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Meet the Flockers
What Is Bio-floc Shrimp Farming?
Adjusting the Carbon/Nitrogen Ratio
Barry Bowen and Robins McIntosh
The Evolution of the Bio-floc Technology
Shrimp farming, the production of marine shrimp in impoundments, ponds, raceways and tanks, traces its origins to Southeast Asia where for centuries farmers raised incidental crops of wild shrimp in tidal fishponds.
Modern shrimp farming was born in the 1930s when Motosaku Fujinaga, a graduate of Tokyo University, succeeded in spawning the kuruma shrimp (Penaeus japonicus). He cultured larvae through to market size in the laboratory and succeeded in mass-producing them on a commercial scale. For more than 40 years, he generously shared his findings and published papers on his work in 1935, 1941, 1942 and 1967. In 1954, Emperor Hirohito honored him with the title “Father of Inland Japonicus Farming”.
In the mid-1970s, when fishermen and hatcherymen began supplying large quantities of seedstock, shrimp farming began a rapid expansion that continues today. In some cases, the results were astounding. Large extensive farms in Ecuador recaptured their entire investment in the first year (sometimes with the first crop); small-scale intensive farms in Taiwan produced dozens of shrimp millionaires; and semi-intensive government farms in China reaped untold profits from formerly unused land around the Gulf of Bohai.
Today, over fifty countries have shrimp farms. In Ecuador, Mexico and Brazil, the leading producers in the Western Hemisphere, shrimp exports generate hundreds of millions of dollars a year. In Thailand, the leader in the Eastern Hemisphere, they have passed the two billion dollar mark. Vietnam, India, Indonesia and China all think they will surpass Thailand as the leading producer of farmed shrimp. Malaysia, Taiwan, Bangladesh, Sri Lanka, The Philippines, Australia and Myanmar (Burma) have shrimp farms, and there are shrimp farms throughout Central and South America. Honduras, Panama and Belize have big industries, while smaller industries exist in Colombia, Guatemala, Venezuela, Nicaragua and Peru. Many countries in the Middle East have shrimp farms, with Iran and Saudi Arabia taking the lead.
In the early 1990s, after two decades of solid growth, viral diseases and challenges from the environmental community began to impede the development of traditional shrimp farming. For the last five years, viral diseases alone have probably cost the industry a billion dollars a year. All the while, the environmental community has been chipping away at some of shrimp farming’s flaws, like habitat destruction, effluents, displacement of local people, and any other issue they could hang a fundraising campaign on.
Now, a new way to farm shrimp has evolved that protects shrimp from disease and protects the environment from shrimp farming, creating the possibility that shrimp farming could become the cleanest agriculture industry in the world!
A marriage of Asian intensive shrimp farming and American science, the new technology incorporates bits and pieces of successful shrimp farming lore from around the world.
It’s also very expensive, energy intensive and at the very beginning of commercial development.
What Is Bio-floc Shrimp Farming and How Does It Work?
Most shrimp farming is done in outdoor ponds that depend on the sun and a robust algal community to process the nitrogenous wastes from the shrimp and to supply oxygen to the pond water. The shrimp also pick up some essential nutrients from the algae, creating a nifty arrangement, but a difficult relationship. Blame the algae. It blooms, it crashes, it takes the day off when it’s cloudy, works against you at night, and has days when it just does its own thing. Picture ten “identical” shrimp ponds, all in a row. Each will have a slightly, and sometimes dramatically, different algal community, leading to wild swings in water quality variables that slow shrimp growth and create endless management problems for the shrimp farmer.
Bio-floc shrimp farming encourages a bacterial community in the pond. Once established and maintained, bacteria-dominated ponds are more stable than algae-dominated ponds. The bacteria accumulate in clumps called flocs, more about flocs in a moment, and gobble up the nitrogenous wastes ten to a hundred times more efficiently than algae, they work night and day, pay little attention to the weather—and turn those nitrogenous wastes into high-protein feed for the shrimp.
Bio-floc shrimp farming works anywhere: in the tropics, in temperate climates, in the desert, close to town, in buildings and in greenhouses. It promises to revolutionize shrimp farming.
Amazingly, almost all the equipment and know-how for putting together a bio-floc shrimp farm are available right off the shelf. The problems is that it takes tens of millions of dollars to make it work and operating costs are high. Here are some of the pieces you need to put a bio-floc shrimp farm together:
• Filters to exclude disease carriers from incoming water
• High stocking densities of disease-free, genetically improved shrimp, like Peaneu vannamei,
that graze on naturally occuring organisms in the ponds
• Recycling of water within the farm to remove sludge and maintain desirable
• Zero water exchange with the environment
• Biosecurity to keep diseases out
• Lots of aeration and mixing of pond water
• Pond liners
• Sludge removal from center drains
• A good source of inexpensive carbohydrate (molasses, wheat) to stimulate a
• Greenhouses or buildings to keep temperatures above 30°C
• A laboratory for diagnosing disease and assessing water quality
In this case, the whole really is greater than the sum of its parts because of the magical relationship that develops between the microbial community in bio-floc ponds and the shrimp. Unlike flow-through ponds where algae dominate, bacteria take over in these ponds, aggregating in microbial flocs that also contain fungi, protozoans, algae and nematodes—a veritiable shrimp feast. The flocs process nitrogenous wastes, and the shrimp feed on the flocs, a symbiosis that stabilizes water quality and supports rapid shrimp growth. These ponds teem with tiny little critters and shrimp are the top predators. They’re in heaven.
The technology requires lots of aeration, some adjustments to local conditions, and you have to prime the pond for bacteria by adjusting the carbon/nitrogen ratio in the pond, but once the bacteria take over, the pond mostly takes care of itself. Because the shrimp pick up a lot of nutritients from grazing on the floc community, feed costs drop and so do the labor costs associated with feeding.
These ponds produce ten times more shrimp than semi-intensive ponds and forty times more shrimp than extensive ponds. When covered with greenhouses or housed in buildings, they offer the only real option for stopping viral diseases. And if that doesn’t get you excited, they have almost zero impact on the environment. Yup, it sounds almost too good to be true, but it appears to be working, and shrimp farmers all over the world are assessing its potential.
Adjusting the Carbon/Nitrogen Ratio
Adjusting the carbon/nitrogen ratio can be tricky. It’s done by feeding the bacteria exactly what they want: a diet with a carbon/nitrogen ratio of around 12:1, or higher, accomplished by adding molasses, wheat, tapioca or some other inexpensive carbon source to the water. The shrimp supply the nitrogen. The farmer supplies the oxygen. The bacteria take the bad stuff out of the water and convert it to food for the shrimp.
