Split Pond Technology Makes Its Debut on an Alabama Inland Shrimp Farm Gregory N

Split Pond Technology Makes its Debut on an Alabama Inland Shrimp Farm Gregory N. Whitis and David Teichert-Coddington

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

WWW.WAS.ORG • WORLD AQUACULTURE • SEPTEMBER 2017 65 Circulators used to move water between shrimp holding and waste treatment areas of split-pond systems at Green Prairie Shrimp. production season. In one trial, jumbo shrimp (57 g) were produced area devoted to culture and 80 percent devoted to water treatment. in the water treatment cell, amounting to about 18 percent of total For shrimp culture, we recommend that the ratio of culture area production. During the night, shrimp congregated near screens in the to treatment area should be doubled (e.g. 40-60) given the benthic flowing water. Unlike in catfish split pond management, water was feeding behavior of young shrimp. circulated continuously. Nighttime levels of dissolved oxygen in the Split ponds offer the possibility of polyculture without mixing shrimp ponds, due to conservative stocking and feeding rates, were species in the same water body. The greatest disadvantages of typically much greater in comparison to the water treatment areas of polyculture in the United States is the additional time and labor catfish split ponds, which typically become anaerobic at night. required to harvest and separate fish by species for marketing So far, split ponds have underperformed conventional ponds in (Tucker et al. 2014). In earlier work, Whitis et al. (2013) shrimp survival and production but other advantages of the split pond experimented with polyculture of striped mullet Mugil cephalus and have become apparent. Only about one-third of the aeration power Pacific white shrimp. In a replicated tank system, shrimp post-larvae is required for the split pond versus that required to aerate traditional and fingerling mullet can coexist without any significant mortality or shrimp ponds. Also, feeding a 0.5- to 1-ha culture pond is much production issues. Mullet fingerlings need two years to reach market faster than feeding along the periphery of a 2-2.5 ha pond. The small size (1 kg) when grown with shrimp and will develop roe at the end culture pond that is part of a split-pond system can also be fitted with of the second year. In the event of establishment of a commercial automatic feeders more practically than a large pond. The harvest of mullet hatchery in the United States, striped mullet would be a very a small pond in the split-pond system is much faster and less labor viable candidate for shrimp polyculture in split ponds. intensive than a large conventional pond. Greene Prairie conserves In the fall of November 2015, rainbow trout were stocked in much of their water at harvest by pumping from a full pond to an one of the shrimp split ponds at Greene Prairie Aquafarm. After empty pond. A split pond built properly can retain water in the all shrimp were harvested in the fall of 2015, 8600 rainbow trout treatment pond when the shrimp holding area is drained, thereby weighing 136 g each were stocked in a 1.94-ha split pond at 4433 per requiring much less pumping energy and time to reduce water levels. total water hectare. All fish were stocked in the 0.4-ha fish holding Construction of split ponds for catfish have 20 percent of the area, resulting in a density of 21,500 fish per hectare in the fish

66 SEPTEMBER 2017 • WORLD AQUACULTURE • WWW.WAS.ORG Striped mullet stocked as a polyculture species in a split-pond system. holding cell of the split pond. Following 142 days of feeding during a For more information on split ponds, the reader is encouraged relatively mild Alabama winter, using a feed with 45 percent protein to read Partitioned Pond Aquaculture Systems by Craig S. and 19 percent fat, trout were harvested in April. Total production Tucker, David E. Brune and Eugene L. Torrans in the June was 1102 kg/ha with a survival rate of 77 percent. The main cause 2014 issue of World Aquaculture (vol. 45, issue 2). of mortality was thought to be predation by solitary eagles. The purpose of the production trial was to determine whether Alabama’s References mild winters would permit the growth of rainbow trout to a Brown, T.W, E.L. Torrans and C.S Tucker. 2015.Performance marketable size. The average size of the harvested trout was 500 g, evaluation of intensive, pond-based culture systems for catfish which is considered marketable by processors. This double-cropping production in Mississippi. Research Symposium of the Catfish feature of a split pond on an inland shrimp pond could have further Farmers of America. (Copy of abstract available from G.N implications for catfish producers wishing to single-crop catfish in Whitis). summer and grow rainbow trout in winter. Tucker, C.S and T.W Brown. 2015. Split pond design considerations for catfish farming. Research Symposium of the Notes Catfish Farmers of America. Gregory N. Whitis, Auburn University. Alabama Cooperative Tucker, C.S, D.E. Brune and E.L Torrans. 2014. Partitioned pond Extension System, Alabama Fish Farming Center, 529 S. aquaculture systems. World Aquaculture 45(2):9-17. Centerville Street, Greensboro, Alabama 36744, USA. whitign@ Whitis, G.N, L.A Roy and D. Teichert-Coddington. 2013. U.S. auburn.edu field trials show promise for mullet farming in polyculture. David Teichert-Coddington, Greene Prairie Shrimp, Box 10152, US Global Aquaculture Advocate. July/August 2013. Highway 43, Boligee, Alabama 35443, USA.