When Alaska shellfish turns deadly

In the Alaska wilderness, at least you can see the things that'll kill you. That's what I say when I get tired of questions about bears.

But it's not true. The smallest things that can kill you here are single-celled creatures you need a microscope to see. They can find their way into the food chain, into your clam bucket, your chowder, and then into your nerve cells. Minutes or hours later, you tingle or go numb. Nerve cells shut down in a rapid cascade until you lose control over limbs and lungs.

This is paralytic shellfish poisoning, or PSP. It comes from a tiny species of plankton called Alexandrium, which produces an even tinier chemical called saxitoxin, which is a thousand times more toxic than sarin gas, and was once studied as part of our biological weapons program in the 1950s and 1960s.

Alexandrium is an algae — more specifically, a dinoflagellate. It gets light from the sun, moves slowly through the water by beating tiny whiplike hairs, and divides to make more Alexandrium.

"Algae bloom like flowers," said Rosie Robinson at the Kachemak Bay National Estuarine Research Reserve. "Each species has a little different criteria it prefers, different conditions that allow it to dominate."

For years, Robinson and other staffers at the reserve have gone out sweeping tiny nets through harbors and coves, before focusing a drop or two of water under a microscope and identifying dozens of types of algae on a field guide they created. One algae fills the bay with tiny distinctive cells, then it dies off, to be followed by another. There are patterns to the blooms, like the crocuses blooming before the lupines before the fireweed in my yard. But the ocean is more complex — chaotic — as if you could wake up one morning to find your roses replaced by your neighbor's dandelions.

Most algae are harmless to us. A few are not. As they are slurped into the siphons of clams, their poisons can begin to accumulate.

Ever year, someone in Alaska eats toxic shellfish. Louisa Castrodale, at the Department of Epidemiology, is the one who gets the call when they do.

Last May, a Kodiak clammer was airlifted to the intensive care unit of an Anchorage hospital with PSP, and while ventilators kept the patient breathing, Castrodale coordinated doctors and labs and airplanes, tracking down a urine sample, family members who shared the meal, and the last leftover clam — which proved to be 75 times more toxic than anyone should eat.

"It's a public health emergency every time — other people might have eaten the same shellfish, or been at the same beach," she said. There was one other Alaskan reported sick last year — and around 120 since 1993. Four perished. But the number of people sickened is unreliable. "All we see is the tip of the pyramid," she said. "The toxin goes through the body so quickly, and people who just feel a little funny don't report it." Even a death could get mistaken for a heart attack.

'OK to eat?'

I talked to Castrodale from the top of a snowy ridge, looking down over Kachemak Bay. It was spring, sunny, and the time of year when the lowest tides cycle back into the daylight. I got off the phone, put my skis back on, and continued up the mountain with my friend. "So what did you find out?" he asked. "I saw some clam holes the other day. Are they OK to eat?"

From our ridge, we looked down into the dark blue water of Jakolof Bay, dotted by the bright buoys of an oyster farm with muddy clamming beaches beside it. Even within that tiny dimple of water, the answers were very different. I shrugged. "It's complicated."

Margo Reveil runs that oyster farm, selling fat Pacific oysters at the Homer Farmers Market. Once a week in summer, and once a month in winter, she sends oyster samples to a state lab, as all commercial growers are required to do.

But that's not where she begins. Along with the nets and the skiffs, she has a microscope to identify the algae. She has PSP field tests to get a crude measure of toxin levels before the official state testing. And she has years of experience with the tide cycles and weather in that part of the bay, anticipating dangerous times, and holding back the harvest.

Locals like me, who might be digging clams 100 yards away, have none of that.

"They (the diggers) should be testing," Reveil said, "The test is $36 dollars, so it's expensive, but no one should be eating those without testing. Alaska is the only coastal state that doesn't test its beaches consistently, and I've always found that frustrating. The state is big, but the inhabited areas aren't that big."

An invisible risk

"Alaska has a long dark history with biotoxins," said Kimberly Stryker, who runs the commercial shellfish testing program at the Department of Environmental Conservation. In Southeast, you can see it on the map — Peril Strait, Poison Cove, Deadman's Reach. All are named for the first recorded outbreak of PSP. That was in 1799, when a hundred Kodiak men hunting otters for the Russians died from toxic mussels, the deadliest outbreak in Alaska history. In the 1940s, the Alaska butter clam canning industry was shut down when it was discovered that the clams were toxic. Even the name of the poison — saxitoxin — comes from the scientific name of the butter clam, and it was first identified from a sample of Alaska clams. People have been eating shellfish forever here, in an uncomfortable, myth-ridden relationship with an invisible risk.

Toxins can't be cooked or rinsed out of shellfish. They can't be tasted or seen. The water doesn't look red when the clams are toxic. And if you chew up a piece of clam and hold it under your lip to test for tingling (a technique I was taught in a village on the Alaska Peninsula), you might get sick from that alone. Or notice nothing until it's too late, because the acids in your stomach transform the poison into a much more toxic form.

