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Research Project: Water Quality and Production Systems to Enhance Production of Catfish

Location: Warmwater Aquaculture Research Unit

2016 Annual Report

The overall objective of this project is to increase profitability of catfish aquaculture by improving farm-level production efficiency. This will be accomplished by developing new production systems and management practices that allow greater control of the culture environment, with the end result that the genetic potential of catfish can be fully expressed. Studies will also be conducted on the use of ultrasound to kill the intermediate host of an important catfish pathogen and reduce bacterial loads in processing plant cold-water washes. Over the next 5 years, we will accomplish the following objectives: 1) Enhance Control of Pond-Based Ecosystems to Maximize Production and Product Quality. Sub-objective 1.1 Optimize split-pond design for food-sized catfish aquaculture. Sub-objective 1.2 Maximize catfish production potential of conventional ponds using intensive aeration. Sub-objective 1.3 Evaluate management practices to reduce the final size variation resulting from variable growth rates in hybrid catfish. 2) Determine the Suitability and Feasibility of Polyculture or Off-season Production of Other Species Using Catfish Culture Infrastructure. Work on this objective will focus on developing technologies for production of a secondary, non-catfish species, such as tilapia, in split-ponds. Production of secondary filter-feeding species can potentially increase on-farm profits by generating an additional crop at little extra expense and may improve water quality in split-pond systems by feeding on plankton and detritus that are an oxygen-consuming waste product in catfish monocultures. 3) Develop Acoustic Technology and Methodologies to Improve the Production and Profitability of Pond-based Aquaculture in the United States. Sub-objective 3.1 Develop and test the potential for control of ramshorn snails in ponds using ultrasound. Sub-objective 3.B. Develop and test the potential for ultrasound to reduce bacteria in the cold-water wash in processing plants. Work on this objective will be conducted using congressionally mandated funds administered through Specific Cooperative Agreement 58-6402-9-427 (“Development of Active and Passive Acoustic Measurements to Improve Production and Profits of U.S. Aquaculture”) between the ARS Warmwater Aquaculture Research Unit, Stoneville, MS, and the National Center for Physical Acoustics, at the University of Mississippi. Under this Agreement and as part of this Project Plan, novel application of acoustic technology will be tested and developed, including Sub-objective 3.A, developing and testing the potential for control of ramshorn snails (a disease vector in catfish ponds) using ultrasound, and Sub-objective 3.B, reducing bacteria in the cold-water wash in catfish processing systems using acoustic cavitation.

Four, 7-acre earthen ponds at the National Warmwater Aquaculture Center at Stoneville, Mississippi, will be modified into split-ponds (Sub-objective 1.A). Pump-performance curves will be developed by systematically changing pump operational parameters for four pump types—one pump for each split-pond. High aeration rates will be used to culture hybrid catfish (channel catfish x blue catfish) and measured variables will include fish growth, survival, production, processing yield, feed conversion ratio, dissolved oxygen concentrations, and water quality variables measured biweekly. Relationships among average flow rate (pump type) and fish growth, feed conversion ratio, and selected water quality variables for each year over the 3-year study will be assessed using regression analysis and results will yield different options for farmers using this technology in the industry. Six, 0.25-acre ponds with 24 horsepower/acre of aeration for hybrid catfish production will be used in this study (Sub-objective 1.B). Dissolved oxygen, temperature and aerator status will be continuously monitored and the aerators controlled using a pond oxygen monitoring and control system already in place. Water quality will be measured biweekly for hybrid catfish production. Response variables will include final fish weight, weight gain, net production, processing yields, survival, feed consumed, feed conversion ratio, aerator usage), and economics Relationships among stocking rate, aerator usage, feed consumed, weight gain, feed conversion ratio, and selected water quality variables will be assessed using regression analysis. This model should allow us to recommend a stocking rate that will allow satiation feeding through the growing season and will be tested on commercial ponds. Twelve, 1-acre ponds (10-hp of aeration per acre) will be used to produce hybrid catfish at the Delta Branch Experiment Station, Stoneville, MS (Sub-objective 1.C). Production parameters, coefficients of variation in size, and final economics will be compared among treatments using analysis of variance. Pending the results from this study, further studies on hybrid catfish foodfish management practices to reduce growth rate variation, including feeding schedules and practices, will be conducted. For Sub-objective 2, a 4.5-acre split-pond aquaculture system located at the National Warmwater Aquaculture Center in Stoneville, Mississippi will be modified for to allow for the production of hybrid catfish and Blue Tilapia. Production performance will be measured and a performance average will be taken after three production seasons and a partial budget developed to measure gauges of economic efficiency of this production method as compared to conventional split-pond catfish aquaculture. Experiments will be conducted on groups of snails using a commercially available sonicator as the acoustic source to destroy snails (Sub-objective 3.A). The potential use of ultrasonic cavitation to reduce bacteria in the cold-water wash in processing plants will be investigated as well in Objective 3.B. A cost-benefit comparison must be made to determine if the proposed design and technique is warranted.

