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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

2010 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
This is a new project replacing project 6225-63000-007-00D with a start date of 11/13/2009. There was a period between the beginning of FY 2009 and the termination date of the prior project. Some of the progress and accomplishments reported here were initiated under the previous project. Stocking densities, feeding strategies, and water reuse were evaluated for effects on growth rate, feed conversion, time to market, and overall production costs of rearing pompano in low-salinity recirculating systems. It was determined that long-term exposure of pompano to a salinity of 3 mg/L leads to chronic mortality and systemic organ failure, which is partially reversible with an increase in salinity. A Specific Cooperative Agreement was initiated with Purdue University to establish linkages between gene expression and the physiological response of pompano to low salinity to develop targeted strategies to address the problem. Data on total ammonia removal rates (g ammonia removed / m3 media-d) for moving bead biofilters were obtained under low salinity conditions (10-14 mg/L) over three production cycles. Characterization of filter performance is ongoing using various system feed rates, stocking densities, and salinities. The microalgae Spirulina contains natural pigments that have antioxidant and color-enhancing properties, making it an attractive additive to aquaculture feeds. Preliminary observations suggested Spirulina enhances color in pompano, increasing consumer acceptance. A trial was conducted to evaluate the efficacy of Spirulina as a dietary component in finishing diets to increase consumer appeal of market-size pompano. Data analysis is ongoing. Sustainable production of food fish will require alternatives to fish meal in aquaculture feeds. Principal alternatives include plant proteins; however, most are limiting in the amino acids lysine (Lys) and/or methionine (Met). Optimal growth can be obtained by supplementing the diets with Lys and Met. We recently established the Lys requirement for pompano, and trials are underway to establish the Met requirement to ensure plant-based diets contain sufficient levels for optimal growth. To reduce reliance on wild harvested seedstock, protocols were developed for spawning pompano to provide for year-round seedstock and potential domestication. Additionally, growth, survival, and composition of larvae fed an alternative live feed organism were determined to develop optimal feeding strategies. Efficiency of ammonia and solids removal of recirculating aquaculture system components was evaluated to establish design criteria for low-salinity recirculating systems. Energy use, energy efficiency, and daily water budgets were determined for production scale recirculating systems. Less energy demanding low-head systems were developed and evaluated relative to conventional systems that use energy-demanding pumps resulting in substantial cost savings.


4.Accomplishments
1. Increased efficiency of water and energy use in recirculating aquaculture systems. A significant challenge faced by fish culturists utilizing recirculating aquaculture systems is operating these systems with minimal energy and water costs. A low energy use recirculating system was developed and evaluated for the production of market size Florida pompano relative to a conventional type recirculating aquaculture system. Production of market size pompano was achieved in this system while maintaining energy costs at almost 33% of that of a comparable conventional pumping system, and daily water use was kept to less than 5% of the system volume. This information benefits both freshwater and marine fish culturists utilizing recirculating aquaculture technologies by substantially reducing operating costs and water consumption resulting in increased profits per unit production.

2. Improved nitrification from biofilters in recirculating aquaculture systems. Energy cost is second only to feed in terms of the operational costs of utilizing recirculating aquaculture systems. The low energy, water, and capital costs of a moving media bed biofilter make them an ideal biofilter for the removal of toxic ammonia in recirculating aquaculture systems; however, their operation in low salinity conditions has not been described. The rates of ammonia removal using moving media bed biofilters were obtained in recirculating aquaculture systems under low-salinity conditions. The studies indicated total ammonia removal rates were equivalent or slightly greater than conventional biofilters in a low-salinity environment. This accomplishment establishes operational and design criteria for moving media bed biofilters used in low head recirculating aquaculture systems, reducing capital and operational costs of inland marine fish producers.

3. A nutritious alternative live feed for pompano is identified. Pompano require very small prey items at first feeding, but the traditionally used rotifers may not be nutritious enough and too large for recently hatched pompano, and something smaller such as copepods may be more appropriate. Recently hatched Florida pompano were fed the traditional rotifers, copepods, or a mixture of the two. The fastest growth was exhibited in larval pompano fed the mixture, and although survival was the same among pompano fed rotifers or copepods, stress resistance was greater in those fed copepods. Pompano fed copepods had higher levels of some essential fatty acids, which is likely the reason for the better stress resistance. The discovery of a more nutritious first feed for pompano provides hatchery managers an alternative to rotifers that are prone to population collapses that threaten the likelihood for successful marine larviculture.

4. Year-round spawning achieved with pompano. Lack of sustained year–round production of seedstock for grow-out operations is one of the foremost bottlenecks of marine finfish aquaculture. Broodstock production measured as number of eggs, fertilization, egg quality, and hatch rate was quantified at monthly intervals from six distinct populations of Florida pompano broodstock over a 12 month period. Four of the six populations spawned between 7 and 10 months of the year having an average production of 1.9 million eggs/year with no discernable diminishment in egg quality over time. This work demonstrates Florida pompano seedstock can be produced year-round from a modest population of broodstock benefiting marine fish culturists by overcoming one of the foremost bottlenecks of marine finfish aquaculture.

5. Two commonly used feeding stimulants not warranted in pompano diets. Unpalatable fish diets can be improved with feeding stimulants to increase feed intake and growth, thereby shortening the culture cycle and increasing profits; however, feeding stimulants can significantly increase the price of feed. Two conventional feeding stimulants were evaluated for their efficacy in increasing feed intake in very young Florida pompano. A novel approach was developed where the diets were individually marked to measure total intake and to determine if any of the diets were preferentially eaten. Although the results suggest utilization of these expensive feeding stimulants is not warranted in diets for young Florida pompano, they also suggest the ability to predict feed intake with this method is highly accurate, demonstrating the utility of this approach. Culturists producing pompano will benefit from this information by eliminating these feeding stimulants and their associated costs from the feed formulation and final product.


Review Publications
Weirich, C.R., Wills, P.S., Baptiste, R.M., Riche, M.A. 2010. Production characteristics and body composition of juvenile cobia fed three different commercial diets in recirculating aquaculture systems. North American Journal of Aquaculture. 72:43-49.

Weirich, C.R., Wilis, P.S., Baptiste, R.M., Woodward, P.N., Riche, M.A. 2009. Production characteristics of body composition of Florida pompano reared to market size at two different densities in low salinity recirculating aquaculture systems. North American Journal of Aquaculture. 71:165-173.

Last Modified: 9/10/2014
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