FACTORS INFLUENCING SURVIVAL AND GROWTH OF STOCKED WALLEYE (STIZOSTEDION-VITREUM) IN A CENTRARCHID-DOMINATED IMPOUNDMENT

We compared survival and growth of fry and small (mean total length = 48-61 mm), medium (132-145 mm), and large (186-216 mm) fingerling walleye (Stizostedion vitreum) stocked for 4 yr in a centrarchid-dominated impoundment. Mean survival based on fall population estimates 1 and 2 yr after stocking indicated highest survival for large fingerlings (mean survival = 31 and 10%, respectively), followed by medium ones (7 and 4%). Few individuals from the fry and small fingerling size groups were recovered in extensive field sampling. Creel census data reinforced these findings. Thermal stress at stocking and predation by large mouth bass (Micropterus salmoides) were more important than either hooking mortality or spillway escapement in influencing survival. Walleye diets were dominated by bluegill (Lepomis macrochirus) in volume (87%) and frequency of occurrence (84%). Growth rates were slower with bluegill as predominant prey compared with walleye growth in waters containing clupeids and cyprinids and may have been influenced by the abundance and size distribution of bluegill. Based on benefit/cost analysis (survival or catch/cost of rearing), stocking walleye >200 mm provided the highest return on investment.