But, you’ve got to get the carbon/nitrogen ratio of the pond water right to make it all work.
During the last quarter of 2004, the Shrimp List (below), a mailing list for shrimp farmers, carried a great discussion on the carbon/nitrogen ratio in shrimp ponds. Here’s an excerpt from that discussion:
Sunil Kant Verma, a former employee of Hi-Line Aqua in India, asked: Could someone give me information on the carbon/nitrogen ratio in shrimp ponds?
Peter Van Wyk, then an aquaculture project planning specialist at Harbor Branch Oceanographic Institution in Florida, USA, and currently a research associate at the Southwest Virginia Aquaculture Research and Extension Center, in Saltville, Virginia, USA, responded [His comments were updated in July 2006.]:
The feeds used in intensive shrimp ponds typically have at least 35% protein and a carbon/nitrogen ratio of around 9:1. With such a low C:N ratio, carbon becomes the limiting nutrient, and the bacterial populations don’t expand beyond a certain point; however, when the C:N ratio is increased, bacteria proliferate and shrimp growth takes off.
If the C:N ratio is increased, either by feeding lower protein feeds with a higher percentage of carbohydrate, or by adding a carbohydrate source such as molasses in addition to the regular feed, the increased availability of carbon allows the bacterial population to consume a higher percentage of the protein in the organic material. This results in more complete digestion of the organic material in the pond by the bacteria. As the C:N ratio increases, the bacteria resort increasingly to ammonia metabolism to meet their nitrogen requirements. As C:N ratios are increased even further, a point is reached where nitrogen, rather than carbon, becomes the limiting nutrient. This occurs when the C:N ratio reaches about 15:1. At this point ammonia concentrations should be close to zero in the pond. Manipulation of C:N ratios is an effective tool for managing ammonia levels in shrimp ponds.
Increasing the C:N ratio can be accomplished by either holding the feed protein level constant and supplementing the feed with carbohydrate, or by feeding a feed with a lower percentage of protein and a higher percentage of carbohydrate. Both approaches will result in much higher bacterial counts in the pond. The oxygen required to support additional bacterial biomass will increase proportionally with the increase in bacterial population. Likewise, CO2 production will increase, driving pH down. If you are contemplating carbohydrate supplementation to increase C:N ratios, make sure that your pond is well aerated and circulated to keep the organic detritus suspended in the water column where there is sufficient oxygen for the bacteria. Also, once you develop a dense population of bacteria, don’t discontinue the carbohydrate supplementation suddenly. This will starve the bacteria of carbon, causing a die-off to occur and ammonia to spike.
Claudio Paredes, aquaculture business development manager for Agribrands Purina in Venezuela: Do you seed the pond with bacteria, or are they already there?
Peter Van Wyk: It is not necessary to inoculate a pond with commercial bacterial products to manage one of these systems. This can be accomplished simply by maintaining a C:N ratio greater than 12:1, and supplying adequate aeration.
Claudio Paredes: What’s the best way to measure the C:N ratio in a pond?
Dallas Weaver, a water quality specialist and hatchery consultant in California, USA, responded: Measurement of C:N is only part of the story. If you measure TOC (total organic carbon), some of that carbon can be refractory and does not help the bacteria soak up the ammonia. Measuring TOC and BOD (biological oxygen demand) with and without ammonia oxidation inhibition, along with TKN (total Kjeldahl nitrogen) will provide some useful management information.
Kevin Healey, a supplier of bacterial remediation products from Australia, responded: This has been an interesting discussion on C:N ratios, and thanks to Peter for the time he’s taken to provide such clear explanations. I’m in agreement with pretty much all he’s stated, in particular the usefulness of molasses in promoting a bacteria bloom in ponds and the value of using probiotics in hatcheries.
Peter Van Wyk: Measurement of C:N ratios in ponds is not a simple task because the carbon and nitrogen end up in a lot of different places: the feces, the organic floc, the bacteria, the water and the shrimp. Researchers use labeled isotopes of carbon and nitrogen in the feed to study C:N budgets in ponds. Of course this isn’t practical in a production pond. Managing the C:N ratio in a pond is handled more easily by managing the C:N ratio of your feed. I estimate the C:N composition of the feed rather than measure it. I don’t have access to laboratory equipment to measure total organic carbon and total Kjeldahl nitrogen, nor do I have the budget to send out samples to a laboratory for analysis.
Carbon accounts for roughly 50% of the dry weight of most feeds. This is a crude estimate, but carbon content is remarkably constant even for feeds with widely varying compositions. The nitrogen content of the feed is calculated from the protein content. Protein is approximately 16% nitrogen. Although this method for calculating C:N ratios is admittedly crude, it provides a reasonably close estimate of actual C:N ratios.
Barry Bowen and Robins McIntosh
Barry Bowen’s name should go down in the history of shrimp farming as a great visionary who put his own money on the line to build, in 1997, a prototype, bio-floc shrimp farm called Belize Aquaculture, Ltd., which, in 2000 and 2001, expanded into a full-fledged commercial venture with close to 75 acres of ponds in super-intensive production. During its first commercial run, the farm produced at the rate of 30,000 pounds per acre per year! In 2006, Bowen installed his own power plant and embarked on a new expansion of the farm.
Robins McIntosh supervised construction, technology development and start-up operations at Belize Aquaculture, Ltd. He currently works for Charoen Pokphand, a huge conglomerate in Thailand and a major international supplier of shrimp feeds. He helped implement the bio-floc technology on a huge CP shrimp farm in Indonesia.
At the fifth Central America Symposium on Aquaculture (Honduras, August 1999), Bowen and McIntosh were the first to describe the commercial implementation of bio-floc shrimp farming. Bowen said: My primary objective was to develop an environmentally friendly shrimp farm in Belize, a 100% eco-friendly shrimp farm, a shrimp farm with no effect on the environment. That was a tough assignment. In reality, the only way it could be done was with zero-exchange ponds.
With zero-exchange, energy costs are high because aeration is necessary around the clock to keep the system working. We decided to go with 12-horsepower of aeration per acre, a stocking density of 125 PLs per square meter, and a projected harvest of 10,000 pounds per acre per crop, with 2.4 crops per year, for total production of approximately 25,000 pounds per acre per year.
