Walleye Recruitment Relative to Fry Stockings in Eastern South Dakota Glacial Lakes

   Supplemental and maintenance stockings are important tools for the management of Walleye Sander vitreus in South Dakota.  However, survival of stocked Walleyes is often unpredictable. Thus, the objectives of this study were to examine Walleye recruitment relative to fry stockings in eastern South Dakota glacial lakes and estimate the influences of extrinsic factors on recruitment variability.  Using Walleye fry stocking data and corresponding age-2 Walleye relative abundance data from 22 natural lakes over a 17-year period, we developed Ricker stock-recruitment models. Variation in stock-recruitment relationships was examined by parameterizing traditional stock-recruitment models with extrinsic variables including winter severity index (WSI), the change in fall to spring water level, and adult Yellow Perch Perca flavescens relative abundance.  Using Akaike’s information criterion (AICc), stocking rate was the most-supported model in predicting age-2 Walleye recruits. Others models provide insight into additional factors that influenced recruitment.  Age-2 walleye recruitment was negatively influenced by fry stocking rate, Yellow Perch relative abundance and winter severity while the change in fall to spring water levels positively influenced age-2 recruits. Overall, results suggest Walleye recruitment in eastern South Dakota glacial lakes is influenced by a combination of stocking rates, abundance of prey resources, winter severity and local hydrology.