By GARLAND KENNEDY
Sentinel Staff Writer
Toxicity levels in shellfish have risen at the North Starrigavan beach, leading to a warning against eating shellfish from that beach.
The concentration of the paralytic shellfish toxins that cause paralytic shellfish poisoning (PSP) have risen to 540 micrograms of toxin per 100 grams of tested shellfish at the beach, far above the FDA regulatory limit of 80 micrograms of toxin per 100 grams of shellfish, Environmental Lab Manager Kari Lanphier told the Sentinel. Lanphier manages the Sitka Tribe of Alaska Environmental Research Lab on Katlian Street.
Signs of PSP, which can be fatal, include tingling lips and fingers, numbness in arms and legs, nausea, and difficulty breathing, an STA press release said. The toxins that cause PSP are released by a bloom of the phytoplankton alexandrium. Once the toxins are present, cooking or freezing the shellfish won’t impact toxicity levels, an STA-ERL online pamphlet reads.
Lanphier said recent testing was done on blue mussels, as they act as an indicator for risk levels.
“We measure an assortment… at the beach but we primarily test blue mussels. Blue mussels are our sentinel species, our canary in the coal mine. They filter a lot of water,” she said.
Starrigavan estuary is pictured today. Blue mussels harvested from the beach recently were found to contain very high levels of toxins that cause paralytic shellfish poisoning. (Sentinel Photo by James Poulson)
She noted that while blue mussels frequently exceed the FDA regulatory limit for toxin concentration at some point each year, the numbers this year are particularly high.
“This is the highest we’ve ever tested at that location,” she said. The lab has tested Starrigavan shellfish since 2016.
The test was done on June 8.
With Starrigavan blue mussels well above the regulatory limit, Lanphier said, STA-ERL plans to test shellfish at the beach weekly.
“Since we have blue mussels that went above the limit we’ll do everything we can to test weekly,” she said.
As she recalled, blue mussels at Starrigavan didn’t accumulate unsafe toxin levels in 2020, but did in 2019.
“I don’t think blue mussels were above the regulatory limit at Starrigavan in 2020 at all, for that year they never went above so they never dropped. In 2019… they went to 430 in the beginning of July, they were hot for about two weeks and by mid-July they went down. And we had a second bloom in the fall, in October,” she said.
There is no time of the year when shellfish are guaranteed to be safe for consumption.
“In Hoonah last year we had blue mussels above the regulatory limit in December – there’s no hard and fast rule,” she said.
While blue mussel toxicity levels rise and fall in a matter of weeks, Lanphier said shellfish such as butter clams can hold toxins for a long time.
“Butter clams retain toxins, and even though this is the first time we’re seeing blue mussels go above the regulatory limit for a while, butter clams can be toxic at any time of year from any beach,” she said. “All they need is an alexandrium bloom at some point in the last few years… Butter clams are a different beast; they can retain those toxins and they need to be assessed with a different risk than your other subsistence species.”
Anyone interested in consuming shellfish from a local beach can take a sample to STA-ERL for free testing.
“If folks want to harvest any type of species... they can bring it to the lab and we are still able to test those for free,” she said.
The test requires a 100 gram sample, as FDA standards measure toxicity in micrograms of toxin per 100 grams of shellfish. A Sitkan interested in testing should call ahead at (907) 966-9650. Once a test is arranged, Lanphier said, there is a cooler outside the building where people can drop off their shellfish.
