Walleye (Sander vitreus) is an ecologically important and highly prized food fish in the Midwest region. With limited commercial harvesting of wild walleye, the primary supply for the region relies on imported walleye. Developing a robust walleye aquaculture industry is crucial to meet the ever-growing market demand. This study aims to establish a cost-effective feeding strategy and formulate a nutritionally balanced feed to enhance walleye aquaculture.
Two feeding trials were conducted on walleye with an initial body weight of 37 ±1.26 g (n=30) within a flow-through water system (19 – 21 °C). In the first trial, walleye were subjected to four feeding rates (0.8%, 1.6%, 2.4%, and 4.0% of body weight per day) for 6 weeks to determine the optimal feeding rate (OFR). The second feeding trial lasted for 9 weeks and aimed to assess the response of walleye to various diets characterized by differing lipid-to-starch ratios: 0.50, 0.65, 0.83, 1.06, and 1.36. Each treatment consisted of three replicates with 20 fish per replication. Fish were fed four times daily (9:00 a.m., 12:00 p.m., 3:00 p.m., and 6:00 p.m.) using automatic feeders. We employed polynomial regression to estimate the optimal feeding rate and the ideal dietary lipid-carbohydrate combination.
Results revealed that the OFR was 3.51% based on weight gain (Figure 1) and 1.35% based on achieving the lowest feed conversion ratio (FCR). Feeding a diet with a lipid-to-starch ratio of 0.99 resulted in the highest weight gain (Figure 2) and a ratio of 1.04 achieved the lowest FCR. Moreover, visceral fat, whole fish lipid content, and lipid retention displayed statistical differences among the various treatments (P < 0.05). The findings related to the response of walleye to hypoxia and heat shock stressors are currently under analysis and will be discussed in the presentation. The preliminary findings of this study provide essential baseline data for effective feed management and selection in the context of walleye aquaculture, ultimately promoting its sustainable development.