When I first presented Robins McIntosh with these figures, he shook his head and said, “Impossible, I could probably guarantee you 7,000 pounds per acre per crop, but anything above that with today’s technology would not be possible.”
Well, after two years of growing shrimp in our system, we have exceeded those original goals. We are now producing an average of 14,000 pounds per acre per crop, with 2.4 crops per year. And we’ve had much higher yields than that from several ponds. Two weeks ago, one of our harvests yielded 24,000 pounds of 21-22 gram animals per acre.
We are using technology that could be deployed in any warm climate. You don’t have to be at sea level or anywhere near the coast. You could do it in the middle of the Sahara Desert.
At the Fourth Latin American Aquaculture Congress and Exhibition (Panama, October 2000), Robins McIntosh described some of the farm’s practices:
All of our ponds are lined because of our sandy soil, but liners also have many other benefits. Soils become a nonfactor with liners, eliminating all the soil science and the restrictions that soils place on site selection. After a harvest, there’s not a lot of sludge or detritus left; we wash what’s left into a settling basin, and within six days the pond can be filled and restocked. That pond will be in production 355 days a year. We don’t have to dry out the bottom, we don’t have to plough it, we don’t have to lime it. We sun sterilize the bottom and then refill the pond with the same water that came out of it. It’s free of sediment, but full of nutrients, so no fertilizer is necessary.
The Evolution of the Bio-floc Technology
Interview with Harvey Persyn: At the Sixth Central American Symposium on Aquaculture (Honduras, August 2001), I chatted with Harvey Persyn, a shrimp farming consultant and major player in the development of shrimp farming in Colombia, Brazil and Venezuela, about some of his youthful experiences with super-intensive, low-exchange shrimp culture systems. In 1975, while working at Ralston Purina’s shrimp research facility in Crystal River, Florida (on the grounds of the Florida Power Company), Persyn grew shrimp in bacteria-based bioreactors. He worked out the protein levels in the microbial flocs (35%), fed the bacteria with sugar, used low protein feeds, kept everything in suspension with lots of air, analyzed the cycling of the nutrients from shrimp to bacteria and back again, monitored all the important water quality variables, and produced of 2.7 kg/m2 of 18-gram animals. He said one experimental unit had fifteen layers of substrate spaced 2.5 inches apart that produced around 30 kg/m3. Dr. Addison Lawrence, currently a Regents Professor at Texas A&M University, consulted on the project, which continued until October 1981, when Purina closed the facility.
Shrimp News: If you knew about the amazing productivity of these systems, why did you build so many big semi-intensive farms in Latin America?
Harvey Persyn: Basically because the world and investors were not ready for shrimp bioreactors. Investors want a track record. Farmers want their neighbor to try it first. At the time, big semi-intensive farms were the way to go, and they remain the state-of-the-art in the Western Hemisphere today. Belize Aquaculture, the big new super-intensive farm, might change all of that. It and other projects around the world have inspired lots of confidence in bio-floc shrimp farming. The world is ready now.
Interview with Steven Serfling: At the World Aquaculture Society (WAS) Meeting in San Diego, California, USA (January 2002), I interviewed Steven Serfling, president of Sunwater Technologies, a consulting company that specializes in recirculating aquaculture systems. In the late 1970s and early 1980s, Serfling, then running Solar Aquafarms in Encinitas, California, USA, developed a unique bio-floc system for intensive culture of shrimp.
Shrimp News: Hi Steve. Tell me a little bit about the pioneering work you did with shrimp in closed systems in the late 1970s.
Steven Serfling: During the early years at Solar Aquafarms, from 1974 to 1984, the goal was to develop closed-cycle, controlled-environment, ecology-based systems for culturing fish and shrimp. Various types of low-cost, solar greenhouse-covered raceways and circular tanks were developed to allow year-round production in cold-winter climates, like the USA. Many types of aeration and biofiltration were tested to allow the higher production rates required to justify the higher capital investment in the culture system. We first experimented with the freshwater prawns, Macrobrachium rosenbergii, and tilapia during the mid-1970s.
Shrimp News: What got you started with marine shrimp?
Steven Serfling: At that time no one had been able to raise marine shrimp to normal market sizes or to breed them in recirculating tanks. Macrobrachium had immediate potential if we could overcome the density/cannibalism problem. We developed several types of horizontal and vertical habitats and produced Macrobrachium yields equaling 10,000 pounds/acre/year, but that still represented a marginal return on investment. So we switched to marine shrimp, Penaeus vannamei. We calculated that if we could achieve yields of 20,000 pounds/acre/year (say three crops at 6,000-7,000 pounds each) and sold the shrimp head-on, the technology would pay for itself.
Shrimp News: What led you to develop your unusual “microbial soup” water treatment method?
Steven Serfling: We started out testing a variety of conventional water treatment methods and equipment, like trickling filters, submerged biofilms, slow-sand and pressure-sand filters, clarifiers, UV and ozone—all designed to remove solids from the water and keep it clear and sterile. During a visit to several highly productive shrimp estuaries and ponds in Ecuador and Costa Rica, however, it was obvious that shrimp, at least P. vannamei, grew very well in water with high levels of suspended algae and detritus. So we threw out the filters, clarifiers and sterilizers and duplicated the rich estuary ecosystem in our tanks. The nickname that stuck for the treatment process was “ODAS,” for “Organic Detrital Algae Soup,” a mixture of hundreds of different species of microalgae, beneficial bacteria, detrital flocs, protozoans and zooplankton that thrive on shrimp wastes.
Shrimp News: Did you plan to have the shrimp feed on the microbial flocs?
Steven Serfling: No, that was an accidental discovery. I’d heard that vannamei grew well in low-density ponds without commercial feeds, making their living on the natural foods in the pond. I was curious about how vannamei compared to other species, so we ran feeding trials with monodon, stylirostris and vannamei in aquaria. We discovered that vannamei would eat all kinds of stuff that the other species would not touch.
Shrimp News: How did you discover that vannamei could filter algae directly from the water?
Steven Serfling: During that period we were also raising Spirulina algae on a research and pilot commercial scale. We put some live Spirulina in an aquarium with juvenile vannamei and to our surprise the shrimp immediately rose up in the water column and started eating the Spirulina. Within five minutes they had filtered all the Spirulina out of the water, their stomachs turned green and you could watch the Spirulina pass though their systems. But Spirulina is too expensive to grow as shrimp feed, so we looked at other alga species. We learned that regardless of how small the microalgae were, as long as they were attached or trapped in detrital flocs, either suspended or settled, or on biofilms on the sides or bottoms of the tanks, the shrimp would consume the algae, either by picking or filtering. When feeding, they would either swim after the flocs or simply stand on the bottom and sweep them into their mouths.
