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Should Shrimp Farmers Buy
Seedstock from EMS Hot Zones?


Shrimp News: This discussion about purchasing shrimp seedstock from countries and regions infected with early mortality syndrome (EMS) began on The Shrimp List on November 12, 2013, about two weeks before EMS was officially confirmed in India.

Daniel Gruenberg ( The official word from Dr. Lightner’s office at The University of Arizona in the USA on EMS in India is “no word”.  To the enlightened soul, one can easily imagine if the result were negative, the answer would be “EMS-FREE,” screamed at the top of their lungs.

I wish governments would stop trying to sweep diseases under the rug and make some concrete steps to manage them (which can be done if you actually admit you have them).

The solution to EMS has now become a multi-billion-dollar question.  It is time for a paradigm change in this industry.  Despite being hit hard at our farm by EMS in 2013, production is now back to 80% of pre-EMS levels, and steps are being taken to significantly improve production above pre-EMS levels.  We hope to accomplish this in early 2014.

Unfortunately, our industry is fraught with pseudo-science.  Industry pundits are still hanging onto the idea of manipulating pH levels to control EMS, while multiple controlled experiments have shown no significant effect from pH.  There are rumors that low salinity ponds don’t get EMS, but I have seen it in ponds with salinities as low as two parts per thousand.

With all the focus on Vibrio parahaemolyticus as the cause of EMS, folks have forgotten about genetics; however, the vice president of a leading shrimp farming company contacted me to say that he thought genetics played a key role in EMS.  So far, every country to get EMS has either a genetics program focused on selection for high growth, or they have poorly managed or purposely inbred broodstock.

In any case, until India decides to “man-up” and properly disclose its EMS epidemic (or what I strongly believe is at least a “version” of EMS), the science and solution will not move forward and the eventual damage will be much greater.

The denial psychology at work here doesn’t work for cancer patients, and it won’t work for EMS.  Just ask Mexico.  If Mexico had made the proper decision in this regard, it may not have been completely inundated with both EMS and WSSV.

Jorge Velez Cicero ( I couldn’t agree more with your comment about EMS in India and the way Mexico and Dr. Lightner handled it.  Somehow the pressure from some government agencies is more important than the huge losses this disease has caused to the industry worldwide, especially from governmental groups that don’t have the capacity or the interest to help control the situation.  Denial is a big mistake that only puts off the resolution of the problem, be it a cancer, an addiction, or EMS, especially now that we are hearing about different versions of the disease.  Scary.  As soon as I started reading your comments, I thought about the Mexican Government and the way it addressed the problem here, not even calling “the disease” by its proper name, not even after it wiped out 75% of the country’s farmed shrimp production.  You wrote about this particular case in your last paragraph.  Only one correction: Mexico (my home country) is not completely inundated with EMS and WSSV.  Along the Gulf of Mexico, that’s the east coast of Mexico, production is good, and we are trying to stay free of high-impact diseases by taking safety measures in cooperation with the hatcheries that sell us postlarvae.  We hope to maintain our biosecurity programs, and the high prices we’re getting for shrimp this year go a long way towards making that possible.  After that, we can only pray, and we do.

Daniel Gruenberg ( Jorge, to be clear I have no issue with Dr. Lightner.  His hands are tied in what he can disclose.  Also, since I wrote the original message, I learned that India is taking the proper steps in its approach to this possible epidemic.  I wish you the best on the Gulf side and hope you can stay EMS free.

Jorge Cordova ( Jorge, where do you get your postlarvae?  Do you get them from the same hatcheries that are supplying the farms on the west coast of Mexico?

Jorge Velez Cicero ( Yes, in fact our main supplier is located within the red zone on the west coast, where EMS is rampant.  I can only guess that our biosecurity and a good genetic program are responsible for the absence of disease.  After the outbreak, we allowed postlarvae from only one supplier to enter our production zone, and, after five months, we are still clean.  In a couple of weeks, the 2013 harvest will be over in this part of Mexico.

Jorge Cordova ( Congratulations, you’ve managed to succeed in the middle of the storm.  I support the good genetics aspect of your program.  Keep it up.

Luis Fernando Botero ( Jorge Velez Cicero, I hope I’m wrong, but isn’t it extremely risky to move postlarvae from a region where a massive EMS epizootic event has only recently taken place (the northwest coast of Mexico) to a new geographical area where EMS has not been detected (so far)?  It appears to me that regardless of the precautions your postlarvae supplier may be taking, the postlarvae are coming from an EMS infested area, and it’s still too early to determine with certainty how safe it is to move the material to EMS-free areas.  For the sake of your company, the other farms along the Gulf of Mexico and those around the Caribbean Sea, you must be very careful.

