Natural reproduction of walleye in Iowa's natural lakes is extremely limited, and so these fisheries have been sustained by annual stockings of sac-fry and fingerlings. It is absolutely critical that managers have the ability to document the success or failures of these stockings. For years, managers have been using electrofishing CPE as an index of walleye abundance. These managers recognize the need to determine the relationship between population densities and electrofishing CPE. Population densities of both young-of-the-year (YOY) and yearling walleyes were made each year with very intensive mark-recapture estimates.

Factors that may affect catchability of walleyes were recorded during the sampling period each year. These factors included, secchi disk depth, general weather conditions, water temperatures, number of individuals dipnetting fish, and type of shocking boat (AC vs. DC shockers). These factors were used to develop regression models to predict the density of both YOY and yearling walleye. So far, fall electrofishing CPE was significantly related to the density of both YOY and yearling walleyes in Iowa's natural lakes. Therefore, using CPE data as an index of walleye abundance appears to be justified. Hopefully, the inclusion of additional variables in future regression models will increase the usefulness of these models.

These findings will be of direct benefit to management of walleye populations in all water bodies in Iowa, and will become an integral part of the overall strategy for maintenance and improvement of those fisheries. Also, the synthesis of historical trend data, and the development of a standard method of analyzing trend data will aid the development of comprehensive plans to manage walleye populations.