Location: Warmwater Aquaculture Research Unit
2006 Annual Report
Dissolved oxygen is arguably the most critical water quality parameter in warm water aquaculture. Over $50 million in potential profit are lost annually from the direct effects of low oxygen. An additional $100 million may be lost from poor growth and food conversion and a variety of environmental and pathogenic diseases directly related to the stresses of poor water quality. Although a variety of aerators and oxygen monitors is now commercially available, little is known regarding the impacts of sub-lethal oxygen levels on catfish production efficiency. Once these impacts have been identified and quantified, logical economic decisions with respect to water quality management can be made.
Various aquatic microbes produce metabolites that impart ‘off-flavors’ to fish, rendering them unmarketable and adding $70 million to annual production costs. Oscillatoria perornata, a blue-green algae, is reported to be the major cause of MIB-related off-flavor in the Mississippi Delta. Other algae produce other metabolites resulting in off-flavor and unmarketable fish, whereas other algal species produce toxic compounds causing direct fish mortality. Controlling these nuisance algae and maintaining optimum water quality must begin with a fundamental understanding of the algal species involved and environmental conditions controlling algal dynamics.
The goal of this research project is to increase production economics from commercial warm water catfish ponds through improved water quality management. Improved management will result in more intensive catfish production (greater per-acre yields) across the industry. Higher per-acre production will require less ground water pumped for each pound of catfish produced, as well as less overall discharge to the environment.
Two approaches will be used to accomplish this goal. The first will focus on the impacts of low dissolved oxygen on growth and production of catfish, and the development of improved equipment and techniques for oxygen management. The second approach will be the identification and control of nuisance algae, with an emphasis on those groups primarily responsible for off-flavors and toxic blooms. It is expected that both approaches will result in improved applied pond management techniques for the industry which will help to solve these costly production problems, increase efficiency and profitability, provide a quality product for consumers, and minimize environmental impacts of aquaculture.
The objectives of this project are to: 1)discover, develop, and apply methods to predict off-flavor episodes and manage off-flavor compounds; 2)identify optimal water column conditions for balanced growth of bacteria, phytoplankton, and zooplankton resulting in reduced secondary metabolite formation, and enhanced fish survival and production; 3)determine influence of chemical and biological factors on catfish respiration, growth and production, and develop and test management methods to minimize limits on production; and 4)develop new equipment and technologies to improve profitability of catfish farming. Research planned under this CRIS will address several National Program Action Plan Components: Integrated Aquatic Animal Health Management (Component #2); Reproduction and Early Development (#3); Growth, Development and Nutrition (#4); Aquaculture Production Systems (#5); Sustainability and Environmental Compatibility of Aquaculture (#6); and the Quality, Safety, and Variety of Aquaculture Products for Consumers (#7).
FY 2006 (Year 2) (1) Complete second year field data using modified sensor windows (if needed), apply model to data developed for first year (jackknife approach). (2) Complete 2nd year experiments, and begin EPA registry for acceptance for commercial use. (3) Complete field based purging studies using laboratory results to calibrate chemical additions. (4) Complete pond treatments to maintain optimal nutrient ratios, monitor nutrients, and plankton. (5) Complete pond treatment to obtain optimal nutrient ratios; monitor ponds for algal composition. (6) Complete laboratory bioassays of microcystin using adult catfish and euglenoid toxin identification using NMR, x-ray crystallography. (7) Complete 2nd year food fish production trials at CGRU and Delta-Western Research Center. (8) Complete first harvests of fish reach market size; restock for second cycle. (9) Complete re-design of phase-II u-tube. Initiate production testing. (10) Modify SONAR use and deployment based on end user feedback; continue transition to end user. (11) Fabricate and test sample transducers utilizing new materials.
FY 2007 (Year 3) (1) Complete modification of sensor windows as needed to specifically identify off-flavor producing algae, collect field data for verification of method. (2) Complete field trials in commercial pond facilities. (3) Complete 2nd year field based studies. (4) Complete commercial pond treatments. (5) Complete optimization of nutrient additions and repeat nutrient additions in TCNWAC ponds. (6) Determine patent potential to euglenoid neurotoxin. (7) Complete fingerling production at low DO to augment research at medium oxygen levels previously completed. (8) Continue second production cycle (each production cycle may take 12-18 months). (9) Complete production testing and evaluation in research ponds. (10) Continue transition to end user; begin investigation of additional uses of acoustics to improve production. (11) Begin investigation of alternate sonar transmitter board design.