Shrimp News: I visited your facility during that period and remember you saying, “the water column is the filter.” I thought you were crazy.
Steven Serfling: You weren’t the only one who thought we were crazy! Even though we showed people the “biofilter,” they were convinced we had some elaborate system hidden behind the greenhouses. We tested vertical and horizontal substrates that were originally designed for a Macrobrachium system, including one that was almost identical to the current “AquaMats” product. In fact, we even obtained a patent for a water treatment process that uses vertically suspended biofilms as a key component. But at the densities we targeted at that time with vannamei (7,000 pounds/acre/crop with three crops a year), substrates provided no significant benefit. They may be helpful at higher densities.
Shrimp News: How did you aerate?
Steven Serfling: With diffused air lifts and sometimes paddlewheels. One thing we learned early on was that you had to have continuous mixing and aeration to keep solids in suspension. Otherwise, anaerobic pockets and the resultant hydrogen sulfide would kill the shrimp. In those days, critics said aeration was too expensive for raising shrimp, but our analysis indicated that aeration only added about $0.06 to a pound of shrimp.
Shrimp News: What salinities were you working with?
Steven Serfling: We tested salinities from 3 to 10 parts per thousand (ppt), and the shrimp appeared to do as well at 3-5 ppt as at 10 ppt. We knew that vannamei could tolerate low salinities, but at that time we thought it too risky to raise them in freshwater. It was a closed system, so the cost of salt for 3-5 ppt was very minor.
Interview with John Ogle: At Aquaculture 2004 (Hawaii, USA, March 1–5, 2004), I chatted with John Ogle about the history of super-intensive, bacteria-based shrimp farming. John is a research associate in fisheries and shrimp aquaculture at the University of Southern Mississippi’s Gulf Coast Research Lab, which has embarked on a program to make inland, indoor shrimp farming profitable in the United States. John built and will soon begin running trials at the Lab’s new shrimp research facility in Ocean Springs, Mississippi, which got flooded by Hurricane Katrina (August 2005), but most of the facilities survived.
Shrimp News: What was your first experience with microbial flocs in shrimp farming?
John Ogle: In 1989, we were running experiments on all kinds of filtration systems and weren’t particularly happy with any of them. Out of frustration, in November 1989, we stocked a raceway with Penaeus vannamei that had no filters, just to see what would happen. We ran an air line down the middle of the raceway, and in about 30 days we had this bacterial floc. We knew what it was because it’s the same type of floc that appears in sewage treatment lagoons. What we really discovered was that P. vannamei will live and grow in an aerated, marine sewage lagoon, down to about five parts per thousand salt. Our raceways actually produced a light floc that we called fluff.
It takes about 30 days for the flocs to develop. You go through an algae bloom, some foam, and then almost magically, the thing flips to floc. The shrimp begin feeding on it immediately and you can cut back on the amount of traditional feed that you use.
That was our first experience with floc filters and we have been using them almost continuously ever since. We designed and built a new building just to take advantage of them. In fact, we don’t use any other kind of filter. We even use them in shrimp nurseries.
Shrimp News: In your first trials, how much aeration did you use?
John Ogle: We used a one-inch pipe with holes drilled in it and ran it on a little Sweetwater L-20 Blower. Oxygen levels stayed high, from 4 to 12 parts per million, averaging around 6 ppm. At production densities, these systems remain stable for about 12 weeks, but as the shrimp grow larger, oxygen levels drop and growth slows. We lost a tank that was in production for 22 weeks and contained 25-gram shrimp. The load was so high that the oxygen dropped and we lost them.
We have some zero-exchange, floc-filter systems that have been running for a year, and the shrimp are still perking along. The floc is so thick you can almost take it out with a fish net. What we’re trying to find out now is what levels of floc are ideal for shrimp farming, and then we plan to build a system that takes advantage of those levels.
Taiwan and Thailand: In the late 1980s, hundreds of small-scale shrimp farmers in Taiwan learned that they could produce 10 tons of shrimp per hectare per crop—if they aerated heavily, pumped a lot of water and fed high-quality feeds. Suddenly Taiwan was producing 100,000 metric tons of farmed shrimp a year. Then diseases hit, and it took the industry a decade to recover. In the early 1990s, Thailand appeared to be headed in the same direction, but when the whitespot virus hit, the Thais added some new wrinkles to the Taiwanese technology—reservoirs, settling ponds, filtration, water treatment, waste disposal and zero water exchange—and continued to increase production throughout the 1990s and early 2000s.
Stephen Hopkins: Give Stephen Hopkins (then manager of the Waddell Mariculture Center in Beaufort, SC, USA, now raising tropical fish in Hawaii) credit for publishing the first research on bio-floc shrimp ponds. In the early 1990s, after a tour of intensive shrimp farms in Taiwan in the 1980s, Hopkins and his colleagues—Paul Sandifer, Al Stokes and Craig Browdy—began conducting research on super-intensive production in bio-floc ponds. Their results are well documented in the annals of the World Aquaculture Society.
The United States and Latin America: Researchers and consultants in the United States and shrimp hatcheries and farms in Latin America contributed the following:
• Disease-free, genetically improved seedstock, like Penaeus vannamei, which
• A scientific understanding of zero-exchange ponds
• New feeding strategies that take advantage of the pond ecology
• Pilot and industrial-scale tests of bio-floc shrimp farming
Ken Leber and Gary Pruder and Shaun Moss: In 1988, Leber and Pruder, researchers at the Oceanic Institute in Hawaii, showed that under intensive culture conditions, juvenile shrimp reared in organically rich pond water and fed either a medium or high-quality diet grew significantly faster than juveniles fed identical diets but reared in clear well water. Growth enhancement likely resulted from the assimilation of suspended organic matter produced in the pond. Shaun Moss, current shrimp program director at the Oceanic Institute, continues to look at the benefits of the nutrients in pond water.
Russ Allen: In 1994, Russ Allen, a shrimp farming consultant, built a small pilot-scale, bio-floc system in his shop, followed, in 1998, by a $500,000, prototype system in a barn behind his house. Allen says: Using bio-flocs is a completely different, nontraditional method of managing shrimp ponds. Instead of managing algal density and oxygen through water exchange, water is never pumped in or out of the pond during a production cycle. Water quality is managed through fertilization, feeding rates and, in intensive culture, aeration. Increased production per unit area brings the farmer much higher profits, although at a higher capital investment (aeration equipment, electric installations, fuel costs and seedstock).
