Location: Warmwater Aquaculture Research Unit2015 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.
The focus of this 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. This is the last funded year of a three-year regional research (Arkansas, Mississippi and Alabama) examining production and economics of in-pond raceways, split-ponds, and intensively aerated ponds. Agricultural Research Service scientists at Stoneville 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. Results from the first year of on-farm production were impressive with yields greater than three to four times the national average. 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 does not appear to be a concern to farmers due to increased production rates. Scientists are currently collecting and analyzing data for the second year of production, and results so far are verifying the first years’ results. 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. Thorough economics analysis will be performed once scientists in all three states have collected all production performance data. Initial investment costs and operating expenses will also be included in this analysis. Assessment of advantages, disadvantages, and trade-offs of each of these new production systems will result and 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, MS, completed the construction of four new 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 are currently being developed and can be 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 are being 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, we 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, MS, to be used as a comparison of production performance and profitability of new systems. Hybrid catfish were stocked in March, 2015 in all systems for food fish production and production performance is presently being monitored. Work on the development of the U-tube aerator has evolved into a verification through demonstration project of a number of years. 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 three consecutive years in a commercial-scale 8-acre pond at the Stoneville research station. Production results have been impressive and energy use efficiency has been reduced as compared to traditional farming methods. As a fourth year of production is begun using this technology, scientists look forward to the possibility of on-farm trials. A study has begun with hybrid catfish using stocking rates ranging from 6,000/acre to 36,000/acre. With an aeration capacity of 24 horsepower/acre, dissolved oxygen will be controlled at optimum levels and it will be determined when, or if, ammonia concentrations limit feed intake and growth. This is one study in a larger effort to increase production efficiency of catfish through intensification. Agricultural Research Service scientists are collaborating with Mississippi State University scientists on a project designed to minimize production of 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, will examine the impact of “topping off” larger fish once during the growing season. Six ponds will be partially harvested in August using a Heikes Panel Sock. Production efficiency and final harvested fish size distributions will be determined. Work continued on the use of ultrasound to kill ramshorn snails and by extension trematodes. The lab setup in Oxford, MS, was moved to Mississippi Valley State University to facilitate experiments. 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. Some tests have been conducted but new collection efforts and tests are underway at the time of the reporting. Work progressed on the use of ultrasound to improve the water quality in processing plants. The equipment to collect water quality samples and test viability of bacteria as well as acoustic sonication equipment to potentially eradicate target bacteria have been assembled. 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. University of Mississippi personnel are continuing to work with Agricultural Research Service scientists in Stoneville to obtain water samples from processing plants.
1. Work on 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 (DO) concentration has remained above 3.0 milligram/liters (mg/L) in the area where the power-tube airlifts (PTAs) are located even when the other side of the pond (outside of the safety zone) has had a DO 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. This preliminary evaluation in a commercial-size catfish pond allowed researchers to define loading limits for the 2nd generation PTAs and to continue monitoring fish production using this technology in 2015. A patent “Water Aeration System and Method” was awarded on December 30, 2014 (Patent # US 8,919,744) for this invention.
Straus, D.L., Farmer, B.D., Beck, B.H., Bosworth, B.G., Torrans, E.L., Tucker, C.S. 2014. Water hardness influences Flavobacterium columnare pathogenesis in channel catfish. Aquaculture. 435:252-256.