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<br />
<br />Based on early fish collection records, archaeological finds, and other observations, the Colorado
<br />pikeminnow was once found throughout warmwater reaches of the entire Colorado River Basin
<br />down to the Gulf of California, and including reaches of the upper Colorado River and its major
<br />tributaries, the Green River and its major tributaries, and the Gila River system in Arizona
<br />(Seethaler 1978), Colorado pikeminnow apparently were never found in colder, headwater areas.
<br />Seethaler (1978) indicates that the species was abundant in suitable habitat throughout the entire
<br />Colorado River Basin prior to the 1850's, No historic records exist that would indicate how far
<br />upstream Colorado pikeminnow once occurred in the Colorado River. The only reliable account
<br />of the species occurring upstream of the Price Stubb Dam near Palisade, Colorado, is from a
<br />Service biologist who reports having captured Colorado pikeminnow 2-3 miles up Plateau Creek
<br />while angling there around 1960 (Bob Burdick pers. com,),
<br />
<br />Critical habitat was designated in 1994 within the 100-year floodplain of the Colorado
<br />pikeminnow's historical range in the following area of the upper Colorado River (59 F,R, 13374),
<br />
<br />Colorado. Mesa and Garfield Counties: and Utah, Grand. San Juan, Wavne. and Garfield
<br />Counties, The Colorado River and its 100-year floodplain from the Colorado River Bridge at exit
<br />90 north offInterstate 70 in T. 6 S., R, 93 W., section 16 (6th Principal Meridian) to North Wash,
<br />including the Dirty Devil arm of Lake Powell up to the full pool elevation, in T. 33 S" R, 14 E.,
<br />section 29 (Salt Lake Meridian),
<br />
<br />The Service has identified water, physical habitat, and the biological environment as the primary
<br />constituent elements of critical habitat. This includes a quantity of water of sufficient quality that
<br />is delivered to a specific location in accordance with a hydrologic regime that is required for the
<br />particular life stage for each species. The physical habitat includes areas of the Colorado River
<br />system that are inhabited or potentially habitable for use in spawning and feeding, as a nursery, or
<br />serve as corridors between these areas. In addition, oxbows, backwaters, and other areas in the
<br />100-year floodplain, when inundated, provide access to spawning, nursery, feeding, and rearing
<br />habitats, Food supply, predation, and competition are important elements of the biological
<br />environment.
<br />
<br />Status and Distribution
<br />
<br />Colorado pikeminnow were historically distributed throughout warmwater reaches of the
<br />Colorado River Basin from Wyoming and Colorado south to the Gulf of California, By the
<br />1970's they were extirpated from the entire lower basin (downstream of Glen Canyon Dam) and
<br />from portions of the upper basin as a result of major alterations to the riverine environment.
<br />Having lost some 75-80 percent of its former range, the Colorado pikeminnow was federally
<br />listed as an endangered species in 1967 (Miller 1961, Moyle 1976, Tyus 1991, Osmundson and
<br />Burnham 1998).
<br />
<br />Colorado pikeminnow are presently restricted to the Upper Colorado River Basin and inhabit
<br />warmwater reaches of the Colorado, Green, and San Juan Rivers and associated tributaries, The
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