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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Research Project #418587


Location: Warmwater Aquaculture Research Unit

2010 Annual Report

1a. Objectives (from AD-416)
1. Develop and test novel equipment and strategies to increase gas exchange and the efficiency of fish production while minimizing equipment and energy costs. 2. Develop acoustic technology and methodologies to improve the production and profitability of aquaculture in the United States. 3. Determine effectiveness of new germplasm and novel aeration technologies on commercial scales.

1b. Approach (from AD-416)
We have made great strides in understanding the relationships between dissolved oxygen, feed consumption, feed conversion, growth, production and susceptibility to disease, and we will continue to learn more about the impacts of oxygen on fish health, development, growth, and production economics. However, we have learned enough to shift our focus to applications – development, testing and tech transfer of new equipment and techniques to improve oxygen management efficiency in both hatchery and pond systems. We havealso learned a good deal on the use of active SONAR systems to observe and quantify food sized and larger fish in the acoustically complex environment of commercial ponds. We will continue to improve our understanding of this field but will expand it to include other acoustic applications. Acoustic sounds, both from catfish and man-made sources, will be introduced into ponds to determine if the fish can be made to respond in a predictable, desirable manner to improve seining. One of the main objectives of CRIS 6402-31000-008-00D (Catfish Genetics, Breeding, and Physiology) is to “Initiate development of channel catfish and blue catfish germplasm with improved growth, yield, and esc resistance for eventual transfer to commercial producers”. This CRIS has been tasked with developing a procedure that will be used for future on-farm testing and preliminary commercial evaluation of new lines before full-scale release to the industry. Once in place, this model could also be used for assessment of new aeration or pond monitoring equipment, chemical treatments, vaccines, and algal control methods.

3. Progress Report
Research in this new research project focuses on design and testing of a new catfish egg incubator, management techniques to increase catfish fry survival, improved oxygen management and production efficiency in catfish production ponds, and new uses for active and passive acoustic techniques such as improved harvest efficiency, snail control, improving vaccine uptake, counting fish and determining initial pond survival of catfish fry and shrimp. Work continued on the see-saw incubator at a collaborating commercial catfish hatchery. Research compared hatch and fry survival rates of the see-saw with traditional paddle-type incubators. An additional 16 incubator units (troughs) were constructed, bringing the total at this hatchery to 32 units. Research during FY 2010 focused on effect of egg loading rate on hatch rate and survival to swim up. An initial field trial was conducted of an in-pond confinement system for short-term (three week) culture of catfish fry before they are released to the open pond. This technique may improve overall fry survival rates in large ponds, and provide an opportunity to vaccinate slightly larger (and more immune-competent) fish than are currently available. Continuing research on oxygen requirements of catfish in pond production systems indicates that both blue catfish and blue X channel hybrid catfish consume more feed at lower dissolved oxygen concentrations than channel catfish, and will convert feed better due to reduced mortality. This can result in significant energy and feed savings by the industry as they move to hybrid catfish production. Preliminary research has indicated that premature hatch of catfish fry may be a cause of the so-called “triple-tail” deformity and a study is underway to verify this. Results will be available when the fish are larger and fin morphology can be determined. Work on development of the U-tube aerator has been delayed pending the recruitment of a HQ-funded post-doctoral research associate. Candidates are being interviewed. Work progressed on the use of acoustics to modify fish behavior to improve seining by moving them away from nets during harvesting. A portable sound delivery system has been assembled for input of sounds into commercial ponds and will be tested later in the summer. A passive acoustic monitoring system was assembled and tested for using sound levels in ponds as a means of determining survival in recently-stocked freshwater prawn and shrimp ponds. A prototype unit was delivered to a commercial shrimp farmer for evaluation. Work continued on an individual fish-sizer which can provide the size distribution of a sample of captured fish.

4. Accomplishments
1. Development of the See-saw Catfish Egg Incubator. Traditional paddle-type catfish egg incubators have served the industry well for nearly a century but require a high water exchange rate and lose efficiency at egg loading rates above 6.8 kg (15 lbs) per trough. ARS researchers at Stoneville, Mississippi, in collaboration with industry partners, have developed a new incubator (the see-saw) which can incubate more eggs using less water and labor. In a direct comparison at a similar egg-loading rate (11.8 kg per trough), the see-saw produced 2.32 times as many swim-up fry as the traditional incubator. Additional studies indicate that over three times as many eggs can be hatched in the see-saw using 10-20% as much water, saving considerable labor, space, ground water, and energy for pumps and heaters. In commercial field trials thus far over 100 M egg have been hatched. Upon completion of the field trials, technology transfer plans are expected to result in rapid adoption by the catfish industry as well as by public-sector hatcheries which are typically space-limited.

2. Improved Catfish Feed Conversion through Pond Oxygen Management. Dissolved oxygen is assumed to be the most critical water quality parameter in warmwater aquaculture but controlled studies of the impact of this diurnally-fluctuating parameter on channel catfish have been lacking. ARS researchers at Stoneville, Mississippi, are concluding a long-term research program examining the impact of pond dissolved oxygen (DO) concentrations on blue, channel, and blue X channel catfish growth, production, food consumption and food conversion. These studies were made possible by the use of a computer-controlled pond oxygen monitoring system which could initiate aeration at precise DO set-points and continuously record DO, temperature and aerator usage. Results with all three species show that higher DO concentrations than previously thought (best performance at minimum daily DO concentrations of 2.5-3.0 mg/L) are required for optimum food conversion and growth, and this improved growth will significantly shorten the production cycle (currently from three to five years) down to two years from egg to food fish. While food conversion is not directly impacted by DO, a shorter production cycle reduces fish losses to all causes, significantly improving food conversion. Feed is the greatest single cost in catfish production. Increased growth resulting from improved DO management can reduce food conversion ratios from an estimated industry-wide 2.5-3.0:1 to 2.0:1, greatly improving the profitability of catfish farming.

3. Development of an Acoustic Fish Counter/sizer. Methods for determining average weight of catfish during harvest has not changed in the last century. Developing a technique that is both fast, minimizing stress on the fish, and accurate, assuring valid counts for stocking or sale, would improve both the efficiency and profitability of aquaculture. Scientists and staff with the University of Mississippi, National Center for Physical Acoustics at Oxford, Mississippi, in collaboration with scientists at the University of Arkansas at Pine Bluff, Arkansas, have developed an acoustic fish-sizer which can provide the size distribution of fish as they pass through a restrictive pipe into a pond or transport tank. Measurements predicted a mean weight of 0.64 kg (1.42 lbs) for a fish sample that had a (individually) measured mean weight of 0.65 kg (1.43 lbs). This work could lead to improved speed and accuracy of fish sample counts, while reducing stress on the fish. This could mean higher survival if fish are stocked, or improved product quality if sold to a processor.

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.

Review Publications
Torrans, E.L., Ott, B.D., Jones, R., Jones, Jr., R., Baxter, J., Mccollum, B., Wargo, III, A., Donley, J. 2009. A Vertical-Lift Incubator (The "Seesaw") Designed for Channel Catfish Egg Masses. North American Journal of Aquaculture. 71(4):354-359.