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

' squawfish were radio-tracked by Service personnel from 1980-88 (Tyus 1990) and
five were tracked by National Park Service and Colorado Division of Wildlife
workers in 1982 (Wick et al. 1983). Collections made on the two known
spawning grounds during 1981-88 produced 308 Colorado squawfish, of which
208 were ripe and an additional 67 fish showed secondary sex characteristics
associated with breeding condition (Tyus 1990). Four fish tagged in the White
' _ -River were recaptured at the Yampa and Gray canyons spawning areas, and the
recapture of five fish tagged and recaptured in the Yampa River spawning
grounds after 2 or more years indicate a fidelity to that area (Tyus 1985,
1 1990).
It is possible that the Yampa spawning aggregation is historical; Holden and
Stalnaker (1975b) reported increased numbers of ripe Colorado squawfish in the
' lower Yampa River in July 1968-70, and Seethaler (1978) reported ripe fish
there in 1974-75. Successful reproduction was substantiated when larval
Colorado squawfish (9 to 13 mm [.35-.51 in] TL) were taken below river
kilometer (RK) 32 (rivermile.[RM] 20) on the Yampa and downstream Green River
in 1980, 1981, and 1982, and below RK 40 (RM 25) in 1983; however, only one
has been collected upstream from these points (Haynes et al. 1984; Tyus et al.
' 1987).
-Gray Canyon of the Green River was suspected as a spawning site in 1981 when a
radio-implanted Colorado squawfish from the White River was tracked to that
- location (Radant et al. 1983; Tyus et al. 1982a). Spawning was confirmed
there in 1983 (Tyus 1985). Additional Colorado squawfish have been tracked to
Gray Canyon, and 111 ripe fish were collected there in 1981-88 (Tyus 1990).
' Radiotelemetry studies also show upstream and downstream movement of adult
Colorado squawfish in the upper mainstem Colorado River. One dramatic example
was provided by a fish radio-tagged in Gypsum Canyon of upper Lake Powell on
' April 5, 1982. On July 9, 1982, the fish was located in the lower Cataract
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Canyon area. The next contact was made above the Black Rocks area o
Colorado River some 258 km (161.25 miles) upstream. This movement was
accomplished in 41 days and was believed related to spawning. At the end of
September, the fish was located in the Colorado River near Clifton, Colorado,
approximately 320 km (200 miles) from its furthest documented downstream
location. However, not all radio-tagged fish in the mainstem Colorado River
have displayed such dramatic migratory behavior. Radiotelemetry studies
conducted by the Colorado River Fishery Project from 1982-85 (Archer et al.
1985; Miller et al. 1983) in the Grand Valley region of the Colorado River
found that movement during April to October was generally limited to 40-48 km
(25-30 miles).
Two reaches of the Colorado River containing suspected spawning areas are
' Black Rocks to Loma (RK 217-233 [RM 135-145]) and Grand Junction to Clifton
(RK 257-290 [RM 160-181]) (Archer et al. 1985). Location of larval squawfish
aggregations and the presence of suitable spawning habitat in the Colorado
River near Cataract Canyon 22-29 km (14-18 miles) below the confluence of the
Green River, in Professor Valley at above the confluence of the Green River at
RK 121-137 (RM 75-85), and upstream from the Dolores River confluence at
RK 160-185 (RM 100-115) indicate spawning is occurring in or near these areas
as well (Archer et al. 1985; Valdez 1990).
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