Progress Report
The focus of this in-house research project is to develop a more complete understanding of the impacts of water quality, particularly dissolved oxygen and ammonia, on economics, growth and production of channel and hybrid catfish, and to develop new equipment, production systems and management strategies to utilize that information. The ultimate goal is to reduce the production costs for American fish farmers, making them more competitive in a world economy and providing quality fish to American consumers at a fair price. A three-year regional research project (Arkansas, Mississippi and Alabama) examining production and economics of in-pond raceways, split-ponds, and intensively aerated ponds was extended an additional year with no funds to allow for incorporation all publications and presentations in the final report. An Agricultural Research Service scientist at Stoneville, Mississippi monitored the production performance of channel and hybrid catfish cultured in intensively aerated ponds and split ponds on a number of commercial catfish farms in Mississippi. In general, feed conversion and survival in these systems was better than traditional farming methods in catfish ponds. Direct energy use was also monitored and was found to be slightly greater than traditional farming methods, but is only a fraction of total operating expenses and doesn’t appear to be a concern to farmers due to increased production rates. Even with feed rates two-to three times the previously-recommended amount, water quality in these systems, in general, has remained within acceptable levels for catfish production. Assessment of advantages, disadvantages, and trade-offs of each of these new production systems will guide commercial farmers in future planning. As part of a second three-year regional project involving four institutions and three states (Mississippi, Arkansas and Alabama), Agricultural Research Service scientists in Stoneville, Mississippi operated four split-ponds at the Mississippi State University Delta Branch Experiment Station. The main objectives of this study are to evaluate four pumping systems either in common use or currently considered for use in commercial-sized split-ponds. Performance models have been developed and are being used by scientists and industry personnel producing fish within these systems. An important aspect of split-pond operation is costs associated with the pumps, conveyance structures, and installation of both. Thus, initial investment costs of the four pumping systems that were evaluated in this study have been compiled. In addition, the cost of pumping water between the fish-culture basin and waste-treatment lagoon can be expensive depending on the pumping system used. Therefore, scientists calculated the operational expense of four different pumps used in split-ponds over a simulated production season to act as a baseline economic indicator of electrical energy use and potential profitability. Four 3.5-acre intensively aerated ponds have also been constructed in Stoneville and are being used as a comparison of production performance and profitability of new systems. Hybrid catfish were initially stocked (10,000 per acre) in March, 2015 in all systems for food fish production and fish were harvested from October, 2015 through January, 2016. Production performance was impressive, although slightly lower than desired due to stocking small fingerlings. However, net production in the split-ponds ranged from 12,084 to 13,278 pounds per acre, survival was 86.6 to 96.1 %, and FCR was 1.81 to 1.99. The intensively aerated ponds had slightly lower net production ranging from 8,499 to 13,777 pounds per acre, survival was 54.5 to 93.1 %, and FCR was 1.83 to 1.90. Hybrid catfish were restocked (~15,000 per acre) into these systems in late March, 2016 and production is being monitored for a second year, and finally a third year in 2017. To date, no water quality parameters reached critical levels. Work on the development of the U-tube aerator has evolved into a demonstration. This new aerator has been studied in detail and oxygen transfer and aeration efficiency have been shown to be comparable to paddlewheel aerators. This technology has been used to produce hybrid catfish food fish for four consecutive years in a commercial-scale 8-acre pond at Stoneville, Mississippi. Production results have been impressive and energy use efficiency was reduced as compared to traditional farming methods. As a fifth year of production is begun using this technology, scientists look forward to the possibility of on-farm trials. The first year of a two-year study has been completed with hybrid catfish at stocking rates ranging from 6,000/acre to 36,000/acre. With an aeration capacity of 24 horsepower/acre, dissolved oxygen can be controlled at optimum levels and it will be determined when, or if, ammonia concentrations limit feed intake and growth. First year production was 35,674 pounds per acre at the highest stocking rate and food conversion ration averaged 1.84. No water quality parameters reached critical levels. The study is now in its second year using similar stocking rates but with larger fish stocked to further push the system. It does appear that potential production rates in conventional earthen ponds are higher than previously believed. This is one study in a larger effort to increase production efficiency of catfish through intensification. Agricultural Research Service scientists at Stoneville, Mississippi are collaborating with Mississippi State university scientists on a project designed to minimize production of hybrid catfish larger and smaller than the preferred size range of processors (1-4 pounds). The first study, using twelve 1-acre ponds stocked with ungraded hybrids at a rate of 10,000 fish/acre, examine the impact of “topping off” larger fish once during the growing season. Six ponds were partially harvested in August using a Heikes Panel Sock. Production efficiency and final harvested fish size distributions were determined. Grading did result in more uniformity (less large and small fish, but overall production was also reduced. Scientists at the University of Mississippi in Oxford, Mississippi continued work on the use of ultrasound to kill ramshorn snails, an intermediate host of the catfish trematode. While some progress has been made, the industry has, by and large, adopted the use of copper sulfate to eliminate snails. In so doing there has been a low incidence of snail infestations which did not allow for collection of sufficient snails to perform statically significant tests. Work was begun on compiling the results from the conducted experiments to begin the process of publication. With the significant lack of snails, investigations into other possible areas of research have begun. University of Mississippi scientists at Oxford, Mississippi continued work on the use of ultrasound to improve the water quality in processing plants. Unfortunately, due to miscommunications with processing plant personnel, water samples from the cold water wash have not yet been collected. As a temporary surrogate, water samples with bacteria from ponds at University of Mississippi, catfish ponds at the National Warmwater Aquaculture Center, as well as other sites have been collected and analyzed in order begin work on the techniques to sonicate and treat the water to investigate efficacy. Optimum acoustic and experimental parameters were determined, and preparatory work began on experiments with a much larger sample size. University of Mississippi personnel are continuing to work with Agricultural Research Service scientists in Stoneville, Mississippi to obtain water samples from processing plants.