FY 2008 (Year 4) (1) Complete model development, development of specific wavelength low-cose sensor systems. (2) Begin EPA registry and acceptance for commercial use. (3) Technology transfer. (4) Repeat in commercial ponds, modify protocol as needed. (5) Technology transfer - demonstration in commercial ponds. (6) Complete industry-wide synoptic survey for euglenoid toxin in ponds. (7) Continued pond production trials. Protocols used will be determined by results of years 1-3. (8) Complete second production cycle harvest. Analyze data. (9) Complete fabrication of commercial prototypes and initiate testing on commercial farms. (10) Continue investigation of additional uses of acoustics to improve production. (11) Complete incorporation of new transmitter and software for improved performance.
FY 2009 (Year 5) (1) Technology transfer to industry-commercialization of spray plane or handheld sensor systesm. (2) Complete EPA registry requirements. (3) Completed in Year 4. (4) Technology transfer. (5) Technology transfer - demonstration at a commercial scale. (6) Technology transfer regarding toxic algae in catfish production systems. (7) Complete production trials at CGRU and Delta-Western Technology transfer. (8) Technology transfer. (9) Complete testing on commercial farms. Technology transfer. (10) Complete investigation of additional uses of acoustics to improve production. (11) Complete field test of sonar with new transmitter.
The mass of an unknown carotenoid found in the euglenoid algae was confirmed independently by collaborators. This carotenoid is the first identified from the division euglenophyceae and may serve as the first pigment marker for identification of this group. USDA ARS Catfish Genetics Research Unit collaborated with of NOAA to confirm mass of this compound. Rapid identification of these species could greatly reduce potential for harmful algal blooms and thereby increase the efficiency of catfish production in the US.
It is difficult to measure oxygen consumption of catfish eggs since they clump together when deposited. USDA ARS Catfish Genetics Reseaerch Unit worked on methods to overcome this problem so metabolism of eggs could be measured. A closed, stirring micro-respirometer was developed, using locally-available materials, that proved suitable for use with small clumps of catfish eggs. Data was collected using this respirometer that resulted in new recommendations on oxygen management in commercial catfish hatcheries.
Disposal of fish wastes from research facilities or small-scale processors is problematic. USDA ARS Catfish Genetics Research Unit studied various methods of fish disposal for use on the research facility. A modular, reusable composter was developed for a cost of less than $40.00 that can convert 5000 pounds of fish and fish waste into garden fertilizer. Composting is a simple, low-cost, “green” method of fish waste disposal that has widespread application for disposal of small volumes of fish and fish waste.
Blue catfish have potential as a commercial culture fish but it was believed that their oxygen requirements were higher than channel catfish. Scientists with the USDA ARS CGRU conducted a study at the Delta-Western Research Center to determine the relative impact of low oxygen on food consumption and production of channel and blue catfish. It was determined that while channel catfish food consumption decreased 9.5% and net fish production decreased 851 lbs/acre when the dissolved oxygen concentration dropped below 3.0 mg/L, blue catfish actually consumed slightly more feed (+0.9%) and had slightly higher net production (+156 lbs/acre) than blue catfish maintained at a dissolved concentrations above 4.0 mg/L. Blue catfish may have more potential as a commercial culture species than previously thought, and certainly merit further examination.
Orientation of traditional paddlewheel aerators in large commercial catfish ponds can potentially impact water quality and fish production costs. USDA, ARS Catfish Genetics Research Unit collaborated with Dillard and Company, Inc. to test a unique aerator placement strategy on ten 17-acre commercial ponds. Net fish production, feed consumption, feed conversion, electricity usage for routine aeration, and the need for emergency aeration all showed numerical improvements with the new aerator placement. Farmers can easily adapt existing equipment to this new system, increasing fish production and reducing production costs.
Development of effective inventorying methodologies is critical for the future of the catfish industry. The National Center for Physical Acoustics at the University of Mississippi collaborated with MS State University, Delta Research and Extension Center, MS Valley State Univ., and some commercial operators such as America’s Catch, Itta Bena, MS, and Aqua Farms, Leland, MS, to operate the Aquascanner Catfish SONAR. This use is planned to continue into the current season. As signal processing routines and data acquisition techniques are improved, this SONAR system should act as a valuable tool for pond inventorying.
