8123

• UCREFRP Catalog Number: 8123
• Author: Wydoski, R. S.
• Title: Coordinated Hatchery Facility Plan
• USFW Year: 1994.
• USFW - Doc Type: Need for Captive-Reared Endangered Fish and Propagation Facilities.
• Copyright Material: NO

humpback chub stocks are considered to be relatively stable since the
catch-per-unit-of-effort in monitoring these stocks has remained
rather constant. However, a railroad track near the Black Rocks
Canyon on the Colorado River poses a potential for a catastrophic
event such as a chemical spill. In addition, the close proximity of
Westwater Canyon to Black Rocks also places it in potential jeopardy
from a catastrophic event. These stocks were categorized as "Priority
1" within the species (Table 3). However, there is some interchange
between the two stocks. Thirty adults will be collected from Black
Rocks Canyon in 1995 and maintained in refuge ponds on the Horsethief.
State Wildlife Area CO as a precaution against potential loss of this
wild stock.
Phenotypes of the humpback chub in the Yampa River and Desolation-Gray
Canyons in the Green River vary considerably that indicates possible
hybridization with roundtail chubs at these two locations.
Collection of additional adults will be postponed until results of the
Gila systematic and genetic studies are available in an interim report
in 1995 and a final report scheduled for 1997. The remaining humpback
chub stocks were prioritized as: Yampa River - 2; Cataract Canyon -
3; and Desolation/Gray Rocks Canyons - 4 (Table 3).
4. Colorado souawfish. Colorado squawfish stocks in most reaches of the
Upper Colorado River Basin were considered to be stable because
spawning and recruitment has been documented. Therefore, this species
was assigned "Priority 4".
The Colorado squawfish in the upper Colorado River, upstream from
Westwater Canyon, was ranked as stock priority "1" (Table 3) because
fewer fish are found in this river reach when compared to other large
river reaches in the upper basin and this reach has a high potential
for recovery.
Th
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C
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o squawfish stock in the Gunnison River is extremely small
and is declining (Table 2). Several Colorado squawfish were collected
in the Gunnison River in the fall of 1982. However, this river was not
sampled again until the summer of 1992 when no squawfish were
collected. During 1993, 5 wild adults were captured in the Gunnison
River upstream from the Redlands Irrigation Diversion Dam and 5
additional wild adults were captured below the diversion (Pfeifer,
1993, Personal Communication). The 5 wild fish that were captured
below the Diversion were radio-tagged and released above the
Diversion. Two of the fish captured above the diversion were also
radio-tagged. These fish were tracked after release and will
continued to be tracked to determine movements and habitat use. The
Gunnison River stock may have depended upon recruitment from the upper
Colorado River but upstream movement of endangered fish is prevented
by the Redlands Irrigation Diversion Dam. Future construction of a
fishway at the Redlands Diversion is planned to provide access for
endangered fish into the Gunnison with the intent of recolonization
through natural migration (Burdick and Kaeding 1990). Initially, the i
Gunnison will be monitored to determine if wild fish use the newly
constructed passage facilities. If wild fish do not use the fishway,
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