Location: Warmwater Aquaculture Research Unit
2021 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
The cost of producing stocker hybrid catfish was evaluated at fingerling stocking densities of 40000, 60000, and 80000 fish/acre. Preliminary results suggest high built-up of nitrogenous waste associated with increased feeding rates in traditional open ponds and the strategy of raising hybrids under high stocking densities without restricting feeding rates. Survival ranged from 0%-43% primarily due to high ammonia built up in water along with secondary water quality related stress induced diseases. Year 1 data demonstrated production of three fish crops in two seasons is not economically feasible. This in combination with covid restrictions has led to the termination of this project. Funds will be redirected to other projects to reflect industry priorities.
Economics of raising channel catfish in intensively aerated ponds was evaluated at stocking densities of 6,000, 8,000, 10,000, and 12,000 fish/acre. A treatment of hybrid catfish fingerlings stocked at 12,000 fish/ac was concurrently evaluated for comparison channel catfish production showed a nominally linear increasing yield trend with stocking density. This trend was not seen in the relationship between costs and stocking density: the highest breakeven price was associated with the lowest density treatment (6,000 fish/acre), and the least cost was associated with the intermediate density of 8,000 fish/acre. The hybrid catfish treatment outperformed channel catfish treatments in terms of yield and resulted in a lower cost of production and better long-term returns This study indicated channel catfish do not perform well at densities greater than 8,000 fish/acre in single-batch production systems.
Proven stocking recommendations are required for the efficient implementation of recent developments in multiple-batch production. Ponds were understocked with 7000, 8250, and 10500 fingerlings/acre over equal weights of carryover fish. Density-dependent differences were absent for gross, net, daily net yields, marketable yields, growth, and survival. Sub-marketable yield and feeding rate increased significantly with increased understocking density. Economic analysis revealed increased breakeven prices and diminished net returns with increased stocking density when sub-marketable fish were not considered as revenue. These differences in production costs and profits became minimal when sub-marketable fish were included as revenue. All three density treatments attained positive annual net cash flows. This study validates channel catfish understocking densities of 7000–10500 fish/acre improve cost efficiency in intensively aerated, multiple-batch production systems.
The effects of winter warehousing of market size hybrid catfish in intensive production systems were evaluated under different marketing scenarios. After reaching market size, fish treatments consisted of complete harvest in the fall, complete harvest in the following spring (over winter) and partial winter harvest/complete spring harvest. Economic analysis determining cost of production and quarterly cash flow budget will be simulated to account for the cash inflow and outflow associated with warehousing of market-size hybrids and financial risk associated with harvest delays at the end of the study.
The effects of long-term restricted feeding followed by full feeding on production and processing characteristics, and economics was evaluated in market-size hybrid catfish. Fish were fed once or twice weekly for 4 months or once or twice weekly for 4 months followed by 15- or 30-day daily full feeding. Fish fed once weekly for 4 months gained about 30% weight and those fed twice weekly gained 70% weight but with decreased fillet yield. Based on economic analysis and processing yield, it is suggested fish fed once weekly should be given full feed for 15 days to improve fillet yield before harvest. Fish fed twice weekly can be harvested without a reconditioning period.
This study evaluated dietary protein concentrations and replacing fish meal with porcine meat and bone meal (PMB) for pond-raised fingerling channel catfish. Diets were formulated to have 28, 32, or 35% protein using soybean meal, cottonseed meal, and fish meal as protein sources. A fourth diet contained 32% protein with fish meal being replaced with PMB. Small fingerlings were stocked at 70,000 fish/acre and were fed once daily to apparent satiation. There were no significant differences in total diet fed, gross yield, final weight, feed conversion ratio, survival, or condition factor among diets. Results show a diet containing about 30% protein can support optimum growth of pond-raised channel catfish fingerlings fed once daily to apparent satiation. PMB can completely replace fish meal in a 32% protein diet. Economic analysis suggests considerable cost savings by replacing fish meal with PMB and reducing protein concentrations.
A pond study is on-going to examine 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. 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 and will be harvested in the fall.
Azomite is a hydrated sodium calcium alumina silicate mined from a volcanic deposit in Utah. The product contains many micronutrients that may be beneficial in preparing catfish nursery ponds for stocking. Effects of Azomite on water quality, chlorophyll-a, phytoplankton and zooplankton were negligible. Overall, there were no beneficial effects of adding Azomite to channel catfish nursery ponds. Aquashade, a dye used to minimize light penetration through water, was also evaluated to control off-flavor. Dye treatments had no effect on nitrite or total ammonia concentrations, hours of supplemental aeration, phytoplankton standing crops, or fish production. Supplementing catfish fry diets with live or dried zooplankton was shown to increase growth by 20% over the initial 5 days on feed. Live zooplankton was also shown to improve vaccine efficacy. However, this effect was not observed with diets supplemented with dried zooplankton. No differences in growth and disease resistance were observed in repeated studies and the project was terminated.
