Improved reliability of percid production in rearing ponds
Annie Jacob, Ph.D. Student, and David A. Culver. Funded by: Ohio Department of Natural Resources, Division of Wildlife, Federal Aid in Sport Fish Restoration.

Project FADR39 is a continuation of work begun in 1987 designed to optimize the filling schedule, stocking density, and fertilization regimens of ponds used for raising walleye, saugeye, and yellow perch fingerlings for stocking in Ohio reservoirs. A total of eight doctoral students and two master’s students have worked on this project over the years. Success with their experiments performed at the Hebron, Senecaville, and St. Mary’s hatcheries has led to fertilization and stocking modifications that have increased pond production of fish five-fold. Research results emphasize the importance of maintaining appropriate nutrient loadings to assure that phytoplankton species most edible to zooplankton are present to support the growing percid fry. Research originally conducted in the late 1980’s and early 1990’s set target limits for pond nutrient concentrations at 30 _g/L phosphate-phosphorus and 600 _g/L ammonium-nitrogen. Our recent research, however, has shown that the target concentration of phosphate (30 µg PO4-P/L) could be reduced to 20 or even 10 µg PO4-P/L without reducing fish survival or growth, although plankton production was reduced.

Recent decreases in survival and fish growth in the ponds of two hatcheries have led us to focus our study on copper and herbicide carryover from catfish culture in the summer to percid culture in the same ponds the following spring. We are also monitoring the ponds at six state hatcheries for zebra mussels, and have identified treatments that will kill zebra mussel veligers that might occur in fish transport trucks, without killing the juvenile fish being transported.

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Dave Culver's Limnology Lab

Dave Culver can be emailed at culver.3 "at" osu.edu