Luis Fernando Botero ( Jorge Velez Cicero, last night, I just could not stop thinking about your comments on moving postlarvae from a region with EMS to a region without EMS.  I’m guessing that you’re not the only shrimp farm to do this.  Regardless of the biosecurity measures that you are taking, I really think it’s a bad idea!  I really hope that nothing catastrophic comes from it.

Jorge Velez Cicero ( Hi Luis, my comments were not meant to cause concern, but only to inform Daniel that not all of Mexico was under the onslaught of WSSV and EMS.  My colleagues and I are well aware of the dangers of transporting postlarvae from the west coast (infected) to the east coast (uninfected), but we really have no choice as all breeding activity is concentrated on the west coast.  Having to live with this fact, the only course of action, besides pursuing a different professional activity, is to do a good job (at least to the best of our abilities) of choosing a clean hatchery with the best biosecurity measures in place, a history of broodstock testing for WSSV, YHV and IHHNV for several generations, and the documentation to prove it—backed up by several yearly visits.  We also test every shipment with a rapid detection kit before unloading any postlarvae.  This has proven effective for the last ten years, as we have avoided the introduction of WSSV to our region.  Since EMS’s arrival in Mexico in April 2013, we have narrowed our selection to only one hatchery with a proven genetic program, and we are now checking hepatopancreases for Vibrio at the postlarval stage.  I repeat: so far, so good.  We dry our ponds every winter for a mandatory 70-day period and are looking forward to next year.  We welcome comments, suggestions and ideas—critical or otherwise.

John Birkett ( I’ve heard that shrimp farmers in the state of Chiapas, on the west coast of Mexico, but 2,000 kilometers south of the infected shrimp farms in northwest Mexico, are purchasing their postlarvae from hatcheries in northwest Mexico.  The farms in Chiapas have not reported any EMS problems.

Joseph Paul ( Jorge Velez Cicero, I’m interested [in your rapid detection kit].

Luis Fernando Botero ( John, do you think it’s ok to ship postlarvae from an EMS-infected region to an uninfected region?  Do you think it would be ok for shrimp farmers in Honduras, Belize, Nicaragua, Panama, Venezuela or even Ecuador to import postlarvae from northwest Mexico?

I’m overwhelmed by the silence on this issue from the rest of the members of The Shrimp List.  Am I the only one who considers this a terrible mistake, one with potentially catastrophic consequences?  C’mon guys, wake up!  Or simply tell me I am wrong, explain why, and I’ll do my best to shut up (not guaranteed)!

Matthew Briggs ( Luis, I am definitely in your camp on this one.  Of course, it’s a bad idea to move stocks from infected to uninfected areas, and especially to do so without a specific, sensitive test to screen the animals before moving them.  We still do not have a test for EMS, and merely checking for Vibrios is not going to cut it.  [Shrimp News: A test kit is being developed and should be ready for the market early in 2014.]

In some circumstances, especially where there’s no alternative available, farmers will take a chance, disregarding the consequences their actions might have for others.  That’s human nature.  Government should be expected to ban such introductions for the common good.  Without government intervention, EMS will surely spread around the world.

Have we learned anything from the spread of WSSV from Asia to the Americas, of IMNV from Brazil to Indonesia, of TSV from Ecuador to the world?  The answer, apparently, is “No”.

Hank Bauman ( Luis, I don’t know the entire history of postlarvae shipments and distributions in Mexico.  It’s possible that the postlarvae were shipped to the Gulf side and other countries before the outbreak of EMS hit the Pacific side.  But I find it almost unbelievable that the Mexican government would allow the continued movement of live animals out of the red zone to other parts of the country, not to mention other countries.

Looking at the spread of EMS in Asia, it appears EMS moved on ocean currents over a period of years from Northern China to Viet Nam, Malaysia and Thailand.  If it had been transferred with broodstock and seedstock, it seems the pattern of dispersal would not have been quite so linear.  It would have popped up in some non-adjacent countries.

