Intensive culture methods of walleye during ongrowing

Abstract

Cultural technology is described for on-growing Walleye (Sander vitreus) on formulated feeds from pond- and tank-reared fi ngerlings 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 fi ngerlings for enhancement stocking. At that site, the production interval is 155 days from hatch to fall fi ngerling 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 fi ngerling size now allows 85–90 % survival during habituation of pond fi ngerlings to formulated feeds. In phase III, use of grading fi sh 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 discus