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al. 1982) failed to detect any Colorado pikeminnow in these upstream reaches. More recently, electrofishing surveys in the 1990's by CDOW (Anderson 1997) and USFWS (Wydoski 1994, Osmundson 1999, R. Burdick, unpublished data) also found none. One anecdotal observation from the 1960s appears to have merit; another probably does not. Robert Burdick, a USFWS biologist who has captured many Colorado pikeminnow during his professional career remembers his grandfather and he catching several Colorado pikeminnow in the lower end of Plateau Creek while angling for trout in the mid-1960s. The only other known observation is less reliable. Pressey (1968), a writer for a popular outdoors magazine, provided an account of an angling trip upstream of Glenwood Springs in 1963 during which he caught a fish he could not immediately identify; he later concluded the fish must have been a Colorado pikeminnow: "I was shocked to see a nearly black fish of about 15 inches" (380 mm) "that possessed cross-hatched scales of small size." "...The mouth of the fish was more toward the bottom of the head like a sucker, but still possessed the mandible-like action of a trout or bass." The far upstream location of this observation (well within cold-water, salmonid habitat) and the author's description suggests a misidentification; however, as with other anecdotal information, readers are encouraged to judge for themselves the validity of such accounts. Analysis of temperature regime suitability for Colorado pikeminnow indicates that individuals of this species are likely to establish year-round home ranges in the Colorado River as far upstream as De Beque, Colorado, if given the opportunity. Also, limited use by Colorado pikeminnow in reaches upstream of De Beque is anticipated (Osmundson 1999) based on observations of Colorado pikeminnow distribution in the Yampa (Kesler 1995) and Gunnison (Burdick 1995) rivers. Critical habitat for Colorado pikeminnow in the Colorado River extends upstream to Rifle, Colorado (USFWS 1994). General Approach Because no individuals of either species have been recently found in riverine habitats upstream of the Price-Stubb Dam, no habitat use data are available that might provide