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Scott Horton

Shrimp Farm Manager



On February 23, 2016, at the World Aquaculture Society Meeting in Las Vegas, I interviewed Scott Horton about his long career in shrimp farming.  Most recently, Scott was production manager in the Mexico in the states of Sinaloa and Sonora for Grupo Acuicola Mexicano (GAM), the largest integrated shrimp farm in the country.   He was also head of technical support for GAM.  Currently, he is doing shrimp farming consulting out of Los Mochis, Mexico.


Shrimp News: Hi Scott, where were you born and where did you grow up?


Scott Horton: I was born and raised in Miami, Florida, USA.  My family is from Alabama, but my father went into the Army in 1943 and was stationed in Miami before being sent to Europe in 1944.  My mother went with him to Miami where she worked with the Army Air Corps.  My Dad came back to Miami in 1946 and they never left.


Shrimp News: Tell me about your formal education.


Scott Horton: During my last two years of high school, I went to school for half a day, and for the other half of the day, I worked as a volunteer with Dr. Won Tack Yang at the Rosenstiel School of Marine and Atmospheric Science, an academic unit of the University of Miami.  A Korean scientist, Dr. Yang received special training under Dr. Motosaku Fujinaga at his Prawn Institute in Yamaguchi Prefecture in Japan.  At the University of Miami, Dr. Yang and his colleagues developed hatchery and growout technology for the Atlantic pink shrimp (Penaeus duorarum).  He also worked with stone crabs and described their larval stages.  That gave me my first taste of aquaculture.  Also at that time, I met Yosuke Hirono and Jim Norris who were doing some of the first shrimp culture work in the Western Hemisphere at Turkey Point, south of Miami.


I lived in Miami until graduating from high school in 1976, leaving for Florida Atlantic University (FAU), where, in 1979, I earned a Bachelor of Science Degree in Biology with a minor in Chemistry.  I worked on freshwater prawn (Macrobrachium rosenbergii) farming with Dr. Sheldon Dobkin.  At the time, prawns were thought to have great aquaculture potential in the United StatesJeff Peterson had also worked for Dr. Dobkin, finishing just before I arrived.


Between my Bachelor’s Degree and the beginning of my Master’s Degree, I had six months to kill, so I took a job at the Miami Seaquarium as a diver.  We were mainly underwater janitors, cleaning the windows and bottoms of the tanks, but we also put on a feeding show in the reef tank.  It gave me a unique chance to interact with the porpoises, killer whales and reef fish, which was great.


In 1981, I received a Master’s in Aquaculture from Texas A&M University, where I was at first a student of Dr. Robert Brick.  Bob left about half way through my time at A&M and took a job at King James Shrimp, one of the first attempts at intensive, indoor shrimp farming in the United States.  Dr. David Schmidly, who worked on population genetics in mammals, became my major professor.  I did my Master’s thesis on the “Intraspecific Variation in Penaeus stylirostris and vannamei”.  In those days, there was no DNA analysis to determine sub-species or populations.  I did morphometrics and multivariate analysis.  For my thesis, I was attempting to determine if there were differences in populations of the two species along their range from northern Peru through Mexico that might later be used to help guide genetic programs.  It turned out that there were no variations that could separate sub-populations of the two species.


Shrimp DNA work was started a year or so later by Dr. Jim Lester at the University of Houston.  I later combined my work with some of Jim Lester’s early data, and we prepared a paper that was denied for publication by the World Aquaculture Society because it was not relevant to aquaculture—which sounds ridiculous today in light of the current importance of the genetics in those two species in shrimp farming.  Dr. Addison Lawrence was on my thesis committee and so was Dr. Isabel Pérez-Farfante, co-author of Penaeoid and Sergestoid Shrimps and Prawns of the World.  I did some of my research with her at the Smithsonian Institution.


