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<br />IV. EVALUATION DISCUSSION <br /> <br />A. Pivotal Endangered Species Act Compliance Issues <br /> <br />Before summarizing and discussing the advantages and disadvantages of each of the compliance <br />alternatives, three pivotal ESA-related issues should be addressed: (1) the sequence of events <br />necessary to effect recovery of endangered fish in the Lower Colorado River, (2) the ability of <br />any conservation plan to determine and provide adequate mitigation for impacts associated with <br />incidental take and adverse modification of critical habitat in the Lower Colorado River corridor, <br />and (3) Reclamation's preparation of the BA for the operation of the Lower Colorado River <br />Basin reservoirs and river system. The understanding and interpretation of these issues will play <br />an important part in the decision-making process, <br /> <br />1. Species Recovery Potential for the Four Big River Fish <br /> <br />It is our judgement that below Grand Canyon (Study Area Segments II-V), successful recovery <br />of endangered fish in the form of self-sustaining populations is not possible due to predation and <br />competition by an overwhelming number of nonnative fish. Until the problem of nonnative fish <br />can be addressed effectively, the endangered species management approach for the next decade <br />in this reach of Colorado River should be to develop a comprehensive conservation strategy that <br />works to, first, prevent the extinction of the bony tail and the razorback sucker, and, second, <br />maintain sufficient genetic variability within the two species to make future eventual recovery <br />possible. <br /> <br />We believe that prevention of extinction and maintenance of long-term genetic variability can <br />be accomplished by means airier than operational changes to Lower Colorado River reservoirs <br />and dams. We are referring to a comprehensive and coordinated conservation plan based on <br />hatcheries, isolated grow-out facilities, and monitoring and research programs. Until such a <br />strategy is implemented, the potential continues to exist for haphazard and uncoordinated efforts <br />to effect operational changes in system reservoirs and dams. As a case in point, the Service and <br />other native fish working groups, in cooperation with o:her agencies, has effected operational <br />changes in releases into and out of Lake Mohave as part of a program to limit nonnative fish <br />predation on razorback suckers in man-made rearing embayments, These operational changes <br />potentially could be reversed and additional recommendations for future operational changes <br />prevented by the more cost-effective, off.channel conservation strategy, <br /> <br />FINAL REPORT <br /> <br />December 20. 1994 <br />Page xiv <br />