7713

• UCREFRP Catalog Number: 7713
• Author: U.S. Fish and Wildlife Service, C. R. F. R. T.
• Title: Colorado Squawfish Recovery Plan.
• USFW Year: 1991.
• USFW - Doc Type: \
• Copyright Material: NO

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In September 1962, the area of the Green River now impounded by Flaming Gorge
Dam was treated with rotenone in order to establish more favorable conditions
for game fish species. This poisoning effectively eliminated Colorado
squawfish in the reservoir basin, and an accident occurred in which a small
proportion of the toxic substance apparently travelled downstream past a
detoxification station to the vicinity of Dinosaur National Monument. Banks
(1964) noted a significant reduction in the number of species captured at four
' stations within Dinosaur National Monument shortly after the accidental
treatment. The greatest reduction appeared to occur at the Gates of Lodore in
the northern and most upstream portion of Dinosaur National Monument, while
the least impact was noted at a downstream site. However, Binns et al. (1963)
concluded that little long-term impact to the fish species composition had
resulted from the treatment.
' Colorado squawfish have disappeared from areas upstream of reservoirs (e.g.,
Salt River above Roosevelt Lake, Arizona; Green River above Fontenelle and
Flaming Gorge dams, Wyoming; San Juan River above Navajo Reservoir, New
1 Mexico) and in reaches that appear little changed from predevelopment
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conditions. Reasons for these disappearances or declines are not fu
understood, but probably involve subtle changes in habitat, competition and
predation from introduced species, blockage of spawning migrations, lack of
suitable spawning habitat, post-dam eradication programs, and/or loss of adult
fish from angling. In summary, the absolute cause for the decline of Colorado
squawfish is not fully understood but is probably related to a combination of
factors, including direct loss of habitat, changes in flow and temperature,
blockage of migration routes, and interactions with introduced fish species.
' Sensitive Areas and Priority Recovery Areas
Sensitive Areas
' The Biological Subcommittee of the Upper Colorado River Coordinating Committee
developed criteria and prepared a list of sensitive areas depicting the
location of important spawning, nursery, juvenile, and- adult habitats, both
' past and present, in the Upper Basin (U.S. Fish and Wildlife Service 1987)
(Figure 3). The Recovery Team has adopted this report and has recommended
that a similar document based on appropriate criteria be developed for the
' Lower Basin. Because Colorado squawfish have been extirpated from the Lower
Basin, criteria would be established primarily to identify priority areas for
research and recovery.
' Priority Areas for Recovery
The highest priority Colorado squawfish recovery areas occur in the Upper
' Basin, and include, in order of importance, the Green, Colorado, and San Juan
subbasins. The Green River subbasin includes the mainstem Green, Yampa,
Little Snake, White, and Duchesne Rivers. The Colorado River subbasin
includes the Gunnison and the Dolores Rivers, and the San Juan subbasin
includes the Animas River. The Green River subbasin contains the largest and
most viable population of squawfish in the Colorado River basin (Tyus 1991b).
As such, the Green River and its tributaries constitute the highest priority
site for recovery and maintenance of Colorado squawfish.
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