High Levels of Toxin Found in Kodiak Shellfish

Steamed butter clams. Yu Morita / Flickr
Steamed butter clams. Yu Morita / Flickr

Kayla Desroches/KMXT

A person recently fell ill with parasitic shellfish poisoning after consuming butter clams from Roslyn beach in the Chiniak area.

Julie Matweyou, Kodiak agent with the Alaska Seagrant Marine Advisory Program, says the incident was nonfatal, but the clam samples came back with an extremely high level of toxin.

“Just to give some reference, the highest reported toxin in the Kodiak region in butter clams has been 8532 micrograms of toxin per 100 gram shellfish, and again the preliminary results of the shell fish from the illness last week is close to 6000, so we’ve almost reached our upper  limit of toxicity.”

Matweyou says the regulatory level for safe consumption is 80 micrograms.

She explains microscopic phytoplankton produce a naturally occurring toxin that poisons shellfish and causes PSP. She says Kodiak has the phytoplankton called alexandrium, which blooms starting in May, and she says while the bloom starts to die down in September, that doesn’t make shellfish safe to eat.

“We often refer to PSP as Alaskan roulette. There’s really not a very safe time to do it. Especially when we experience these high toxin levels like we just saw here in Kodiak. Some clams can hold the toxins for extended periods of time, and particularly the butter clam can hold the toxins for up to two years.”

Matweyou says the last few winters have been warm, and probably affected the number of toxins in the water. She recalls last year’s warm water patterns.

“We had very interesting dynamics with that pseudo-nitzschia bloom, which is another marine harmful algal bloom, and we saw that extending all the way from California all the way along the coast of Alaska up to Dutch Harbor last year. I was not monitoring the water continuously through the summer, but we did see pseudo-nitzschia here in Kodiak, and I did see Alexandrium here in Kodiak last year.”

She says she’s no longer monitoring those toxins due to the removal of funding.

Matweyou reminds people to err on the side of caution and not to consume locally harvested shellfish.

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