Chilkat Valley News - Serving Haines and Klukwan, Alaska since 1966

Levels of paralytic shellfish poison (PSP) — toxins produced by algae that can kill humans when concentrated in seafood — were relatively low last year in Haines, where extremely high amounts have been recorded in the past, according to a statewide report by the Knik Tribe.

An anemone sample collected at Viking Cove last June had PSP levels of 62.5 micrograms per 100 grams. The U.S. Food and Drug Administration’s limit for human consumption is 80 micrograms per 100 grams, although some people have gotten sick from as low as 60 micrograms per 100 grams, according to Bruce Wright, chief scientist at the Knik Tribe.

​​The highest level of PSP in mussels ever recorded in Alaska was at Viking Cove in 2014. The poison registered at 21,600 micrograms per 100 grams, or about 270 times consumable levels — enough for one mussel to kill five humans, Wright said.

“Last year’s levels seem to be really low in everything we tested in Haines. If everybody (was) out there eating mussels, 95% of them (wouldn’t) have (had) symptoms. But I know someone who was hospitalized (and put on a respirator) from eating butter clams with 60 micrograms for 100 grams,” Wright said. (That instance was not in Haines.)

Local biologist Sandy Barclay, along with high school science students, collected samples last year for Wright.

PSP is produced by microscopic algae and is most prevalent and dangerous to humans during algal blooms. Those blooms usually occur in Alaska only when water temperatures rise above 8 degrees Celsius, and last year’s temperatures were low compared to years past, Wright said.

The primary poison producer in Alaska is a single-celled phytoplankton called Alexandrium, Wright said. The toxins, emitted as a self-defense mechanism by the algae, accumulate in the tissues of filter-feeding shellfish, like mussels, oysters, clams and scallops, as well as in a range of other organisms, like crabs and marine mammals.

“Toxins move through the food web,” Wright said. Sandlances feed on small crustaceans called copepods that eat algae, and all kinds of marine animals eat sandlances, Wright said. A seal that eats a sandlance that ate a copepod that ate toxic algae could show traces of PSP.

Barclay said she harvested 10 blue mussels from Viking Cove once a week for five months and collected a one-time sample of other organisms, including chitons, snails, blennies (a small fish), Nereis worms, anemones, sockeye salmon internal organs and more.

“It was rewarding to contribute to scientific knowledge. It’s always interesting to see what the results are because they’re always changing,” Barclay said. “I discovered new organisms I had never seen before.”

Despite the low PSP levels last year, Barclay said harvesting and eating local mussels still can be risky. “I think the general consensus is you don’t eat local mussels here in this area,” she said.

The management strategy for non-commercial harvesting is that all shellfish are potentially unsafe and consumption should be avoided, Barclay said.

Wright started researching PSP more than 40 years ago, and the Knik Tribe started its annual monitoring in 2006. More recently, Wright said he’s “been testing all kinds of species in the marine food web.”

For example, last year was the first time he tested an anemone from Haines, and it just so happened to have higher levels of PSP than samples of mussels and other organisms that are known to carry the toxin. “Why would there be PSP in an anemone?” Wright asked. Because everything in the ocean is eating everything else, he said.

In June 2018, a sample of Haines mussels tested at 3,594 micrograms per 100 grams — nearly 45 times the FDA’s limit. Three or four mussels would have been enough to kill a human, the CVN reported at the time.

In high doses, the toxins can cause paralysis and death in marine organisms and in humans, sometimes within just a few hours of ingestion. Some of the chemicals are 1,000 times more potent than cyanide, according to a state public health fact sheet. One of the most potent of them is called saxitoxin. When the Soviet Union shot down American U-2 spy plane pilot Francis Gary Powers during the Cold War, the CIA had given him a small dose of saxitoxin, taken from an Alaskan shellfish, to inject in case of capture.

The highest level of PSP detected in 2021 was over 3,360 micrograms per 100 grams in mussels collected near Akutan, Wright said.

Wright said over 200 people in Alaska have died from paralytic shellfish poisoning. Most recently, a woman died in 2020 after eating mussels collected from a beach in Unalaska.

There is no antidote for PSP, but victims can be saved with respirators if their breathing muscles become paralyzed. Extremely high doses of PSP, though, can stop the heart. Heating or freezing shellfish doesn’t neutralize the toxin.

“For the Haines area the big concern has been people coming down from the Yukon. They’ll come down, and they’ll go along the shoreline on low tide and pick mussels off the rocks and eat them right there. That’s really risky,” Wright said.

Wright is doing tests on king salmon and is seeking winter king carcasses. Anyone willing to send them can contact Wright at bwright@kniktribe.org.

*Correction: The original version of this article reported that a Haines fisherman died in 2010 of a suspected case of paralytic shellfish poisoning (PSP) after eating crab. In fact, despite several media reports that PSP was suspected in his death, an autopsy showed that the fisherman, John Michael “Mike” Saunders, died of heart failure not caused by PSP. The article was updated on 2/10/22.