During my time as a Master’s Degree student at Texas A&M, I met fellow students Mario Callejas, a Nicaraguan who recently died in a tragic accident, and George Chamberlain.  During those days, I met some Ecuadorean shrimp farmers, and I made a few trips to do some minor consulting work.  I worked in Santa Rosa, El Oro Province, for Alfonso Grunauer, the father of Heinz Grunauer of Prilabsa.  When I got my Master’s Degree, my plan was to continue on and get a Ph.D. because the experts back then thought shrimp farming was going to explode in the United States.  I decided that I would go to Ecuador for a few years and get some practical experience and then come back and finish my Ph.D., thinking that I would be a very marketable commodity in the new shrimp farming industry in the United States.  As things turned out, I never left Latin America and the industry never took off in the United States.


At the end of getting my Master’s Degree and before moving to Ecuador, while I was still writing my thesis, I got a job at the National Marine Fisheries Laboratory in Galveston, Texas, working with Corny Mock and Jim McVey, who was head of the Lab.  At the lab, Oswald Brown was doing groundbreaking work on shrimp maturation.  I was working in the shrimp hatchery doing grunt work, mostly algae counts.  At that time, my co-workers were Josh Wilkenfeld; Eduardo Velarde, who I think is in Costa Rica growing fish; and Rex Ito, who’s selling tuna in California.  After about three months, the government cut the funding for the lab and turned it over to Addison Lawrence, who put Joe Fox in charge.  After six months there, I finished defending my Master’s thesis, and immediately moved to Ecuador.


At the Galveston Lab, Corny Mock hated me at the beginning just because I came out of Texas A&M and was hired by Jim McVey.  At the beginning he would not even speak to me.  But I was a hard worker, always the first guy in the lab in the morning to do my algae counts, and after a month Corny took a liking to me and expressed this by insulting me and several generations of my ancestors using profanity, that bordered on poetry.


During those years at Texas A&M, I met Tom Zeigler, Chairman of the Board at Zeigler Bros. feed mill in Pennsylvania, today one of the leading producers of shrimp feed in the Western Hemisphere, and I would also drive to Tulane University to visit with Dr. Samuel Meyers, an aquaculture nutrition specialist.  Both were great to take the time to mentor me.  Tom is still my mentor, so either I am a poor student or he has a lot to pass on.  Other guys I met at A&M were Ken Johnson, Don Lewis and Jack Parker.


Shrimp News: Tell me about your career.


Scott Horton: I arrived in Ecuador in 1982 and could not speak Spanish (some say I still can´t speak it).  Guayaquil was a different world from what it is today.  During my first year, I did consulting work for three different companies: Miguel Seminario, Nutril, and the International Executive Services Corp.  In 1983, I took a full-time job as production manager at a 500-hectare, semi-intensive shrimp farm on Mondragon Island, located in the mouth of Guayas River.  We stocked wild postlarva.  I was there for the big El Niño of 1983.


When I got to Ecuador, I was maybe the second or third American there.  Mark Rosenblum, who later ran a big farm in Mexico, was there, and Peter Shayne and Jeffery Graham were already industry leaders in Ecuador.  I met Peder Jacobson at his hotel, but he was not yet involved in the industry.  Within a year there were a bunch of Americans working in Ecuador, including Brad Price, Zandy DeBeausset and Phil Boeing.


Phil Boeing was a pioneer in commercial hatchery operations.  The French couldn’t get their Semacua Hatchery working, so the owners brought in Phil, who had a background in mollusk culture, and he was able to get Ecuador’s first big hatchery up and running.


Then in 1985, I started doing consulting work for the Pantaleon Group in Guatemala working with Peter Fairhurst to build and operate a semi-intensive farm.  I quit Ecuador and went back to the United States for six months to see if I really wanted to stay in aquaculture because by then I knew that if I were going to work in shrimp farming, I would have to live outside of the United States.  I supported myself by doing consulting work, first for a company in Nigeria, while I continued to work for the company in Guatemala.  After six months, I made the decision that I was going to stay in shrimp farming and moved to Guatemala.


