PERFORMANCE EVALUATION OF SPLIT-POND SYSTEMS OPERATED AT TWO DIFFERENT  WATER TURNOVER RATES FOR PRODUCTION OF HYBRID CATFISH Ictalurus punctatus x I. furcatus

Aquaculture production in the U.S. is largely dominated by catfish and is important to the economies of several southern states. Due in part to the dramatic increase of feed prices and competition with imports, alternative production technologies have been employed in an effort to increase yields and profitability. One such technology is the split-pond system (SPS), which utilizes a pump to circulate water between a fish culture basin and water treatment basin that are typically separated by an earthen levee within the pond. There are considerable variations in design between SPSs, especially with regard to water flow rate. Currently, slow rotating paddlewheels and screw/auger type pumps are used to move water in culvert-based SPSs in Arkansas. These two pumps have variable pumping capacities, causing varied amounts of water flow between the SPSs of different sizes. In the SPSs, a pump actively moves water through the treatment basin during the day and water circulation (horizontal and vertical water mixing) by pumps provides the opportunity for more contact between green algae and nutrients (ammonia and carbon dioxide), thereby increasing their utilization efficiency. Thus, water flow rate (turnover rate) is a primary factor to determine carrying capacity production. This study determined the effect of two different turnover rates on hybrid catfish production in SPSs. At the Aquaculture Research Center at University of Arkansas at Pine Bluff six 0.2 hectare ponds were retrofitted into SPSs with slow rotating paddle wheels and baffles creating a 20% fish culture area and an 80% water treatment area. A 6-month study was conducted to evaluate the effect of flow rate on production of hybrid catfish. Three ponds were operated at high flow (10 hour whole pond turnover rate) and three ponds were operated at low flow (20 hour whole pond turnover rate) treatments to mimic various whole pond turnover rates on commercial farms with slow rotating paddle wheels and auger pumps, respectively. Various water velocities were achieved with the use of variable frequency drives to power slow rotating paddlewheel motors. Water was circulated for 12 hours/day. All ponds were stocked at a rate of 29,653 fish/ha. Fish were fed to satiation daily (28% protein floating feed). Flow rate had no effect on length, weight or K in hybrid catfish.