Location: Warmwater Aquaculture Research Unit
2020 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
Improving Efficiency in Catfish Aquaculture is a new project beginning January 1, 2020. All pond production studies associated with this agreement have been initiated (March-April) but will not be harvested for data collection until October 2020. Since the reporting period is during the mid-point of the production season, production studies have not been completed and are reported as substantially met. Completed studies will be reported in the 2021 progress report.
1.1. Cost of producing stocker size hybrid catfish is being evaluated by stocking fingerlings (0.08lb/fish) at 40000, 60000, and 80000/acre in replicates of five. Fish are being fed once daily to satiation, and ponds will be clean harvested in early fall. The stocker sized fish will be stocked in intensively aerated and split-pond systems at 10000 fish/acre. Preliminary results suggest high built-up of nitrogenous waste associated with increased feeding rates in intensively aerated ponds.
1.2.A. The economics of raising channel catfish in intensively aerated ponds operated under the single-batch cropping system is being evaluated in 1-acre experimental ponds. Channel catfish fingerlings averaging 0.09 lb were stocked at 6,000, 8,000, 10,000, and 12,000 fish/acre with six replicate ponds per treatment. A treatment of hybrid catfish fingerlings stocked into five replicate ponds at 12,000 fish/acre is serving as a control to compare the economic performance of channel catfish against optimal hybrid catfish stocking densities. All ponds were provided with a fixed-paddlewheel aerator (10 hp/acre) and are being fed once daily to apparent satiation. Upon harvest in early winter, relative economic performance of the treatments will be evaluated using enterprise budgeting techniques.
1.2.B. Economic efficiency of channel catfish raised in a traditional multi-batch production system is being evaluated. Twelve one-acre ponds were understocked with 6000, 8000, and 10000 fingerlings/acre (mean weight = 0.08 lb/fish) over equal weights of carryover fish (~1.0lb/fish @ 4000 lb/acre). Fish are being fed once daily to apparent satiation with a 28% protein floating feed and aerated with a single 10 hp electric paddlewheel aerator. Upon harvest in early winter, relative economic performance of the treatments will be evaluated using standard cost and cash flow analysis.
1.2.C. This study is planned for 2021 production season.
1.3. Effects of partial harvest and overwintering of hybrid catfish is being conducted in 15 one-acre ponds. Ponds were stocked with 10,000 fish/acre and managed in intensively aerated ponds (10-hp/acre). Five replicate ponds are serving as controls which will be harvested after ~200 days, while another five-replicate treatment will represent a partial-marketing scenario (30% of market-sized fish harvested) at the end of ~200 days and later completely harvested during spring of 2021. The third treatment with five replicates will be maintained without harvesting until the spring of 2021 (~300 days). An enterprise budget will form the basis of economic analysis. Quarterly cash flow budget (2-year) will be simulated to account for the cash inflow and outflow associated with warehousing of market-size hybrids as well as the financial risk associated with production delays arising from warehousing.
1.4 A The effects of long-term restricted feeding followed by full feeding on production and processing characteristics, fillet composition, and economics of market-size hybrid cat¿sh will be evaluated. Market-size fish averaging 1.49 lb have been stocked into 24 ponds (0.1 acre) at about 7,000 sh/acre. Fish are being fed either once or twice weekly and will continue to be fed for four months or fed once or twice weekly for four months followed by 15- or 30-day daily full feeding. All fish are being fed to apparent satiation on days fed.
2.2 The effects of available lysine (AL) concentrations in 28 and 32% protein diets on production and processing characteristics, proximate composition, and lysine concentrations in the fillet of channel catfish are being investigated. Diets were formulated to contain 28% protein with 1.22 and 1.43% AL, and 32% protein with 1.43 and 1.63% AL, which were equivalent to 4.37, 5.1, 4.46, and 5.1% AL of protein, respectively. Fingerlings with a mean initial weight of 32 g/fish were stocked into 20 ponds (0.1 acre) at 8,000 fish/acre. Fish are being fed the experimental diets once daily to satiation.
2.3 The effects of dietary Azomite or sea salt on the growth performance and disease resistance of channel catfish was conducted under laboratory conditions. Fingerlings were fed diets supplemented with Azomite (0.25% or 0.50%) or sea salt (0.5% or 1.0%) for 9 weeks in trial 1 and for 5 weeks in trial 2. The growth performance (weight gain and feed conversion ratio) and survival were determined at the end of the feeding trials. The resistance to Edwardsiella ictaluri infection was also evaluated in fish fed diets containing 0.5% Azomite or 1.0% sea salt in trial 2. There was no significant difference in the growth performance of the fish fed Azomite- or sea salt-supplemented diets compared with control animals (P > 0.05). The mortality rate of the fish 28-day post E. ictaluri challenge did not differ significantly among groups receiving different dietary treatments. The results indicate dietary supplementation with Azomite or sea salt at the tested levels had no significant effect on either growth performance or disease resistance against E. ictaluri in channel catfish fingerlings.
