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endangered fish and propagation facilities in the Recovery Program was summarized by Wydoski (1994). Propagation activities produce more fish than are needed to meet specified requirements. This additional production allows the hatchery manager to compensate for unknown or unpredictable attrition rates to ensure that specified requirements are met. Planned captive propagation minimizes the production of endangered fish that will be excess to Program needs. However, fish that are surplus to actual need become a liability to the Recovery Program because their care requires use of valuable resources (e.g., people, facilities, and funds). Therefore, Recovery Program participants discussed, in detail, various alternatives for the use of captive-reared fish and procedures for disposal of captive-reared fish that are considered to be surplus to Recovery Program needs. The numbers of fish that are produced through captive rearing will vary so actual numbers of fish to be affected cannot be specified in this document. Water development in the Upper Colorado River Basin has resulted in changes in the historic water regime of this important river system that, in turn, has affected water temperatures and habitat such as backwaters and flooded bottomlands that were apparently crucial to successful recruitment of the endangered fishes. Construction of dams in the upper basin also blocked natural migrations of endemic fishes. Nonnative fishes were introduced, either intentionally or accidentally, that have become established in the river and are suspected to be competitors with, or predators on, the native fishes in this unique river system. Presently, nonnative fish species constitute 76% of the fish species (42 of 55 species) in the Upper Basin (Tyus et al. 1982). These changes have resulted in the razorback sucker (Xyrauchen texanus), bonytail (Gila ele4ans), humpback chub (Gila cypha), and Colorado squawfish (Ptychocheilus lucius) being listed as "endangered" under the Endangered Species Act of 1973, as amended. These endemic fishes are important biological components contributing to the natural ecosystem function of the Upper Colorado River Basin. They once played a positive and important role in the lives of Upper Basin residents by providing sport fishing opportunities and food (Quartarone 1993). Although spawning has been documented and larvae or juveniles of some of the endangered fishes have been collected in the upper basin, the primary limiting factor is poor survival in the early life stages that results in inadequate recruitment to maintain self-sustaining wild stocks. USES OF CAPTIVE-REARED ENDANGERED FISH Captive propagation is an important part in restoration of endangered fish and wildlife species because it provides animals for refugia, research and development, information and education, and stocking. The following endangered fish needs (i.e., purpose by species) were identified by Recovery Program participants: