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 Warmwater Aquaculture Research Unit: Stoneville, MS
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ARS Home Southeast Area Stoneville, Mississippi Warmwater Aquaculture Research Unit Research





- Bosworth, Brian
- 2023
- 2022
- 2021
- 2020
- Publications
- Aquaculture (106)

Research Project: Improving Efficiency in Catfish Aquaculture **Location:
                            Warmwater Aquaculture Research Unit** 2022 Annual Report **Objectives**
                                

1. Develop improved production strategies for hybrid and channel catfish.
1.1. Expanding temporal harvest of hybrid catfish in intensive production systems.
1.2. Optimization of channel catfish production in intensively aerated single and multiple batch production systems.
1.3. Economic losses associated with warehousing market-sized hybrid catfish in intensive production systems.
1.4. Evaluate effects of longer-term maintenance feeding on body weight, survival, and processing yield of market-size hybrid catfish and determine optimum refeeding duration before harvesting.

2. Develop cost-effective feeds and optimal feeding practices for catfish aquaculture.
2.1. Compare diets containing fish meal, animal by-products, and all plant protein sources for growth and health of channel and hybrid fingerlings.
2.2. Optimize lysine supplementation in diets for channel and hybrid catfish.
2.3. Evaluate feed additives on growth and health of channel and hybrid catfish.

3. Environmental manipulation to improve growth and health of catfish.
3.1. Development of methods to promote natural food sources in catfish nursery ponds.
3.2. Evaluating chemical treatments and treatment strategies to control disease vectors.
3.3. Effects of natural feed supplementation on channel catfish growth and health.

4. Identify economic factors influencing cost-efficiency of catfish aquaculture.
4.1. Evaluate the economics of various traditional and alternative catfish production strategies.
4.2. Economic risk associated with various catfish production technologies.
4.3. Monitoring the adoption of various production enhancing technologies in the U.S. catfish industry. **Approach**
                                

We will develop improved production strategies for hybrid and channel catfish by exploring strategies to expand the temporal harvest of hybrid catfish from intensive production systems, optimize channel catfish production in intensively aerated single and multiple batch production systems, quantify economic losses associated with warehousing market-sized hybrid catfish in intensive production systems, and evaluate effects of longer-term maintenance feeding on body weight, survival, and processing yield of market-size hybrid catfish. We will develop cost-effective feeds and optimal feeding practices for catfish aquaculture through the comparison of diets containing fish meal, animal by-products, and all plant protein sources for growth and health of channel and hybrid fingerlings, optimization of lysine supplementation in diets for channel and hybrid catfish, and evaluation of feed additives on growth and health of channel and hybrid catfish. To obtain environments for improved growth and health of catfish, we will develop methods to promote natural food sources in catfish nursery ponds, evaluate chemical treatments and treatment strategies to control disease vectors, and determine the effects of natural feed supplementation on channel catfish growth and health. We will also determine economic risks associated with catfish production technologies and monitor the adoption of various production-enhancing technologies in the U.S. catfish industry. **Progress Report**
                                

Nutrition and Feeding: Diets containing 10% Porcine meat and bone (PMB) meal or more improved net yield and lowered feed conversion ratio during food fish production. Similar results were observed in experimental pond studies evaluating effects of lower protein diets and replacing fish meal with PMB. No differences in total feed fed, gross yield, FCR, survival or water quality variables were observed.  Results showed diets containing about 30% protein can support optimum growth of pond-raised channel catfish fingerlings of 2 g and larger in fertilized ponds fed once daily. Economic analysis suggested considerable cost savings by replacing fish meal with PMB meal. An ongoing study is evaluating diets supplemented with 1.5% catfish oil (CFO), or 1.5% menhaden oil (MHO) improves channel catfish condition before winter fasting and prevents protein catabolism. Dietary treatments have not affected weight, survival, hepatosomatic index, and whole-body proximate composition. However, fish fed CFO presented a significantly higher feed conversion ratio when compared to the control diet. Fat accumulated in the intraperitoneal (IP) cavity was also affected by dietary treatments. While fish fed CFO had the highest fat accumulation in the IP cavity, they were also more efficient in converting feed protein when compared to fish fed control diets. This suggests CFO supplementation aids protein-sparing effects and prevents amino acids from being used as metabolic substrates. Data indicates increased diet lipid will help maintain fish condition during winter fasting. Supplementing diets with additional iron have increased red blood production and minimized losses associated with anemia in market size fish. Hybrid catfish were fed graded doses of iron sulfate. No differences were observed for production performance and whole-body proximate composition. However, a linear correlation was observed where fish fed graded doses of iron presented higher hematocrits. Survival following enteric septicemia of catfish (ESC) challenge decreased with increasing iron. Research is being conducted to determine the effect of approved antibiotics on intestinal microbiome of healthy channel catfish. Following antibiotic therapy, fish fed probiotics following bacterial challenge had higher survival compared to fish fed the control reference diet.  Information will be used to develop feeding regimes to reestablish beneficial gut flora following antibiotic therapy.

Pond Ecology: Trematode infestations cause significant production losses and have been linked to farm closures. Current control measures rely on breaking the trematode life cycle by minimizing snail populations during catfish production. Applying copper sulfate to the pond margins is the most used method of snail control. While effective in killing snails, copper can result in fish losses due to oxygen deletions and direct toxicity to fish at elevated water temperatures when infestations are most problematic. To improve on treatment safety, multiple low dose treatments were effective in killing snails, and treatment levels 6 times less than a single dose treatment killed snail eggs and emergent embryos. While effective with a much higher safety level, treatments required 4 weekly treatments which creates logistical problems related labor and application time. A mechanized system for copper sulfate application was developed to improve treatment accuracy and increase application efficiency. The system uses a radar groundspeed sensor and a logic-based control system to distribute granular copper sulfate evenly and accurately along the pond margins in a single pass. The spatial and temporal distribution of snails is being evaluated in commercial catfish production systems to better refine treatment recommendations.

Production Management: A comparative economic study developed with commercial catfish farm data revealing split-pond systems using hybrid catfish were the least-cost production strategy, followed by multiple-batch systems employing channel catfish with increased aeration rates and intensively aerated ponds using hybrid catfish. Several previously profitable practices are no longer profitable. Economies of scale were evident throughout the analysis but stemmed from two different effects: intensification of production in individual ponds; and larger farm size. Information is being used to make profitable production strategy recommendations as industry practices evolve. Traditional multiple-batch production systems using channel catfish at lower stocking densities were no longer profitable under current market conditions. Results of this study suggest improved aeration rates and higher stocking densities can enhance production in multiple-batch systems. Given today’s production costs recommended stocking rates in traditional multiple batch systems is no less than 8,000 head per acre. 
Biomass of fish carried over winter determines the production capabilities of multiple batch channel catfish production strategies. A study was conducted to evaluate the effect of varying biomass of carryover fish understocked with the same number of fingerlings. Partial harvest and total marketable yield were higher for higher carryover biomass treatment. Economic analysis revealed decreased breakeven prices and increased net returns with increased stocking biomass. The lower biomass (3,000 lbs/acre) treatment was not profitable while the two higher treatments attained positive net cash flows. The effects of winter warehousing of market-sized hybrid catfish in intensive production systems were evaluated under different marketing scenarios. Fish treatments consisted of complete harvest of market-sized hybrid catfish in the fall, complete harvest in the following spring (over winter), and a partial winter harvest/complete spring harvest. The study did not find any significant difference in production other than feed fed being significantly higher in the fully overwintered treatment. Economic evaluations are underway determining the cost of production and cash flow associated with warehousing of market-size hybrids and financial risk associated with harvest delays.

Technological progress: High yield and greater control over the production process were the major reasons for the adoption of alternative catfish production technologies. High investment costs and increased risks associated with these technologies were the main deterrents of adoption. Characteristics of the technology such as productivity, perceived risk, and adoption costs, influenced early adoption decisions. Institutional factors such as prior involvement in Extension/research programs and farm characteristics of the scale of operation also shaped adoption decisions. Early adopters had significantly larger farms and a significantly greater percentage of hybrid catfish use. Adopting alternative, more intensive, production practices has been accompanied by increased adoption of complementary technologies of fixed-paddlewheel aeration, automated oxygen monitors, and hybrid catfish. As a result, the average aeration rate in the tristate region has increased to 4.2 hp/acre with 97% of catfish farms adopting automated oxygen monitors. About 53% of the water surface area in the tristate region was used for hybrid catfish production. Fingerling producers have also adopted a feed-based, oral vaccine against Enteric Septicemia of catfish, with 83% of the fingerling farms and 73% of the fingerling production area vaccinated against ESC in 2020. Increased adoption of productivity-enhancing technologies in the U.S. catfish industry explain the 59% increase in foodfish productivity since 2010. **Accomplishments**
                                

