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United States Department of Agriculture

Agricultural Research Service

2007 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.

Potential of blue catfish Ictalurus furcatus as a commercial food fish. Blue catfish have potential as a commercial culture fish, but it was believed that their oxygen requirements were too high to culture commercially in existing systems. USDA ARS CGRU conducted a second study to quantify the relative impact of low oxygen on food consumption and production of blue catfish. It was determined that blue catfish food consumption decreased only 19% when the morning dissolved oxygen averaged 1.8 mg/L during the growing season, compared to an estimated 28% reduction for channel catfish. Blue catfish have more potential as a commercial culture species than previously thought, and certainly merit further examination. Action Plan Components 4a – Regulating Feed Intake, and 5b – Production Intensity.

Aerator placement strategy. Orientation of traditional paddlewheel aerators in large commercial catfish ponds can potentially impact water quality and fish production costs. USDA ARS CGRU collaborated with Dillard and Company Inc. to conduct a second study of unique aerator placement strategy on ten 11.5-23 acre commercial ponds. Net fish production, feed consumption, feed conversion, electricity usage for routine aeration, and the need for emergency aeration will all be measured. 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. Action Plan Components 5b – Production Intensity, and 6e – Environmental Sustainability.

Mortality of catfish eggs and fry in commercial hatcheries is highly variable but usually ranges from 10 to 30% of the eggs brought into the hatchery. Previously (FY2005 and 2006) USDA ARS CGRU and Mississippi State University Extension Service studied oxygen management practices in 20 commercial hatcheries while measuring oxygen requirements of catfish eggs and fry. It was shown that the highest oxygen concentration (approximately air-saturation) is required by catfish eggs during the last day of incubation. A follow-up study was conducted this year that further confirmed the impact of dissolved oxygen concentration of embryo development, hatch rate and survival. Spawns incubated with a DO concentration of 5.9 mg/L (approximately 74% air saturation) hatched an average of 23.5 hours later than those incubated with 16 mg/L, and had a survival to hatch of only 37%, compared to 75%. Through collaborative work between CGRU and Mississippi State Extension Service (MAFES) a technology transfer program was instituted that has resulted in widespread adoption by the industry of their oxygen management recommendations. The changes already adopted by the industry are expected to result in a 10-20% increase in fry production by the catfish industry. Action Plan Component 3e – Early Life Stage Development and Survival.

Remote sensing in highly turbid Case 2 waters. Rapid assessment of ponds to detect harmful algal blooms is appealing as a management tool for producers. USDA ARS and University of Nebraska tuned plant biomass models for application in aquaculture production systems. The tuned model provided a model that was 80% accurate, and over 25% better predictor of biomass than previous models. Action Plan Components 5b-Production Intensity, and 6e – Environmental Sustainability.

A toxin produced by algae has been purified. Four years ago, evidence was found for production of toxins by a division of algae previously thought of as benign. Two species of the division Euglenophyta were found to produce toxins. USDA-ARS and NOAA isolated the toxin-this compound is a low molecular weight protein. Current efforts are underway to assess what induces toxin accumulation in this common algal species. Action Plan Components 5b-Production Intensity, and 6e – Environmental Sustainability.

Aquascanner SONAR. Research efforts have continued with University of Mississippi (UM), continues to collaborate with Dillard and Company Inc. and researchers at MSU-MAFES and MS Valley State Univ., on the field use of the AquaScanner side scan sonar system. The units were used to predict, in advance, estimated biomass in ponds including at least one that had an unexpectedly low yield. A provisional patent was filed in Spring 2007 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. Action Plan Components 5b – Production Intensity; 5e – Live Aquatic Animal Handling, Transport, and Inventory.

Individual fish sizer. Current acoustic modeling techniques allows for estimation of total biomass in ponds, but producing actual counts or size distribution of said fish is problematic. Preliminary work on the development of an individual fish sizer by UM/NCPA in conjunction with colleagues at the University of Arkansas Pine Bluff shows promise. It is anticipated that this acoustic fish sizer can determine the size distribution of a small sub-sample of fish as they are passed through a restrictive pipe and back to the pond. Preliminary field tests indicated that the correlation between the acoustic echo and fish weight in an in-situ dynamic test was comparable to previous static tests. Future work will focus on improving repeatability, ease of use and large scale field testing. Action Plan Components 5b – Production Intensity; 5e – Live Aquatic Animal Handling, Transport, and Inventory.

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 (2006) the industry produced over 564 M pounds at a wholesale price of 79.6¢/pound. 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.

6.Technology Transfer

Number of new CRADAs and MTAs1
Number of active CRADAs and MTAs1
Number of invention disclosures submitted1
Number of patent applications filed1
Number of non-peer reviewed presentations and proceedings10
Number of newspaper articles and other presentations for non-science audiences1

Last Modified: 10/21/2014
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