Walleye Sander vitreus are a highly sought-after northern Midwest fish species known for their nutritional quality and recreational attributes; however, the population has been decreasing with the ever-changing climate of our lakes. The objective of this study is to determine the optimal feeding rates for walleye juveniles and provide baseline information on feed management for walleye aquaculture.
We conducted three two-week trials in indoor systems run with flow through water at 18 to 20°C. Walleye were fed with commercial diets (50-55% protein, and 15% lipid) at 6 different feeding rates (% initial body weight daily) ranging from 5.0 to 17.5 % in Trial 1, and 2.5 to 15% in Trial 2, with 30 fish per tank. In Trial 3, walleye were fed with 5 different feeding rates from 2.0 to 8.0% body weight daily with 15 fish per tank. The initial body weight was 0.95 g, 2.31, and 9.3 g for Trial 1, 2 and 3, respectively. An optimal feeding rate was estimated using polynomial regression method based on the percentage of weight gain during each 2-week feeding. Our results showed that an optimal feeding rate was 22%, 12.5%, and 7.7% for fish ranging from 1-3 g, 2-5 g, and 9-17 g, respectively. The survival was significantly impaired (P<0.05) when walleye were fed at 5% body weight daily in Trial 1. Trial 2 and 3 showed high survivals (>97%) from all treatments. Condition factor, expressed as the ratio of body weight and the cube of length, was significantly lower for underfed fish compared to those fed at their optimal feeding rates or higher. The nutritional composition of walleye is pending for analysis and will be available for the presentation. The result of this study will provide preliminary information for developing feed management of walleye culture and designing future studies on nutritional requirement.
Effect of different feeding rate on the weight gain (WG, % body weight) of walleye juvenile