No one really knows why algae put so much effort into making poisons. Alexandrium makes saxitoxin, and causes PSP. Another algae called Pseudo-nitzschia produces domoic acid, the source of amnesiac shellfish poisoning. But they don't poison their predators. Most of the creatures that eat the algae aren't affected by them.

The toxins can bind metals, and scientists speculate they may collect needed metals, or protect the cells from excess. Alternately, they might carry signals between algal cells. It may only be an accident, the havoc they wreak on the complex nervous systems of creatures higher up the food chain. That accident has impacts that ripple through the ecosystem.

Butter clams may accumulate saxitoxin to protect themselves from sea otters. Sea otters have evolved to taste the toxin, and can throw out poisonous clams. Schools of anchovies eat Pseudo-nitzschia without a problem, but sea lions in California die of seizures when they swallow them. Both toxins have been detected in marine mammals across Alaska, with effects scientists are still working to understand.

Error-riddled myths

Years ago, I went with my son's preschool class to harvest clams on a low-tide April morning. Three- and 4-year-olds stomped through the mud in miniature rubber boots, carrying miniature shovels, putting butter clams and littleneck clams in mud-filled buckets before cooking them up in the classroom. They thought it was safe because they trusted us. I thought so because I relied on my own set of error-riddled myths.

I thought that we were safe because there were commercial farms nearby. But their tests are not public, and each species of shellfish accumulates and stores the toxin differently. I thought it was too early in the year. But people have gotten PSP in every month of the year. Mostly, I thought that we were safe because everyone else in my town thought we were too. Because it hadn't been a problem in the past.

People have always eaten shellfish, and in some ways, the myths must have worked for them. There are patterns of temperature, light and current, patterns of geography, runoff and circulation. Some places, times and species are safer than others. But the ocean is changing.

"Kodiak, Southeast and the Alaska Peninsula are always hot," said Stryker, "but now it's been showing up in Cook Inlet, and in Prince William Sound, and in places we really hadn't seen it before. As managers, we want predictability, and we really don't have it. These shifts aren't going to stop."

Warmer water helps all algae. Reveil's oysters now plump up all year, in food-rich winter water that used to be crystal clear. In 2015, "The Blob" brought a bloom of Pseudo-nitzschia along the Pacific Coast, affecting sea lions farther north than had ever been seen before. But the conditions that allow harmful species to outcompete harmless species are more complicated to determine. Rain and glacial melt create freshwater lenses on top of the saltwater, a stratification that may help Alexandrium bloom. Ocean currents may transport toxic species to places they weren't before, and acidification can change how much toxin an algae produces.

'Would you eat the clams?'

Angie Doroff, at the research reserve, sketched circles on the map with her finger, explaining the shifts and swirls in Cook Inlet currents. "It's like a toggle," she said. "If we get more freshwater runoff here, then the current can come around that corner, and you could turn a place that's historically been safer, like Kachemak Bay, into a place that's always hot."

I cringed when I told my preschool clamming story to Stryker. "Would you eat the clams?" I asked her.

"Before I came to work here at DEC I did. But now, probably not, especially because of how much things are changing. We see it in places we've never seen it before."

We'll only see changes if we look for them. Monitoring programs are some of the least-sexy pieces of science. Robinson and the other folks at the research reserve spent years diligently looking for toxic algae they never saw, until they did two years ago. Now they hang a cage of mussels in the Homer harbor, pulling them out to send to a new testing lab set up by Southeast Alaska Tribal Ocean Research, a partnership that has begun, for the first time, to monitor a few of the beaches where subsistence clammers dig.

[More on the Southeast Alaska Tribal Toxins network]

All of these programs are subject to the political winds of government funding. The state agency that tests commercial shellfish has lost 20 percent of its staff in three years. The draft federal budget eliminates the Kachemak Bay National Estuarine Research Reserve entirely.

So should you eat clams?

The official state line is "harvest at your own risk" and "don't eat shellfish alone." Commercial shellfish is certified safe; everything else is untested. To that, we can add a handful of things we're sure of:

• That butter clams hold toxin for years — longer than almost any species — and are responsible for half the poisonings.

• That mussels accumulate a lot of toxin quickly.

• That crab meat isn't toxic, but crab guts can be.

• That day to day, and bay to bay, the answer will change.

• That scientists think the problem will get worse. And perhaps, if we keep tracking the patterns, we'll be able to say more.

[PSP fact sheet]

Erin McKittrick is a writer, adventurer and scientist based in Seldovia. She's the author of "A Long Trek Home: 4,000 Miles by Boot, Raft and Ski," the children's book "My Coyote Nose and Ptarmigan Toes" and "Small Feet, Big Land: Adventure, Home and Family on the Edge of Alaska." Her next book, "Mud Flats and Fish Camps: 800 Miles around Alaska's Cook Inlet," is due out this spring. Find her at GroundTruthTrekking.org.