additionally, there is a need to establish relationships among river discharge, spatial
extent of flooded habitats for nursery areas, and dispersal patterns of razorback sucker
larvae. Present sampling should be expanded to include other river reaches (e.g., Echo
and Island-Rainbow parks) and habitats, These efforts would benefit the evaluation of
light-trap CPUE and provide information for improving the monitoring program.
4. Efforts to document razorback sucker reproduction in the lower Green River should be
expanded and possibly include radio-tracking of adults in spring to locate spawning areas
and assess movements and habitat use.
5, Understanding the relationships between biological processes and water temperatures as a
function of discharge is important in management of regulated flows to benefit recovery
of the endangered fishes. However, much of the temperature data presently recorded by
the U.S. Geological Surveyor U.S, Fish and Wildlife Service (Channel Monitoring) in
rivers of the upper basin are inadequate for accurate analyses of such relationships. A list
of priorities for acquisition of temperature data should be developed by researchers and
used as the basis of a monitoring program employing continuous-recording thermo graphs
linked to real-time data stations.

REFERENCES

BEHNKE, R. J., AND D. E. BENSON. 1983. Endangered and threatened fishes of the upper
Colorado River basin. Colorado State University Extension Service Bulletin 503A.
BELL, A, D. BERK, AND P. WRIGHT. 1998. Green River flooded bottomlands mapping for two
water flows in May 1996 and one water flow in June 1997. Technical Memorandum No,
8260-98-07. U.S. Bureau of Reclamation, Technical Service Center, Denver, Colorado.
BESTGEN, K. R. 1990. Status review of the razorback sucker, Xyrauchen texanus. Final Report
of Colorado State University Larval Fish Laboratory to U. S. Bureau of Reclamation, Salt
Lake City, Utah.

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