Location: Warmwater Aquaculture Research Unit
2008 Annual Report
NP 106, Components: 1, 2, 3, 4, 5, 6; Problem Statement: 1a, 2g, 3e, 4a, 5b, 5e, 6c, 6e.
Hybrid catfish fry have been produced experimentally for nearly five decades. While most studies show them to be superior to channel catfish, limited fry/fingerling availability has precluded commercial production. However, in the last few years experimental reproduction techniques (hormone injection of female channel catfish, followed by hand-stripping and artificial fertilization with blue catfish sperm) have approached commercial potential. This year close to 40 million hybrid catfish eggs have been produced on commercial catfish farms, and research in this project has been expanded to include the evaluation of improved germplasm, such as hybrid catfish, developed under inhouse project 6402-31000-008-00D, in both research and commercial sized ponds. Research ponds have been stocked this year with hybrid catfish at 16,000/acre and are being maintained at two different morning dissolved oxygen concentrations while the fish are being fed to satiation. Feeding rates in June have exceeded 150 pounds/acre/year. This research will prove valuable as further improvements in reproductive techniques increase the availability of fingerlings.
NP 106, Components: 1, 2, 4, 5; Problem Statement 1a, 2g, 4a, 5b.2. Aerator placement strategy:
Orientation of traditional paddlewheel aerators in large commercial catfish ponds can potentially impact water quality and fish production costs. A USDA scientist has collaborated with a commercial fish farm to conduct a second study of unique aerator placement strategy on ten 11.5-23 acre commercial ponds. The initial study showed promise, and if similar results are obtained in this study farmers can easily adapt existing equipment to this new system, increasing fish production and reducing production costs. Net fish production, feed consumption, feed conversion, electricity usage for routine aeration, and the need for emergency aeration were measured. The ponds were recently harvested and the data are now being analyzed.
NP 106, Components: 5, 6; Problem Statement: 5b, 6e.3. New catfish incubator design:
Catfish eggs have been incubated in essentially the same way for the past century. Egg masses are placed in a screen basket and water is circulated with rotating paddles. An ARS scientist theorized that a different method, one in which the eggs are placed in baskets which are periodically lifted out of the water, could be more efficient. A commercial-scale unit was fabricated and tested at a commercial hatchery during the 2008 spawning season. While standard troughs are loaded with not more than 18 pounds of eggs and require at least 2½ gallons per minute (GPM) of water flow, the new design incubated up to four times that amount on as little as 2 GPM water flow. While development of this incubator is still in the preliminary stages, it appears that it will save both space and water compared to existing equipment.
NP 106, Component: 3, 6; Problem Statement: 3e, 6c.4. Application of ultrasound technologies to control microbial populations in ponds resulted in dramatic decreases in bacterial abundance and selected mortality of algae in ponds.
Fish growth was not affected if ultrasound was off during feeding.
NP 106, Components: 2, 3; Problem Statement: 2g, 3e.5. The causative algae and associated toxin responsible for over $1.1 million dollar losses has been identified and the structure fully characterized.
Characterization includes both time of flight (TOF) mass spectrometry and nuclear magnetic resonance (NMR) analyses. The toxin is produced by certain Euglena species and is a novel compound. ARS is currently completing patent application.
NP 106, Components: 2, 6; Problem Statement: 2g, 6e.6. Aquascanner SONAR:
University of Mississippi (UM) National Center for Physical Acoustics (NCPA) scientists and staff have continued with the field use of the AquaScanner side scan sonar system. The units were used to predict, in advance, estimated biomass in ponds The Acoustic predictions have typically been within 20% of the mass reported by the farmer although data from more ponds that are subject to complete harvesting would help solidify prediction accuracy. The provisional patent was published in spring 2008 and work continues to focus on the best route to use the technology in the field whether through UM construction with direct sales, licensing to a third party manufacturer or a spin off service company. NCPA has responded to requests by investment firms interested in using the technology to evaluate farm purchases.
