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. Specific areas of research have been identified through interactions with industry, extension service representatives, and research personnel in other disciplines and other states. At present, the program focuses on management of environmental off-flavors, dissolved oxygen, waste discharge, pond fertility, assessing the impact of various management practices on the physiology and behavior of cultured catfish, studying the spawning behavior of channel catfish, and developing new technologies to improve catfish harvest and resource management. 2.How serious is the problem? Why does it matter? Question 2: Pond aquaculture is profitable because natural processes provide many of the resources needed to sustain the aquaculture crop. However, rates and magnitudes of all natural processes are variable in time and space, resulting in unstable and unpredictable environmental conditions. Ecosystem instability increases as nutrient loading rates increase, and, in the extreme example of catfish culture ponds, environmental conditions can rapidly deteriorate and affect productivity, product quality, or the environment outside the pond. For example, populations of odor-producing blue-green algae may become established in catfish ponds causing fish to develop undesirable "off-flavors." These fish are unmarketable until flavor quality improves, causing an economic hardship on farmers. Problems related to off-flavors cost catfish farmers $15 to 75 million per year, and, additionally, have economic impacts far beyond the farm because inconsistent product quality may adversely affect market demand. The importance of managing pond environmental quality is also evident from the recent decision by the United States Environmental Protection Agency to develop nationally applicable discharge standards for aquaculture. 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 is in the aquaculture national program area (NP106) 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 generally fall within three areas defined by the USDA/ARS Aquaculture National Program 106:. 1)genetic improvement;. 2)reproduction and early development; and. 3)growth, development and nutrition. 4.What were the most significant accomplishments this past year? Question 4: A. Single Most Significant Acccomplishment during FY 2003 Commonly used pond fertilization practices for catfish nursery ponds were developed over 40 years ago and have not been studied in Mississippi catfish ponds. Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville Mississippi, compared the responses of phytoplankton and zooplankton to various fertilization methods in catfish nursery ponds in Mississippi. We found that these ponds responded more to nitrogen additions than phosphorus additions, and increasing nitrogen application stimulated the phytoplankton bloom more quickly and significantly increased preferred zooplankton densities. Dramatically changing previous pond fertilization methods can increase the densities of important zooplankton, thereby improving fry growth, survival and health. B. Other Significant Accomplishment(s) The United States Environmental Protection Agency recently announced the decision to develop nationally applicable discharge standards for aquaculture. Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville, Mississippi, responded by evaluating a simple environmental management system to reduce the amount of waste produced within catfish ponds and decrease the volume of water discharged from ponds. After 2 years of study, average mass discharge of total nitrogen, phosphorus, suspended solids, and 5-day biochemical oxygen demand has been reduced by over 80% in ponds managed with the system. Catfish farmers can easily adopt these practices, which will allow catfish farms to be operated with little or no impact on the environment. Zooplankton populations are important components of the pond ecosystem, yet have been largely ignored in catfish production. Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville Mississippi, determined zooplankton feeding preferences for catfish fry. We determined that catfish fry show a preference for the largest zooplankton as soon as they are able to forage. This has implications for management of fry ponds; stocking decisions should not be based on total zooplankton densities, but on the numbers of large zooplankton taxa present. For some species of fish, zooplankton are the sole source of nutrients; nutrient value of zooplankton selected by catfish had not previously been studied. Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville Mississippi, determined the nutritional value of large zooplankton from catfish nursery ponds. These zooplankton met or exceeded all nutritional requirements for channel catfish fry. If fertilization practices maintain large numbers of appropriate zooplankton, all fry nutritional requirements should be met through natural pond productivity, reducing feed costs for fry farmers. Development of effective waste management plans for pond aquaculture depends on characterization of the water discharged from ponds. A study was conducted by Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville, Mississippi, to assess quality of pond effluents when ponds are drained and to characterize the nature of the material discharged. When ponds are drained, the initial flush of water discharged consists of pond water and a slurry of sediment that has accumulated over the screen inside the pond, but the effluent clears in 5 to 30 minutes and all water subsequently discharged is simply pond water. Since only a small proportion (1 to 4%) of the total solids discharged during pond draining was contained in the initial flush, it will be uneconomical to design elaborate treatment facilities to remove the material in that small volume of water. Processes that rely on gravity settling are the most economical method of removing solids from the initial flush of water released when ponds are drained. Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville, Mississippi measured the settling characteristics of solids in catfish pond effluent and used non-linear equations to calculate design criteria for settling basins. For average pond discharge rates, removal of 95% of solids requires a basin area ranging from 95 to 125 square meters. These data will allow environmental engineers to design effective treatments for catfish pond effluents. It is economically impractical to build new treatment facilities to remove solids from catfish pond effluents; however, existing drainage ditches may act simultaneously to transport water and remove solids. A study was conducted by Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville, Mississippi, to assess the capacity of ditches with volunteer vegetation to remove solids and nutrients from catfish pond effluents. At typcial pond effluent discharge rates, in excess of 95% of the solids in initial pond draining effluent was removed after the effluent traveled 120 to 220 meters downstream in a 1-meter wide ditch. This was consistent with the results of basin-design modeling and show that it is unnecessary to build elaborate facilities to improve catfish pond effluent quality because considerable improvement in quality occurs as effluent flows down the simple drainage ditches that are common features of most commercial catfish farms. Farm-raised catfish often develop undesirable "off-flavors" that cost catfish farmers $15 to 75 million per year. Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville Mississippi developed safe, inexpensive treatments for algae-related off-flavors with copper sulfate and diuron. These treatments have been widely adopted by the catfish industry and reduce the incidence of undesirable flavors by over 50% with benefit to cost ratios of approximately 40 to1. Chemical algicides are the most effective treatment for algae-related off-flavors, which cost catfish farmers $15 to 75 million dollars a year. A study was conducted by Mississippi State University scientists at the National Warmwater Aquacultrure Center in Stoneville, Mississippi, to determine whether exposure of channel catfish to diuron, the most commonly used algicide, resulted in tissue residues exceeding the EPA tolerance level of 2.0 ppm. The study showed that diuron residue levels in fillets remained well below 1 ppm after treatment and there was no carryover of residues in fish from one year to the next. Results show that this algicide can be safely used to manage this important problem in catfish farming. Currently there are only two algicides, copper sulfate and diuron, registered for managing algae-related off-flavors in pond-raised catfish. Mississippi State University scientists at the National Warmwater Aquacultrure Center in Stoneville, Mississippi cooperated with personnel from the USDA-ARS Natural Products Research Unit, Oxford, Mississippi, to identify and evaluate new algicides for use in managing algae-related off-flavors. One promising compound--a modified anthroquinone--identified in laboratory screening was tested in outdoor mesocosms and found to be selectively algicidal to odor-producing blue-green algae, thereby reducing levels of odorous compounds in water. Individual differences in the swimming performance of fish have inheritable components which might be important in establishing the superiority of closely related species, families, or lines of fish. Therefore, Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville, Mississippi conducted a series of swim-tunnel studies to establish the aerobic and anaerobic swimming capacity of channel, hybrid blue x channel, and blue catfish fingerlings. Channel catfish were the best endurance swimmers; hybrid catfish the best sprinters; and blue catfish the poorest swimmers at all tested speeds (30 to 120 cm/sec). The results of these studies should be useful to researchers interested in breeding a superior catfish for commercial production. Current catfish harvesting techniques are based on ancient technology and harvest efficiency is low, leading to costly carryover of many fish in culture ponds. Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville, Mississippi, tested a large number of waveforms and electrode configurations to determine if electrical waveforms could be identified that would repel catfish to an area for capture without causing immobility or injury. The studies demonstrated that an electrical system using a low to high frequency waveform with a 6.0-60 Hz sweep, and a 2-millisecond pulse width over a 4 second sweep time could be used to capture 92% of the fish present in a concrete vat in a single pull. These results indicate that it might be possible to develop electrical equipment that would be useful in increasing the harvest efficiency of conventional seines. Preliminary research indicates that induced electrical fields might be successfully used to improve the harvest efficiency of catfish in a pond environment. Harvest trials were conducted in ponds by Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville, Mississippi, to compare the catch efficiencies of a conventional seine and an electrically enhanced seine. The average total harvest was 22% higher using the electrically enhanced seine. These results demonstrate for the first time that a pulsed direct current electrical waveform can be used to improve the harvest efficiency of a conventional seine and validate the effectiveness of using a low to high frequency waveform with a 6.0 to 60 Hz sweep and a 2-millisecond pulse width over a 4-second sweep time to aid in the capturing of catfish in ponds. Spawning success is highly variable by brood channel catfish and is considered an important problem in catfish farming because dependable reproduction is essential to the development of any food-animal industry. For the last three years, Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville, Mississippi, and University of Mississippi scientists at the National Center for Physical Acoustics have been monitoring breeding populations of channel catfish during the spawning season to determine if they produce sounds during breeding and whether these sounds are important to their mating success during pre-spawning, spawning, and post-spawning activities. A number of low frequency sounds have been identified and are being evaluated to determine their characteristics and importance. This research is expected to lead to improvements in brood pond management. The size and complexity of modern catfish farms make it difficult to track and manage people, equipment and data in real time. Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville, Mississippi, and in the Department of Agricultural and Biologicial Engineering developed a wireless networking infrastructure with specialized hardware and software products that enables custom-designed and "traditional" instruments to become networked and web-enabled distribution devices. The system will reduce the cost and simplify the management of electronic information on the farm. Mississippi State University scientists at the National Warmwater Aquaculture Center in Stoneville, Mississippi, are testing a GPS (global positioning system) capable wireless network and related software in a five-pond (node) web-based system. Water quality data collected by the automated system will be integrated with and compared to comparable data collected by hand. This comparative study will be invaluable in defining the advantages and limitations of a fully automated, scalable, web-based system for use on client farms. C. Significant accomplishments/activities that support special target populations Off-flavor problems in commercial catfish culture reduce profits and methods developed to control off-flavor producing algae in ponds will benefit operators of small farms. 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. Off-flavors 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: Previously, it was not clear which zooplankton catfish fry consumed, or if fry consumed zooplankton at all. Research at the National Warmwater Aquaculture Center in Stoneville, Mississippi, determined that catfish fry do consume zooplankton and have a preference for the larger zooplankton taxa. These larger zooplankton are highly nutritious for catfish fry, providing all known nutritional requirements. Changing fertilization regimes to increased nitrogen application rather than phosphorus can develop a phytoplankton bloom more quickly and significantly increase the densities of desired zooplankton. Research at the National Warmwater Aquaculture Center in Stoneville, Mississippi, also determined the waveform and electrical array that was most effective in capturing catfish, demonstrating that electricity could be used effectively to improve harvest efficiencies. Other major accomplishments have been development of effective control measures for algae-related off-flavors, development of management practices to reduce the environmental impacts of pond effluents, and identification of previously unreported low frequency sounds produced during catfish reproductive events. 6.What do you expect to accomplish, year by year, over the next 3 years? Question 6: Preliminary studies indicate that zooplankton in the diets of catfish fry may increase growth, survival and overall health of the fry. Over the next 3 years, studies will quantify the amount of zooplankton needed in the diet to elicit a growth affect and the role of zooplankton and fish health, immune response, and vaccination effectiveness. Zooplankton populations in nursery ponds should be able to support fry growth without addition of commercial diets for at least some period of time; studies will determine how long zooplankton can support fry before prepared diets must be offered. Other accomplishments should include development and transfer of specific guidance for environmental management of catfish ponds and development and assessment of a novel pond aquaculture system based on deep-water diffused aeration and previously described components of the "partitioned aquaculture system." Physiological studies will focus on (1) determining and comparing the fatigue and recovery rates of channel, blue, and hybrid blue x channel catfish; (2) comparing the effect of swim angle and water flow speed changes on the swim performance of channel and blue catfish; (3) determining the effect of various disease on the swimming performance and fatigue and recovery rates of channel catfish. Acoustic studies will focus characterization of the sounds produced during spawning, as well as characterization of ambient noises present in catfish ponds and determine their effect on catfish behavior and health. Studies will also continue to build and field test an innovative electrically enhanced seine; if these tests are successful, harvest demonstrations will be conducted on commercial farms. 