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problematic. The study was expanded in FY 1994 after determination that the 1992/1993 level of sampling was inadequate to fulfill study goals. Study #35. Flow Effects on YOY Squawfisl~--Overwinter Survival. Study Goals The primary goal of this study is to gain an understanding of the relationship between winter river discharges and other important environmental variables and the survival of young fish (particularly Colorado squawfish) in the Green River. The specific objective of the study is to assess overwinter survival and movement of fishes with emphasis on endangered species. Relationship to Research Program Relatively little information is available on the effects of overwinter flows on the survival of endangered fish, particularly early life stages. Data collected in this study is necessary for evaluation of effects of winter releases from FGD on young fish. The Overwinter Survival Study is closely linked to a companion study The Effects of Flow Regulation and Ice on Overwinter Nursery Habitat of Age-0 Colorado squawfish. The study will also draw on data from ISMP, Effects of Winter and Spring Flows on Movement, Dispersal, and Survival of Young Colorado Squawfish (Study #36), the Nursery Habitat Study (Study #33), Annual Assessment of Reproduction (Study #32), and Early Biology Studies (completed). Results from the Winter Data Synthesis Study (funded by NPS) will also be integrated with this research. Description of Work An ongoing study being conducted by BIO/WEST Inc. via contract with UDWR. Fall and spring sampling trips using techniques consistent with ISMP are conducted to assess year class strength of Colorado squawfish and evaluate overwinter mortality. Year class strength is evaluated in light of relevant variables to test hypotheses on overwinter survival of young squawfish. Methods may be expanded to integrate better with Study #36. HYPOTHESIS-TESTING STUDIES Study # 36. Effects of Winter and Spring Flows on Movement, Dispersal, and Survival of Young Colorado Squawfish. Study Goals The primary goal of Study #36 is to provide in#ormation on the effects of winter and spring flows on the movement of young Colorado squawfish. Specific objectives of this study include: -Determine downstream movement of young Colorado squawfish over the winter period. -Determine the effect of the timing and magnitude of spring flows on the dispersal of age-1 Colorado squawflsh. Flaming Gorge Research Program 25