Allen also designed and built the first phase of Belize Aquaculture, Ltd.
The Global Aquaculture Advocate (www.gaalliance.org): The Advocate, the bimonthly publication of the Global Aquaculture Alliance, covered the development of bio-floc shrimp farming better than any other aquaculture publication. Give George Chamberlain, president of GAA, and Robins McIntosh, former general manager at Belize Aquaculture, credit for spreading the word on the scientific aspects of the new technology.
Robins McIntosh: In the August/October 1999 issue of The Advocate McIntosh wrote: The basis of the culture system in ponds is the promotion of a bacteria-dominated, stable ecological system, instead of the phytoplankton-dominated system, which can be highly unstable. The ponds are fed a combination organic mix and shrimp feed from the start of the cycle, at a rate that is much greater than would be consumed by the shrimp. The idea is to promote the growth of bacteria and establish a large outdoor bioreactor, or a system similar to a sewage oxidation pond. The ponds start out with a phytoplankton bloom, but by week 8-10 of culture, these blooms are replaced by microbial flocs. Ponds can be easily differentiated as to their stage of development. Young ponds will be green and create large amounts of foam on the surface. Older ponds will turn brownish/blackish in color and be free of foam on the water surface. Water from the older ponds is dominated by large organic/microbial flocs that rapidly settle out if water circulation is stopped. Once the ponds reach this older stage they are highly stable and can assimilate large amounts of organic inputs. Ammonia levels are generally under 2 ppm, pH generally ranges from 7.0 to 7.5, and dissolved oxygen levels range from 4.0 to 6.0 mg/l. Feeding levels as high as 450 kg/ha/day have been used.
More McIntosh: In the February 2000 edition of The Advocate, McIntosh said: In a zero-exchange, intensive, culture system, it is important to keep solids in suspension as much as is possible. At times, the organic loading in our system can reach 500 kg of feeds/hectare/day. Belize Aquaculture uses paddlewheel aerators to set up a circular flow pattern in square ponds. Around the outer areas of the pond where water flow rates are greatest, the detritus and other organics are kept in suspension. As the water flow rates diminish towards the center area of the ponds, larger, heavier particles settle out. In our ponds, water flow rates of 6.0-12.0 meters per minute are used to keep organic material in suspension. Towards the middle of the pond the flow rates decrease to less than 6.0 meters per minute and solids begin to fall out of suspension.
At the World Aquaculture Society Meeting in Las Vegas, Nevada, USA (February 15, 2006), a special, all-day session brought people from around the world together to discuss bio-floc shrimp farming. They formed a working group within WAS to facilitate communications among interested parties, gave the technology its name—“bio-floc” aquaculture—and established a home for the group at the Agricultural Engineering Society’s website (http://www.aesweb.org/starter.htm, click on Bio-Floc Workgroup in the left hand column).
Dr. Greg Boardman, professor of civil and environmental engineering at Virginia Tech University in Blacksburg, Virginia, USA, and Dr. Yoram Avnimelech (below) chaired the session.
The fourteen presentations varied in length from 20 to 40 minutes. The papers will be published by the Agricultural Engineering Society. Dr. George Chamberlain, a former president of WAS and current president of the Global Aquaculture Alliance, moderated the discussions after the morning and afternoon sessions.
Dr. Yoram Avnimelech: Dr. Avnimelech has taken the lead in the bio-floc aquaculture movement. He is head of the Sea of Galilee Water Shed Research Unit, Chief Scientist of the Israeli Ministry of the Environment, and Dean of the Department of Agricultural Engineering at Technion (the Israel Institute of Technology), where he holds the Samuel Gorney Chair. He has done consulting work in Israel, the United States, South America, Australia and Thailand and has been a visiting professor in various countries, including Belgium, the United States, Australia and the Netherlands. He has published more than a hundred papers in refereed journals, edited four books and trained many graduate students.
Lytha Conquest (Aquatic Feeds and Nutrition Department at the Oceanic Institute in Hawaii, USA).
What’s in floc? Another world: phytoplankton, fungi, silicates, amoeba and nematodes (which disappear quickly because the shrimp selectively pick them out and because they are much larger and easier to grab). Also flocs trap a lot of debris, like fecal material, dead plankton and feed particles. In fact, much of the feed that goes into the pond is not eaten by the shrimp. Instead, it becomes a fertilizer that stimulates a natural food chain that culminates in the flocs. Within the world of the floc, there are a lot of dissolved organics, like simple sugars.
One of the studies that we’re doing right now at the Oceanic Institute is harvesting the floc and extracting various aqueous solid components and incorporating them into shrimp feeds. In April 2006, we plan to start trials with those feeds in clear water systems to see if we get enhanced growth from the floc.
Dr. David Brune (Carter Newman Endowed Chair of Natural Resources Engineering and professor of agriculture and biological engineering at Clemson University, South Carolina, USA).
At Clemson University we have been working with suspended culture microbial systems for twenty years. Currently, we use a partitioned aquaculture system, which has modules for water treatment, tilapia and shrimp. In 2005, we gave tilapia 33% of the system. Algae in these systems assimilate the ammonium, the tilapia harvest the algae, and the water goes back to the shrimp.
In 2005, we added a small, activated sludge reactor to concentrate the sludge as much as possible. We can aerate the sludge at one milligram a liter of oxygen, and then aerate the shrimp at three or four milligrams a liter of oxygen. There is no point in wasting all that energy to aerate the sludge at three or four milligrams per liter, when it only requires one. The idea is to get the respiratory demand of the sludge out of the shrimp module. The sludge reactor was amazingly successful. We were able to concentrate 1,000 milligrams per liter of bacterial solids into a small cylinder.
In 2005 and 2006, we have not removed a single thing from the system. We’re producing 35,000 pounds of shrimp per acre—and we have not removed a thing from the system. No water, no sludge, nothing. There was no nitrate accumulation in the water column. There was no nitrogen in the system. Basically, the nitrogen just degassed.
Dr. Craig Browdy (Senior Marine Scientist at the Waddell Mariculture Center in South Carolina, USA):
The goal of our research is to develop shrimp farming systems that can be applied commercially in the United States. We’re doing a lot of research on replacing sea salts with artificial salts. We use a nursery phase. We feed with trays and use high-protein Zeigler feeds.
