2003 Annual Report 1.What major problem or issue is being resolved and how are you resolving it? Question 1: The overall goal of this project is to develop management practices that provide greater control of environmental quality in channel catfish aquaculture ponds. There are specific areas of research have been identified through interactions with industry, extension service representatives, and research personnel that are unique to hill-farming areas of the commercial catfish industry, and also a clear need for diversification and efficiency in the freshwater aquaculture industry in the United States. There is a lack of efficient management practices for alternative freshwater species to achieve economically enterprises; thus our approach is to develop appropriate management strategies. Off-flavor caused by certain species of blue-green algae is the most serious water quality problem in commercial catfish farming, including on farms located the Ahill@ areas of East Mississippi. Off-flavor fish can not be processed and therefore must be held in ponds until flavor quality becomes acceptable. Additional costs are incurred from holding off-flavor fish because additional feed is required to maintain fish body weights and potential revenue may be lost as fish die from diseases during the holding period. Blue-green algae dominate the phytoplankton communities of most eutrophic commercial catfish ponds. As phytoplankton density increases, primary productivity will be limited by the availability of nutrients to the availability of light. In light-limited phytoplankton communities, blue-green algae possess a number of attributes that allows their competitive dominance over other species. One logical approach to the control of off-flavor is to attempt to shift the community composition away from dominance by blue-green algae. Current knowledge of the eco-physiology of blue-green algae suggests that a number of approaches may be efficacious. Mixing of pond water is one approach that may overcome the light-limitation of more desirable green algae. This study was designed to evaluate the effect of water mixing on phytoplankton community composition, water quality and fish production in catfish ponds. Reproductive success in catfish is relatively low; thus, there is need for improvement. To achieve this we are conducting also studies to elucidate hormone cycles, egg quality and reproductive performance in channel catfish. 2.How serious is the problem? Why does it matter? Question 2: The United States foreign trade deficit for seafood is $ 6 billion annually. There is an ongoing need to increase domestic production to address consumer demand while ensuring that the products of domestic enterprise will compete favorably with retail costs of imports. Off-flavor represents a key impediment to industry expansion. The current drive toward production intensification will be constrained in part by off-flavor. The most important production problems identified by producers include off-flavor, diseases, and bird depredation. Reproductive success in catfish varies greatly from year to year, but spawning by mated pairs of brood fish may be less than 50% and eggs are sometimes of poor quality. Improving reproductive performance is essential to the continued success of the catfish industry in the United States. Overall, the ability to better manage the pond environment will result in enhanced production efficiency, improved product quality, and reduced environmental impacts of aquaculture. 3.How does it relate to the National Program(s) and National Program Component(s) to which it has been assigned? Question 3: The USDA/Agricultural Research Service (ARS) national research program is divided into three main areas:. 1)animal production, product value, and safety,. 2)natural resources and sustainable agricultural systems, and. 3)crop production, product value, and safety. Research objectives for the Catfish Genetics Research Unit fall under the animal production, product value, and safety area. The main goal of this research area is to enhance the production, value, and safety of foods and other products derived from animals which have a major impact on the American economy, world markets, and the U.S. balance of trade. Research in the Catfish Genetics Research Unit and with cooperators under specific cooperative agreements is in the aquaculture national program area within animal production, product value, and safety. Aquaculture research for the USDA/ARS focuses on a rapidly growing agricultural segment of the U.S. economy. With increasing seafood demand, declining capture fisheries, and a fisheries trade deficit exceeding $4 billion annually, aquaculture is poised to become a major U.S. growth industry in the 21st century. The continued growth and competitiveness of U.S. aquaculture will be directly related to the resources invested in research and technology development. A strong research and technology development program for U.S. aquaculture, led by the Agricultural Research Service, will offer significant benefits to both producers and consumers by enhancing the production efficiency, profitability, and quality of aquaculture products and systems. Research approaches for the Catfish Genetics Research Unit for this particular project generally fall within three areas defined by the USDA/ARS national aquaculture research program:. 