Meta Mesdag just needs a few ounces of oyster meat.
The owner of Salty Lady Seafood Company is wading into the murky surf north of Juneau, Alaska. The wind whips up a mist of rain and seawater as she inspects a row of barnacle-encrusted cages exposed by the low tide.
As a commercial oyster farmer, Mesdag has to send a sample of her product to state regulators every week during the selling season so they can test for toxins that cause paralytic shellfish poisoning.
If the test comes back positive, Salty Lady will have to shut down for at least two weeks — a big deal for a business that makes most of its money in the summer.
That hasn’t happened this year, unlike in 2023.
“We had multiple closures,” Mesdag said. “It ended up being almost 10 weeks of closures during a 20-week season.”
Salty Lady laid off the majority of its crew, she said, but the business survived. That summer in 2023 underscored a harsh reality of farming shellfish: It’s almost impossible to prevent or predict poisonous algal blooms, and climate change may be raising the threat, just as Alaska is boosting a new industry farming the seas.
‘When the tide is out, the table is set.’
Harmful algal blooms can be invisible. To keep people from getting sick, someone has to test the water and spread the word.
That’s why Raymond Paddock and James Refuerzo are digging holes at Juneau’s Point Louisa beach on a sunny morning in August. They’re with the Tlingit & Haida Tribes, and they’re part of Southeast Alaska Tribal Ocean Research, or SEATOR, a consortium of Indigenous scientists across the region that issues public alerts about shellfish poisoning.
Refuerzo says when he was a kid, his grandma showed him how to eat gumboots and cockles right out of the sand.
“Our people have been living off of it for thousands and thousands of years,” Refuerzo said. “When times were difficult back then, I’m sure you were able to go down to the beach and grab yourself some shellfish and fill yourself up with much-needed protein in the rugged Alaskan terrain that we lived in.”
Under his feet, the sun shines on a seaside cornucopia: colorful starfish, goopy anemone, lush mats of kelp and algae. Barnacles and mussels seem painted onto every solid surface. Dig a few inches into the sand and you’ll find butter clams, surf clams and blue mussels. There is a reason the Tlingit people have a saying: “When the tide is out, the table is set.”
A bald eagle swoops over Paddock’s head, perusing the beach buffet.
“Majestic,” Paddock said. “They are hunting for shellfish as well. It was probably looking to see if Jimmy left anything on the beach.”
People and animals have been harvesting shellfish in Alaska for thousands of years, and stories of shellfish poisoning go back almost as long. Take Poison Cove, named for an incident in 1799, when roughly 100 people died after eating toxic mussels.
Microscopic phytoplankton called Alexandrium catenella are always in the water. Under the right conditions, they reproduce exponentially, spitting out neurotoxins that contaminate filter-feeders like oysters, clams and mussels. People who eat those shellfish can get sick and even die.
Fatalities are rare today. The state department of health received just 132 reports of paralytic shellfish poisoning resulting in 5 deaths from 1993 to 2021.
Native Alaskans have learned to manage the threat, in part by following an old saying that it’s safer to harvest in months that end with the letter ‘R.’ But Paddock said that’s becoming less reliable.
“It was something my grandparents and their parents and so on would teach us as we were younger,” Paddock said. “Now, with climate change, we’ve seen that that’s changed, and it’s unpredictable.”
Public alerts issued by SEATOR and other groups help subsistence harvesters stay safe, while the state oversees commercial operations. Alaska has thousands of miles of coastline, however, so Paddock said harvesting shellfish outside the bounds of monitoring programs is risky business.
“You’re playing a game of Russian Roulette,” he said, “when we don’t know whether there is a spike in a harmful algal bloom. It’s a crapshoot.”
‘Everything is connected out here’
Scientists studying algal blooms have tracked their impact to some of Alaska’s most pristine wilderness, including Glacier Bay National Park.
On a placid morning in August, oystercatchers comb the beach with their bright orange bills. Sea otters backstroke in the glassy bay. A humpback whale surfaces just offshore, the spout of its blowhole echoing off fog-shrouded cliffs.
Dropped off on a remote beach by a park research boat, John Harley and Sydney Jones of the University of Alaska Southeast are digging for butter clams. Butters hold on to toxins longer than some other shellfish, making them a good indicator. Lately the clams have been telling an interesting story.
“In 2025, some sites, including the site that we’re digging at today, had some of the highest concentrations that we’ve ever seen in Southeast Alaska,” Harley said, both hands plunged into wet sand.
That means a potentially deadly event happened at some point in the previous few months. Out here in Glacier Bay, it might have gone unnoticed, but that data point is valuable. Even with all the testing and alerts, scientists still have a lot to learn about what causes harmful algal blooms.
“It’s not as simple as warm water, instant bloom,” Harley said. Sunlight, salinity, and turbidity might also play a role in the increasingly unpredictable seasons for shellfish poisoning.
“People are concerned about an expansion of the possible bloom window, which has historically probably been somewhat well-defined,” Harley said. “It’s possible that we might, in the future, see blooms in December and maybe even January or February.”
Microscopic algae can even lie dormant in the sediment, sometimes for decades, potentially reawakening in warming water. A scientist studying one such “cyst seedbed” in Alaska’s Arctic waters called it a “sleeping giant.”
Humans aren’t the only ones getting sick. Harley has found toxins in fish, sea otters and even wolf scat.
“It seems that wolves have been fairly successful at foraging on sea otters. And so there’s this interesting sort of possibility of these paralytic shellfish toxins going from a strictly marine environment where they’re produced and then entering into the terrestrial environment,” he said. “Everything is connected out here.”
Climate change is making new connections, too. In recent years, toxic blooms have poisoned fish in the Bering Sea, just shy of the Arctic Circle — another sign that this problem, once confined to the warmest waters and times of year, may be expanding.
Farming the seas
In a seaside lab in Juneau, scientists dote on bubbling tanks of kelp, oysters and baby abalone.
They’re with Alaska Sea Grant, part of a team of researchers at the University of Alaska Fairbanks and National Oceanic and Atmospheric Administration that are studying the state’s growing industry of mariculture, or ocean farming.
Every state with a shellfish business has to contend with harmful algal blooms. Alaska’s industry is relatively small, but ramping up thanks in part to federal money.
James Crimp, a shellfish mariculture specialist, said Alaska has a good system to catch blooms before they make people sick. But if the state has to keep shutting down small businesses for weeks at a time, it could be “death by a thousand cuts” for an industry that’s still trying to establish itself.
“Consuming commercially harvested shellfish from the state of Alaska is very safe,” he said. “What we want to focus on is just making little tweaks in the testing process to make sure we get to the same end result, but cheaper and more effectively for growers.”
That would be a welcome development for Mesdag of Salty Lady Seafood, who is back from the oyster farm and shucking in her garage, preparing that sample to send to the state.
Salty Lady does its own testing, too, measuring everything they can about the water around the farm to maximize oyster growth, and maybe stay one step ahead of the next algal bloom.
“We just like to know what’s in the water,” she said, “because we’re entirely dependent on it for our industry.”
She and the rest of Southeast Alaska will have to adapt, however the ocean might change. But some things are beyond human control.
“Harmful algae is just nature’s way of reminding us that we are not always in charge,” Mesdag said.
This article was originally published on WBUR.org.
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