1a.Objectives (from AD-416)
Develop technology and methodology for both passive and active acoustic applications to improve the production and profitability of aquaculture in the United States. This includes the use of ultrasound to mechanically clean water, utilizing acoustic stimuli on catfish to improve seining operations and passive acoustic monitoring of small fry. This project supports the unit objective to develop new equipment and technologies to improve profitability of channel catfish farming.
1b.Approach (from AD-416)
Preliminary acoustic measurements of commercial algae control systems will be made in the National Center for Physical Acoustics (NCPA) calibration tank. Customized equipment will be assembled at the NCPA and delivered to National Warmwater Aquaculture Center (NWAC) for lab and field trials by USDA personnel. Measurements on fish stimuli with sound will be made at USDA-NWAC tanks and ponds with later trials performed in conjunction with seining to determine effectiveness. Equipment for passive monitoring of catfish fry will be assembled at the NCPA. Measurements will be made by NCPA personnel at USDA-NWAC facilities.
The purpose of this agreement is to investigate active and passive acoustic techniques to improve the profitability of U.S. aquaculture. Work progressed on the use of acoustics to improve seining by pulling or pushing fish away from seine nets during harvesting. Natural and man-made sounds were collected and analyzed and tests using these sounds on fish are in progress. In order to deliver the sounds into the water a ruggedized portable sound delivery system was assembled and tested in research ponds at USDA-National Warmwater Aquaculture Center (NWAC). A different portion of the original project focused on the potential use of ultrasound for algae control. That objective was ultimately removed but preliminary research did reveal other possible uses of ultrasound to improve aquaculture. One application, killing snails to control trematodes, shows promise. Initial laboratory tests using a commercially available sonicator (used for welding plastic) is capable of killing individual snails in fish tanks nearly instantaneously. More thorough testing indicates efficacy rates of approximately 50% on batches of 10 snails in fish tanks. It is unclear if the lower mortality rates are due to the particular snails used, their distribution in the tanks or the statistics of small numbers. More testing is underway. To be fair, testing in fish tanks provides some gain in sound levels compared to what is expected in ponds due to reverberation from the tank walls. Tests with lowered sound power levels to mimic pond absorption showed lower efficacy rates. Work is underway to determine if higher power levels are possible or if alternate driving frequencies can provide some benefit. Alternate approaches to achieve more sound power in the pond would be the use of multiple sonicators in conjunction with a focusing device (parabolic dish or semi-cylinder submerged in the water) to re-create some of the reverberation achieved in the lab testing. Such a device could be attached to a truck or four wheeled vehicle which carries the electrical power generation in the envisioned field delivery device. The development of such a field device for continued testing will be part of the focus of the upcoming year’s effort. Lastly, the work on the individual fish sizer described in last year’s report was presented at a scientific conference. The ADODR monitors this project through telephone calls and e-mails to the collaborator, and through annual reports and periodic meetings with the collaborator.