Laserfiche WebLink
23 <br />"Reasons for decline of most native fishes in the Colorado River Basin <br />have been attributed to habitat loss due to construction of mainstream <br />dams and subsequent interruption or alteration of natural flow and <br />physio-chemical regimes, inundation of river reaches by reservoirs, <br />channelization, water quality degradation, introduction of nonnative <br />fish species and resulting competitive interactions or predation,•and <br />other man-induced disturbances (Miller 1961, Joseph et al. 1977, <br />Behnke and Benson 1983, Carlson and Muth 1989, Tyus and Karp 1989). <br />These factors are almost certainly not mutually exclusive, therefore <br />it is often difficult to determine exact cause and effect <br />relationships." <br />The virtual absence of any widespread recruitment in the wild suggests a <br />combination of biological, physical, and/or chemical factors that may be <br />affecting the survival and growth of early life stages of razorback suckers. <br />Within the Upper Basin, recovery efforts endorsed by the Recovery <br />implementation Program include the capture and removal of razorback suckers <br />from all known locations for genetic analyses and development of discrete <br />brood stocks, if necessary. These measures have been undertaken to develop <br />refugia populations of the razorback sucker from the same genetic parentage as <br />their wild counterparts such that, if these fish are genetically unique by <br />sub-basin or individual population, then separate stocks will be available for <br />future augmentation. Such augmentation appears to be a necessary step to <br />prevent the extinction of razorback suckers in riverine habitats throughout <br />the Upper Basin. <br />Critical habitat has been designated within the 100-year floodplain of the <br />razorback sucker's historical range in the following sections of the Upper <br />Basin (59 F.R. 13374). <br />Colorado. Moffat County. The Yampa River and its 100-year floodplain from <br />the mouth of Cross Mountain Canyon in T. 6 N., R. 98 W., section 23 (6th <br />Principal Meridian) to the confluence with the Green River in T. 7 N., R. <br />103 W., section 28 (6th Principal Meridian). <br />Utah Uintah County and Colorado. Moffat County. The Green River and its <br />100-year floodplain from the confluence with the Yampa River in T. 7 N., <br />R. 103 W., section 28 (6th Principal Meridian) to Sand Wash in T. 11 S.. <br />R. 18 E., section 20 (6th Principal Meridian). <br />