1. Development of circulation equipment for use in split-pond aquaculture systems. Pump performance tests have been performed on four pumping systems in four commercial-scale split ponds. In summary, the selection for a pumping system in a commercial environment requires a compromise among pumping efficiency, initial investment cost, and reliability. Long-term studies are underway to better define the relationship between water flow rate and fish production in split-ponds. The information already developed (initial costs and efficiencies) has helped to identify the pumping system most appropriate for split-pond aquaculture and recommendations are being adopted by the industry. Most farmers are now using one of the pumping systems evaluated by Agricultural Research Service scientists.

2. Impact of grading hybrid catfish fingerlings on food fish production. Hybrid catfish grow rapidly but not uniformly. It is not unusual in a pond harvest to have some individual fish weighing over five pounds while others are less than a pound. This can be undesirable with some processors paying a discounted price for both larger and smaller fish. ARS scientists at Stoneville, Mississippi found that food conversion and mean weight at harvest were not affected by grading fingerlings. However, the proportion of fish above and below the processor-preferred size range was decreased when fingerlings were graded. Stocking well-graded fingerlings is an important aspect of producing a uniform population of harvest-sized fish when processors do not want very large or very small fish. Most farmers are now purchasing graded fingerlings.

3. Development of a new aerator for the catfish industry. Two commercial-scale power-tube airlift aerators were installed in 2012 in an 8-acre catfish production pond for onsite field testing. Dissolved oxygen concentration has remained above 3.0 milligram/liters (mg/L) in the area where the power-tube aerators are located even when the other side of the pond (outside of the safety zone) has had a dissolved oxygen concentration of close to 0.0 mg/L. Catfish production results so far have been encouraging and continue to improve with 5,987 pound (lb)/acre and food conversion ratio (FCR = 2.2), 12,399 lb/acre (FCR = 2.0), 15,664 lb/acre (FCR = 1.7) for years 2012, 2013, and 2014, respectively. The fish were over wintered for the 2015 production season and a partial harvest occurred in 2016. We plan to harvest the remaining fish later this year and report production results for the 2015 and 2016 growing season. This preliminary evaluation in a commercial-size catfish pond allowed us to define loading limits for the 2nd generation power-tube aerators and to continue monitoring fish production using this technology in 2015. A patent “Water Aeration System and Method” was awarded to Drs. Brown and Torrans on December 30, 2014 (Patent # US 8,919,744) for this invention.

