EFFECTS OF FORMULATED FEED ON WATER QUALITY IN FINGERLING WALEYE PRODUCTION PONDS

Six 0.04-ha plastic-lined ponds were used at the Iowa Department of NaturalResources’ Rathbun Fish Culture and Research Facility to evaluate the use ofsupplemental fish food on walleye (Sander vitreus) fingerling growth and survival,and on the benthic invertebrate community. Walleye were stocked 3-4 days posthatch on 2 May 2003, and harvested 5-6 June 2003. Organic fertilizer (alfalfapellets, 112kg/ha/week) was used to increase primary production and inorganicfertilizers were added periodically to maintain a target nutrient ratio of 7:1 nitratenitrogento total phosphorus (NO3-N: TP). Additional nutrients in the form of LansyCW fish feed were added to three of the six ponds. The objective of this project wasto determine the effect of a commercial fish diet on water quality. At the end of theculture season, there were significant differences between water chemistryparameters in the ponds; the feed treatments had higher levels of nitrogenouscompounds and total phosphorus