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<br />Salt Ri,,;r L-S 60/SR 77 Bridgl: to Roosl:vl:lt Lakl: <br /> . <br />\- -:rJ.: Rh.:r Prl:SCOll :-.lational Forl:st Boundary to Horsl:shoe Lake <br />L"ll!l)rado River Park<:r Dam to I mp<:rial Dam <br />Humpback Chub <br />Grund Canyon Gkn Canyon Dam to Lake M<:ad <br />Bony tail <br />I.l)\\ cr Colorado Ri\<:r Park<:r Dam to lmpl:rial Dam <br /> <br />Task 4c: Habitat Carrying Capacity <br /> <br />Best estimates of habitat carrying capacity will be made by examining past and existing records of <br />population densities and population structure for given reaches of river. Channel geomorphology, <br />existing habitat evaluations, river hydrology, river temperature, and existing fish population densities <br />wi II be considered. Although historic, pre-development population levels may not be <br />determinable-or achievable-densities for existing conditions can be estimated from recent and <br />ongoing studies. Among the infonllation to be used are past studies of population size for razorback <br />suckers in the Green River (Tyus 1987, Tyus and Karp 1990, Lanigan and Tyus 1989, Modde et a1. <br />1996). and in the lower Colorado River (Minckley 1983, Marsh and Minckley 1989, Dowling and <br />Minckley 1993, Dowling et al. 1996); studies of Colorado pikeminnow in the Green River (Tyus et <br />al. 1982. Tyus 1990). and in the Colorado and Gunnison rivers (Valdez et a1. 1982, Osumundson et <br />al. 1997. Osmundson and Burnham 1998. Osmundson et al. 1998); studies of humpback chub in the <br />upper basin (Valdez and Clemmer 1982. Kaedingetal. 1990, Chart and Lentsch 1997, Utah Division <br />of Wildlife Resources 1995). and in Grand Canyon (Kaeding and Zimmerman 1983, Douglas and <br />Marsh 1996. Valdez and Ryel 1995. 1997); and studies of bonytail in the Green River (Vanicek <br />1967). Past efforts to release hatchery-reared fish will be evaluated to provide a perspective of the <br />role of hatcheries in achieving recovery goals. <br /> <br />Task 4d: Recovery Goals <br /> <br />F or each sub-population. densities of reproducing adults (number per mile) will be determined, based <br />on minimum effective population size and best estimates of habitat carrying capacity. Population <br /> <br />6 <br />