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METHODS Young of year The study area was divided into three sub-reaches for comparative analysis of YOY catch and habitat data: above canyon (RK 204 - 199.4); canyon (RK 199.2 - 190.4); and, below canyon (RK185.6- 176). In 1992, low velocity habitats were sampled on four occasions in conjunction with the fish community sampling. Beginning in 1993, fish community sampling was reduced to twice annually and specific YOY sampling trips were added to better determine time of hatch, YOY densities, growth, and habitat relationships. Larval and young of year fish were collected with a beach seine (4.6 m; 1.5 mm mesh) or a smaller one-man seine (1 m; 0.8 mm mesh). Larval drift nets (fished passively and towed through main channel habitats), larval dip nets, and larval light traps were used throughout the study, but did not prove effective. An effort was made to identify, enumerate, and release fish (see Appendix Table 1 for list of species encountered). However, if necessary, fish were preserved in 10% buffered formalin for lab processing. Physical data was collected to characterize the habitat (Appendix Table 2 for definition of habitat types) as well as the specific area seined according to the Interagency Standardized Monitoring Program ISMP guidelines (refer to McAda et al 1994). Catch per unit effort (CPE) is presented as fish / meterZ~ Arithmetic means were calculated for summary analyses. Hatching dates were back-calculated for each Age 0 cohort using formula developed by Muth (1990). Standard lengths of Age 0 Gila spp. (required to calculate days after hatch) were generated from total lengths collected in the field and lab using the following regression: SL = 2.02 +.7205 (TL) Spawning date was calculated by subtracting an additional 6 days from the hatch date (from Muth et al. 1985, Marsh 1985). Spawning period was determined for an entire sample of YOY chubs collected on one occasion each summer. The results of that analysis were plotted against the environmental variable (flow and temperature) to characterize the condition at the time of spawn. Various flow and temperature parameters were correlated with July and August YOY CPEs (Table 1), hatching dates, growth of YOY, and habitat type availability. Pearson correlation coefficients, analysis of variance, t-tests and multinomial tests for habitat preference were run on STATISTIX . 3