Relations between Environmental Variables and Age-0 White Bass Abundance in Four Missouri River Reservoirs

Abstract

ABSTRACT Age-0 white bass (Morone chrysops) catch per unit effort (CPUE) in standardized seine samples from 1983 to 1995 was correlated with environmental data in the four South Dakota Missouri River reservoirs (Lakes Oahe, Sharpe, Francis Case, and Lewis and Clark). Environmental parameters that were significantly (P≤0.05) correlated with CPUE varied among reservoirs. In Lake Oahe, age-0 abundance was higher 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 January, April, and May, and less discharge and lower inflow during July. In Lake Francis Case, age-0 abundance was higher in years with higher spring precipitation, evaporation and temperature, and in years with greater decline in elevation from May to July. In Lewis and Clark Lake, age-0 abundance was higher in years with high spring and annual inflow, high reservoir elevation in March and elevation increase from April to May, and increased annual storage. Multiple regression models were developed for each of the four reservoirs with age-0 white bass CPUE as the dependent variable; coefficients of determination ranged from 0.90 to 0.94. Although the relations we observed were correlations and not necessarily cause and effect, the results of this study provide insights into white bass biology in the Missouri River reservoirs.