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United States Department of Agriculture

Agricultural Research Service

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Research Project: INTEGRATED APPROACHES FOR IMPROVING EFFICIENCY AND SUSTAINABILITY OF LOW-SALINITY MARINE AQUACULTURE PRODUCTION

Location: Harry K. Dupree Stuttgart National Aquaculture Research Center

2011 Annual Report


1a.Objectives (from AD-416)
Objective 1: Determine nutrient requirements and develop feeding strategies and diets for optimal growth, efficiency, and reproductive success of marine fish reared in low-salinity recirculating systems. Subobjective 1A. Develop nutrient digestibility values for traditional and novel feed ingredients, resulting in broader ingredient choices for Florida pompano. Subobjective 1B. Determine indispensable amino acid (IAA) requirements for Florida pompano juveniles in low-salinity and/or seawater. Subobjective 1C. Reduce the utilization of fish meal and fish oil during the life-cycle production of Florida pompano reared in low salinity. Subobjective 1D. Evaluate dietary strategies to improve growth and performance of marine fish reared in low-salinity environments. Objective 2: Develop year-round spawning strategies for captive broodstock and larviculture methods for sustainable seed production of high-value marine finfish for culture in low-salinity environments. Subobjective 2A. Develop improved spawning protocols for sustainable seed production of high-value marine finfish. Subobjective 2B. Develop improved larviculture methods for sustainable production of high-value marine finfish. Subobjective 2C. Develop optimal methods for acclimatizing larval or juvenile Florida pompano to low-salinity culture conditions. Objective 3: Develop and evaluate solutions that improve efficiency of water and energy utilization and waste management technologies for environmentally sustainable low-salinity recirculating aquaculture systems. Subobjective 3A. Improve efficiency of system components in a low-head recirculating aquaculture system that will result in less water and energy use, greater carrying capacity, and increased cost efficiency. Subobjective 3B. Develop a cost-effective effluent management strategy that will provide treatment and reuse of effluent water and sludge from a low-salinity recirculating aquaculture facility. Subobjective 3C. Evaluate sustainable production of market size Florida pompano in low-salinity recirculating systems.


1b.Approach (from AD-416)
Florida pompano will serve as a model species. Key nutrient requirements and availability of nutrients from alternatives to fish meal and fish oil will be determined and diets developed for production in recirculating, low-salinity systems. Strategies for inducing Florida pompano to spawn, and less labor-intensive and economical methods for rearing larval fish will be developed to provide a consistent supply of fish for year-round culture. Culture system components will be designed and evaluated to develop cost-effective methods for maintaining a healthy environment for marine fish reared in low salinity, and effluent treatment strategies developed to reduce environmental impacts of rearing fish to market size.


3.Progress Report
During the reporting period the project 6225-63000-008-00D was identified for closure as a Congressional earmark reduction. The progress reported here builds on the accomplishments of FY2010 and represents progress between the beginning of FY2011 and termination of the project. Increased stocking densities, and optimal feeding strategies, water reuse, and a simplified energy-efficient alternative to traditional recirculating aquaculture systems were evaluated for effects on growth rate, feed conversion, time to market, and the overall production costs of rearing pompano in low-salinity recirculating systems. Through completion of two growth studies it was determined chronic mortality previously observed following long-term exposure of pompano to a salinity of 3 g/L could be eliminated in rearing conditions of 6 to 8 g/L salinity. Under the conditions of these studies it was determined pompano could be reared from 50 g to market-size (650 g) in 263 days. A graduated optimal feeding rate for pompano reared in low-salinity, based on increasing fish size, was determined for the 263 day growth period. Final densities at harvest approximated a two-fold increase over densities previously attained in production scale low-salinity recirculating systems. Results of both studies indicated the simplified system resulted in better growth and survival and outperformed the traditional recirculating aquaculture system based on simple economic analysis. It was hypothesized the better performance observed with the alternative recirculating system was the ability to overcome water quality limitations observed in traditional recirculating systems, namely difficulty in removal of carbon dioxide and its effect on water pH. A small-scale prototype vessel (reactor) containing a specialized calcium carbonite was designed and evaluated for its ability to remove dissolved carbon dioxide in a low-salinity recirculating aquaculture system under a variety of water quality parameters including different alkalinity and pH. A larger scale reactor was then incorporated into an operating marine recirculating aquaculture system to evaluate its efficacy. A mathematical model was developed and verified with the larger recirculating aquaculture system establishing equilibrium at an alkalinity of approximately 135 mg/L as CaCO3, carbon dioxide of approximately 9 mg/L, and a pH of approximately 7.0 within 4 days and remained stable throughout a 2-week observation period. This type of reactor has the potential to simplify alkalinity and pH control, and aid in carbon dioxide removal in recirculating aquaculture systems, overcoming one of the principal limitations of recirculating systems. The specialized calcium carbonite is less expensive than the traditionally used and less efficacious sodium bicarbonate, increasing control of the water quality and reducing production costs.