3.1 Azomite® is a hydrated sodium calcium alumina silicate mined from a volcanic deposit in Utah. The product contains many micronutrients which may be beneficial in preparing catfish nursery ponds for stocking. A 5-week study is being conducted to compare water quality, phytoplankton, and zooplankton populations in ponds treated with 0 kg/ha, 50 kg/ha, or 100 kg/ha Azomite® in Channel Catfish Ictalurus punctatus nursery ponds.
3.2 Studies will be conducted to determine the toxicity of copper sulfate to snail eggs, larvae, immature and reproductively mature snails as well as effects of copper on snail reproduction. Snail colonies have been expanded for laboratory and field testing.
4.1. On-farm production records detailing costs associated with various management strategies are being collected for analysis as part of an ongoing industry survey. An economic analysis will capture both variable and fixed costs associated with the various production strategies followed on commercial catfish farms. Farm data on production strategies will include data on investment capital needed to convert traditional open ponds to alternative production systems as well as operating costs including fingerlings, feed, labor costs, electricity usage, and repair and maintenance. Efforts will be made to investigate the economies of scale associated with catfish farming practices.
4.2. The production records from the ongoing survey in Objective 4.1 will be used to stochastically predict the economic risk associated with various catfish farming practices. Monte Carlo simulations (1,000 iterations/ simulation) will be run for the risk analysis for each production scenario using Crystal Ball® (Oracle, Redwood Shores, California, USA). Probability distributions of net returns above total costs will be generated by setting net returns greater than or equal to the $0 as a limit reference point for a farmer to avoid losses. Probability levels of technologies being profitable (certainty levels of achieving net returns above the reference point) will be recorded. The contribution of each risk variable to variation in net returns will be measured as an indicator of risk. Efforts will be made to stochastically rank production alternatives based on the inherent economic risk.
4.3. Survey results evaluating the adoption of alternative catfish production technologies suggest intensively aerated ponds and split-ponds systems are increasingly being adopted by the U.S. catfish industry. Adoption of these two alternative production technologies is considered the primary reason for the recent increase in productivity in the U.S. catfish industry. In-pond raceways that were also characterized as having high initial investments are no longer in use on U.S. catfish farms likely due to the high fixed costs as well as the lack of profitability. The catfish production area in intensive-aeration systems appears to have outpaced that of split ponds in recent years. This may be due to the entry of more risk-averse producers who have taken advantage of readily available paddlewheel aerators, a complementary production improving technology with greater ease of adoption at lower investment cost than split ponds. Much of this growth is from the early-majority and late-majority adopters, who began to adopt mostly intensive-aeration systems and some additional split-pond systems in recent years. The watershed ponds in west Alabama and east Mississippi are easier and less expensive to set up for intensive aeration scenarios as they require no dirt work or pond modification compared to split ponds. Compared to watershed ponds, levee-style ponds common to the Mississippi River Delta can be easily converted to a split pond system, which increases adoption in this region.
Accomplishments
Review Publications
Guy, E., Mischke, C., Colvin, M., Allen, P. 2019. Zooplankton selectivity by black buffalo in fertilized ponds. North American Journal of Aquaculture. 81:215-221.
Mischke, C., Filbrun, J., Li, M., Chatakondi, N.G. 2019. Quantifying the contribution of zooplankton to channel catfish and hybrid catfish growth in nursery ponds. Aquaculture. 510:51-55.
Rosser, T., Khoo, L., Wise, D., Mischke, C., Greenway, T., Alberson, N., Reichley, S., Woodyard, E., Steadman, J., Ware, C., Pote, L., Griffin, M. 2019. Arrested development of Henneguya ictaluri (cnidaria: myxobolidae) in female channel catfish × male blue catfish hybrids. Journal of Aquatic Animal Health. 31:201-213.
Mischke, C.C., Wise, D.J., Tucker, C.S., Griffin, M.J., Baker, B.H., Greenway, T.E., Byars, T.S., Tiwari, A. 2019. Copper sulfate pre-treatment for snail control reduces channel catfish survival. North American Journal of Aquaculture. 81:160-168.