To mitigate losses associated with trematode infestations, research has focused on eradicating snails from ponds. Whole pond treatments with 0.64-1.27 mg/L copper (Cu) have been effective in killing snails; however, Cu can be toxic to fish and may result in oxygen depletions due to its algacidal properties. Given these constraints, the potential for repeated low doses of Cu as a safe, yet effective snail treatment was investigated. Adult marsh mams-horn snails received four weekly doses of 0, 0.10, 0.19, 0.38, and 0.76 mg/L Cu. Treatments of 0.38 mg/L Cu killed 100% of snails with partial mortality observed at doses < 0.38 mg/L Cu. Similar results were observed in experimental pond trials. A second study evaluated the effects of repeated Cu doses on egg and juvenile snail survival. Two weekly doses of 0.19 mg/L Cu were enough to kill embryos, and all doses = 0.05 mg/L Cu prevented snails from hatching. Repeated weekly doses < 0.38 mg/L Cu may reduce adult snail populations, prevent eggs from hatching and be safer to fish than a single dose of 0.64-1.27 mg/L Cu. These data also suggest weekly doses of 0.05 mg/L Cu may suppress snail populations by limiting snail hatching and impeding juvenile snail survival.
A comparative economic study was developed with data from 325 ponds on 38 commercial catfish farms (Alabama, Arkansas, and Mississippi) providing estimates of production cost, profitability, and indicators of farm liquidity for common catfish growout strategies. Profitability differed across catfish farming practices. The split-pond system using hybrid catfish was the least-cost production strategy, followed by the multiple-batch system employing channel catfish with increased aeration rates and intensively aerated ponds using hybrid catfish. Long-term profitability of catfish farming practices increased with increases in farm size. Only split and intensively aerated ponds (hybrid catfish and multiple-batch production with channel catfish with increased aeration rates) were profitable in the long-run on small farms.
The U.S. catfish industry has undergone significant technological progress to achieve cost efficiencies. Producers have been increasingly adopting improved production practices such as split ponds and intensively aerated ponds in recent years. Subsequently, there has been increased adoption of complementary technologies such as fixed-paddlewheel aeration, automated oxygen monitors, and hybrid catfish. A multi-state survey conducted during 2019-2020 in Alabama, Arkansas, and Mississippi, revealed the increased adoption of intensively aerated ponds (15,788 acre) and split ponds (2,940 acre). Over 31% of the foodfish production area is under intensive production. Adoption of such intensive practices has also led to greater use of complementary production technologies. As a result, the average aeration rate in the tristate region has increased to 4.12 horsepower/acre with 96% of catfish farms adopting automated oxygen monitors. About 53% of the water surface area in the tristate region was in hybrid catfish production. Results indicate productivity enhancement and technological progress in the U.S. farm-raised catfish industry.
Accomplishments
1. Factors affecting catfish aquaculture profitability. Catfish farming practices have changed, resulting in an approximately 50% increase in productivity (lb/ac produced) over the 4 years from 2014 to 2018. Economic evaluation of commercial catfish production strategies provides insights into the costs and profitability structures of the various catfish farming practices observed across the U.S. industry, with a focus on the underlying causes for economic success or failure. Previously profitable practices may no longer be profitable given changes in cost structures and economic conditions. Newer, more intensive farming practices are generally more profitable but require greater attention to cost efficiencies than past extensive practices. Profitability was sensitive to feed efficiency, especially in more intensive systems. Economies of scale is a reality in catfish farming, stemming from two different effects: (a) production intensification in individual ponds creates cost efficiencies by spreading fixed costs over greater volumes of production per acre; and (b) increased farm size reduces costs of production through better capacity utilization of equipment and management. Nevertheless, simply intensifying production and/or increasing farm size is not sufficient to ensure profits. ARS researchers in Stoneville, Mississippi, showed profitability and liquidity risk also varied with choice of stocking density, aeration rates, equity levels, and channel or hybrid catfish. Thus, careful cost control and analysis, including assessment of efficiency of use of capital assets, is essential to make management decisions.
2. Technology adoption in catfish aquaculture. Technology adoption is critical for the evolution and maintained profitability of U.S. catfish aquaculture. ARS researchers in Stoneville, Mississippi, found that recent survey monitoring technological progress in catfish industry suggested the catfish industry is evolving through the increased adoption of intensive production technologies, developed through the previous project agreement, such as intensively aerated ponds and split-pond systems. More than 33% of the catfish production area in 2019 was under intensive production. The average aeration rate in the industry in 2019 was 4.2 hp/acre, a 68% increase in just the last decade. More than 96% of the surveyed farms had adopted automated oxygen monitoring systems. About 53% of the catfish production area was using hybrid catfish. Accurate estimates of the technology progress will provide valuable insights for policymakers in making future industry decisions.
