The Prawn Goodbye

A Mysterious Plague Is Wiping Out Shrimp Around the World

By Michael Zelenko


Industrial shrimp farming operation. Image via 

Despite what hackneyed reality shows like Big Shrimpin’ and Ragin’ Cajuns would have you believe, the majority of our shrimp aren’t caught in the wild by mono-toothed shrimpers with names like Blimp and Pecker Head. They’re farm-raised in big, boring aquaculture ponds. For better or worse—probably worse, considering the system’s brutal environmental impact—this type of industrial shrimp farming has managed to sustain our growing craving for crustaceans over the past quarter century. But there’s something in the water: A mysterious, untreatable disease is laying waste to shrimp farms around the world, driving up prices and threatening your next scampi.

Between Costco’s colossal cocktail platters, the Outback Steakhouse’s all-you-can-eat deals, and Red Lobster’s Shrimp Lover’s Tuesday, an average American consumes almost four pounds of shrimp a year—three times as much as they did 30 years ago and far more than any other seafood product. That translates into 1.2 billion pounds of delicious shrimp eaten in the United States every year, over 90 percent of which is imported. Increasingly, those shrimp are raised in aquaculture farms located in tropical parts of the world like Thailand, Indonesia, China, India, Mexico and Ecuador.

So what’s behind the prawn goodbye? The disease is called “acute hepatopancreatic necrosis syndrome,” though it’s commonly known as early mortality syndrome, or EMS. Here’s how EMS works: a bacteria enters the shrimp’s stomach. It kills the shrimp’s appetite, and causes the hepatopancreas—the shrimp’s two-in-one liver/pancreas wondergland—to release poisonous toxins. As the organ collapses, a secondary bacteria attacks. Within days, mortality rates in an aquaculture pond can reach 100 percent.


The juvenile Penaeus vannamei on the left shows gross signs of EMS/AHPNS, specifically a pale atrophied hepatopancreas and an empty stomach and midgut. The shrimp on the right is unaffected.

The disease first emerged in China in 2009. From there, it crept south to Vietnam and Malaysia before unleashing a shrimpocalypse in Thailand, the world’s largest supplier of shrimp, in 2013. Thailand lost 40 percent of its stock to EMS in 2013. Domestic Thai shrimp prices doubled and the cost here in the US—Thailand’s primary export market—jumped 20 percent. Landry’s Inc., the company that owns Bubba Gump Shrimp Co., announced that it was considering menu changes and raising prices.

Although the culprit bacteria have been identified, no one knows how to cure or completely prevent the spread of EMS. “If someone is saying they have a cure for EMS, they’re lying,” Fiona Robinson, the Associate Publisher and Editor of SeaFood Business magazine told me over the phone. “They’re only researching it now. It might take a year or more to figure out how to get rid of it, if you can get rid of it.”

But Professor Donald Lightner, who studies infectious diseases of farmed aquatic species at the University of Arizona, might be closer than the rest. Lightner started studying the disease in 2010. In March 2013, his team published a paper that identified the causes of the disease, and toward the end of 2013, they developed a test to detect it.

“The test we’ve developed could be used to identify stocks that are already infected,” Prof. Lightner said over the phone. But with no treatment available—“if we had one, we’d be marketing it intensely right now,” he said with a chuckle—the only recommendation is to slaughter entire stocks, similar to what we saw with cattle and swine during the UK’s foot-and-mouth outbreaks or Asia’s avian flu pandemics.

“We think it moves with live animals, from hatcheries to brood stock,” he said. “The only way it could’ve possibly gotten to Mexico is if somebody smuggled in some adult shrimp.” From Thailand, Lightner said, the disease could spread to Indonesia and India. From Mexico, it could scamper south to farms in neighboring countries Honduras, Guatemala, and Ecuador.

Though Dr. Lightner says EMS has no affect on humans—as far as we know—the disease is having secondary, unforeseen consequences.

Alfredo Quarto is the executive Director of Mangrove Action Project, an organization that advocates for the conservation and restoration of mangroves around the planet. Though they lack the celebrity appeal of rain forests, mangroves are critical forest ecosystems that protect coastlines from hurricanes and tsunamis, and sequester massive amounts of carbon. A UN report from 2006 indicates that between 1980 and 2005, 20 percent of the world’s mangroves were destroyed. With their easy access to clean water and tropical climates, mangroves occupy ideal shrimp farming territory. Quarto estimates that “over half the modern mangrove loss since the 1970s has been done by shrimp farming.”


Shrimp farm expansion in the Gulf of Fonseca (Honduras/Nicaragua). Image courtesy UNEP

As shrimp farms collapse in Thailand and prices rise, other countries are scrambling to cash in on demand. In India, earnings from shrimp exports increased almost 90 percent during the last eight months of 2013. That boom means new farms, in new places. “[Shrimp farmers] move to a place free of disease with better water quality—a place that’s pristine, or at least healthy. But you’re spreading unsustainable systems to keep making your money. We call it rape and pillage—you move on from an area that’s been devastated to create new devastation elsewhere.”

Aaron McNevin, WWF’s director of aquaculture, says the industry is gradually coming around to the fact that mangrove exploitation isn’t sustainable from an environmental or even economic standpoint. (In time, the naturally occurring sulfur found in mangrove soil, once tilled up and exposed to rain, produces sulfuric acid. To fix the problem, farmers have to treat their ponds with copious amounts of agricultural limestone to up pH levels.) But that doesn’t mean mangrove destruction is no longer a threat. “There’s a lot of fear on WWF’s side, particularly in Myanmar and coastal Africa,” McNevin said. “We see those as the next frontiers of global shrimp farming.”

EMS isn’t the first disease to shock the industry: In 1993, white spot syndrome eradicated stocks in China practically overnight—and farmers from Saudi Arabia to Mexico are still fighting to keep it under control. And EMS won’t be the last pandemic disease either. “Disease is a major factor in aquaculture,” Alfredo Quarto. “When you go to a conference on seafood aquaculture, half of it will be about diseases: how to treat them and how to avoid them.” In big shrimp agriculture, disease has become endemic.

While it’s easy to blame big business, these problems stem as much from our bottomless appetite for shrimp’s tender pink flesh as they do from production practices. “When I was growing up in a middle class family,” McNevin said before we got off the phone, “shrimp was a delicacy. It was only purchased when high-class people came over, or people you really wanted to impress. Now, the constant availability of shrimp is something we have to look at carefully. It goes beyond shrimp for shrimp cocktails, or for scampis, or pastas. When you start to look at shrimp as a topping for burgers, or in these really cheap frozen meals, you have to ask: Are we really absorbing the cost of what it takes to grow these things?”

“We’re going to be increasing the demand for shrimp in the future. In a lot of places, people look to America to what wealth and what luxury can be. Does that mean going to a Golden Corral and getting a huge thing of shrimp that’s always there no matter what, eating half of it, and throwing it away? The notion of that picking up in countries that have way more people than we do is really scary.”

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