RELATIONS BETWEEN ENVIRONMENTAL VARIABLES AND AGE-0 WHITE BASS ABUNDANCE IN 4 MISSOURI RIVER RESERVOIRS

Age-0 white bass (Morone chrysops) catch per unit effort (CPUE) in sta ndardized seine samples from 1983 to 1995 was correlated with environm ental data in the four South Dakota Missouri River reservoirs (Lakes O ahe, Sharpe, Francis Case, and Lewis and Clark). Environmental paramet ers that were significantly (P less than or equal to 0.05) correlated with CPUE varied among reservoirs. In Lake Oahe, age-0 abundance was h igher in years with high flushing, low discharge from its upstream dam , and warmer air temperature during June and July. In Lake Sharpe, age -0 abundance was higher in years with cooler air temperature during Ja nuary, April, and May, and less discharge and lower inflow during July . In Lake Francis Case, age-0 abundance was higher in years with highe r spring precipitation, evaporation and temperature, and in years with greater decline in elevation from May to July. In Lewis and Clark Lak e, age-0 abundance was higher in years with high spring and annual inf low, high reservoir elevation in March and elevation increase from Apr il to May, and increased annual storage. Multiple regression models we re developed for each of the four reservoirs with age-0 white bass CPU E as the dependent variable; coefficients of determination ranged from 0.90 to 0.94. Although the relations we observed were correlations an d not necessarily cause and effect, the results of this study provide insights into white bass biology in the Missouri River reservoirs.