The bacteria (I’m just theorizing and guessing based on what I’ve read and heard) may enter a dormant or “sleeping” phase and get transported in the bilge of ships or even on frozen shrimp.  How did it get to Mexico?  Although Dr. Lightner couldn’t infect live animals with frozen EMS-infected shrimp, the pathogens may lie in a dormant phase and come back to life when discharged into the right oceanic conditions.

Since shrimp seem to die very quickly once infected with EMS, how would they survive the long period and stress of shipping long distances?

Either way, transference in live shrimp or frozen shrimp looks very uncertain.

Luis Fernando Botero ( Jorge Velez Cicero, I was a victim of the Taura virus that hit Cartagena, Colombia, many years ago and had to sell out for peanuts, so I sympathize with your arguments and situation, but I disagree with the way you are handling the situation.

There is a fundamental flaw in your approach.  If you win with one crop and continue to roll the dice with subsequent crops, you might stay ahead of the game for a while, but if you lose just once, you will lose everything, and that, my friend, is a bad bet.  Chances are that if you keep playing that game, sooner or later you will loose it all, and so will the shrimp farmers around you, along with the processing plants, their employees and their families.  Moreover, you may become responsible for all the damage!

You say you don’t have options, but you do have options.  Many shrimp farmers around the globe have come to the point where it’s necessary to build their own hatchery, or processing plant, or even feed mill, in order to continue in business; and I truly think that there is no better time for this than now, when prices are at historic highs.  The time has come for you and for your colleagues around the Gulf of Mexico to start construction of your own hatchery, and stop playing such a stupid game (sorry Jorge, but it is true!).

Finally, I would like to add that I appreciate your courage to have brought the subject to this forum; maybe it was unintentional, maybe not, but you stood by it, and that type of courage and responsibility is needed in the industry.  I am certain that many of the problems our industry faces today are a consequence of hiding information of great relevance to all of us.

Larry Drazba ( I would like to echo Luis’s comments and congratulate him on expressing them so logically and eloquently.

John Birkett ( Luis, to answer your question, I have to admit that I can’t think of a good reason for moving postlarvae from a region with a new, relatively unknown pathogen to a clean region.  You have to be desperate to do that.  It would be better to import postlarvae from Guatemala or to build a hatchery.

John Birkett ( Hank, from first hand info, I’ve heard that the shipments of postlarvae to Chiapas occurred in the past 60 days.  As Matt Briggs said (above), history repeats itself.  Humans spread diseases all over the world, even when they’re aware of the consequences.

Jim Wyban ( Luis, preventing the spread of EMS is vital to all shrimp farmers.  The best way of achieving this is to stop the movement of live animals from hot zones to clean zones.  The most likely explanation of India’s EMS outbreak is the import of infected animals from a hot zone.  The idea that ocean currents spread EMS to India is not very likely, and even more unlikely in the case of Mexico.  Mexico’s industry should heed the warning expressed in this discussion and stop the movement of live animals out of its hot zone.

Jorge Cordova ( Hi Jorge Velez Cicero, I think there must be a lot to learn from your ten-year experience of purchasing postlarvae without contracting WSSV and your recent experience of purchasing postlarvae without contracting EMS.  Please tell us more about the measures you took to prevent the transfer of disease?

Jorge Velez Cicero ( Joseph Paul, sorry for the delay.  Since I don’t know where in the world you work, I won’t bother you with the name or phone number of the distributor in Mexico for the field detection kit I talked about (above), unless you want to get it from him.  But if you Google shrimple wssv test kit you will get several hits, including a video from YouTube.  If, after that, you need the particular info, this distributor has three stores in Mexico, and I’ll be glad to give you the details.

Shrinibas Mohanty ( Has any country instituted a crop holiday to prevent the spread of EMS?

Shrimp News ( It was at this point in the discussion, November 27, 2013, that EMS was confirmed in India and India instituted a crop holiday.

A. Ravi Kumar ( If all the measures fail to prevent the entry and spread of an epidemic, a crop holiday/fallow period is the last option in biosecurity.

Jorge Velez Cicero ( Luis, regarding your comments, there is no need to apologize; your position, and everyone else’s opinion is consistent with scientific thought and classical disease management, not to mention common sense.  Also, I know I have brought this upon myself, but the input from The Shrimp List is invaluable and hard to come by via standard publications.  I thank all of you for your honest opinions.  We will finish our harvest, enjoy the holidays with our families and come back next year.