Catfish farming is truly a national industry with 624 commercial producers located in 32 states. While there are some large farms, the majority are small family owned and operated, averaging only 160 water acres. USDA classifies 84% of these catfish farms as small businesses, with annual sales of less than $500,000, and 38% with annual revenues of less than $25,000. In spite of low pond-bank prices during most of the past decade, farmers have survived through increased efficiency, producing more fish on fewer acres each year. Last year (2015) overall production was nearly 316 million pounds, an increase of 10% from 2014. The average pond bank price was $1.14 /pound, down 4% from $1.19/pound received by farmers in 2014. The continued high pond-bank price has produced some optimism in the industry, but with increased foreign competition, and high feed and fuel prices, the future is uncertain. Those dedicated catfish farmers are the primary customers of this research through the availability of innovative technologies, management strategies and equipment to increase their efficiency even more. Utilizing research developed primarily by ARS scientists at Stoneville, Mississippi, some farms now have an average on-farm net fish production of over 12,000 pounds/acre with an average food conversion ratio of better than 2.0:1. ARS scientists at Stoneville, Mississippi, believe that if there were a truly level playing field (no “dumping” of fish produced by state-run foreign economies), the breakeven price of U.S. farm-raised catfish would now be competitive with imports. Research on water quality management is critical for success of all catfish farms, but will have far greater impact on smaller farms with a generally narrower profit margin. Catfish processors benefit from a more stable fish supply resulting from improved off-flavor management and detection methods. Average consumers also benefit from the increased availability of higher-quality, safer domestic products at a reduced price.

Review Publications
Torrans, E.L., Ott, B.D. 2015. No evidence for intercohort cannibalism in mixed-size cultures of food-size and fingerling hybrid catfish (channel catfish x blue catfish) grown in ponds in winter or summer. North American Journal of Aquaculture. 78(1):52-56.
Kumar, G., Engle, C., Tucker, C.S. 2016. Costs and risks of catfish split-pond systems. Journal of the World Aquaculture Society. 47:327-340.
Torrans, E.L., Ott, B.D., Bosworth, B.G. 2015. Impact of minimum daily dissolved oxygen concentration on production performance of hybrid female channel catfish x male blue catfish. North American Journal of Aquaculture. 77(4):485-490.
Boyd, C.E., Tucker, C.S. 2014. Handbook for aquaculture water quality. Handbook for Aquaculture Water Quality. P.439.
Brown, T.W., Tucker, C.S., Rutland, B.L. 2016. Performance evaluation of four different methods for circulating water in commercial-scale, split-pond aquaculture systems. Aquacultural Engineering. 70:33-41.
Tucker, C.S., Pote, J.W., Wax, C.L., Brown, T.W. 2015. Improving water-use efficiency for ictalurid catfish pond aquaculture in Northwest Mississippi, USA. Aquaculture Research. 48:447-458.
Mischke, C.C., Tucker, C.S., Wise, D.J., Brown, T.W. 2015. DEET (N,N-diethyl-m-toluamide) toxicity to channel catfish Ictalurus punctatus sac fry. Journal of the World Aquaculture Society. 46:(3)344-347.
Bosworth, B.G., Ott, B.D., Torrans, E.L. 2015. Effects of stocking density on production traits of channel catfish Ictalurus punctatus x blue catfish Ictalurus furcatus hybrids. North American Journal of Aquaculture. 77:437-443.
Boyd, C.E., Tucker, C.S., Somridhivej, B. 2016. Alkalinity and hardness: Critical but elusive concepts in aquaculture. Journal of the World Aquaculture Society. 47:6-41.