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<br />1 <br /> <br />t <br /> <br />1 <br /> <br /> <br />1 <br /> <br /> <br />1 <br /> <br /> <br /> <br />1 <br /> <br /> <br />Status <br />Based on available information, roundtaii chubs now occupy approximately 45% of their <br />historical range in the CRB. They are extirpated from much of the LCRB (~70% of <br />historical LCRB habitat; similar decline is portrayed by Voeltz 2002), including the San <br />Francisco River, Arizona and New Mexico; the San Pedro River, Arizona; and, the <br />Colorado River and tributaries in Grand Canyon and downstream. In the UCRB, they <br />have been extirpated from ,approximately 45% of historical habitat, including the Price <br />River and portions of the San Juan, Gunnison, and Green rivers. In addition to <br />extirpation, decline has been observed in remaining populations of the Gila, Salt, San <br />Juan, Gunnison, White, Yampa, and Green rivers (Hinckley 1973, Platania 1990, <br />Wheeler 1997, Lentsch et al. 1998, Propst 1999, Bestgen and Crist 2000, Anderson pers. <br />comm.). <br />Stratification of runt collection Locations using existing migration barriers and suitable <br />habitat produced 15 preliminary populations of roundtail chubs in the CRB (Table 6 and <br />Figure 8). Unfortunately, abundance and population trend estimates are largely <br />unavailable. For two short reaches (each < 10 km long) of the Colorado River near <br />Grand Junction, Anderson (1997) estimated the number of raundtail chubs over 150 mm <br />at approximately 2,500 fish in 1994 and 1995. Bryan and Robinson (2000) estimated <br />roundtail chubs in the lower Verde River below Bartlett Dam to number over 6,000 <br />individuals. <br />Final Report September 2002 <br />31 <br /> <br />