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27 Substudy Objective No. ~. ~. To assess the current status of knowledge on endangered fish species in the Upper Colorado River Basin and determine potential study objectives for continued research in 1986. Approach: The primary task during the transition period was to develop a renewal study plan regarding the endangered fishes research in the Upper Basin within Colorado. As a relative newcomer to the current scope of work being conducted in the Upper Basin, my obvious course was to review the current literature to assess the existing knowledge of these species' life history, their ecosystem, and management. As such, the primary references were the 1984 publications of recovery plans for Colorado squawfish, humpback chub, and bony tail written by the U.S. Fish and Wildlife Service (U.S. Fish and Wildlife Service 1984a, b, c). These documents provided a convenient summarization of the existing literature. The opportunity also arose to participate with the CRFP Biological Subcommittee on the task of research prioritization in the Upper Basin. This activity resulted in a guiding document (CRFP Recovery Team Biological Subcommittee 1985), and provided the necessary input from cooperating agencies and experienced biologists on research needs and wants. RESULTS The obj€ctive of the literature review was to form a list of study objectives for these endangered fish species that appeared relevant to concerns in the State of Colorado. This list is provided below by general subcategories: I. Spawning ecology objectives: A. To determine yearly characteristics of the spawning population of Colorado squawfish in Yampa Canyon with respect to length frequency, age composition, growth, recruitment, mortality rate, relative abundance (elf), and sex ratio. B. To determine spawning behavior of Colorado squawfish with respect to spawning frequency, fidelity to spawning grounds (homing versus straying), and home range of adult fish. II. Early life history objectives: A. To determine survivorship and sources of mortality of young-of-the -year squawfish in the Yampa-Green sub-basin with respect to planktonic and nektonic life stages, stranding, predation, potential interspecific competition and water quality changes.