As we increased stocking densities, we started using oxygen injection instead of traditional aeration. Now we only use oxygen injectors, and we use heat exchangers in the winter. We capture all our sludge, dewater it, and we’re working on treating it to reduce its volume. We reuse all our water. The water we’re using now is producing its third crop. We’ve kicked production up to 6.7 to 6.8 kilos per square meter. In one trial, we stocked four-gram juveniles and in 59 days produced 16.5-gram shrimp, with a growth rate of about 1.47 grams per week and survival rate of 84%.
Once you have a stable microbial community in the system, it’s very important to reuse the water because you don’t have to go through an algal crash to get the system started again.
The shrimp love the floc; they turn upside down and eat it off the surface.
In our current trials, we’re doing some filtration to reduce the density of the flocs. Trials by others have indicated that when you crop the floc, growth and survival of the animals increases. We crop the floc to avoid shading out the algae, which produce all those nice sugars that vannamei like. In fact, I think those sugars might be the elusive pond water growth factor.
Discussion After the Morning Session
Dr. Rod McNeil: We need to look at more species. I’ve done some work with P. esculentus in Australia and it’s a real vacuum cleaner when it comes to flocs. Its relative nitrogen assimilation efficiency compared to P. vannamei is about 15% higher, so why are we stuck on vannamei?
Steven Serfling: We found that the algae add a key nutritional supplement to the system. People didn’t know this twenty or thirty years ago, but now it’s pretty well known that plant pigments, not just beta-carotene but a whole bunch of carotenoids, and other phytochemicals have incredible nutrition qualities, not just for tilapia and shrimp, but for the zooplankton in the system. They are filter feeding that algae all the time. The shrimp consume them in the flocs and get their “greens” that way.
I would like to say something about the disease prevention benefits of using these systems. In 28 years of using these systems with fish, we’ve never had a disease problem with any species of fish. A massive jungle of microorganisms surrounds and protects the fish. We never restricted anyone from putting their hands in the tanks. You can add sugar or other sources of carbon to these systems and in a few hours your ammonia will drop. To get a drop like that in an algae-based system can take thirty to sixty days, or longer, depending on water temperatures.
Dr. Nyan Taw (formerly with PT Central Pertiwi Bahari, a huge shrimp farm in Sumatra, Indonesia, that has commercialized bio-floc technology on part of its farm):
Robins McIntosh (who now works for the Charoen Pokphand Foods, which owns PT Central Pertiwi Bahari) came to our farm three years ago, and with his advice, we started our super-intensive project.
We aerate with Taiwanese paddlewheels at 20 to 28 horsepower per hectare, depending on stocking density. The higher the stocking rate, the lower the survival.
If the sludge and floc get too high we siphon some sludge out or add or drain water.
The 26 ponds in our first commercial trials averaged 22 metric tons of shrimp per hectare per crop of 16 to 18 gram shrimp, with feed conversion ratios of 1.1 to 1.2. In our regular ponds, the FCR was 1.5 to 1.6. Production costs are 15% to 20% lower with floc systems because the of low FCR.
Dr. Shaun Moss (program director for the United States Marine Shrimp Farming Program, the Oceanic Institute, Hawaii, USA):
Our best production so far, 8.9 kilos per square meter!
Christine Beardsley, from the Scripps Institution of Oceanography in San Diego visited us at the Oceanic Institute and identified the protein content of shrimp feces. When a shrimp defecates, the protein content in its fecal strand is only about 15% that of a high-protein feed pellet. After twelve hours, however, it rises to 40% and after a day it goes up to 80%. So there’s protein enrichment of the fecal strand over time. Where’s the protein coming from? If we look at the increase in the bacterial abundance in the feces over time, we see an incredibly high incubation rate. These fecal strands are very important substrates for bacterial colonization, which subsequently can be consumed by the shrimp. We talk about using nitrogen over and over again; well here’s a mechanism for doing that because the bacteria are soaking up the organic and inorganic nitrogen from the water and converting it into protein. The bacterial species that develop on the fecal strand are different from the species associated with the flocs in the water column.
Michael Mogollon (former vice president of production at OceanBoy Farms, an inland, low-salinity, organic, bio-floc shrimp farm in Florida, USA):
What I’m going to talk about today is the system of bacteria/algae management we use at our farm.
We draw water from the Florida aquifer, 1,000 feet down. It has just enough salinity for shrimp and it’s fairly adequate in all the necessary iconic content. High hardness, good alkalinity, a good balance of ions. And very importantly, for our organic certification, it’s free of pesticides and contaminants.
We do a lot of sophisticated plumbing and water movement and have a full lab where we do our own water quality testing. We use bio-flocs in maturation and in the hatchery; we don’t discharge any of that water. In the hatchery, we don’t change any water from day one until day seventeen, from zoea to a PL-10.
The growth of our broodstock is excellent. They usually put on 2.1 grams per week.
In the larval rearing tanks, we use filters to remove some of the solids from the water.
In our nursery ponds, where the animals spend thirty days before being stocked in the growout ponds, we have a feed conversion of 1:1. We stock between 5,000 and 8,000 animals per cubic meter. Survival rates are very good, 90% plus.
In our growout ponds, we use about 25-HP of paddlewheel aeration per hectare. Average stocking density is 110 per square meter. Growout lasts 115 days. Survivals are 65% and improving. We go for a 41/50 count whole shrimp. The growth rate is typically a little over 0.9 grams per week. We get about ten tons per hectare with a feed conversion of 2.0. Our feed conversion is not that good. We remove a lot of solids so that we don’t have to face nitrite spikes. Nitrite is very lethal at our low salinities. We do molasses additions. The system is very stable. Major catastrophes are very, very rare, now.
Dr. Rod McNeil (a shrimp farming consultant who has implemented several bio-floc shrimp farms around the world):
I’ve been working with OceanBoy and a number of other bio-floc shrimp farms. I also visit shrimp farms all over the world and do a lot of data collection, looking at the difference in microbial performance from one farm to the next.
If we look at the nutritional value of flocs produced in the dark and the light, the fatty acid content is much lower in flocs produced in the dark, but the protein content is much higher. Calcium, magnesium and silica are heavily concentrated in the flocs.
Discussion After the Afternoon Session
Dr. George Chamberlain: It might help to establish a working group on microbial floc shrimp farming, a group that can pull everything together and communicate information to everyone who is interested.
