2007 Annual Report 1a.Objectives (from AD-416) Develop feeds and feeding practices for optimal nutrition, increased production, and improved water quality of pond-raised catfish; Increase the reliability, efficiency, and cost-effectiveness of catfish fry production through the use of new and improved technologies; Apply engineering approaches to design new or modified live aquatic animal harvesting equipment; Increase the reliability, efficiency, and cost-effectiveness of catfish production through the use of new and improved culture system technologies. 1b.Approach (from AD-416) Content and sources of protein and carbohydrate in traditional catfish diets will be manipulated to measure economic performance of diet. The effects of interactions among fish size and feeding schedule on economic performance of catfish farming will be measured. New nursery pond management strategies, nitrogen and phosphorous fertilization rates, and zooplankton supplementation will be analyzed to improve fry growth and survival on commercial farms. An induced electrical field will be incorporated into a seine to test harvest efficiency. Partitioned aquaculture systems will be developed and tested for utility on commercial farms. An environmental management system will be developed for pond aquaculture consisting of proven or easily implemented technologies to improve catfish production efficiency, reduce environmental impacts, and conserve water. 3.Progress Report This report serves to document research conducted under a Specific Cooperative Agreement between MS Agricultural & Forestry Experiment Station (MAFES)and ARS. Additional details for this subordinate project may be found in the in-house project 6402-31630-001-00D, “Improving Production Efficiency of Pond-Raised Channel Catfish.” Nutrition and Feeding--1) A 2-year study was completed using 32%-protein diets with either 0 or 8% menhaden fishmeal and four combinations of plant feedstuffs. Weight gain and feed conversion ratio were better in fish fed diets with 8% fishmeal, regardless of feed ingredient combinations, but the differences were relatively small (5.7% for weight gain and 4.5% for feed conversion ratio). Fishmeal levels, feed ingredient combination, and their interaction did not significantly affect feed consumption and processing yield of the fish. These results add to the debate whether fish meal is an essential component of catfish feeds. A similar factorial experiment was initiated in using 28%-protein diets with the same fishmeal levels and feed ingredient combinations.. 2)Channel catfish were fed for 3 years either to apparent satiation once daily; apparent satiation every other day; or daily to no more than 90 kg/ha. Market-size fish were selectively harvested from each pond at the end of each growing season and fingerlings were under-stocked in each pond at the beginning of each growing season. The first 3 years of data showed that the amount of feed fed differed among treatments and was highest for the daily satiation feeding regimen, followed by the daily restricted feeding, and was lowest for every-other-day satiation feeding. Total weight of market-size fish followed the same trend, but the difference between fish fed daily to satiation and at a restricted ration was not statistically different. No significant differences in processing yields (carcass, fillet, or nugget yields) and fillet protein concentrations were noted among different feeding regimens. Nursery Pond Management--Optimum nitrogen fertilization rate for fry nursery ponds is 22 kg/ha per application. Studies are being conducted to determine the optimal P fertilization rate. The new fertilization strategies are being implemented on various cooperative farm sites and farmers are reporting positive results. Harvesting--The miniaturized fish stimulator was redesigned using a new transformer manufactured by a custom transformer vendor. The results of trials conducted in concrete vats indicated that the fish stimulator was ineffective and underpowered. A magnetic wire spooler will be purchased or built that will allow testing of custom transformers. The performance on this project was monitored by regular discussions with the MAFES PI and with frequent collaborations between the MAFES staff and the staff at Catfish Genetics Research Unit. This five-year agreement terminated in March 07 and ongoing work has continued under a new SCA documented in project 6402-31630-001-03S.