Location: Warmwater Aquaculture Research Unit2012 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:
The focus of this research project is to develop a more complete understanding of the impacts of water quality, particularly dissolved oxygen (DO), on growth and production of catfish, and to develop new equipment or management strategies to utilize that information. The goal is to reduce the production costs for United States fish farmers, making them more competitive in a world economy and providing quality fish to U.S. consumers at a fair price. We have completed testing of the see-saw incubator at a collaborating commercial catfish hatchery. We believe this incubator is ready for commercial application and technology transfer efforts have begun. Preliminary studies have begun examining the effect of DO concentration during egg incubation on the so-called “triple-tail” deformity of channel catfish; work was also begun on the DO requirements of channel catfish fry. A third year of research on DO requirements of hybrid catfish in ponds was completed and indicates that hybrid catfish consume more feed at lower DO concentrations than channel catfish, and should convert feed better in commercial ponds due to reduced mortality resulting from a shorter production cycle. Two studies are underway with hybrid catfish examining relative growth rates over a range of sizes and the comparative effects of fish density and DO concentration on growth and production. Work on development of the U-tube aerator has progressed. An air-lift type system was tested and was determined to be a more efficient means of moving water with the u-tube than other mechanical systems. A patent application for this device is now pending with the U.S. Patent and Trademark Office. The u-tube has been scaled up and installed in an 8-acre pond at National Warmwater Aquaculture Center (NWAC). The new aerator will be evaluated in this commercial-scale setting. If this test goes well, expansion to on-farm trials will begin as early as next year. Other aquaculture engineering projects are underway and show promise. The water supply system at a commercial hatchery was redesigned to include a counter-current heat exchanger to reduce the cost of heating water. Early results indicate a possible savings of up to $500 per day or $22,500 per season in propane. Work has also begun on determining the most economical design for water-moving equipment for use in split-pond production systems. Thus, existing slow-rotating paddlewheels (SRP) are currently being evaluated for performance and reliability at NWAC. Work progressed on the use of sound to move fish in advance of seine nets to improve harvesting. Other means of evaluating the noise’s effectives on fish motion are being pursued in the summer of 2012 with one possibility being direct assessment on ponds slated for harvesting. Work continued on the use of a commercially available sonicator (a high amplitude acoustic source) to eliminate the Ram’s Horn snail, an intermediate host to trematodes that infect catfish. If successful, the use of chemical controls would be reduced or perhaps eliminated.
Torrans, E.L., Ott, B.D. 2012. Effects of DO concentration in growout performance of blue catfish with comparison to channel catfish. North American Journal of Aquaculture. 74(2):273-282.