Washington State Turns to Neurotoxins to Save Its Oysters

A pesticide from the group of chemicals linked to colony collapse disorder will now be sprayed in US waters. What could go wrong?

Kim Patten, scientist and researcher of Washington State University, in Bay Water, WA
Photographer: Cameron Karsten/Bloomberg Business

Early morning in Willapa Bay

Six decades ago, when Dick Sheldon first got into the oyster business, the tide flats of Washington states Willapa Bay were almost free of blight. There were no crabs (well, almost none) and Sheldon used to hike onto the mud at low tide, with a bucket for oysters. “We’d walk a mile or more, even when it was freezing outside, with the wind blowing at 50 miles an hour,” he remembers wistfully, “and then we’d stoop to the mud and start gathering them and throwing them into the buckets.”

In Sheldon’s memory, the oysters were bountiful and the mud floor was firm and pleasant to walk on. Then the shrimp arrived, and everything changed. Burrowing shrimp dig holes in the mud and live there. They pock the tide flats with a zillion holes, and today Sheldon, the 80-year-old eminence grise at his family’s small Northern Oyster Co., considers Willapa Bay a vanished world floored by “quicksand. If you’re not careful out there,” he says, “you’re up to your waist in that shit.”

The shrimp began proliferating—mysteriously, like a plague of locusts—in the early 1960s. They dominated the bay floor where oysters lived, but back then there was a simple solution: The oystermen just bombed the shrimp with carbaryl, a DDT-era neurotoxin. The shrimp, which few humans would want to eat, died. Oyster harvests were good, and along the bay, in towns like Nahcotta and South Bend and Oysterville, eight now-defunct oyster canneries flourished.

By the early 2000s, though, carbaryl had become a legal liability. Numerous researchers have linked the chemical to cancer, and in 2002 environmentalists strong-armed the Willapa/Grays Harbor Oyster Growers Association (WGHOGA) into beginning a 10-year phaseout.

A way of life and a small corner of the world were suddenly in jeopardy. Willapa Bay produces more cultured oysters than any other bay in the U.S., yielding about $35 million a year in product. The oyster industry forms the economic backbone of Pacific County, pop. 20,000, where road signs celebrate “The Oyster Capital of the World.” But in 2002, oystermen were scrambling to figure out a new way to kill off shrimp—and they found just the scientist to help them.

Kim Patten, an agricultural extension specialist for Washington State University
Kim Patten, an agricultural extension specialist for Washington State University
Photographer: Cameron Karsten/Bloomberg Business

Kim Patten, an agricultural extension specialist for Washington State University (WSU), tried blasting the shrimp to bits with dynamite. He did not succeed. He turned his sights next on hitting the shrimp with “a very thin layer of sprayable concrete,” he says, “just an eighth of an inch, so they’d suffocate.” No luck. “By the time the concrete firmed up,” Patten says, recounting a test run, “the shrimp had already poked holes through it.” 

Patten, who was trained as a horticulturalist, tried electrocution, super-spicy habanero peppers, and mustard gas. The shrimp held their ground. At last he turned to a newer neurotoxin, imidacloprid, which temporarily paralyzes the shrimp, so that they stop digging and within two days suffocate in the mud.

Imidacloprid is the world’s most popular pesticide, and highly controversial. It belongs to a family of neurotoxins, neonicotinoids, that is increasingly being blamed for colony collapse disorder—the sharp die-off of honeybees that has plagued North America since 2006. The U.S. Fish and Wildlife Service, the National Marine Fisheries Service, the National Audubon Society, and the Xerces Society, which advocates for invertebrates, have all opposed the chemical’s use on Willapa Bay. But their protests are now moot. On April 16, the Washington Department of Ecology approved the spraying of imidacloprid on 1,500 acres of Willapa Bay and 500 acres of nearby Grays Harbor. In about a month, crop-dusting helicopters will begin dousing both estuaries with the chemical.

Unlike carbaryl, imidacloprid dissolves in water, meaning that fish will swim through trace quantities of the chemical and oysters will grow in an imidacloprid-laced bay. It will be a first: Imidacloprid has never been applied on water before in the U.S. 


Created in 1986 and first registered in 1994 by Bayer, a $4 billion German chemical and pharmaceutical firm, imidacloprid is now ubiquitous. About 90 million acres of American cropland, an area the size of Montana, is planted with imidacloprid-treated seeds. Meanwhile, 2.5 million acres are sprayed, gassed, or powdered with the chemical. Countless suburban lawns and golf courses are also treated with imidacloprid. Dog owners use imidacloprid-laced products such as Marathon and Admire to keep fleas off their pets.