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: Off-flavor treatment regimens have been described in producer's trade journals and at several Extension workshops. Technologies have also been described in a regional publication published by the Southern Regional Aquaculture Center. That technology has, therefore, been transferred to the appropriate user group, and is currently in widespread use. Effluent management practices have been described in a producer's trade journal, at scientific meetings, in various workshops, in book chapters and in documents submitted to the U.S Environmental Protection Agency. Results of studies of zooplankton selective by channel catfish fry were presented at scientific meetings and results have been disseminated to catfish farmers through verbal communications and have been submitted to an extension publication and a scientific journal. Studies of pond successional changes have been published in a scientific journal, an extension publication, and presented at scientific and extension meetings. Swim-study results have been presented at Extensions workshops and published in an Extension newsletter. The electrical seine studies have been presented at an Extension work shops and at a scientific meeting; one article has been published and another article submitted to a scientific journal. The sound studies have been presented at an Extension workshop and a portion of the work presented at a scientific meeting. The web-based wireless network system has been presented at scientific meetings. 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: Beecham, V. R., Parsons, G. R., Minchew, C. D. Swimming endurance of fingerling channel catfish, Ictalurus punctatus, blue catfish, I. furcatus, and hybrid blue x channel catfish. Southern Division of the American Fisheries Society. February 12-16, 2003, Wilmington, North Carolina. Hargreaves, J. A., Tucker, C. S. Measuring dissolved oxygen concentration in aquaculture. Southern Regional Aquaculture Center Publication Number 4601. 2002. 6 p. Mischke, C.C., Wise, D.J., Zimba, P.V. Catfish fry pond fertilization. National Warmwater Aquaculture Center Catfish Hatchery Management Workshop, March 27, 2003, Stoneville, Mississippi. Mischke, C.C., Wise, D.J., Li, M.H., Zimba, P.V. Zooplankton and catfish fry culture. National Warmwater Aquaculture Center Catfish Hatchery Management Workshop, March 27, 2003, Stoneville, Mississippi. Mischke, C.C., Li, M.H., Wise, D.J., Zimba, P.V. Zooplankton Nutritional Value: Nursery Pond Fertilization Effects. NWAC News. 2002. v. 5(2). p. 8-9, 12. To, S. D. F., Minchew, C. D. In-pond local area network: In-pond inventory system. Agricultural Machinery Conference. May 6-7 2002, Cedar Rapids, Iowa. Tucker, C. S. EPA proposes "no regulation" of catfish ponds. Delta Council Report. 2002. v. 6(9). p. 2. Tucker, C. S. Environmental impacts of catfish farming. Delta Business Journal. 2002. v. 5(1). p. 62. Tucker, C. S. EPA to regulate catfish pond effluents. Delta Business Journal. 2002. v. 4(10). p. 63. Tucker, C. S. Solar power for catfish pond aeration. The Catfish Journal. 2003. v. XVII(7). p. 24. Tucker, C. S. Environmental impacts of catfish farming. Delta Business Journal. 2003. v. 5(1). p. 62 Tucker, C. S., Harris, S. Catfish pond effluents. NWAC News. 2002. v. 5(1). p. 3. Tucker, C. S., Harris, S. New publications produced by the Southern Regional Aquaculture Center. NWAC News. 2003. v. 5(2). p. 3. Tucker, C. S., Kingsbury, S. K., Ingram, R. L. Diuron residues in catfish exposed in consecutive years. NWAC News. 2003. v. 5(2). p. 4. Tucker, C. S., Kingsbury, S. K., Ingram, R. L. Diuron residues in farm-raised catfish. The Catfish Journal. 2003. v. XVII(7). p. 15, 20. Wise, D.J., Terhune, J.S., Mischke, C.C. Evaluation of AQUAVAC-ESC vaccinated fish using single and continuous dose challenge models. National Warmwater Aquaculture Center Catfish Hatchery Management Workshop, March 27, 2003, Stoneville, Mississippi. Review Publications Zimba, P.V., Mischke, C.C., Brashear, S. 2003. Pond-age water column trophic relationships in channel catfish ictalurus punctatus production ponds. Journal of the World Aquaculture Society 219:291-301. Mischke, C.C., Wise, D.E., Li, M.L., Zimba, P.V. 2003. Role of zooplankton in catfish fry culture: summary of nwac investigations. 2003 Catfish Farmers of America Annual Convention and Research Symposium, February 20-22, Hilton Sandestin Beach Resort, Destin, Florida. Page 24, Abstract #19. Zimba, P.V., Mischke, C.C., Li, M.H., Grimm, C.C. 2003. From fry to fillets: effects of water quality on optimal pond performance. 2003 Catfish Farmers of America Annual Convention and Research Symposium. February 20-22, Hilton Sandestin Beach Resort, Destin, Florida. pp. 11-12, Abstract #5.