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Why Has Vietnam Been the Only
Country to Recover from EMS

 

On July 30, 2014, I sent the following questions to the 6,950 registered readers on my mailing list:

 

Of the countries that have been struck by early mortality syndrome (EMS/AHPNS), only Vietnam has made a significant recovery.

 

Why has Vietnam been the only country to recover from EMS?

What is Vietnam doing different that has allowed it to double its shrimp exports to the United States?

What do you think accounts for the spread of EMS?

What measures do you think should be taken to stop EMS?

 

Here Are Some of the Answers

 

Dr. A. Venkateswara Rao (dravrao@neospark.co.in): product manager for Neospark Drugs and Chemicals Aquaculture Division in India, reports:

 

There are various reasons for the significant recovery from the EMS outbreak in Vietnam—quality seedstock, improved water quality, better management of pond bottoms, better health management and the implementation of proper biosecurity protocols.  APC Company Limited (Distributor for Neospark Aquaculture Products in Vietnam) has done extensive work on educating the farmers on best management practices to control EMS.  In May 2013, Neospark and APC organized technical seminars in the Mekong Delta to resolve the EMS problem and our protocols are still being used.

 

During the seminars we focused mainly on the “Three Bios”—Biosecurity, Bioremediation and Biomineralisation.  We advised farmers to implement the Three Bios two to three days before stocking postlarvae.  The farmers that implemented the Three Bios had good crops.

 

Leo Cababasay (leo@bluearchipelago.com), a shrimp farm manager in Malaysia, reports:

 

Why has Vietnam been the only country to recover from EMS?  I don’t believe Vietnam is the only country to recover from the EMS outbreak.  Here in Malaysia, especially on the east coast, a lot of farms are producing shrimp.

 

What do you think accounts for the spread of EMS?  It spreads through broodstock, fry and seawater.  I have encountered EMS in water coming directly from the sea and in postlarvae coming from different hatcheries.

 

What measures do you think should be taken to stop EMS? I don't think there is a silver bullet to stop it.  One author mentioned a holistic approach, and I totally agree with that approach.  We need to use bioflocs, nursery systems, prevention of Vibrio parahaemolyticus dominance in the ponds, and most important of all, closer monitoring of pond water to prevent wide fluctuations in water parameters that stress the shrimps.

 

Gustavo de la Rosa (gdelarosa@proaqua.mx), a distributor of feed, probiotics and equipment in Mexico, reports: I don’t know much about the situation in Vietnam, but what we are seeing with EMS in México is that postlarvae (PLs) from imported strains of broodstock, mainly from Panamá and Ecuador, appear to have better survival rates (50-80%) than locally produced postlarvae.  The growth rates of the imported PLs, however, are slower than the high-growth strains that have been developed over the years by some of the leading hatcheries in México.

 

Consequently, shrimp farmers are now betting on longer growout cycles and survival rates, even though food conversion ratios will increase.

 

As to the spread of EMS, I have heard lots of guesses, but the ones that make the most sense to me are:

• The dredging of the estuarine areas

• The dumping of ballast water by cargo ships

• The use of homemade probiotics

 

Kana Washizu (kanaw@aq1systems.com), a supplier of sound-based feed monitoring equipment (AQ1Systems) from Japan, reports:

 

I recently visited shrimp farms run by Japanese companies in Thailand, Malaysia and Vietnam.  Because of the spread of EMS, we are not getting a proper chance to introduce our systems to the farmers because they are too busy dealing with the EMS problem.

 

Harry Ako (hako@hawaii.edu), a college professor in Hawaii who worked on the whitespot and IHHN viruses in Hawaii, reports:

 

Before the EMS outbreak, I toured several provinces in central Vietnam and shrimp farms in the Mekong Delta.  Later, I hosted Nguyen Thi Xuan Thu and introduced her to the specific pathogen free concept by setting up meetings with experts in Hawaii.  I took her to visit iAqua (Kauai), a broodstock producer in Hawaii, where she had discussions with Jim Sweeney.  She is a very smart lady, and from what I saw later, she learned what she saw and implemented it in Vietnam.

 

 What do you think accounts for the spread of EMS? Complete lack of any concept of biosecurity or hygiene.

 

What measures do you think should be taken to stop it?  Adapt biosecure programs like those used in Hawaii.  I think shrimp farmers in the countries affected by EMS are putting too much emphasis on bioflocs.  Bioflocs are not the magic bullet.  Farmers need to take a holistic approach to the EMS problem.

 

Joseph Paul (popychenkavalam@yahoo.com), a researcher and farmer in South Asia, reports:

 

What measures do you think should be taken to stop EMS?  Through the use of a combination of several plant-based ingredients at the nursery stage for 14 days, a new process called “Nupola Protocol” has been reported to be successful against EMS.  The protocol focuses on stimulating the cellular immunity of shrimp to fight off pathogens.  The strategy alternates between immune priming and growth activation.

 

Khanh Le (khanhle@gmail.com), owner of two shrimp farms in Vietnam, reports:

 

Why has Vietnam been the only country to recover from EMS?  I think it was because we were hit so hard that we had to do something.  We brought scientists into the country to identify the root cause of the problem.  Scientists from Auburn University in the United States helped us.  We knew that the primary cause of EMS was a Vibrio even before Dr. Lightner announced that Vibrio parahaemolyticus caused it.  We took extensive steps to reduce Vibrio-counts in the ponds before we stocked postlarvae.  We raised the PLs in nursery ponds for two weeks before we stocked them into growout ponds.

 

What do you think accounts for the spread of EMS? Releasing water from EMS-infected ponds and not preparing ponds correctly.

 

What measures do you think should be taken to stop it? Proactive pond management.  Using sediment ponds and water treatment ponds.  During my six years of farming shrimp in Vietnam, I’ve only seen a few cases of whitespot and EMS in isolated ponds that did not spread to other ponds.  I was always able to make a profit.

 

Jean-Francois Le Bitoux (jflebitoux@hotmail.com), DVM and an aquatic disease consultant who worked in Ecuador during the early days of shrimp farming, reports:

 

Why has Vietnam been the only country to recover from EMS?  Basically, because there are some smart chaps doing a good job there!

 

What accounts for the spread of EMS?  Poor pond management!

 

What measure should be taken to stop EMS?  Stop blaming external factors for causing EMS!   Always look at farm management practices first!   In fact, in aquatic diseases, most of the time the "germ" is a secondary invader in a degrading ecological situation.  It takes more than a silver bullet to get rid of it!

 

Daniel Nugraha (danielmnugraha@gmail.com): I was in Vietnam for a week in June 2013.

 

Why has Vietnam been the only country to recover from EMS?  They tried everything—antibiotics, bioflocs and pond liners—but the thing that appeared to help the most was switching to high-quality broodstock.

 

What is Vietnam doing different that has allowed it to double its shrimp exports to the United States? It implemented a two-stage farming strategy: nursery ponds and growout ponds.

 

What do you think accounts for the spread of EMS? Broodstock and PLs.

 

Source: Bob Rosenberry, Shrimp News International.  Why has Vietnam Been the Only Country to Recover from EMS?  August 4, 2014.

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