Intensive Culture Methods of Walleye During Ongrowing

Cultural technology is described for on-growing Walleye (Sander vitreus) on formulated feeds from pond- and tank-reared fingerlings to sub-adult. Current literature is reviewed and a description given of the regimen used by the Iowa Department of Natural Resources, Rathbun Fish Hatchery (RFH) for production of Walleye fingerlings for enhancement stocking. At that site, the production interval is 155 days from hatch to fall fingerling with three phases: (I) pond-culture, (II) habituation to formulated feed indoors, (III) on growing outdoors to 250 mm (140 g). For many years, the critical limitation was during phase II, but academic and applied research on feed composition, tank environment, and fingerling size now allows 85–90 % survival during habituation of pond fingerlings to formulated feeds. In phase III, use of grading fish before stocking has reduced cannibalism and a practical protocol for treatment of common diseases has increased survival. Considerations for post-stocking survival have included improvement in methods for harvest and transport. Suggestions are given for future research to further improve growth and survival, and strategies are for discussed for application of the RFH protocol to produce fish for the food-fish market.