1. New treatment strategy for controlling snail populations in catfish production ponds. Trematode infestations on catfish farms have been linked to significant production losses and farm closures. Since recognition as an emergent disease in the late 1990’s, management strategies have been developed to break the trematode life cycle by eradicating the snail intermediate host in the pond environment. Copper sulfate is the most widely used treatment option and is highly effective against snails with a single application of 3 ppm but this treatment level can result in increased mortality in fish, especially when water temperatures are elevated. These losses are associated with direct toxicity to fish and algacidal properties of copper, causing algal bloom die offs that result in oxygen depletion within the pond ecosystem. Recent research by ARS researchers in Stoneville, Mississippi, generated from this project has demonstrated that weekly low-dose copper treatments (1.0-1.5 ppm) spread across four weeks are as effective in killing snails and treatment rates <0.1 ppm can halt snail reproduction and kill snail embryos. This approach is being combined with a new delivery system to better manage snail populations and reduce trematode populations in catfish ponds. 2. New technology for delivering controlled dosage of copper sulfate to catfish production ponds. Snails are an intermediate host to trematodes that cause significant production losses in catfish production. Copper sulfate pond treatments are used to control snail populations but are inconsistent and unreliable in concentration and distribution which increases potential risks to fish health and production.  To improve treatment accuracy and increase application efficiency, ARS researchers in Stoneville, Mississippi, in collaboration with researchers in Mississippi State University, Mississippi, developed a mechanized delivery system to apply copper sulfate crystals consistently and uniformly along the edge of the pond. The system was designed in a three-point hitch configuration, for tractor attachment, and driven in a single pass in a 2 to 5 mph range around pond margins. The system utilizes a radar groundspeed sensor and a logic-based control system to distribute granular copper sulfate evenly and accurately along the pond margins in a single pass. The delivery system is being further evaluated in field trials. 3. Economics and risk of catfish production. An economic analysis showed that an optimal amount of 4,000-5,000 lbs/acre of channel catfish can be carried over the winter in multiple-batch systems. Relative risk associated with commercial catfish production strategies were estimated by ARS researchers in Stoneville, Mississippi, with multiple batch farming of channel catfish being the least risky production strategy with greater probabilities of lower cost of production. Split ponds and intensively aerated ponds had a greater probability of maximizing returns. Price risk was not a significant contribution to economic risk for any production strategy in the short term (1-year) as fish prices remained relatively high and less fluid. Increased adoption of productivity-enhancing technologies such as intensively aerated ponds, split-ponds, automated oxygen monitors and ESC vaccinations were the central drivers of the rise in productivity of the U.S. catfish industry. **Review Publications**
                            *Cunningham, F.L., Hanson-Dorr, K.C., Ford, L., Middleton, D.R., Crain, A., Durst, L., Ware, C., Griffin, M.J., Mischke, C.C., Wan, X., Hanson, L.A. 2020. Environmental factor(s) and animal vector(s) associated with atypical Aeromonas hydrophila abundance and dissemination among channel catfish ponds. Journal of the World Aquaculture Society. 51:750-762. https://doi.org/10.1111/jwas.12608.*
                                *Mischke, C.C., Wise, D.J., Griffin, M.J., Rosser, T.G., Tiwari, A., Rehman, J.U., Ashfaq, M.K., Khan, I.A. 2021. Effects of multiple, low-dose copper sulfate treatments on the marsh Rams-Horn Snail. North American Journal of Aquaculture. 83:363-371. https://doi.org/10.1002/naaq.10207.*
                                *Li, M.H., Wise, D.J., Mischke, C.C., Kumar, G., Greenway, T.E., Tiwari, A., Lucas, P. 2020. Reducing dietary protein concentrations and replacing fish meal with porcine meat and bone meal do not affect growth or feed conversion of pond-raised fingerling channel catfish, Ictalurus punctatus. Journal of the World Aquaculture Society. 51:364-372. https://doi.org/10.1111/jwas.12653.*
                                *Kumar, G., Hegde, S., Wise, D., Mischke, C.C., Dorr, B. 2021. Economic losses of catfish to Avian Predation: A case report. North American Journal of Aquaculture. 83:127-137. https://doi.org/10.1002/naaq.10170.*
                                *Mischke, C.C., Wise, D.J., Li, M.H., Tiwari, A. 2020. Azomite application does not positively influence water quality, phytoplankton populations, or zooplankton populations when preparing Mississippi channel catfish nursery ponds for stocking. North American Journal of Aquaculture. 82:414-418. https://doi.org/10.1002/naaq.10163.*
                                *Tiwari, A., Woodyard, E.T., Rosser, T.G., Griffin, M.J., Mischke, C.C. 2021. Temperature modulation and feed supplementation significantly improve population growth of laboratory-reared dero digitata (Annelida: Naididae). North American Journal of Aquaculture. 83:327-335. https://doi.org/10.1002/naaq.10201.*
                                *Griffin, M.J., Ware, C., Rosser, T.G., Woodyard, E.T., Mischke, C.C., Byars, T.S., Wise, D.J. 2020. Monoculture of female channel (Ictalurus punctatus) × male blue (I. furcatus) hybrid catfish mitigates proliferative gill disease caused by Henneguya ictaluri (Cnidaria: Myxobolidae) in catfish aquaculture ponds. Journal of the World Aquaculture Society. 51:729-739. https://doi.org/10.1111/jwas.12695.*
                                *Li, M.H., Wise, D.J., Kumar, G., Bosworth, B.G., Mischke, C.C., Aarattuthodiyil, S., Rutland, W., Lucas, P.M. 2020. Effects of long-term restricted feeding followed by full feeding on growth, processing yield, fillet proximate composition, and economics of marketsize hybrid catfish, female Ictalurus punctatus × male Ictalurus furcatus. Journal of the World Aquaculture Society. 51:931-943. https://doi.org/10.1111/jwas.12727.*


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