Cooperative research conducted under Non-Funded Cooperative Agreement, “Test of Novel Aerator Placement Strategy for Managing Dissolved Oxygen on Commercial Channel Catfish Farms,” with Dillard and Company, Inc., was established on April 29, 2004. The purpose of this agreement was to determine the effects on fish production, water quality and economics of concentrating paddlewheel aeration in large commercial ponds, compared to the current method of placing aerators to maximize total pond aeration and circulation. Ten 17-acre ponds were selected for use in the study and were brought into the study in pairs as they were stocked during the 2004 growing season. Each pair was stocked near the same date with a single batch of graded, similarly-sized catfish. One pond of each pair was aerated with the new aerator placement, and the other was aerated using the existing system. Ponds were “clean harvested” by multiple seining as the fish reached market size. Water quality, feed input and fish production were monitored. Data on electric usage by aerators was not available for all ponds in the study due to faulty hour meters which were initially used. The study was planned to run for two complete production cycles, but the second production cycle could not be initiated due to a severe industry-wide fingerling shortage in 2005. Stocker-size fish were not available to restock all ponds for food-fish production after the first harvest, and some were used for fingerling-to-stocker grow out or other purposes, and will not be available for this research study. This study was scheduled to run through April 30, 2007 but will be terminated at the end of this fiscal year.
Cooperative research conducted under Non-Funded Cooperative Agreement, "Development of a Powered U-Tube Aerator (“Power Tube”) for Use in Commercial Fish Ponds,” with Southern Machine Welding, Inc., was established on Nov. 11, 2003. The purpose of this agreement is to develop and test a novel aerator design for use in commercial fish ponds. A prototype u-tube has been constructed and installed in a 0.4 ha pond at the MSU. Delta Branch Experiment Station. The tube was fabricated from a 36” diameter corrugated culvert and was buried to a depth of 20 ft below the pond bottom. The motor, gear box, impeller and open loop vector AC drive were all installed as planned. This initial prototype shows promise. With an impeller speed of 150 RPM, the motor draws 12.7 amps (5.36 hp) and has an output of 8300 gpm. A variety of diffuser types have been tested. Oxygen transfer efficiency tests have been conducted. It is expected that both the technical (improving efficiency) and practical (reducing cost and producing a unit that can operate reliably in a commercial environment) recommendations will be incorporated into a Phase II design for continued testing in future years. This agreement was due to expire on October 31, 2006 but we anticipate a renewal through September 30, 2008 to continue this high potential collaborative project.
Cooperative research under specific cooperative agreement, “Acoustic Technologies for Evaluating Catfish Production,” with the University of Mississippi, was established on September 7, 2004. The purpose of this agreement is to continue development and technology transfer of the AquaScanner SONAR for use in assessing catfish populations (numbers and weight) in commercial catfish ponds. The SONAR was operated at additional farms in the MS Delta including (but not limited to) America’s Catch in Itta Bena, MS, and AquaFarms in Leland, MS . The farm operators are providing feedback on the pond contents after seining to compare with the acoustic output. This use is planned to continue in the current season. Analysis of the previously collected data indicates good correlation of the acoustic data with biomass but less so with size distribution. To address this goal, preliminary work began on modifying one of the spare SONAR units to act in concert with the main unit to scan individual fish after they have been seined with a sub-sample seine net. This work is proceeding in collaboration with the University of Arkansas at Pine Bluff. The inexpensive vertical temperature probe discussed in last year’s annual report was used to confirm the need to acquire data at night when the temperature gradients that develop in the water during the day have dissipated. Research colleagues in the biological sciences have indicated interest in this device and several units are available as needed. The need to acquire data at night has often run afoul of the need to oxygenate the pond at night since the entrained bubble cloud is easily observed in the acoustic scan and typically masks everything it covers. This problem, however, may have spawned an additional use for the SONAR in determining aerator placement and pond recirculation patterns. Aqua Farms in Leland, MS, has expressed interest in this measurement and plans are underway to incorporate these tests as part of the measurements planned for the current season. A provisional patent has been filed for the technology and assembly of several additional units is nearly complete. Fabrication of a new transducer to increase the acoustic source level was unexpectedly delayed by the long lead time required to custom fabricate the relatively large (4”) ceramic disk required. Delivery is expected by the end of the summer and fabrication and testing of the new transducer is expected shortly thereafter. As an alternate solution to the overall problem of increasing the acoustic source level, the existing transducers were subjected to increased voltage levels to determine if they could provide higher source levels and if the existing electronics could withstand the higher voltages. Preliminary measurements indicate that a modest increase in source level is achievable, but these changes will need to be monitored to ensure that the internal electronics do not suffer long term degradation.
A new model for assessing algal biomass in catfish ponds was developed the USDA, ARS Catfish Genetics Research Unit in collaboration with University of Nebraska. This new remote sensing model provides over 15% greater accuracy of algal biomass estimation than previous models.
A prototype commercial-scale powered U-tube aerator was developed by the USDA, ARS Catfish Genetics Research Unit in collaboration with Southern Machine Welding, Inc. (“Big John Aerators”). The initial prototype shows promise, moving over 8300 gpm of water. Further development continues.
