7332

• UCREFRP Catalog Number: 7332
• Author: Valdez, R. A., et al.
• Title: Final Report Habitat Suitability Index Curves for Endangered Fishes of the Upper Colorado River Basin.
• USFW Year: 1987.
• USFW - Doc Type: \
• Copyright Material: NO

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this report. As an example, the data summary table for Colorado squawfish,
size 1, is provided as Table A-3 in Appendix A.

From these summary tables, it was determined that data were available for
adult razorback suckers from the Colorado and Green rivers, but little or no
information was revealed for other life stages of this species. Data available
for humpback chub was primarily for juveniles and adults from Black Rocks and
Westwater Canyon of the Colorado River, and from Yampa Canyon and Gray Canyon
of the Green River System. Some data were available for YOY humpback chub
collected in the early 1970's from Desolation Canyon of the Green River. No
data were available describing the spawning habitat of either the razorback
sucker or humpback chub. The summary tables revealed that the majority of the
data available were for YOY and adult Colorado squawfish. However, a
substantial amount of data was revealed for larvae and juveniles. The only
spawning data for this species were from the Yampa and Green rivers. The
summary tables consistently revealed that essentially all available data for
these three species were collected from April through October. The need to
describe winter habitat use by these fish is being addressed by a BOR-funded
program to develop HSI curves for razorback sucker and Colorado squawfish
during the winters of 1986-87 and 1987-88,

HSI CURVES FROM PREVIOUS STUDIES

Methods

Another aspect of Task A was to research the Ii terature and identify
previous studies where HSI-type curves had been developed for these rare fish.
Six studies were identified in which curves were developed for Colorado
squawfish, humpback chub, or razorback sucker. These studies are briefly
discussed in this report, and the associated curves are presented. A narrative
comparing these curves with those developed from this project is presented in
the discussion section of this report. The FWS curves developed in 1984 are
excluded from this analysis, since their validity is the focus of this study.

Results

The curves that were identified from previous studies, and a description
of the study, are presented in Appendix B.

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