1)aquaculture production systems;. 2)sustainability and environmental compatibility of aquaculture; and. 3)quality, safety, and variety of aquaculture products for consumers. 4.What were the most significant accomplishments this past year? Question 4: A. Single Most Significant Accomplishment during FY-2003 Crawfish is an important aquatic crop in the south but wild harvest and traditional forage-based production is highly variable and seasonally limited. Studies were conducted to develop techniques to produce crawfish in ponds without planted forage. A 300% increase in per-acre annual production was achieved and the overlap period of harvest of red swamp crayfish in production ponds without planted forage relative to production ponds with planted forage was further reduced. This will make the product available at times when it has not been previously available, improving marketing opportunities and production economics for farmers. B. Other Significant Accomplishment(s), if any Freshwater prawns is becoming an important crop for small farmers in the South, but small- or variable-sized product at harvest has a lower value. Grading of stocked post-larvae and use of substrate were studied as means of increasing net production, while increasing both product size and uniformity. At low stocking densities (8500/A), it was determined that the addition of substrate to the water column of a Macrobrachium rosenbergii production pond still improves production, but the enhancing effect of size grading is not longer manifested. This will result in a more efficient production and an increase in net returns arising from a larger (higher priced) product, combined with a reduction in variable costs, reducing breakeven prices. C. Significant accomplishments/activities that support special target populations The USDA Census of Aquaculture conducted in 2000 classified 84% of catfish farms as small businesses, with annual sales of less than $500,000. Of the 1,370 catfish farms in the United States, 38% (515) reported annual revenues of less than $25,000. Production problems that result production losses can disproportionately affect small farms because they are more susceptible to economic impacts related to interruption of cash flows and there is less probability of having acceptable fish to sell from at least one pond on the farm when only a few ponds are available. 5.Describe the major accomplishments over the life of the project, including their predicted or actual impact. Question 5: Extension of the growing and harvest season for red swamp crawfish farming through the development and successful application of management practices to unconventional production ponds containing no planted forage. A 28.7 % increase in individual harvest weight of freshwater prawns and a corresponding increase in overall production with little increase in operational cost accomplished through a pre-stocking size-grading management practice. Effected phenotypic change of males to females in juvenile populations of the freshwater shrimp through feeding of a formulated diet containing the hormone dopamine to arrest testicular development. Successfully replaced traditional dead fish bait with equally effective high protein formulated baits for the trap harvest of red swamp crawfish at cold water temperatures (< 17-18 C). Further reduced overlap period of harvest of red swamp crayfish in production ponds without planted forage relative to production ponds with planted forage. This will result in the extension of the availability of product at times when it has not been available from either the traditional capture fisheries or culture of this species, and a 300 % increase in annual production on a per acre basis. At low stocking densities (8500/A), determined that the addition of substrate to the water column of a production pond of Macrobrachium rosenbergii still improves production, but the enhancing effect of size grading is not longer manifested. This will result in a more efficient production and an increase in net returns arising from a larger (higher priced) product combined with a reduction in variable costs; a reduction in breakeven prices. Although the toxicity of ammonia to fish is well established, a study conducted as part of this project indicated that ammonia in catfish ponds is unlikely to have deleterious effects on fish growth and production. A control system to control pH to reflect normal diel fluctuation in eutrophic catfish ponds was used to assess potential transient toxicity experienced by fish during culture. The level of ammonia leading to fish growth reduction in this study is rarely experienced by fish in culture ponds using current management practices. A study on the effect of pond mixing on phytoplankton community composition and fish production indicates that the extent of mixing provided by the devices used was insufficient to shift phytoplankton community composition away from dominance by blue-green algae. Fish production was not affected by mixing. The effects of hormones on reproduction and egg quality