Michel Alain ( Dr. Ravi Kumar says a crop holiday/fallow period is the last option in biosecurity.  Let me be provocative here and politically incorrect.  When it becomes necessary to institute a crop holiday, that’s pretty good evidence that the biosecurity strategies that we’ve developed over the past decade have failed.

“Biosecurity” is an ill-defined, but very fashionable word in our industry.  If you ask ten shrimp farmers to tell you what biosecurity is, you will probably get ten different answers.  Be biosecure and everything will be fine is the current mantra.

In the future, maybe “biosecurity” will come to mean learning to live with the pathogens that infect shrimp.  They are already here, or they are on the way.  To eradicate them by sophisticated water treatment and barriers is “mission impossible”.  They will always find a way to enter in our farms, either because of equipment failures or because of weaknesses in our biosecurity systems.  If all else fails, they will mutate and sneak in.

We need to study the life cycles of the pathogens, learn when they are the most virulent and when they are vulnerable.  We need to co-evolve with them.  We need to learn how to boost the immune systems of our shrimp to stay ahead of the pathogens.  The new biosecurity paradigm will include the development of resistant strains.

Remember, our ancestors domesticated the land animals and then co-evolved with them.

Mark Rigby ( Alain hit the nail right on the head, expressing what many of us must be thinking.  It would be nice if someone came up with a good definition of “biosecurity”.

We work with intensive closed systems and have the luxury of very high densities and very low water exchange, so complete filtration and (almost) 100% sterilization of incoming water is not a problem.  So, you would think that biosecurity is easy to achieve.  Well, it’s not that easy.  Something gets in sooner or later, either with new stock, through the air, or in a drop of water under a fingernail!  There’s no way on earth that any outdoor pond can be 100% biosecure when insects, copepods, sand hoppers, birds and the wind, not to mention PLs, can all carry disease onto the farm.  Of course stop wild crabs and shrimp from getting into your ponds, but your animals must still be capable of withstanding the disease challenges they will ultimately face.  There’s no need to reiterate good genetics, feed, culture conditions again; everything that Daniel and others have mentioned makes good sense.

In our closed recirculation systems we don’t try to grow animals in a sterile environment, but strive to achieve a stable environment.  Create good water quality and the shrimp will look after themselves.  Ask any farmer of any animal what is more realistic, a 100% pathogen free farm or 80 to 95% pathogen-resistant animals.  The former is impossible; the latter is reality.

Shrinibas Mohanty ( Mark, I agree with your view.  We should learn to live with the pathogens.  There is no way to stop bacteria with a crop holiday.

Patrick Wood ( Well said Alain and Mark.  It’s all about prevention, not by exclusion, but by adapting.  Evolution is the only way any form of carbon life can survive on this planet.

Ramraj ( There were no known cases of EMS/AHPND in India when this discussion began over a month ago.  Subsequently, MPEDA screened about 200 samples for EMS/AHPND, and after confirming with the University of Arizona (USA), informed stakeholders that two of the samples had tested positive for EMS/AHPND.  Soon thereafter, MPEDA posted proactive measures for dealing with the outbreak to its website.

The process of sample collection, testing and confirmation of the presence of EMS/AHPND was done in a month’s time.  Neither the Government of India nor the stakeholders had any intentions of hiding the facts, as suggested by the banter of a few on this forum.

A. Ravi Kumar ( To prevent EMS/AHPND, has anybody tried treating postlarvae with formalin (a clear, colorless, aqueous solution of 40 percent formaldehyde) before releasing them into a pond, as we did with tiger shrimp.

Daniel Gruenberg ( Ravi, I have not tried formalin, but based on my more than 14 months’ experience with this disease, I would be quite surprised if it had any effect on EMS/AHPND

Vibrio parahaemolyticus, the bacteria that carries EMS/AHPND, inhabits the stomach of the animal so any dipping of postlarvae with formalin would not be able to affect the bacterial flora of the stomach.  I would suggest contacting farms in previously hit EMS/AHPND countries, find out what effective steps they have taken to control the disease and use that information as your starting point.

Ramraj ( Ravi, Disinfectants like formalin and iodine are used in egg and nauplii washing to prevent vertical transmission of pathogens through trans ovarian and fecal contamination.  Treating postlarvae with these compounds will in no way help to control systemic or enteric infections.

Source: 1. The Shrimp List (a mailing list for shrimp farmers).  Subject: India EMS...Time for Paradigm Change.  November 12 to December 1, 2013. 2. Bob Rosenberry, Shrimp News International, December 1, 2013.

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