The National Center for Physical Acoustics at the University of MS, collaborated with MS State University, Delta Research and Extension Center and MS Valley State Univ.ersity, as well as some commercial operators, such as Harvest Select, Inc., Inverness MS, Jim Murphy Farms at Sunflower, MS, to operate the Aquascanner Catfish SONAR to determine its effectiveness for performing fish inventories in ponds. As signal processing routines and data acquisition techniques are improved, this SONAR system could act as a valuable tool for pond inventorying.
Major accomplishments and impacts expected over the life of the new CRIS project are: 1)discover, develop, and apply methods to predict off-flavor episodes and manage off-flavor compounds; 2)identify optimal water column conditions for balanced growth of bacteria, phytoplankton, and zooplankton resulting in reduced secondary metabolite formation, and enhanced fish survival and production;.
Recommendation on oxygen management in catfish ponds have been disseminated through an industry trade journal, a research/industry newsletter, and several presentations to state and national industry groups.
On-farm demonstrations of new fertilization practices led to adoption by several large catfish producers. One of the largest supply companies has also adopted these fertilization practices when assisting producers with pond management.
Bacterial densities in channel catfish ponds were monitored for one year – levels are similar to those found in many pristine lakes. This information highlights the high quality of farm raised catfish from production ponds relative to wild-caught fish.
Bucollo, A.P., M.J. Sullivan, P.V. Zimba. 2006. Effects of nutrient enrichment on biomass and primary production of sediment microalgae in Halodule wrightii Ascherson (shoalgrass) seagrass beds. Phycological Society of America annual meeting 7-12 July 2006, Juneau, Alaska, Abstract 11, page 30.
Coln, P.D., J. D. Heffington, J. D. Bell, and J. P. Chambers, “Temperature Gradient Measurement in a Shallow Water Environment”, Mississippi Academy of Sciences Meeting (2/06), Vicksburg, MS.
Li, M., E. Robinson, C. Mischke, E. Torrans, and B. Bosworth. 2006. Effects of organic fertilization and organic diets on production of channel catfish Ictalurus punctatus in earthen ponds. Aquaculture 2006, February 13-16, Riviera Hotel and Casino, Las Vegas, NV. Abstract #162, Book of Abstracts, page 167.
Torrans, L. 2006. A micro-respirometer for measuring oxygen consumption of channel catfish Ictalurus punctatus eggs and fry. Aquaculture 2006, February 13-16, Riviera Hotel and Casino, Las Vegas, NV. Poster #201 and Abstract #324, Book of Abstracts, page 329.
Torrans, L. 2006. Disposal of small-scale fish processing waste through composting. Aquaculture 2006, February 13-16, Riviera Hotel and Casino, Las Vegas, NV. Poster #705 and Abstract #325, Book of Abstracts, page 330.
Torrans, E. L. and P. D. Dees. 2006. New thoughts on paddlewheel placement. Catfish Farmers of America Catfish Research Workshop, February 23-24, San Antonio Texas, Abstract, Page 31, Book of Abstracts.
Torrans, E. L. and C. D. Hogue, Jr. 2006. Pushing the envelope – what’s possible? Catfish Farmers of America Catfish Research Workshop, February 23-24, San Antonio, Texas, Abstract, Pages 33-34, Book of Abstracts.
Torrans, L. and J. Steeby. 2006. Oxygen consumption of channel catfish eggs and fry: implications for hatchery management. Catfish Farmers of America Catfish Research Workshop, February 23-24, San Antonio, Texas, Presentation and Abstract, Pages 22-23, Book of Abstracts.
Torrans, L. and J. Steeby. 2006. Oxygen consumption of channel catfish Ictalurus punctatus eggs and fry: implications for hatchery management. Aquaculture 2006, February 13-16, Riviera Hotel and Casino, Las Vegas, NV. Presentation and Abstract #323, Book of Abstracts, page 328.
Torrans, L. and J. Steeby. 2006. Oxygen management at channel catfish hatcheries. Global Aquaculture Advocate, June, 9(3):56,57.
Triemer, R., M. Bennett, P.V. Zimba, P. Moeller, and K. Beauchesne. 2006. A novel pigment biomarker for identification of some Euglenophyceae. Phycological Society of America annual meeting 7-12 July 2006, Juneau, Alaska. Abstract 139, page 80.
Zimba, P.V. 2006. An update on algal toxin occurrence in channel catfish production ponds. Catfish Farmers of America meeting. 23-25 February 2006. San Antonio, TX.