The original version of this article contained incorrect information. The following corrections have been made:
• There are no safe months to eat shellfish.
At the beginning of the article, the corrected quote from Nicole Kovacs reads “There are no safe months to eat shellfish.”
Please be aware that toxins can be present in shellfish even during winter months. Visit www.seator.org/data for more information on local shellfish toxins.
• In addition, samples are sent to the Sitka Tribe of Alaska’s Research Lab, which was incorrectly identified in the original article.
• Finally, butter clams can hold toxins for a period of two years.
“The Skagway News” apologizes for the errors.
By SUZANNE ASHE
FOR THE SKAGWAY NEWS
An old myth specifies the best time to eat shellfish is during months that contain the letter “R” (e.g. September through April), and to avoid eating shellfish in months that do not contain an “R” (May through August).
But that’s just a myth.
“There are no safe months to eat shellfish,” said Nicole Kovacs, program manager at Taiya Inlet Watershed Council in a December interview.
Every other week from mid-November until March, and then every week from March until autumn, Kovacs pulls on her Xtratuf boots and digs for blue mussels at Nahku Bay. She packages up samples and sends them to the Sitka Tribe of Alaska’s Research Lab for testing.
“From the people I’ve talked to, they say [Nahku is] where they have collected mussels in the past,” Kovacs said. “So, that’s the first place I’m going to go to. Once I get the hang of it, I’ll start taking samples from other locations too.”
Kovacs has some testing equipment at the Skagway Traditional Council office. She can test water samples by looking at slides under a microscope, but sends the mussels to Sitka to be tested.
The state test lab in Anchorage prioritizes commercial shellfish and tests them first, but the Sitka lab can have test results for subsistence shellfish back quickly. The Sitka lab opened last spring.
“The water temperatures are getting warmer, so that’s leading to a rise in the algal blooms,” Kovacs said.
The samples Kovacs sends to Sitka are tested for Alexandrium spp, which produces saxitoxin, which causes Paralytic Shellfish Poison, also known as PSP. The first symptoms of PSP are a tingling of the lips and tongue. Cooking or freezing toxic shellfish will not make shellfish safe if saxitoxin is present.
Alexandrium in the water forms cysts that can bloom anytime if the temperature and other conditions are right, according to Kovacs.
Kovacs looks for toxins in plankton when she collects samples. She hasn’t found levels that would raise any alarms.
PSP isn’t the only danger that can be lurking in shellfish.
Psuedonitzschia spp produces domoic acid, which leads to amnesic shellfish poisoning – permanent short-term memory loss.
And Dinophysis spp can produce okadaic acid, which causes diarrhetic shellfish poisoning – no, you don’t want this one either. Kovacs, who has a degree in environmental sciences, went through training for the project this fall and began collecting samples in November.
“Algae likes warmer water,” Kovacs said. “Originally people knew, the natives in this area knew, they couldn’t harvest shellfish in the summer months because they caused people to be sick. Now the warmer temperatures are extending into the winter. Toxic algal events can happen all year long.”
Toxins can be in the water, even if there is no red tide. Red tide is a naturally occurring phenomenon where the population of the phytoplankton Karenia brevis rapidly increases, coloring the water red and posing a threat to marine life.
“I’m sure you’ve heard of ‘The Blob,’” Kovacs said describing an example of a red tide phenomenon that gained notoriety in 2014. It’s a large mass of relatively warm water that hugs the coast of North America from Mexico to Alaska.
PSP can cause a red tide, but a lot of the time these toxic events have no distinguishing color to them. The ocean water looks clear, and a lot of people mistake that for it being safe.
Shellfish filter a lot of the water, so they accumulate a lot of the toxins in them. Blue mussels are able to get rid of it pretty quickly – within a few days. At the opposite end of the spectrum, butter clams hold toxins for up to two years. In the winter, shellfish hold on to toxins for a longer time.
Cooking or freezing shellfish won’t kill off the toxins, Kovacs said. The only way to really know if the blue mussels or butter clams collected locally are safe is to send then for testing, or by checking the latest test areas online.
The Skagway Traditional Council’s shellfish toxin testing updates are available at: www.seator.org/data
The Blob tracker: alaskapacificblob.wordpress.com
Sitka Tribe of Alaska Environmental Research Lab: www.seator.org/lab.