4.Accomplishments
1. Alternative recirculating aquaculture system outperforms traditional recirculating system. Although recirculating aquaculture technologies allow intensive fish production, increased biosecurity, and reduction in water use and effluent discharge, traditional systems are expensive to operate, and capital and energy intensive. Therefore improvements in cost and energy efficiencies are needed to maximize profits per unit of volume. ARS researchers in Fort Pierce, FL, in collaboration with Florida Atlantic University, demonstrated greater production and economic efficiencies using a low-energy, low-pressure recirculating system in a direct side-by-side comparison with traditional recirculating systems for the production market-ready Florida pompano in low-salinity environments. By nearly doubling the number of pompano produced per unit volume, while also establishing greater cost and production efficiency, this technology provides marine fish producers an option that can be readily implemented to offset some of the $10 billion annual US seafood trade deficit.

2. Preferable method for the removal of off-flavors in fish developed. Accumulation of compounds that impart unpalatable flavors in harvested fish presents a challenge to the aquaculture industry, particularly when recirculating aquaculture technologies are used. The traditional approach to address this challenge utilizes large-volume water exchanges at the end of the production cycle; however, this is unsuitable in areas with limited water resources or water discharge constraints. ARS in collaboration with Florida Atlantic University researchers designed a filtration device utilizing wax paraffin beads and evaluated it relative to large-volume water exchanges. Following production of market-size pompano, water samples and fish fillets were chemically analyzed for off-flavor compounds over a 14-day period, and samples were evaluated by a trained taste test panel for residues of off-flavor. Chemical analysis indicated no differences between the two methods in concentrations of off-flavor compounds, and the taste test panel could not detect unpalatable flavors. This new technology for reducing unpalatable compounds in fish reared in recirculating systems expands opportunities to inland areas previously underutilized due to limited water resources or water discharge constraints.


Review Publications
Garr, A.L., Acosta-Salmon, H., Riche, M.A., Davis, M., Capo, T.R., Haley, D.I., Tracy, P. 2011. Growth and survival of juvenile queen conch, Strombus gigas fed artificial diets containing varying levels of digestible protein and energy. North American Journal of Aquaculture. 73:34-41.

Pfeiffer, T.J., Summerfelt, S.T., Watten, B.J. 2011. Comparative performance of CO2 measuring methods: Marine aquaculture recirculation system application. Aquacultural Engineering. 44(1):1-9.

Riche, M.A., Williams, T. 2011. Fish meal replacement with solvent extracted soybean meal or soy protein isolate in a practical diet formulation for Florida pompano (Trachinotus carolinus, L.) reared in low salinity. Aquaculture Nutrition. 17:368-379.

Pfeiffer, T.J., Riche, M.A. 2011. Evaluation of a low-head recirculating aquaculture system used for rearing Florida pompano to market size. Journal of the World Aquaculture Society. 42:198-208.

Rotman, F.J., Riche, M.A., Van Wyk, P., Benetti, D.D. 2011. Efficacy of a commercial probiotic relative to oxytetracycline as Gram-negative bacterial control agents in a rotifer (Brachionus plicatilis) batch culture. North American Journal of Aquaculture. 73:343-349.

Last Modified: 9/10/2014
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