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Range DescriptionHistorical range included rivers of the Colorado River basin: mainstem Colorado River and major tributaries (Gunnison, White, Yampa, Dolores, San Juan, Uncompahgre, Animas, and Green rivers), from Mexico and Arizona to Wyoming.
Present distribution is drastically reduced. By the mid-1980s, this species occurred only in the Upper Colorado River basin of Colorado, Utah, New Mexico, and Wyoming; mainly in the Green River in Utah and in the Yampa and Colorado rivers in Colorado and portions of Utah; wild fish have not been seen below Glen Canyon Dam since 1968. Adults predominate in the White and Yampa rivers, young in the Green River (Tyus 1986); juveniles reported as rare in the Green River system (see Karp and Tyus 1990).
Spawning occurs in the Green River sub-basin in the lower Yampa River and in Gray Canyon (a segment of the Green River above its confluence with the Price River); nursery areas include the Green River between the Colorado River and the San Rafael River, and a segment of the Green River upstream and downstream from the confluences of the Duchesne and White rivers (Tyus 1991). Spawning also may occur in Labyrinth and Stillwater canyons of the lower Green River, but if so, populations apparently are small (Tyus 1991). River mile 130 on the Colorado River, near the Colorado-Utah state line, has been identified as a spawning site used in multiple years (see Federal Register, 21 March 1994). The presence of small larvae in the upper main-stem Colorado and San Juan rivers indicates successful reproduction, but low numbers suggest limited reproduction or recruitment (Tyus 1991). Colorado Pikeminnows were recently recorded in the Little Snake River, Colorado (Wick et al. 1991) and Wyoming (Marsh et al. 1991). The species was reconfirmed as occurring in the San Juan River from 4.4 km downstream from Shiprock, New Mexico, to Lake Powell, Utah (young of year were found near Lake Powell and near the confluence of the San Juan River and Montezuma Creek and near the confluence of the San Juan River and the Mancos River) (Platania et al. 1991). See also Sublette et al. (1990) for relatively recent records from New Mexico and southeastern Utah.
Beginning in the mid-1980s, an experimental population was being established in the Salt and Verde rivers, Arizona (USFWS 1990, Minckley and Deacon 1991).