The chemical is no longer proprietary—it went off patent in 2005—but David Fischer, an ecotoxicologist with Bayer CropScience, speaks of imidacloprid with almost parental pride. “It’s far safer than chemicals like carbaryl,” he says. “You can handle it without any health risks, and you need only about one-tenth as much of it. And it’s precise, too: It can target certain receptors in invertebrates that you don’t have in higher animals like birds and humans.”

Research on imidacloprid paints a much darker picture. In one 2012 study, published in Science, British researchers found that bees fed sugar water spiked with neonicotinoids were less able than control bees to produce queens in their hives; they didn’t gather enough food. In another study, published in the same issue of Science, French researchers found that bees fed neonics had difficulty getting back to the hive from a half-mile away. Neonic defenders have maintained that bees could learn to avoid treated plants, but in a study published this week in Nature, a British researcher, Geraldine Wright, found that this was not so. Wright sequestered honeybees in boxes and gave them a choice between plain nectar and nectar laced with neonics. The bees favored the poisoned nectar.

The burrowing shrimp is native to Willapa Bay
The burrowing shrimp is native to Willapa Bay
Photographer: Cameron Karsten/Bloomberg Business

In 2013, the European Commission banned the use of three neonicotinoids—clothianidin, methamphetamine, and imidacloprid—on flowering plants. Last month a coalition of beekeepers, farmers, and environmental advocates delivered more than 4 million signatures to the White House calling for laws to protect pollinators.

As Charles Benbrook, a WSU toxicologist, sees it, “Imidacloprid is malware. It doesn’t blow up any buildings, but it inserts itself ruinously into the neurological code of a species.” Taking a stance that many of his colleagues would consider extreme, he argues, “Imidacloprid is more dangerous than old-school chemicals like carbaryl—definitely. It’s insidious.”

Bayer’s Fischer is dubious of such sweeping pronouncements. “A lot of the studies done on neonics expose bees to very high dosages,” he says. “They’re artificial force-feeding experiments done in a laboratory.”

Russell Groves, a University of Wisconsin entomologist who closely tracks imidacloprid, notes that neonics are not the sole cause of bee die-off. Mites play a role, he says, as does a poor diet. Still, Groves is worried. “Here in Wisconsin,” he says, “neonics are showing up in measurable levels in our riverine systems, and in our lakes, and it’s a little spooky to think about the unintended consequences they may bring.”

A 2014 Dutch study, published in Nature, found that the population of insect-eating birds declined rapidly—3.5 percent a year—in areas with high concentrations of neonics on the surface of the water. The birds died, the authors believe, because they were eating poisoned bugs.

Another 2014 study, published in the Japanese Journal of Clinical Ecology, found that when patients in Gunma prefecture consumed imidacloprid-treated food, they were inordinately inclined to record abnormal cardiograms and complain of chest and muscle pains. 

In Washington, Benbrook worries that imidacloprid may wreak havoc on the Pacific Northwest’s salmon fishing industry once the fish begin plying their way through waters tinged with the neurotoxin. “What will the chemical do to their brains?” he says. “Will they still be able to swim 1,000 miles upriver and spawn? We don’t know. That homing ability is something science doesn’t understand.” 


Patten with a male and a female shrimp
Patten with a male and a female shrimp
Photographer: Cameron Karsten/Bloomberg Business

Imidacloprid is popular because it provides what many consider a safe solution to agriculture’s most ancient, human-caused plight: pests. On Willapa Bay, the pest problem is convoluted, and steeped in layers of man-made affliction. The bay’s cash crop, the Pacific oyster, is an alien from Japan, introduced in 1928 after locals harvested a native species, the Olympia oyster, to commercial extinction. The burrowing shrimp, in contrast, are native to Willapa Bay. The shrimp abound now, in part because dams went up on the Columbia River in the mid-20th century. The dams ended the freshwater floods that once killed off shrimp. Meanwhile, overzealous fishermen took away the shrimp’s predators and loggers denuded the nearby hills, making the bay silty and less hospitable for fish. In time, Willapa Bay became less a wild place than a beleaguered, highly cultivated farm banking on a single crop, oysters.

When he arrived on the bay in 1990, Patten, the horticulturalist, was familiar with monocrop aquaculture. He was there to aid the area’s other farmers, the cranberry growers. But his charge, as an agriculture extension specialist for a land-grant university, was to help all farmers, and he soon became friendly with Dick Sheldon, who toured Patten around Willapa Bay to show him how a weed, Spartina grass, was choking oyster beds. Eventually, Patten earned worldwide acclaim by discovering that he could kill off Spartina with imazapyr, an herbicide previously used along railroad tracks.

