Advancement of a viable food-fish market for walleye (Sander vitreus) requires a domesticated captive broodstock that produces high quality gametes and viable offspring. Furthermore, out-of-season spawning techniques that result in year-round fingerling availability is needed for the walleye market to develop. Both of these industry needs require a better understanding of proper nutrition in walleye broodfish diets. Previous studies in other Percids such as Eurasian perch and pikeperch have shown that dietary lipid and fatty acid composition of broodfish diets play an important role in egg quality and fry survival. These studies have shown that the highest hatching rate and early survival in Percids have been obtained when the broodfish diet included forage fish, either as the sole food source or as a supplement to dry feed. The walleye in this study represent a lower Mississippi River strain from Genoa, Wisconsin. Brood fish were raised under two feeding regimes that included one cohort raised 100% on pellets and one cohort raised on both pellets and forage fish. Results indicate that neither broodstock egg production nor fertilization success was influenced by feed regime. Egg size was significantly smaller for broodstock relative to wild fish but did not differ between pellet fed and minnow fed broodstock. Feed-trained fingerlings from each diet cohort were then co-mingled in an aquaponics system at an average weight of ~20 g. A fin clip was used to distinguish the two cohorts. PIT tags were also used to track the growth of 30 individuals per cohort. Growth has been monitored approximately every 30 days and is ongoing until food-sized fish have been attained with an average weight of approximately 1.0 lb (454 g).
Note: The growth study described above will conclude in January of 2023 to permit final analysis of the growth comparison of the two walleye cohorts to be presented at the 2023 Aquaculture America conference.