WWW.WAS.ORG • WORLD AQUACULTURE • SEPTEMBER 2017 65 (CONTINUED ON PAGE 66) crop. The main disadvantage is a reduced reaction time for responding to dissolved oxygen crises because of the higher biomass confined in the fish holding area. Given the success of the catfish industry adopting this new production innovation, Greene Prairie Shrimp, Alabama’s largest inland marine shrimp farm, constructed three split ponds in 2014 and 2015. The goal was not to increase total production, but to decrease the costs and effort of production. Shrimp production was achieved with mixed results, mostly unrelated to the splitpond design. This farm has experienced increasingly lower survival and poorer production over the past three years and other shrimp farms in the USA have documented similar trends. Unfortunately, testing of the split pond system was initiated during this same period of poor production, so its usefulness as a design for shrimp farming has not yet been properly assessed. However, a number of lessons have been learned about managing split ponds for shrimp. One of the harder lessons learned was the installation and use of properly designed screens at both ends of the interior levee. Ponds were stocked with 20-d old post-larvae but with high size variation. Screen material with a mesh size of 0.7-1 mm is required to retain these shrimp. The circulation flow through this smallmesh screen becomes restricted by biofouling, even after a few days of immersion. Water circulation between the shrimp and water treatment cells was not implemented for at least 2-4 weeks after stocking. Nevertheless, post-larval and juvenile shrimp managed to escape the shrimp cells through the screens and prosper in the non-aerated water treatment cells without artificial feed during the The use of split ponds in the United States catfish industry is quickly achieving a foothold. Following applied research by Drs. Craig Tucker and Les Torrans at the USDAARS Warmwater Research Unit, the industry now has over 809 ha of split ponds. Split ponds are pond-based outdoor systems featuring two or more ponds separated by interior levees. Fish are confined in a smaller lagoon, usually 15-20 percent of the total water surface area, while the larger lagoon(s) serve as waste treatment areas. Water is continually circulated through the system via concrete channels or culverts placed at both ends of the interior levee when oxygen is photosynthetically produced in the water treatment area. When nighttime respiration decreases oxygen to critically low concentrations, circulation is typically stopped between the sections and mechanical aeration is applied in the fish-holding lagoon only. Current field results suggest that the theoretical limit of roughly 9 t/ha in an open pond can be achieved using split-pond technology. Actual production in split ponds on commercial catfish farms yielded between 6.5 and 8.2 t/ha of catfish with a survival rate of 82-91 percent and a FCR of 1.8-2.4 at a water pumping rate of 0.425 to 0.630 kWh/lb of fish produced (Brown et al. 2015). It appears that the most limiting factor in split-pond production is the overall efficiency and reliability of the circulation device used. High yields are only possible with efficient circulation. The main advantage of the split-pond production system is providing more control over conventional ponds. Fish confinement in the fish production area facilitates efficient feeding and harvesting, aeration is applied in a smaller body of water, cheaper chemical treatments (less water), and enhanced vigilance of the fish Split Pond Technology Makes its Debut on an Alabama Inland Shrimp Farm Gregory N. Whitis and David Teichert-Coddington Pacific white shrimp grown in low-salinity water at Greene Prairie Shrimp. The main advantage of the split-pond production system is providing more control over conventional ponds. Fish confinement in the fish production area facilitates efficient feeding and harvesting, aeration is applied in a smaller body of water, cheaper chemical treatments (less water), and enhanced vigilance of the fish crop.
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