Today, Sheldon calls Patten “our savior.” But environmentalists have another, crueler nickname for him: “Chemical Kim.” In the early 2000s, Patten drew new ire when he approached Bayer, in hopes that the German company would help get imidacloprid use licensed on Willapa Bay. 

As Patten tells it, Bayer balked, telling him, “We’re not going near the aquatic use of pesticides because of the liability issues.” (Fischer of Bayer CropScience notes that his company had reason to worry: “On all our imidacloprid labels, it says, ‘Do not apply directly to water.’ You don’t want to hit nontarget organisms like crabs.”)

Patten considered three other insecticides and approached their makers. He says all three companies turned him down, fearing the risk. Then, after Bayer’s patent for imidacloprid expired, a third-party supplier emerged. Nufarm, a $2.6 billion Australian chemical firm, agreed to sell imidacloprid to Willapa growers, but the situation was delicate. Nufarms prospective profits from the sale—less than $100,000 a year—were scant. The political risks were high. Patten knew the company would be unlikely to petition the U.S. Environmental Protection Agency for a label licensing imidacloprids use on Willapa Bay.

The oyster growers needed a lobbyist, and they found one in Alan Schreiber, an entomologist who runs a rural Washington consulting firm that helps farmers navigate pesticide law. Schreiber, who once worked for the EPA, says, We were afraid that if Nufarm submitted the registration, people would go to their headquarters and protest in the lobby. He concocted a novel approach: The oyster growers (or, officially, WGHOGA) would approach the EPA themselves. The arrangement was unusual. The request is made, typically, by a large chemical company. As Schreiber sees it, “This was outside the box, outside the room, outside the department store. 

If the oyster growers had more standing, they might have asked for permission to use two pounds of imidacloprid per acre when they approached the EPA about four years ago. Patten’s experiments had shown that much was needed for maximum effect. Terrestrial farmers are limited to a half-pound per acre, though, and to get more than that, WGHOGA would have needed to spend roughly $10 million on environmental impact studies. The group pursued a label for a half-pound per acre, hopeful that oystermen could make that scant dosage work by simultaneously killing off an invasive weed—Zostera japonica—whose roots suck up imidacloprid and make it less effective. Patten has obtained permission to kill the weed with yet another chemical, called imazamox. Still, there remains a distinct chance that shrimp hit with only a half-pound per acre of imidacloprid won’t die. They could simply go down, paralyzed for a couple of days, before bouncing back—into poisoned waters. 

Patten knew this in 2013, but he nonetheless traveled to the EPA’s offices in Washington, D.C., twice with a coterie of oyster growers. Schreiber made four such trips. “I’m not saying the EPA cut us slack, he says, but they did realize that oyster growers were in a pinch—that a 160-year-old industry was on the verge of collapse.

In an e-mailed statement, the EPA later said that the plight of oystermen did not guide its decision to approve imidacloprid. EPAs registration decisions are based on the potential human health and environmental effects associated with the use of the pesticide, the agency wrote. “The registration was granted because EPA found that this use of imidacloprid met the statutory standard of the pesticide law, the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).” 

When the EPA gave Willapa Bay a thumbs-up in June 2013, it left the final decision on imidacloprid use to the state’s Department of Ecology. 


The tide flats of Willapa Bay
The tide flats of Willapa Bay
Photographer: Cameron Karsten/Bloomberg Business

I made my first trip to Willapa Bay last December, and Patten was still jubilant. That was a miracle, he said of the EPA’s decision. I never thought it would happen.

Sheldon was worried, however. “If we don’t get two pounds per acre,” he said with contempt for the burrowing shrimp, “the little bastards won’t die. And that’s a tragedy.”

It was a cold, clear morning, and Sheldon was milling about on the gleaming, lacquered wood floor of the Willapa Harbor Community Center. The Department of Ecology was about to hold a hearing, and a crowd was forming—ready to testify either for or against imidacloprid use on the bay. There were about 50 people, and Sheldon, dressed in a camouflage jacket, was playing the heavy. At one heated juncture, he stepped toward Pacific County’s five or six eco-activists, who were huddled by the exit. Then, grimacing, he thrust his middle finger in their faces. 