The following group was formed:
Yoram Avnimelech, Chairman (email@example.com)
Lytha Conquest, Secretary (firstname.lastname@example.org)
Shaun Moss (email@example.com)
Rod McNeil (firstname.lastname@example.org)
Michael Mogollon (email@example.com)
Marc Verdegem (firstname.lastname@example.org)
Greg Boardman (email@example.com)
At Aquaculture America 2003 (Louisville, Kentucky, USA, February 18-23, 2003), Dan Fegan, then with Thailand’s National Center for Genetic Engineering and Biotechnology and now regional technical manager of aquaculture for Alltech Biotechnology, Inc., which markets natural feed additives, talked about shrimp farming in Thailand.
During the question and answer session, Shrimp News asked Fegan if anyone in Thailand was following the Belize Aquaculture model of super-intensive, bio-floc shrimp production. He said: “There’s a lot of interest in it, but it’s too complicated. Pokphand has done some work on it, but pretty much the attitude is ‘If it ain’t broke, don’t fix it’” [implying that the current production system in Thailand was working just fine]. For a number of reasons (cost of energy, unlined ponds, skill levels), Fegan said the Belizian model might not be feasible within the Thai context.
No one knows how many shrimp farms are employing the bio-floc technology. The best examples of the of farms that have implemented the new technology are Belize Aquaculture, Ltd., in Belize, OceanBoy Farms in Florida, USA, and PT Central Pertiwi Bahari in Indonesia.
Central Pertiwi Bahari, a huge, integrated shrimp farm—hatchery, feed mill, power plant, laboratory, processing plant, cold storage and container vessels—produced 35,000 metric tons of shrimp in Lampung, South Sumatra, Indonesia, in 2004. The farm, part of Thailand’s CP Group, produces two crops a year from around 3,500, half-hectare ponds. In addition, it has nearly 130 experimental, intensive ponds of various sizes, where it tested the bio-floc farming before commercializing it on part of the farm.
The bio-floc trials were carried out in ponds of various sizes, shapes and types (lined and earthen) from mid-2002 to early 2004. Trial results showed that bacteria flocs were not easy to develop in earthen ponds. This could be due to suspended sediments caused by high aeration. In lined ponds, however, bacteria flocs developed. Vannamei can be stocked at very high densities (up to 300 PL/m2) in these ponds.
In small, lined ponds (0.2 ha) production was nearly 30.0 metric tons per hectare, compared with around 20 tons per hectare in larger ponds. This could be because bacteria flocs are much easier to manage in small ponds than in large ones. The record production was 49.7 metric tons per hectare from small (900 m2), densely stocked (280 PL/m2), round, lined ponds.
OceanBoy Farms, Inc.: At the First International Intensive Shrimp Culture Symposium in Belize (November 2004), Michael Mogollon, vice president of production, described OceanBoy Farms, an inland, freshwater, zero-exchange shrimp farm in Florida, USA, that uses bio-flocs in its maturation facilities, larval rearing raceways and growout ponds. Some excerpts:
Broodstock, hatchery, nursery and growout are all recirculating. Most of the water we are using on the farm is four years old, used over and over again for eight crops.
Nurseries are very important to us because we need to have all our juveniles ready to be transferred into the growout ponds by mid-March for the first crop and then again in mid-July for the second crop. We have a growout period from April through November and do mass stocking and mass harvesting. Over the course of one or two months, as we get ready for stocking, the nurseries are used to stockpile juveniles. The purpose of the nurseries is acclimation and holding. We use a lot of aeration, a lot of mixing, and a lot of constant feeding of the animals. The basic philosophy here is that constant feeding and water mixing keeps cannibalism in check. And if you are very rigorous about those two, you can come up with 90% plus survivals after thirty days of nursery culture.
After approximately thirty days in the nurseries, the juveniles are transferred to growout ponds for approximately 120 days, with aeration of approximately 25 horsepower per hectare, mostly paddlewheels, but with some aspirators in the center of the ponds. We inject oxygen into ponds on those nights when oxygen levels fall below critical levels.
We stock at 100 PLs per square meter and get two crops a year, from two, 120-day cycles. Growout survivals are 65%. We shoot for a 41/50 whole animals, although sometimes we let ponds go a little bit longer for clients who want larger shrimp. We get growth rates of around a gram a week.
Our hatchery produces very hearty PLs; they’re very active, vigorous, big for their age and extremely fit.
We’ve learned how to manage many water quality problems over the last few years, including high pHs, swings in pH, and nitrite toxicity. We do this by managing the algae and bacteria in the ponds to create a fairly stable environment for the shrimp. As other people have pointed out, when you do this type of culture, you’re really taking care of bacteria and the shrimp are along for the ride. Managing algae and bacteria is what we really focus on. When we get them right, the animals grow to their full potential.
We have not had any viral diseases in four years of operation.
In 2005, we are going to build an additional 16 ponds that will give us a total of about 80 hectares.
Question: How much are your construction costs per hectare?
Michael Mogollon: Our construction costs are very high, probably around $120,000 per hectare.
Question: What percent of the farm is taken up by treatment ponds?
Michael Mogollon: About 12%.
Question: How much protein do you use in your feeds?
Michael Mogollon: We start in the nurseries with 55% protein feeds and slowly bring that down to 31% in the growout ponds. We have to work on this because high-protein feeds mean more ammonia and more stress on the animals. We expect to lower the protein level in the feed every year until we’re down to approximately 22%.
Question: When is your growout period?
Michael Mogollon: We start stocking the growout ponds on March 15, and we harvest the last ponds during the first week of December.
Here’s contact information on most of the people mentioned in this report:
(In Alphabetical Order)
Russell Allen, President, Seafood Systems, Inc., 3450 Meridian Road, Okemos, MI 48863 USA (phone 517-347-5537, email firstname.lastname@example.org).
Yoram Avnimelech, Professor (Emeritus), Technion, Israel Institute of Technology, Department of Civil and Environmental Engineering, Haifa, 32000 Israel (phone 972-3-7522406, fax 972-3-6131669, email email@example.com).
Greg Boardman, Professor, Virginia Tech University, Department of Civil and Environmental Engineering, 417 Durham Hall (0246), Blacksburg, VA 24061 USA (phone 540-231-1376, fax 540-231-7916, email firstname.lastname@example.org).
Barry Bowen, President, Bowen and Bowen, Ltd., #1 King Street, Box 37, Belize City, Belize (phone 501-227-7031, fax 501-227-7062, email email@example.com).
Craig Browdy, Senior Marine Scientist, Marine Resources Research Institute, 217 Ft. Johnson Rd., Charleston SC 29422 USA (phone 843-953-9840, fax 843-953-9820 email firstname.lastname@example.org).
