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Diving Shrimp Ponds with Alec Forbes


From 2004 through most of 2006, Dr. Alec Forbes, a shrimp farming consultant who developed innovative shrimp farms all over the world, worked for Namibia’s (southwest Africa) Ministry of Fisheries and Marine Resources.  Alec wanted to try shrimp farming in Namibia.  In late 2006, however, he was medivacked to Bethesda Naval Hospital in Bethesda, Maryland, USA, with a severe lung problem that required a transplant.


On August 5, 2007, the Forbes family reported:


“This is Penni Forbes, Alec’s youngest daughter.  Some of you may have already been informed but for those who haven’t, I’m sorry to tell you that my father passed away on the 30th of August at 10:30 p.m.  He had some continuous problems with his recent lung transplant and the last problem was unrepairable.  A critical valve in his right lung failed on the 29th and the doctors told us that nothing could be done.  All his children flew into Virginia to be with him in his final hours.  We turned off the life support at 6 p.m., and he later passed peacefully with all his loved ones around him.  He is being cremated on Monday, the 3rd of September.  Please feel free to contact me at penniforbes@hotmail.com for more information.  He was a wonderful man and will be sorely missed by all.”


Alec’s résumé (excerpts below) reads like a great adventure in shrimp farming.  In 1960, at twenty, he joined the French Foreign Legion, then moved on to the Vietnam War, a formal education, and eventually, in 1985 he designed, built and operated the then largest aquaculture facility in Asia, a 1,700-acre shrimp farm on China’s Gulf of Tonkin.  In 1993 and 1994, he ran the Dole Seafood shrimp farm in General Santos City, Mindanao, the Philippines.


Alec always chattered about diving his shrimp ponds, so, in 2005, I emailed him a list of questions about diving shrimp ponds:


Shrimp News: Where and when did you receive your academic training?


Alec Forbes: Graduated from high school in Kobe, Japan, in the mid-1950s, went on to read medicine at Trinity College, Dublin, Ireland, for two years, then joined the French Army (Foreign Legion, Parachute Regiment) where I continued medical studies.  I eventually received a Ph.D. in Marine Biology from the International Institute for Advanced Studies (awarded through Edinboro University, Pennsylvania, USA) in 1992.


Shrimp News: When and why did you take your first steps into shrimp farming?


Alec Forbes: After six years with the Algerian War and five years in Vietnam in the mid-1970s, I was living in Thailand (spent 14 years total in Thailand) and became most interested in aquaculture and coastal conservation.  I have a keen interest in the laboratory production of larval and postlarval decapods, especially Penaeus monodon.


Shrimp News: When did you dive your first shrimp pond?


Alec Forbes: That’s a question that brings back many memories!  Years ago in China, I figured that in order to grow this animal, P. monodon, I needed to know a heck of a lot more about its behavior and what it does all day.  The textbooks tell us some, but I wanted to walk a couple of miles in monodon’s shell.  My old friends and mentors, Drs. Jim Avault, Robert Romaire, John Manzi and the late Larry de la Bretonne, used to visit me in China and find me squatting in a pond trying to watch the activities of the shrimp in the shallow water.  They suggested diving!  It was another few years before I put that suggestion into practice.


In 1988, under contract to the Government of the Republic of the Seychelles (an island nation in the Indian Ocean), I built some lined ponds and stocked them with monodon juveniles.  I was burning with curiosity to see what they were doing on the lined bottoms.  What happened when they molted?  How did they manage with no place to hide?  Did they fight over food?  I donned my scuba gear and had a look.  It was a real eye-opener, a magnificent experience, which I have since advocated as a part of pond management practices.


The bright sunlight bounced off the bottom and created an ephemeral womb, a beautiful make-believe world.  On the bottom, on the black PVC liner, there was a mat of bright green algae, almost like a putting green in its uniformity, like a lawn one or two centimeters thick—with thousands of shrimp moving through it.  I hung in the water about a meter and a half away from the shrimp.  They came to a complete stop and stared at me with their stalked eyes.  My fins touched the bottom, creating an angry green cloud of algae.  The shrimp scurried away with what I can only describe as recriminatory looks of contempt.  I never again disturbed the bottom or even touched it when I dived ponds.


It’s an acquired skill.  You hang in the water column, hold your breath to stop your air bubbles, approach the shrimp and stare at them as they stare back at you.  They show no fear and are quite comical and pugnacious.  Often my observations were abruptly ended by underwater laughs, followed by choking mouthfuls of pond water, and shrimp darting away, wondering what that strange, ungainly creature was up to!  Forgive my anthropomorphological license.


Shrimp News: What’s to be gained from diving shrimp ponds?


Alec Forbes: Well, as I have stated before, I wanted to get into monodon’s shell and see what it’s like in there.  The closest I could get to that was observing them underwater, in their own habitat, and just watch.  Monodon is a curious creature and loves to investigate and take risks.  If you hang in the water motionless, they will watch you, approach and then “check you out” with their antennae—if you can stay still long enough.  The slightest movement, however, and they crack their tails and are gone.