For 35 years, Sheldon headed WGHOGAs development committee for Willapa Bay. It was his job to stop bayside construction, and according to Sheldon, he once blocked his own nephew from getting a permit to build a hotel. (“Now he hates me,” he said, “but I don’t care. That saves me money on Christmas presents.” Sheldon's nephew disputes that version of events, though both agree he made life difficult for his nephew.) He’s personally bought hundreds of bayside acres to rescue them from development, and he is opposed to the shipping of coal through the Northwest”—if we give that to the Chinese, it’ll come right back to us, as climate change.” But Sheldon isnt worried about imidacloprid. He is, rather, bemused by the handwringing it’s engendered. Just before the hearing began, he sat down beside another aging oysterman, Brady Engvall, and played the rube for my benefit.

“Now, Brady,” he said, “this reporter here says that imidacloprid is bad for bees. Have you ever seen a bee out there on the bay?”

Engvall paused, mock ponderous. “No, Dick,” he said. “I don’t reckon I have.” 

Oystermen on Willapa Bay have another problem besides shrimp. Since 2006, the rising acidity of the ocean, a result of climate change, has made it almost impossible for baby Pacific oysters to form shells on their own. The problem is profound in the Northwest due to what’s called ocean upwelling: In the spring and summer, the region’s prevailing north winds scoop colder, more acidic waters from deep in the sea and push them into the estuaries where hatcheries sit. A form of calcium carbonate, aragonite, is lacking in the cold deluge, and its scarcity is fatal. Aragonite is the stuff that larvae need most for shell-building.

Until recently, local oyster companies got all their larvae from Willapa Bay. Now they’re spending millions to build baby oysters’ shells in contrived environments. One afternoon, I visited the hatcheries of Taylor Shellfish—a $60 million company and the bay’s largest producer of oysters—and watched as a little pump fed a white, chalky substance, carbonate-rich soda ash, into large plastic breeding tanks. Taylor’s staff scientist, Benoit Eudeline, described the soda ash as a stopgap measure. “I don’t want to make things look rosy,” he said. “Each year we break a record for total carbon in the ocean. And what can we do? Go to a totally land-based system for oysters, where you treat all your water to make shellfish? That would be cost-prohibitive.” He shrugged, helpless against the forces of nature.

Oystermen on Willapa Bay
Oystermen on Willapa Bay
Photographer: Cameron Karsten/Bloomberg Business

I called Dick Sheldon one more time. Upon answering, he said, “Let me call you back. I’m skinning an elk.” An hour later, he invited me out for a morning of oystering on his oldest boat, The Northern.

We met in Nahcotta in the murky light before dawn and went out for three hours, trolling first up toward the northern tip of Long Beach Peninsula, where growers deposit two-year-old oysters on “fattening beds” so they can wallow in the bay’s saltiest and most nutrient-rich waters during the last year or so of their lives. We stopped and the boat captain lowered a couple of huge, rusted-out cages onto the floor of the bay and then scooped them back up, full, so that 600 pounds of oysters came clattering down onto the deck. Sheldon nodded in approval. Then we passed a thin sliver of salt marsh, two miles long and just 60 or so feet wide, that Patten had bought as part of his effort to spare the bay’s shore from development. “I go out there with my grandson sometimes,” he said, “just to go duck hunting.”

When we landed, Sheldon’s son, Brian, who now runs Northern Oyster, was at the dock in his pickup. “My dad wants to be buried in that boat,” he said, “but how can I keep myself from selling it?” Brian was uncertain about what imidacloprid could do for the bay, and he had just spent half a million dollars building five large shoreline tubs in which baby oysters, fresh from the hatchery, can spend about 10 days attaching to old oyster shells. “We need those tubs,” he told me, “now that we can’t rely on natural sets of oysters.

“This business isn’t as certain as it once was,” he continued. “It’s hard to keep a proof positive attitude 100 percent of a time. But still I hope my kids get involved in oystering. It’s a beautiful life, being out on the bay, and producing food—that’s a pretty neat thing. I want them to have that opportunity. "

As the Sheldons drove off, seagulls wheeled and squawked in the sky overhead. Tidy coils of rope lay on the docks all around as a light rain pattered down onto the mud flats. Just offshore, in the giant plastic tubs, millions of baby oysters would soon build their tiny shells: fragile armature against a crazy world. 

Early morning in Willapa Bay
Early morning in Willapa Bay
Photographer: Cameron Karsten Photography/Bloomberg

(The original version of this story stated as fact that Sheldon once blocked his own nephew from getting a permit to build to a hotel. The story has been corrected to attribute this recounting to Sheldon and clarify that his nephew disputes the account of the events.)