David Brune, Professor, Department of Agricultural and Biological Engineering, Clemson University, 225 McAdams Hall, Box 340357, Clemson, South Carolina, 29634 USA (phone 864-656-4068, fax 864-656-0338, email email@example.com, webpage http://www.clemson.edu/agbioeng/pages/faculty/brune.htm).
George Chamberlain, Ph.D., President, Global Aquaculture Alliance, 5661 Telegraph Road, Suite 3A, St. Louis, MO 63129 USA (phone 314-293-5500, fax 314-293-5525, email firstname.lastname@example.org, webpage www.gaalliance.org).
Lytha Conquest, Ph.D, The Oceanic Institute, Aquatic Feeds and Nutrition Department, 41-202 Kalanianaole Highway, Waimanalo, HI 96795 USA (phone 808-259-7951, fax 808-259-5971, email email@example.com, webpage www.oceanicinstitute.org).
Daniel F. Fegan, Regional Technical Manager of Aquaculture, Alltech Biotechnology Corp., Ltd., 209/1 CMIC Tower B, 17th Floor, Sukhumvit 21 Road (Asoke), Khlongtoey Nua, Wattana, Bangkok 10110, Thailand (phone +66-2-260-0888, fax +66-2-260-0886, email firstname.lastname@example.org, webpage http://www.alltech.com).
Kevin Healey, Research and Dveleopment Manager, International Animal Health Products, 18 Healey Circuit, Huntingwood NSW 2148, Australia (phone 61-2-9672-7944, fax 61-2-9672-7988, email email@example.com, webpage www.iahp.com.au).
Stephen Hopkins, Owner, Rain Garden Ornamentals, 49-041 Kamehameha Highway, Kaneohe, HI 96744 USA (phone 808-294-3973, email firstname.lastname@example.org, webpage http://www.raingarden.us).
Robins McIntosh, Senior Vice President, Charoen Pokphand Foods Public Company, C.P. Tower, 27th Floor, 313 Silom Road, Bangrak, Bangkok 10500, Thailand (phone 662-625-8250, fax 662-638-2254, email email@example.com).
Roderick McNeil, Ph.D., Meridian Aquatic Technology, LLC, 303 Kerr Dam Road, Polson, MT USA 59860 (phone 406-883-6920, fax 406-883-6922, email firstname.lastname@example.org, webpage www.aquamats.com).
Michael Mogollon, Vice President of Production, OceanBoy Farms, Inc., 2954 Airglades Boulevard, Clewiston, FL 33440 USA (phone 863-599-0603, fax 863-805-0074, email email@example.com, webpage http://www.oceanboyfarms.com/index.php).
Shaun Moss, Ph.D., Director, Shrimp Department, The Oceanic Institute, 41-202 Kalanianaole Highway, Waimanalo, HI 96795 USA (phone 808-259-3310, fax 808-259-9762, email firstname.lastname@example.org, webpage www.oceanicinstitute.org).
John Ogle, Aquaculture Specialist, Research Associate, Gulf Coast Research Laboratory, P.O. Box 7000, Ocean Springs, MS 39564 USA (phone 228-872-4675, fax 228-872-4204, email email@example.com, webpage http://www.ims.usm.edu).
Anthony Ostrowski, Ph.D., Director of the United States Marine Shrimp Farming Program, The Oceanic Institute, 41-202 Kalanianaole Highway, Waimanalo, HI 96795 USA (phone 808-259-3109, fax 808-259-3121, email firstname.lastname@example.org, webpage www.oceanicinstitute.org).
Claudio Paredes, Aquaculture Business Development Manager, Agribrands Purina Venezuela, Av. Principal de Los Ruices, Edif. Stemo, Piso 6, Los Ruices, Caracas, Venezuela (phone 58-212-2399111, fax 58-212-2352002, email email@example.com, webpage www.agribrands.com).
Harvey Persyn, President, Tropical Mariculture Technology, Inc., P.O. Box 959, Floral City, FL 34436 USA (phone 352-860-1985, fax 352-860-1785, email firstname.lastname@example.org).
Tzachi Samocha, Ph.D., Professor, Regents Fellow, Texas Agricultural Experiment Station, Shrimp Mariculture Research Facility, 4301 Waldron Road, Corpus Christi, TX 78418 USA (phone 361-937-2268, fax 361-937-6470, email email@example.com, webpage http://ccag.tamu.edu/FlourBluff/flour.htm).
Steven Serfling, Steve died in February 2007.
Nyan Taw, Ph.D., Sr. Vice President for Aquaculture and R&D, PT Dipasena Citra Darmaja (DCD group), Exim Melati Building, 8th Floor Jalan, M.H. Thamrin Kav., 8-9 Jakarta 10230, Indonesia (phone 62-21-390-7307, fax 62-21-390-7381, email firstname.lastname@example.org email@example.com).
Peter Van Wyk, Research Associate, Southwest Virginia Aquaculture Research and Extension Center, 424 West Main Street, Saltville, VA 24370 USA (phone 276-496-4999, fax 276-496-4974, email firstname.lastname@example.org, webpage http://arecs.vaes.vt.edu/arec.cfm?webname=saltville).
Marc Verdegem, Associate Professor, Aquaculture and Fisheries Group, Department of Animal Sciences, Wageningen University, P.O. Box 338, 6700 AH Wageningen, The Netherlands (phone 00-31-317-484584, fax 00-31-317-483937, email, email@example.com, webpage http://www.afi.wur.nl/uk).
Dallas Weaver, Ph.D., Consultant, Scientific Hatcheries, 8152 Evelyn Circle, Huntington Beach, CA 92646 (phone 714-960-4171, cell 714-614-3925 emial firstname.lastname@example.org, webpage www.scientifichatcheries.com).
The Shrimp List
Some of the information in this report was gleaned from the Shrimp List, a free, email-based, unmoderated, mailing list for shrimp farmers that distributes information posted by one member of the list to all the other members of the list. Most postings deal with the scientific aspects of shrimp farming and can get quite technical. Anyone can use the list to ask and answer questions, to keep participants up to date on a conference, or to pass industry news around. You don’t have to participate in the discussion. Your email address is not exposed. You can just sit back and read the messages that interest you.
The easiest way to get on the Shrimp List is to send an email to “email@example.com”. To post a message to the list, send your email to “firstname.lastname@example.org”, and to unsubscribe, send your email to “email@example.com”.