NP 106, Components: 5, Problem Statement: b, e.7. Additional uses of acoustics to improve production:
Work continued on an allied grant on an individual fish-sizer which can provide the size distribution of a sample of captured fish in collaboration with the University of Arkansas at Pine Bluff. After a small sub-sample of fish has been captured, they are acoustically scanned as they return to the pond through a restrictive pipe. Work included incorporation of algorithms to convert Acoustic Target Strength (reflectivity) to fish length and fish length to fish weight. The fish-sizing unit is slated for more field testing in the fall of 2008. Preliminary measurements on noise emitted from shrimp during feeding represents a new research spin off in a new area of aquaculture. These preliminary measurements suggest that passive measurements could be used to rapidly (and inexpensively) identify a mass mortality in a shrimp pond so that it could be restocked. A more rigorous measurement might be able to estimate biomass. The Aquascanner SONAR system was also used to investigate fish in smaller (1 acre) ponds. The fish can be observed reacting to external stimuli such as feeding and moving toward the aerator at night in the summer when oxygen levels are presumably at their lowest. This application could be useful to a whole host of research activities but to us it represents a tool to evaluate new research on using acoustics to either attract or repel fish during seining to improve the seining process.
NP 106, Components: 5, Problem Statement: b, e.
5.Significant Activities that Support Special Target Populations
Catfish farming is truly a national industry with over 1,100 commercial producers located in 13 states. While there are some large farms, the majority are small family-owned and operated, averaging only 160 water acres. The USDA/NASS Census of Aquaculture conducted in 2000 classified 84% of catfish farms as small businesses, with annual sales of less than $500,000, and 38% (515) with annual revenues of less than $25,000. In spite of recent historically low pond-bank prices, farmers have survived through increased efficiency, producing more fish on fewer acres each year. Last year (2007) the industry produced over 496 M pounds at a wholesale price of 76.7¢/pound, but with increased foreign competition, and higher feed and fuel prices, the future is uncertain. Those dedicated catfish farmers are the primary customers of this research through the availability of innovative technologies, management strategies and equipment to increase their efficiency even more. Research on management of nuisance algae and dissolved oxygen is critical for success of all catfish farms, but will have far greater impact on smaller farms with a generally narrower profit margin. Catfish processors benefit from a more stable fish supply resulting from improved off-flavor management and detection methods. Average consumers also benefit from the increased availability of higher-quality, safer domestic products at a reduced price.
Li, M.H., Robinson, E.H., Oberle, D.F., Zimba, P.V. 2007. Effects of Various Dietary Carotenoid Pigments on Fillet Appearance and Pigment Absorption in Channel Catfish Ictalarus punctatus. Journal of the World Aquaculture Society 38:557-563.
Torrans, E.L., Steeby, J. 2008. Effects of Dissolved Oxygen Concentration on Oxygen Consumption and Development of Channel Catfish Eggs and Fry: Implications for Hatchery Management. North American Journal of Aquaculture 70(3):286-295. Accepted Aug. 7, 2007; Published on-line Apr. 14, 2008.
Zimba, P.V. 2007. ARS Research on Harmful Algal Blooms in SE USA Aquaculture Impoundments. Advances in Experimental Medicine and Biology. 619:577-579.
Zimba, P. V., 2007. Literature Reference for Anatoxin-a, Literature Reference for Microcystins, Literature Reference for Cylindrospermopsins, Literature Reference for Saxitoxin, and Selected Biotoxin Methods. In: Standardized Analytical Methods for Environmental Restoration Following Homeland Security Events. The Office of Research and Development, National Homeland Security Research Center. Computer Sciences Corporation Alexandria, VA. Sections 8.2.13, p. 137; 8.2.16, p. 139; 8.2.19, p. 140; 8.2.20, p. 141; 8.2.22, p. 142; and Appendix D, 20 p., respectively. (Book Chapters)
Danaher, J., Tidwell, J., Coyle, S.D., Dasgupta, S., Zimba, P.V. 2007. Effects of Two Densities of Caged Monosex Nile Tilapia Oreochromis Niloticus on Water Quality, Phytoplankton Populations and Production When Polycultured With Macrobrachium rosenbergii in Temperate Ponds. Journal of the World Aquaculture Society.