in channel catfish and determination of the optimum stocking density for spawning have been studied. The outcome of this research will provide a better understanding of the spawning cycles of channel catfish. Research studies were conducted to determine testosterone, 11-ketotestosterone, 17b-estradiol, and cortisol hormone levels in sexually mature female and male channel catfish over a 24-month period and to correlate hormonal levels to spawning success/frequency in female catfish. The development of successful predictors of spawning success could lead to more consistent reproductive performance in commercial ponds. This data, combined with the new breakthroughs in identifying the gene that appears to be necessary for spawning to occur, will help identify the individuals and strains of fish that spawn at regular intervals. Successfully reduced the grow-out of hybrid striped bass in earthen ponds from three phases to two phases, resulting in significant operational savings and an increase in net returns. Application of these results to commercial situations may improve economic returns and stimulate hybrid striped bass industry expansion. 6.What do you expect to accomplish, year by year, over the next 3 years? Question 6: Year 1. Further increase efficiency of production of freshwater prawn at a low stocking density (8500/A) by incorporating a feeding strategy consisting of direct feeding with water-stable diets, strategically selected according to size and nutritional content for use at different times during the period of pond production, combined with organic fertilization. Verify production of freshwater prawn at low stocking densities in large scale (2 acre) production ponds. Achieve a decrease in turnover time for the production of market size hybrid striped bass grown in earthen ponds in conjunction with a newly developed 2-phase management strategy that includes lower stocking densities and higher initial stocking weights. Year 2. Develop and test formulated baits to achieve efficient trap harvest of the red swamp crawfish in cold water (< 16 C). Develop a technique to estimate accurately the mean weight of juveniles from the nursery phase of growth of the freshwater prawn to ensure accurate determination of numbers for sale to producers. Year 3. Studies will be based on results of years 2 and 3. 7.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? Question 7: A burgeoning freshwater prawn industry continues to develop in the state of Mississippi based upon the 15 years of research that has addressed different phases of culture of this crustacean. Currently, approximately 500 acres are devoted to the culture of freshwater the state of Mississippi. A number of producers stocked crawfish production ponds this year according to recommendations developed from research devoted to culture in experimental ponds without planted forage. A two-phase growout system (direct stock) that we have developed and tested in experimental ponds is being evaluated in ponds that are part of a commercial hybrid striped bass production facility. Organized/participated in several freshwater prawn and red swamp crayfish workshops offered at locations in central, northern, and southern Mississippi. Information on ammonia in catfish ponds has been transferred to catfish producers through popular, semi-technical articles and workshops organized by the Mississippi State University extension Service. Data collected on reproductive performance in catfish have been transferred to catfish producers and other scientists via semi-technical articles and workshops. 8.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: This does not replace your peer-reviewed publications listed below). Question 8: D'Abramo, L.R. Comparison of two-phase with traditional three-phase production of hybrid striped bass in earthen ponds. Thad Cochran National Warmwater Aquaculture Center Newsletter. 2002. v. 5(2). p. 5. D'Abramo, L.R. Freshwater shrimp farming--why now and what is the attraction? Thad Cochran National Warmwater Aquaculture Center Newsletter. 2002. v. 5(1). p.10-11. D'Abramo, L.R. Meeting the needs of a growing US freshwater shrimp industry through research. United States Freshwater Prawn and Shrimp Growers Association Newsletter. 2002. v. 1(2). D'Abramo, L.R. Freshwater Prawn Farming in the US - Responding to Future Challenges in Agriculture. Delta Business Journal. 2002. v. 5(6). p. 55. D'Abramo, L.R., Ohs, C.L., Hanson, T.R., Montanez, J.L. Production of the red swamp crayfish Procambarus clarkii in earthen ponds without planted forage: Management practices and economics. Technical Bulletin 1115 of the Mississippi Agricultural and Forestry Experiment Station, Mississippi State University, MS. 2002. p. 1-18. D'Abramo, L.R. Freshwater Shrimp - Maintaining the Momentum. United States Freshwater Prawn and Shrimp Growers Association Newsletter. 2003. v. 2(3). D'Abramo, L.R., Ohs, C.L., Fondren, M., Posadas, B., Steeby, J.A. Culture of freshwater prawn (Macrobrachium rosenbergii) in temperate climates: Management practices and economics of pond production. Technical Bulletin of the Mississippi Agricultural and Forestry Experiment Station, Mississippi State University, MS. 2003. p. 1-23.