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November 3, 2013
Acoustic Feeding Control in Large Ponds at Low Densities
Tasmania based AQ1 Systems has pioneered the use of listening devices to manage shrimp feeding. In its October 2013 newsletter, it discusses the use of acoustic feed control in large ponds stocked at low densities, looks at feeder configurations for large and small shrimp ponds, and introduces the latest advances in its Sound Feeding System (SF200).
Dr. David Rasch, director of technology at AQ1, says, “It has always been the AQ1 plan to develop a very smart feeding control algorithm to cover a full range of shrimp farming configurations.” The original SF200 system incorporated the basic features needed to control feeding by analyzing shrimp feeding sounds. It was deployed in seven countries with ponds ranging in size from ten-hectare ponds stocked at ten postlarvae per square meter to a tenth-of-a-hectare ponds stocked at 450 PL/m² and produced up to 30% faster growth and a 20% reduction in feed conversion ratios.
After three years of research, “The data gathered from these deployments gave AQ1 a unique insight on how the acoustic feeding control settings in the SF200 could become self adjusting to produce optimal feeding control in all circumstances and throughout the production cycle,” said Rasch. “In addition to self learning, the SF200 system now has the ability to manage feeding on multiple ponds from a single controller, monitor dissolve oxygen and create environmental alarms which turn feeders off automatically. The system can identify when a feeder is empty or blocked and turn it off when a maximum daily feed target is reached.”
“With the SF200 PC software the emphasis has been on providing users with a rapid understanding of shrimp feeding activity and feed rate and to compare daily feed intake over time. We have also released Thai and Spanish software to assist customers in those markets.”
A very important factor to consider in deciding how many feeders you need is the stocking density. With highly mobile species such as Penaeus vannamei, the number of shrimp per square meter of feeding area can be high (1,000-3000/m²) compared to species such as P. monodon and P. indicus that are less mobile, often larger at harvest and stocked at lower densities.
The control algorithm can self regulate feed delivery rates to compensate for poor feeder spread, low output rates and high stocking densities. However there is a point where the biomass becomes too great for the available feed area and not all the shrimp can enter the feeding zone to eat. This can restrict feeding, slow growth and lead to significant size variation at harvest.
After focusing development P. monodon and P. vannamei in intensive ponds of less than one hectare, some of our readers will be delighted to hear that AQ1 has been studying feeding control in ponds larger than five hectares with lower stocking densities
Several questions had to be answered to adapt the SF200 system to extensive ponds:
• How would the automatic feeding change the location of the shrimp biomass in the ponds?
• Would there be a build up of detritus near the feeders?
• Would there be areas where the oxygen levels dropped?
• Would feeding patterns in large extensive ponds be similar to small intensive ponds?
To investigate these questions, AQ1 deployed imaging sonar to record the movements of shrimp as feeders were turned on and off and to analyze the movement of shrimp in response to different sounds. Not surprisingly the shrimp did not respond to classical music, but they did move around if there was a feeding event happening! AQ1 also took cast net samples at different positions in the pond and discovered that shrimp disperse rapidly around the pond after feeding was stopped.
AQ1 also found that feeding patterns in extensive ponds were very similar to those in intensive ponds. One vital difference is that some extensive farmers were often unwilling to feed the shrimp between midnight and daylight when oxygen levels were low. This caused a prolonged surge in the late morning feeding rate not seen in intensive ponds that were fed around the clock.
Stylibleue, a shrimp farm in New Caledonia, found that there was no build up of detritus on the pond bottoms under the feeders in its seven-and-a-half-hectare ponds. Owner of Stylibleue Edouard Klotz (pictured with the latest SF200 controller and Thai feeders) was asked why he implemented the system and what were his results to date. He said:
“After many years spent trying to improve the classical system of feed distribution and control with feeding trays, I felt incapable of making real progress. AQ1’s acoustic feeding technology (SF200) convinced me because it corresponded exactly to the ideal tool that every shrimp farmer is dreaming of for good feeding management. The productivity gains AQ1 produced on smaller ponds convinced me to take the risk to implement the Sound Feeding System on larger ponds with multiple auto-feeders. We have obtained new insights on when, where and how much the shrimp eat and the SF200 system demonstrated clearly that the classical method of feed distribution is a long way from what shrimp want and need. The SF200 produced the best growth performances (30% above industry average) ever obtained with our species (blue shrimp, P. stylirostris) in our local conditions, and I have decided to invest in more systems”
Information: Ross Dodd, Managing Director, AQ1 Systems P/L, 1/110 Murray Street, Hobart, Tasmania 7000, Australia (phone +61-0-3-6234-6677, mobile +61-0-419-386-526, email firstname.lastname@example.org, webpage http://www.aq1systems.com).
Japan: AQ1 Systems, #307 Sky View Mansion, 2020 Maeda, Shimonoseki-City, Japan 752-0997 (phone +81-832-33-6950, international +81-832-33-6950, fax +81-832-33-6950).
Thailand: AQ1 Systems (Asia), Co., Ltd., No. 1104/157 Noble Cube, Pattanakarn Road, Suanluang District, Bangkok, Thailand.
United Kingdom and Europe: AQ1 Systems, 34 Lawrence Street, 1/L Glasgow G11 5HD, Scotland, United Kingdom (phone +44-777-5560130, fax +44-141 5850200).
Brazil: Felipe Suplicy, Marine Equipment, Lda., Florianopolis, Brazil (phone +55-48-32068922, http://www.marineequipment.com.br).
Ecuador: Alex Maldonado, Agrobimsa S.A. (phone 0999614919).
Italy: SCUBLA S.r.l., Strada di Oselin 108, 33047 Remanzacco (UD), Italy (phone +39-0432-649277, fax +39-0432-649279, website http://www.scubla.it).
Sources: 1. Email to Shrimp News International from Ross Dodd at AQ1 Systems, P/L. Subject: Passive Acoustic Feeding Technology. November 1, 2013. 2. The 4th edition of the AQ1 Shrimp Farmers Technology Newsletter. October 2013. 3. AQ1’s Website. Website visit on November 3, 2013.
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