EMS in 2015: Is the worst over?

Photo: Shutterstock

In the shrimp farming world, the disease needs no

introduction: Early Mortality Syndrome (EMS) has been

ravaging much of Asia, especially Thailand, and parts of

South America for the last four years. So what’s the

verdict for the disease in 2015?

By Avani Nadkarni and Rachel Mutter

“EMS is going to continue to be a problem,” University of Arizona pathologist Donald

Lightner tells Fish Farming International. Lightner and his team discovered that EMS

was caused by bacteria two years ago.

Robins McIntosh, senior vice president at Charoen Pokphand Foods in Thailand, is

taking a slightly more optimistic view. The industry veteran, who has worked specifically

in shrimp aquaculture for more than three decades, says “the bottom is in, the worst is

over.”

“It all seems simple, but three years ago, none of this was in place.

Hindsight is good.” Robins McIntosh, Senior VP, CP Foods

“It will look overall better,” he tells FFI. “We may have a few more repeats, but it won’t be

as catastrophic.” The main reason for that, he explains, is that “we understand it better.”

The CP Foods executive expects continued recovery in Thailand, Malaysia, Vietnam and

China and therefore expects shrimp exports from those nations to rise, too. Now that

EMS causes are better understood, farmers are taking careful precautions to avoid the

disease, he says.

Producers are keeping the bottoms of ponds cleaner and devoting more space to

reservoirs and less to culture ponds — “it’s that understanding that’s led to

improvements,” he says. “We don’t have the same culture ponds we did before EMS.” In

addition, more farmers are keeping the microbial health of ponds at a higher quality.

“It all seems simple,” McIntosh says. “But three years ago, none of this was in place.

Hindsight is good.”

New diseases on the horizon?

With the possibility of EMS improving, are two other diseases waiting on the

horizon? Running Mortality Syndrome (RMS) has recently cropped up in India — and

both Lightner and McIntosh say the causes are still unknown. “We haven’t gotten any

samples of that, so we don’t even know what it is,” Lightner explains. “We could

speculate,” adds McIntosh. “It’s an unknown causative agent [but] export numbers

indicate it’s not a catastrophic event right now.”

In addition, Lightner says the parasite Enterocytozoon hepatopenaei (EHP) “is going to

continue to be a big problem — they’re coming up with some high infection numbers”

mainly in Thailand, but the issue is expanding to Vietnam and south of China. “It’s

causing some slow growth problems in shrimp, mostly in vannamei,” he says.

“[EHP] is going to continue to be a big problem — they’re coming up with some high infection numbers,” Donald Lightner, University of Arizona

According to a November 2014 paper posted on the Network of Aquaculture Centres in

Asia-Pacific (NACA) website, EHP, a “microsporidian parasite,” does not seem to cause

high mortality, but it is still important because of the “severe growth retardation” it causes

in the shrimp. Still, it often took a backseat to EMS.

“We began to warn Asian farmers and hatchery operators after 2009 to monitor P.

vannamei and P. mondon for EHP in broodstock and post larvae,” writes the India- and

Thailand-based authors, including Kallaya Sritunyalucksana, Piyachat Sanguanrut, Paul

Vinu Salachan, Siripong Thitamadee and Timothy W. Flegel, “However, the warnings

were not heeded because of the overwhelming focus on early mortality syndrome (EMS)

or acute hepatopancreatic necrosis disease (AHPND).”

Has Indonesia escaped the scourge?

DISEASE-FREE: CP Prima’s Kalianda hatchery in south Lampung. Indonesian farming

culture has left it free of EMS. Photo: CP Prima on Twitter

And what about Indonesia? Now the world’s biggest producer, what have the country’s

shrimp farmers been doing right to avoid EMS… or is their time yet to come?

We asked Poh Yong Thong, general manager of nutrition and technical service at

Indonesian feed producer PT Gold Coin, who cited ‘bitter experience’ as a large driver in

the country’s avoidance.

“The ability to maintain hygienic pond environment has become the norm

and the cultural practice in Indonesian shrimp farming…

[Indonesia] will continue to outpace neighboring countries.” Poh Yong

Thong, general manager of nutrition and technical service, PT Gold Coin

“Indonesia’s bitter experience in contracting the viral disease IMNV from Brazil has

made it very strict in allowing the inflow of shrimp genetic material,” he tells FFI.

“Implementation in almost all the ponds of a central discharge to drain away sludge and

siphoning the pond bottom have produced very hygienic pond bottoms which discourage

the proliferation of Vibrio,” he says.

And Thong is sure the country has secured itself against future infection.

“The ability to maintain hygienic pond environment has become the norm

and the cultural practice in Indonesian shrimp farming,” he

says. “[Indonesia] will continue to outpace neighboring countries.”