Whilst down there, you have a good opportunity to check out pond conditions.  Is feed accumulating on the bottom?  Do the animals look healthy?  Are they congregating near the inlets, or the outlets, or in one particular spot, or are they avoiding some particular patch of pond bottom?  Diving gives you a chance to check the buildup under your paddlewheels and the molt cycle of your animals.  From a practical point, diving also allows you to check for punctures in the lining around pipe weldings, aerator anchor blocks and walkway anchor blocks.


Shrimp News: Most of the shrimp ponds that I’ve seen are rather murky.  Doesn’t that make observation rather difficult?


Alec Forbes: Most earthen-bottom ponds do tend to be murky and brown and visibility is very poor, particularly when churned up by paddlewheels.  I really think that the most exquisite dives I have made were in ponds with black liners, which seem to reflect the sunlight backwards and create an almost “cathedral stained glass” effect.  On a bright sunny day, if you turn off the paddlewheels and let the water settle, even in earthen ponds you can learn a lot from diving.


Once, while diving earthen ponds with bad visibility in the Philippines, I wore a snow white t-shirt under my diving gear.  On surfacing and exiting the pond, I looked at my erstwhile snow white t-shirt and discovered a very fine selection of algae species clinging to it, which with a field scope could have been identified on the spot.  An added thrill was to find dozens of little delicate sea horses clinging to my shirt, their tiny tails seeking stability and anchorage in the creases of my shirt.


Crabs were a problem in the Philippines, so it was also useful to dive and make a guesstimate of the crab population.


Shrimp News: I gather that some of the shrimp ponds had clear water?


Alec Forbes: No, that’s not the case.  I have dived the odd clear water pond in Fiji, and of course I have dived many clear ponds after construction, but without any shrimp in them, to check on the construction work, the inlet pipes, the outlet gates, and to see how the liner fits the bottom and the banks.


Shrimp News: What have you learned about the feeding behavior of shrimp from diving shrimp ponds?  Would you recommend that shrimp feeding practices be changed based on what you have seen?


Alec Forbes: I have learned an enormous amount about the feeding habits of shrimp from diving ponds, but I would not recommend changing anyone’s feeding practices.  Each farmer has to make up his own mind as to how he wants to feed.  You can broadcast feed, feed from trays, feed around the banks, feed from boats, feed with blowers, feed from the back of a truck—or even feed from motorcycles.  The size of the ponds has a lot to do with it.  I remember years ago reading about a hovercraft equipped with blowers that could zip from pond to pond!  I would love to have done that.  In Australia, four-wheel motorcycles with blowers are used for feeding and they are very effective.


I have also dived ponds as they were being fed, and it is quite fascinating to watch the animals rush to the sinking feed pellets.  They are messy eaters.  They will nibble on a pellet, partially devour it, discard it and move on to the next pellet that’s either in the water column or on the bottom.


One interesting observation: when animals are stocked in a lined pond, the water column has a algal bloom, but the “putting green” algal growth on the bottom is very sparse and the animals take on an almost black coloration, particularly down the carapace and six abdominal segments.  Shrimp, like chameleons, manipulate their color to match their background, protecting them from those predators that come in from above.  The dark color dissipates as the green bottom growth takes hold and by harvest time, the shrimp look perfectly normal.


Depending on the size of the animal, I feed six times daily, once at sunrise, once in the afternoon and four times at night.  Don’t forget monodon are nocturnal creatures.  I do not like to see them swimming around during daylight hours, which usually spells trouble.  In earthen-bottom ponds, they partially dig into the bottom, just leaving their antennae, eyestalks and part of their carapace above the pond bottom as they take their daytime naps.  Also, after molting, they bury into the bottom to hide from predators and to give their shells a chance to harden.


One of my biggest worries about putting monodon in lined ponds: What would they do after molting, when their shells were soft, when they were subject to cannibalism?  They would have no place to hide, no place to dig in!  I remember experimenting with all kinds of substrata, but eventually opted for none at all, and I am very pleased to announce that after many a nervous month, the animals didn’t seem to mind molting on the algae covered bottom.  Cases of cannibalism were few, particularly since all the animals seemed to synchronize their molts and were thus all in the same “boat” so to speak.


Shrimp News: What have you learned about the social and sexual behavior of shrimp from diving shrimp ponds?


Alec Forbes: Like all farmers and biologists, I really wanted to observe mating and spawning, but sadly I only got to witness those behaviors in hatchery tanks.  I did witness many moltings and never tired of watching this fascinating process.  The beautifully colored, shiny clean and exhausted animal would take from three to five minutes to complete the procedure.  I would keep a distance, as I did not want to spook the poor creature in the middle of this miraculous “disrobing”.


Monodon does not really “school” or go around in shoals, but is an independent critter and covers a lot of territory in twenty-four hours.  They preen constantly, are quite social and climb over each other with gay abandon.  I would constantly look for tail rot as I was apprehensive as to what effect the liner might have on shrimp, but seldom, if ever found any traces of fungus.


Shrimp News: Are mask, flippers and snorkel enough, or do you recommend SCUBA?


