7984 - Laserfiche WebLink

Home Browse Search

Nursery Habitat Young-of-year (up to 2.5 inches TL), juveniles (2.5-8 inches), and subadults (8-16 inches) have been captured in shallow backwater areas over silt and sand bottoms (Holden 1973; Holden and Stalnaker 1975a, 1975b; Wick et al. 1979, 1981; Holden and Twedt 1980; Miller et al. 1982a, 1982b; Valdez et al. 1982b; Valdez and Wick 1983; Haines and Tyus 1990; Tyus and Haines 1991). Most of these backwaters were ephemeral along shore embayments with little or no water currents (Tyus and Haines 1991). A significant rearing area for Colorado squawfish occurs in the Green River (Tyus et al. 1987; Tyus and Haines 1991). Two main reaches have been documented, one from Split Mountain to Sand Wash, the other from Green River, Utah to the confluence with the Colorado River. Young-of-year Colorado squawfish have also been found in the Colorado River between Moab, Utah, and the confluence with the Green River (Valdez et al. 1982; Archer et al. 1985). Other significant nursery areas in the Colorado River have been identified: (1) in the upper Professor Valley; (2) between the confluence with the Dolores River and Westwater Canyon; (3) between Black Rocks and Loma; and (4) downstream from the confluence with the Gunnison River (Valdez et al. 1982; Archer et al. 1985; Osmundson and Kaeding 1989). No larval Colorado squawfish have been captured in the White River (Miller et al. 1982a). Some adults that were tagged in the White River have been recaptured or radio-tracked to the Yampa and Gray Canyon spawning sites (Tyus 1990). Osmundson and Kaeding (1989) reported the capture of a single larval Colorado squawfish in the lower two miles of the Gunnison River. The 18 young-of-year Colorado squawfish captured in the San Juan River in 1987 were collected from backwaters. Two were taken downstream of Shiprock, New Mexico; six near Bluff, Utah; and ten were taken in the lowermost 38 miles immediately upstream from Lake Powell. An additional young-of-year also was taken from this area in 1988, collected from a backwater (Platania 1990). In 1990, a young-of-year Colorado squawfish was collected from a backwater near Bluff, Utah (Bill Bates, UDWR, pers. comm.). In 1992, a young-of-year Colorado squawfish was collected below the natural waterfall on the San Juan River (Iashmett 1993). Larval drift is an important part of the Colorado squawfish life cycle (Tyus and Haines 1991), and laboratory studies indicate that "drift" may be active rather than a passive response to water current (Paulin et al. 1990). Larval squawfish drift downstream after hatching in the Green and Yampa rivers and rear in reaches that are removed from spawning areas (Haynes et al. 1984; Tyus and Haines 1991). In the Green River basin, larval Colorado squawfish emerge from spawning substrates and enter the stream drift as young fry (Haynes et al. 1984). The fish are then actively or passively transported downstream for about six days, and they may travel average distances of up to 100 miles to reach nursery areas (Tyus and Haines 1991). These areas are biologically productive habitats that consist of ephemeral alongshore embayments that 22