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United States Department of Agriculture

Agricultural Research Service

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Location: Warmwater Aquaculture Research Unit

2010 Annual Report

1a.Objectives (from AD-416)
The objectives 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 channel catfish respiration, growth and produciton, and develop and test management methods to minimize limits on production; and 4)Develop new equipment and technologies to improve profitability of channel catfish farming.

1b.Approach (from AD-416)
Techniques will be developed to use hand-held as well as airborne imaging systems to identify/quantify cyanobacteria in ponds; algal culture will be used to determine possible control measures for harmful algae; laboratory respirometry and small pond production studies will be used to determine impacts of various water quality parameters on growth and production of catfish; the Aquascanner Sonar will be further developed to provide an accurate inventory of mixed-size catfish populations in large commercial ponds; high potential management applications and equipment will be tested in ponds and tanks on the Thad Cochran National Warmwater Aquaculture Center, and in commercial catfish ponds of cooperators.

3.Progress Report
This is the final report for this project. Substantial results were realized over the 5 years of the project. A prototype U-tube aerator was designed and tested. Further development will be achieved in the replacement research project by an HQ-funded post-doc. A unique aerator placement strategy was tested on ten 17-acre commercial ponds. Farmers can easily adapt existing equipment to this new system, increasing fish production and reducing production costs. The Aquascanner Catfish SONAR was tested on commercial catfish farms to determine its effectiveness for performing a fish inventory. The provisional patent was published in spring 2008. It was determined that catfish spawns incubated with a DO concentration of 5.9 mg/L hatched an 23.5 hours later than those incubated with 16 mg/L, and had a survival to hatch of only 37%, compared to 75% at the higher dissolved oxygen (DO). A micro-respirometer was developed to determine minimum oxygen requirements of adhesive catfish eggs. This data was used to develop a technology transfer program that resulted in a 10-20% increase in fry production by the catfish industry. This work was recognized with two technology transfer awards. A specific remote sensing model was developed catfish production ponds. This new model was able to forecast algal biomass with a model fit of over 80%. The mass of an unknown algal carotenoid was confirmed. This is the first identified carotenoid from the division euglenophyceae and may serve as a pigment marker for identification of this group. A modular composter was developed for a cost of less than $40.00 that can convert 5,000 pounds of fish waste into fertilizer. Composting is a simple, low-cost, “green” method of fish waste disposal that has widespread application. Blue catfish food consumption decreased only 19% when the morning DO concentration averaged 1.8 mg/L, compared to a 28% reduction for channel catfish. Blue catfish may have more potential as a commercial culture species than previously thought. Preliminary field tests of a new fish sizer were completed. Future work will focus on improving repeatability, ease of use and large scale field testing. A unique catfish egg incubator (the see-saw) was fabricated and tested at two commercial catfish hatcheries during the 2007, 2008, and 2009 spawning seasons. It appears that this new incubator will save both space and water compared to existing “paddle-type” incubators. Research indicates that hybrid catfish have improved oxygen tolerance compared to channel catfish. This research will prove valuable as further improvements in reproductive techniques increase the availability of hybrid catfish fingerlings. The causative algae and associated toxin responsible for losses of over $1.4 M has been identified. The toxin, similar to fire ant venom, is produced by certain Euglena species. ARS has patented this product.

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. USDA classifies 84% of these 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 (2009) the industry produced over 466 M pounds at a wholesale price of 77.1¢/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 water quality management 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.

Last Modified: 4/16/2014
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