Alec Forbes: For a quick look at your ponds and to check for possible lining leaks, snorkel, mask and fins are fine but for a prolonged observation of the animals, I would opt for mask, weights, tank, regulator and fins.  Because shrimp are nocturnal, I have found their reduced activity in daylight hours is very easily observed with SCUBA.  At night, our ponds had lights at each corner so it was also possible to submerge and observe active animals, particularly just prior to harvest when they were big, active and extremely curious.


Shrimp News: How active are monodon during the day?  Do they ever show any sign of resting?  Do they have fights?


Alec Forbes: When they reach the juvenile stage and beyond, monodon tend to snooze and slow down during the day.  Of course, the PLs seem to be active most of the time and spend their time foraging around the electric cables that lead from the aerators along the bottom and up the banks to the electrical outlets, or around the staves holding the walkways up.  Any little crack or fissure in an earthen pond will get the animals’ attention and it is fun watching a large shrimp trying to insert itself in a tiny hole in the bank.


It is fascinating to take an underwater flashlight with you at night.  Monodon eyes are bright, a luminous red, or should be, and it’s quite an experience to stare back at thousands of red eyes, all focused on you.  It is also useful to observe eye color as a possible indication of disease.


They do indeed have fights, particularly over pellets, and they will go at it hammer and tong, despite the fact that there are plenty of other pellets nearby.  They seldom if ever fight to the death.  If and when cannibalism of a soft-shelled animal occurs, the attackers consume the eyes first, then the pleopods, and then, at their leisure, they all tuck in on the body!


Shrimp News: Have you observed any unusual shrimp behaviors that have not been reported elsewhere?


Alec Forbes: Again, forgive my anthropomorphological incorrectness, but do these critters communicate?  Who knows, but as any biologist will tell you, when you remove a female from the holding tank to perform an eyestalk ablation, it’s always easy with the first animal because her eyestalk remains turgid, but with the second animal, the eyestalk that you are about to cut cringes away and flattens out along the carapace as if it knows what is coming.  Can anyone explain that?


Like puppy dogs, they know when it’s feeding time and actually recognize the chap approaching on the bank with his bucket of feed.


Sadly my diving days are over.  A virus I contracted in Chile in 2004 has reduced my lung capacity.  I can no longer dive, but I do strongly recommend it to all shrimp farmers.


In conclusion, I would like to add my view on the future of shrimp farming.  It seems inevitable to me that the earthen pond with the effluent going back to the sea is going to go the way of the dodo bird.  Today tropical shrimp are being grown in Germany, Israel, Turkey Italy and many other countries in the temperate zone.  High density, eco-friendly, small, recirculating greenhouse farms are the way of the future.  Happy shrimpin’ all!  Alec.



Excerpts from Alec Forbes’s Résumé


Date of Birth: November 30, 1940.


Nationality: British Subject and Citizen, Australian Citizen, USA Permanent Legal Resident (Hawaii).


Languages: I speak, read and write fluent English, French, Creole and German and have a working knowledge of most European languages and have a good working command of Thai, some Vietnamese, and Japanese.


1960 to 1966: Served in the commando units of the French Foreign Legion infantry and parachute regiments in Algeria and the Sahara desert for six years and cared for the medical well-being of 1,200 soldiers as well as civilian population in areas where we operated.  Continued my medical studies in France.


1985 to 1987: As a consultant to the Government of the People’s Republic of China, I designed, built and operated the then largest aquaculture facility in Asia on the northern coast of the Gulf of Tonkin.  It consisted of 1,700 acres of ponds where I experimented with Penaeus merguiensis, Penaeus chinensis and introduced Penaeus monodon into the country.  As Director and USA representative of this Sino-US Joint Venture, I had a staff of 1,000 Chinese workers and Hong Kong Chinese assistants.


1987 to 1988: I was under contract to I.G. Aquafarm, Inc., a private concern in Thailand, to establish a Penaeus monodon hatchery on the southeast coast near Ang Sila for the production of 20 million postlarvae a year.  During this time I also acted as regional consultant for a number of private sector farms.


1988 to 1991: Under contract to the Government of the Republic of the Seychelles, I spent three years on the remote coral island of Coëtivy in the Indian Ocean, designing, building and starting a Penaeus monodon farm consisting of 68, one-acre ponds.  Support facilities included a processing and cold storage plant, a hatchery, a water quality control laboratory, quarantine facilities, a state-of-the-art biology lab and four experimental ponds for ongoing research.  In 1999, the farm was described as the “perfect example of ecological farming and one of the most successful aquaculture ventures in the world” (University of Hawaii & Aquatic Farms, 1999).


June 1993 to June 1994: Aquaculture Operations Director of Dole Seafood in General Santos City, Mindanao, the Philippines.  I managed four hatcheries, one main farm of 204 hectares water surface, and eleven smaller farms totaling 150 hectares water surface.  Dole subsequently closed down this farm on my recommendation when I discovered soil contamination in the main farm from the use of pesticides and herbicides on the adjacent banana plantations.


Source: Alec Forbes. Interview (email) by Bob Rosenberry, Shrimp News International.  November 10, 2005, and November 14, 2005.


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