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understanding of the life history and movement patterns of each population. For the Colorado pikeminnow, for example, each life history stage has a different geographical locus, and the fish must be able to move freely between different areas. Moreover, the tendency of adults to make extensive use of tributaries argues for maintenance of a web of interconnected habitat in which physical fragmentation is avoided. Development of this perspective on recovery cannot be achieved simply by listing the distribution of individuals in each of the tributaries. It would be aided, however, by setting recovery' goals established in an ecosystem perspective. Such an expanded perspective would result in more consideration of maintaining other native fishes as a necessary part of recovering the endangered fishes. The decision by the Recovery Program to commission this evaluation of the role of tributaries in the recovery of the endangered fishes is a clear signal that the program is tatting a broader view of recovery needs. In the time that the program has been in existence, much has been learned about the ecology of the endangered fishes. The steady accumulation of knowledge has driven an evolution of ideas about recovery. We see this culminating eventually in an ecosystem view that will be guided by a multi- species or ecosystem recovery plan. We developed the following recommendations during the course of this study -The Recovery Program should expand efforts to circumvent or eliminate barriers to fish movement, especially in high priority tributary stre~ims. - The Recovery Program should reevaluate alternatives for providing fish access to upstream areas. Endangered fish populations in tributary reaches provide the best opportunities for range expansion, but a comprehensive system is needed to evaluate recovery success. - The Recovery Program should develop and implement plans for removing nonnative fishes from tributaries and controlling nonnative fish movement into mainstream rivers from source areas in tributary streams. - The Recovery Program should determine environmental attributes of the mouths of tributary streams that result in utilization by larval razorback sucker. - The Recovery Program should establish which tributaries are primary sediment sources for Colorado pikeminnow nursery habitat. - The Recovery Program should initiate a study to measure the release of metals from selected reservoirs in Utah that are known to experience seasonal depletion of dissolved oxygen. xi