Location: Warmwater Aquaculture Research Unit2011 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 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, development of new aeration technology, and new uses for active and passive acoustic techniques. Work continued on testing of the see-saw incubator at a collaborating commercial catfish hatchery. Research compared survival through swim-up stage in see-saw incubators either with or without supplemental oxygen supplied through diffusers in each trough. Survival through swim-up stage averaged 71.2% overall and was not significantly different between treatments. These results confirm that at least 45 pounds of eggs can be incubated in the see-saw without supplemental oxygen if the dissolved oxygen concentration of the supply water is at approximately air saturation. In FY2010 a field trial of an in-pond confinement system for short-term (2-3 week) culture of catfish fry before they are released to the open pond was conducted. This technique was examined as a means of improving overall fry survival rates in large ponds, and may provide an opportunity to vaccinate slightly larger (and more immune-competent) fish. While not statistically relevant (N=2), the two commercial ponds using confinement for a pre-growth period had a higher survival and produced larger fingerlings than did the two control ponds. A third year of research on oxygen requirements of blue X channel hybrid catfish in pond production systems was completed and indicates that hybrid catfish consume more feed at lower dissolved oxygen concentrations than channel catfish, and should 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. Work on development of the U-tube aerator has progressed with the recruitment of a HQ-funded post-doctoral research associate. An air-lift system is now being tested as a more efficient means of moving and aerating water with the u-tube system. A patent application for this device has been submitted through ARS. Work progressed on the use of a sonicator as a “green” method to reduce pond populations of ram’s horn snails, an intermediate host to the catfish trematode. If this is successful, use of chemical controls such as copper sulfate or hydrated lime will not be necessary. Work is beginning on a project aimed at increasing fry survival and decreasing production costs through fingerling stage. Use of supplemental oxygen may improve survival and growth, and allow for production of catfish fry at much higher densities in the hatchery prior to stocking in open ponds. Supplemental oxygen may thus reduce the need for heated well water in the hatchery, conserving both water and energy.