8135

• UCREFRP Catalog Number: 8135
• Author: Valdez, R. A.
• Title: Occurrence of Threatened and Endangered Fishes of the Colorado River in the Vicinity of the Proposed Jacobson Hydro No. 1 Project.
• USFW Year: 1984.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

4-2

of endangered species issued by the Office of Endangered Species in 1964,
and was offered protection by the Endangered Species Act of 1973, as
amended. It is now listed as I endangered' .
The nearest capture of Colorado squawfish to the project site was four
adult fish caught in September of 1979 at river mile 185.1 (Valdez et al.
1982), about 3.1 miles downstream of the site. The nearest capture of a
juvenile was a fish caught in August of 1979 at river mile 138.8, about 49.4
miles downstream of the site. Young-of-the-year (age group 0) squawfish
were captured in September and October of 1983 at about river mile 170
(Archer et al. 1984), about 18.2 miles downstream of the site. There is an
unconfirmed report of adult Colorado squawfish at the mouth of Plateau Creek
(Kidd 1977) at river mile 193.3, about 5.1 miles upstream of the project
site. The field investigation conducted under this project failed to reveal
any Colorado squawfish in the project area, and so the current known
distribution of the species relative to this project remains as stated
above.

4.3 Humpback Chub.
The humpback chub is the most recently described major fish species of
the Colorado River System (Miller 1946). Its similar appearance to the
bony tail and roundtail chub has resulted in much confusion as to its
original distribution. Once thought distributed throughout the Colorado
River System, the species is now confined to a few locales in the upper
basin and one in the lower basin (Valdez 1980; Valdez and Clemmer 1982).
The humpback chub was included in the original list of endangered species
issued by the Office of Endangered Species in 1964 and is offered
protection under the Endangered Species Act of 1973, as amended. It is now
listed as 'endangered'.