Laserfiche WebLink
l0 • <br />Colorado; however, thzy aze increasingly raze. Osmundson and Kaedine (1991) repon that the <br />number of razorback sucker captures in the Grand Junction area has declined dramatically since <br />1974. <br />Razorback suckers are in imminent danger of extirpation in the wild. The specific causes of rhis <br />species' continued decline aze lazgely unknown at this time. As Bestgen (1990) pointed out: <br />"Reasons for decline of most native fishes in the Colorado River Basin have been <br />attributed to habitat loss due to construction of mainstream dams and subsequent <br />interruption or alteration of natural flow and physio-chemical regimes, inundation of <br />river reaches by reservoirs, channelization, water quality degradation, introduction of <br />nonnative fish species and resulting competitive interactions or predation, and other <br />man-induced disturbances (Miller 1961, Joseph et al. 1977, Behnke and Benson <br />1983, Carlson and Muth 1989, Tyus and Karp 1989). These factors aze almost <br />certainly not mutually exclusive, therefore it is often difficult to determine exact <br />cause and effect relationships." <br />The virtual absence of any recruitment suggests a combination of biological, physical, and/or <br />chemical factors that may be affecting the survival and recruitment of eazly life stages of <br />razorback suckers. Within the Upper Basin, recovery efforts endorsed by the Recovery <br />Implementation Program include the capture and removal of razorback suckers from all known <br />locations for genetic analyses and development of discrete brood stocks if necessary. These <br />measures have been undertaken to develop refugia populations of the razorback sucker from the <br />same genetic pazentage as their wild counterparts such that, if these fish are genetically unique by <br />subbasin or individual population, then sepazate stocks will be available for future augmentation. <br />Such augmentation may be a necessary step to prevent the extinction of razorback suckers in the <br />Upper Basin. <br />Critical Habitat <br />Critical habitat has been designated within the 100-year floodplain of the razorback sucker's <br />historical range in the following sections of the Upper Basin (59 F.R. 13374). <br />Colorado. Moffat County. The Yampa River and its 100-yeaz floodplain from the mouth <br />of Cross Mountain Canyon in T. 6 N., R. 98 W., section 23 (6th Principal Meridian) to the <br />confluence with the Green River in T. 7 N., R. 103 W., section 28 (6th Principal <br />Meridian). <br /> <br />