Recruitment dynamics of walleyes (Stizostedion vitreum) in Kansas reservoirs:: generalities with natural systems and effects of a centrarchid predator

Knowledge of factors influencing recruitment dynamics of walleyes (Stizostedion vitreum) in different systems and regions is important for developing a better understanding of walleye ecology. Therefore, we investigated associations among walleye recruitment and climatic, water-level, and biotic characteristics in four Kansas reservoirs during 1985-1999. Walleye recruitment was positively related to spring storage ratios and temperatures and negatively associated with spring water levels and abundance of 130- to 199-mm white crappies (Pomoxis annularis). The influence of juvenile white crappie predation on larval walleyes was examined by conducting a manipulative experiment. Regardless of zooplankton density or water clarity, mortality of larval walleyes resulting from white crappie predation was over 90%. Based on our empirical and experimental results, we propose a biotic-abiotic confining hypothesis (BACH) to explain abiotic and biotic effects on walleye recruitment dynamics. Specifically, high variability in walleye recruitment was observed during years with low densities of 130- to 199-mm white crappies and likely resulted from the effects of abiotic factors. When white crappie abundance was high, walleye recruitment was low and exhibited little variability, suggesting that white crappies can have an overriding influence on walleye recruitment regardless of abiotic conditions.