In Guatemala, I worked with Peter at Pantaleon for the first year then joined a group where I would remain for nineteen years (1987 to 2006).  The company was originally named Esteromar, and was founded by Ricardo Valdes, but since 1989, his brother Jose Luis has run the company.  We started with a fifty-hectare, semi-intensive farm near Iztapa.  During my tenure, working as a team with Jose Luis Valdes, and Carlos Knebusch (Operations Manager), the farm expanded from fifty hectares of semi-intensive ponds to over 600 hectares of intensive earthen ponds with paddlewheel aerators and a shrimp hatchery.  We were producing about 10,000 metric tons per hectare per year, which was exceptionally high for Central and South America at that time.  We used 16 horsepower of aeration per hectare and stocking densities of 65 to 70 per hectare, with two crops a year, normally.  We had some ten-hectare ponds, and got ten metric tons per hectare out of them.  The problem became how to quickly harvest that much shrimp from a pond that big, rather than how to get big production.


We were very quick to accept new technology.  At one point, we were doing 100% of our feeding with feeding trays.  The feeding tray technology came out of Taiwan and was first adopted in Peru.  We heard about it from the Nicovita feed company in Peru.  We used two-man teams in small boats to fill the feeding trays, one man drove the boat and kept the records and the other lifted and filled the trays.  The feeding crews were well paid and got production bonuses because it was such an important job.  We ran the farms semi-intensively without aerators for years.  We were doing three tons per hectare per harvest, maybe four tons if you included partial harvests.  Above three tons biomass was not sustainable.  We continued to feed with feeding trays until we went intensive, which made it prohibitively expensive to feed with trays.  We started broadcasting the feeds and using the trays as “witnesses” to see how much the shrimp were eating.


When we started, we really didn’t have any problems with disease.  Then in 1994, the Taura virus started marching north out of Ecuador.  In April 1994, it hit Honduras, and in October 1994, we got hit with Taura.  We were using wild seedstock at the time, which was about $0.45 cents per thousand, a very good price and good quality, too.  We tried a bunch of things to stop the virus, but nothing worked.  Since postlarva were inexpensive, we decided to overstock our ponds with a hundred postlarva per square meter and harvest the 17% of them that survived.  The animals that survived the outbreak did not break with the disease—and we remained profitable.  In 1999, the whitespot virus hit Guatemala, and we really got clobbered.  We knew immediately that the era of wild seedstock was over.  There were no shrimp hatcheries in Guatemala at the time.  My boss and I got on a plane and flew to Panama and then into Colombia to check out hatcheries.  We decided that Colombia had the best seedstock.  It was certified disease free, and Colombia’s hatchery industry was big enough to support our demand for postlarvae.  We chartered a 727 and flew them out, 22 million at a time.  We did that for a year while we developed our own hatchery.


In Guatemala, Alexander “Zandy” deBeausset, Vice President of Production and Operations at Acuamaya, Guatemala’s largest shrimp farm, and Gabriel Biguria  had a hatchery going a year before us.  They were the first guys in Guatemala to have a hatchery.  We were the second group.


Shrimp News: What is it about Guatemala that has caused it to use the latest technologies and high stocking densities on its farms?


Scott Horton: Guatemala has a dynamic industry.  It produces more shrimp per hectare than Thailand.  All the shrimp farms in Guatemala are intensive.  It’s a small industry, probably only 1,500 to 1,700 hectares of ponds, but it’s all intensive.  Shrimp farms in Guatemala don’t use salt flats.  Since it doesn’t have the broad estuaries like the rest of Central and South America, farmers use expensive agricultural land.  The higher land and security expenses pushed us in the direction of intensive shrimp farming.


Shrimp News: Why does Guatemala have more poaching problems than countries like Mexico?


Scott Horton: In Guatemala, you have much greater populations around the shrimp farms, along with easier access to the farms.  I don’t know of any farms in Guatemala that don’t have armed guards.  In Mexico, the vast majority of the farms have no security or unarmed watchmen.


Shrimp News: Tell me something about your groups production experience in Guatemala.


Scott Horton:  Our group built two farms from scratch and purchased three other farms that were bankrupt and abandoned.  In fact, one of them had gone bankrupt three times.  We became experts at taking over failed farms and making them work.  The original name for our farm was the Esteromar Group; it was later changed to the Tecojate Group.  It’s been renamed again since I left.  Our main products were originally frozen tails, but as we expanded into the European market, first into France and then into Spain, we switched to whole animals.  This switch removed the deheading costs of the shrimp, but you have to suffer greater rejection costs.  The Europeans are very demanding; your shrimp have to be perfect.  The product that was rejected by Europe was de-headed and sold locally.  Toward the end of my tenure in Guatemala, a big market for shrimp had opened in Mexico.


When we went intensive in Guatemala, we got NHP (necrotizing hepatopancreatitis, a bacterial disease).  At the time, NHP was not a big problem because you could treat it with oxytetracycline.  We brought in Paul Frelier, a shrimp disease specialist, who helped us understand NHP, and Bill More, one of the founding fathers of shrimp farming in the Western Hemisphere, helped us manage it.  It was a management issue, not a mortality issue.  When one animal gets sick, you treat the entire pond with oxy.  If even a small percentage t of the animals get sick, you can never get it under control.  I’ve heard that EMS (early mortality syndrome) can be treated with oxy and florfenicol, but if you stop using them it comes back within hours, so there’s no way that you can get rid of it.  You spend a lot of money and get nowhere.  I recommend that shrimp farmers should not use any disinfectants or antibiotics to treat EMS.


In Guatemala, we made the transition from semi-intensive shrimp farming to intensive shrimp farming with the help of Claude Boyd, a water quality specialist out of Auburn University in the United States, who made several trips to Guatemala and helped me design the systems to implement the new, intensive management systems.  We also worked with Don Lightner, the famous shrimp pathologist at the University of Arizona in the United States, especially when we were fighting Taura.


Shrimp News: What was your next job?


Scott Horton: Edgar Arias from Colombia started our hatchery in Guatemala.  When they left, my good friend Neil Gervais came in and expanded the hatchery and worked for us for several years.  He left to join a shrimp farm in Venezuela that was in very bad shape because of Taura.  In 2007, that company, Inmarlaca, offered me a job as a full-time consultant, which I accepted.  I moved out of Guatemala and relocated in Venezuela.  Located on Lake Maracaibo, the farm had 500 ponds, all exactly three hectares each.  It had about 400 employees living on site.  Originally I was brought in to work with Louis Hamper, who had worked with catfish in the United States and then went to Ecuador to farm shrimp.  I was brought in as production manager, but after about two months, I took the title and responsibility of general manager.  I worked there for a year, staying at the farm for five to six weeks at a time, and then going back to Guatemala for a week off.


The job in Venezuela was very challenging because the company had very limited funds.  I had to keep production going and worry about feeding 400 people on the farm everyday.


After I was there for a year, my oldest son, who was in high school at the time, asked me to take a road trip with him to look at colleges in the United States.  He’s very intelligent, but kind of lazy and did not have great grades.  The trip was very important to him, and we both realized that the opportunity may never present itself again, so I quit my job in Venezuela, grabbed some savings, and we went on a road trip through southeastern United States for a month, visiting universities.  We developed a better relationship, and he returned to Guatemala and became a straight-A student for his last two years in high school.


When I woke up from the dreamy road trip, I realized that I was unemployed.  Then I ventured into what I believed to be the next logical step in my life and became a shrimp farm owner.  In 2008, I bought an abandoned 140-hectare shrimp farm in Guatemala that had too much debt.  I thought that if everything went just right, I could handle it, but, of course, that was unrealistic.  Shrimp prices dropped, and I could not get additional financing.


I tried to keep my costs down by stocking at low densities, which would lower all my costs, like feed, postlarvae, labor and power.  With 20/20 hindsight, I should have turned a small section of the farm into intensive ponds, put in aerators, but I didn’t, and the farm never got out of debt.


I had job offers from shrimp farms in Nicaragua and Mexico.  I flew to both places to interview and check out their operations.  I decided to take the job with GAM (Grupo Acuicola Mexicano) in Mexico because it was something different for me, something that allowed me to expand professionally and do things that I hadn’t done before.


I went to work for GAM in Mexico at the end of January 2010.  GAM had started operations in 2006.  In 2008, it built its feed mill, which licenses Zeigler’s technology.  When I arrived, they had a shrimp hatchery, two shrimp farms on the Baja peninsula (not as big as they are now) and five farms in Sonora and Sinaloa.  Because of my expertise in managing farms with whitespot, I was originally hired to run the farms on the mainland (Sonora and Sinaloa) that were having major problems with this disease.


In my second year, a technical team was created to provide advice to our own farms and to client farms.  We sold feed and postlarvae and provided financing and insurance to our clients.  Before providing credit to a farm, we evaluated their entire operation, from its management teams right down to its operating procedures.  It became my job to analyze the farms, keep an eye on them and guide them.  We provided our client farms with a free consulting service.


Shrimp News: I know you have some strong views about the future of shrimp farming.  Tell me a little bit about them.


Scott Horton: During my 33-year career in shrimp farming, I’ve witnessed five pandemics: IHHN (infectious hypodermal and hematopoietic necrosis, a virus), NHP, Taura, whitespot and now EMS.  One thing in common with all of these diseases: they’ve all occurred in earthen ponds.  The one-hectare earthen ponds in Asia are not successful in controlling EMS.  The problem with EMS is the bottom of the pond; it’s not up in the water column.  It’s just not possible to keep the bottom as clean in a one-hectare earthen pond as it is in a small, lined pond, so what’s working against EMS are small, lined ponds, no larger than 3,000 square meters.  In Thailand, the intensive farms that are converting from one-hectare earthen ponds to quarter-hectare lined ponds have been successful against EMS.  On our trip to Asia in January 2015, what impressed me the most was an area in central Vietnam where all the ponds were small and lined and pumping water from wells or well points.  They’re not indoors or covered.  They pay very close attention to the quality of the postlarvae that they stock.  Those farms have never been hit with whitespot or EMS.  They have gone through the two most recent pandemics without sick shrimp.  The key differences between those ponds and the bigger ponds that have been hit with disease are the pond liners, center drains and clean bottoms.


In Mexico, which is recovering from EMS, the farms with lined ponds and intensive stocking densities have been successful in resisting EMS and farms that use improved genetics and good management practices.  That farm uses earthen ponds and lined ponds and well water.  The lined ponds are more successful than the earthen ponds, but they are both successful.  Some farms in Thailand are now adopting this strategy, dividing one-hectare ponds into quarter-hectare ponds, lining them and putting in center drains.  I’m convinced that we can’t continue growing shrimp in big earthen ponds.  The next big diseases are already on the loose in Asia.  I personally think small, deep, lined, square ponds with center drains are the future of shrimp farming.  Circular ponds are more expensive to build, and they don’t use the available land as efficiently.


We’re building a small experimental pond here in Mexico that’s two meters deep.  Deeper ponds are cheaper to build per cubic meter of culture space.  To build a pond that’s two meters deep only cost 10% more per hectare than one that’s a meter deep, but it doubles the production area in cubic meters!  So it makes sense.  You spend less on land, and your aeration is more effective.  You need to keep all the organic matter in the pond in suspension.  At our new farm in Colima, we’re going to use the equivalent of about 50 horsepower of aeration per hectare to keep everything in suspension.  If you feed often with automatic feeders, the feed will never reach the bottom of the pond.  You have to spin the water in the pond fast enough to keep everything in suspension, but not so fast that the shrimp swim against the current because that would cause them to eat more feed.  It’s also important to use probiotics during growout, daily.  They digest organic material.  High quality feeds are also important.  You actually save money by using more expensive high-quality feeds.


There appears to be some relation between blue/green algae and EMS; perhaps the blue/greens make the shrimp more susceptible to the toxins produced by Vibrio parahaemolyticus.  Technology that can be incorporated in these systems is using tilapia in your reservoirs or in cages to filter out blue/green algae, and the mucus formed by the tilapia have certain antimicrobial properties.  In Colima, we are going to put tilapia into our reservoirs.  If you put tilapia in ponds, it’s best to put them in cages, so they don’t interfere with the shrimp harvest.  If you can sell them on the side, that’s just an added benefit.


Information: Scott Edward Horton, Office: Melchor Ocampo 158, Los Mochis, Sinaloa, Mexico (Cell Phone 521-668-137-0112, email:


Source: Scott Horton, Interview by Bob Rosenberry, Shrimp News International, February 23, 2016. Published on March 23, 2016.

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