The Wrangell Tribe’s environmental program office announced last week that most species of shellfish have been cleared for consumption at a pair of local beaches.
On August 24 results from the week’s sampling had indicated levels of saxitoxin – the root cause of paralytic shellfish poisoning – evident in mussels at Pats Creek and Shoemaker Bay beaches had dropped below federal safety guidelines. Conducting the site testing, the Indian Environmental General Assistance Program had previously issued a warning for Pats in January and Shoemaker last August. The Pats site has subsequently been given the all-clear at the end of July, and most of Shoemaker Bay’s shellfish species are also again acceptable to harvest and eat.
The exception is its butter clams, which as a species takes longer to relinquish the saxitoxin it takes in than other filter-feeders. Those near the Shoemaker Bay helipad still maintain elevated levels of the toxin.
“Because we cleared all of our species – minus the butter clams at Shoemaker – we can go ahead and use blue mussels as our indicator species. They pick up fastest,” explained Kim Wickman, Wrangell IGAP’s technician.
For more than a year she has been regularly collecting samples from the two beaches, which then get sent to Sitka’s Southeast Alaska Tribal Toxins laboratory. Operated through Sitka Tribe of Alaska, the program collaborates with other tribal partners, state and federal agencies, and regional fishing groups to monitor toxicity in the region’s shellfish.
Saxitoxin is just one of three potentially deadly neurotoxins produced by species of area phytoplankton. When in bloom, Alexandrium produces enough saxitoxin to be absorbed by nearby filter feeders like clams and oysters. The bivalves themselves are unharmed, but the toxin can be transmitted to humans through ingestion.
The most serious risk posed by local plankton, Wickman warned that people should be aware of the warning signs of PSP if consuming shellfish. “Lips can start getting tingly. Trouble with breathing, light headedness, but tingling lips is like the number one,” she said. “From there it can progress really quickly.”
In severe cases, these symptoms can soon turn to nausea, vomiting, neurological effects, respiratory failure and, ultimately, death. If signs become evident, a person should seek medical assistance immediately.
Wrangell’s IGAP collects shellfish for testing, but also monitors samples of the local water. Using a microscope, Wickman keeps an eye out for Alexandrium and other potentially harmful species, Dinophysis and Pseudo-nitzschia. Dinophysis produces okadaic acid, the cause of diarrhetic shellfish poisoning.
Pseudo-nitzschia produces domoic acid, which can lead to amnesic shellfish poisoning. Symptoms of this include vomiting, nausea, diarrhea, cramps and hemorrhagic gastritis. The substance also damages neurons in the brain, and symptoms can include headache, dizziness, loss of short-term memory, seizures and cardiac arrhythmia.
“These are all ones that are known to cause issues,” Wickman explained. On her slides, she has observed Dinophysis and Pseudo-nitzschia, though contamination of area shellfish by them has not been evident. But the culprit behind saxitoxin has been harder to find.
“Actually, Alexandrium has eluded us. We have not seen that one,” she said. “That’s the most fascinating part of our project.”
With the end of summer, the office will be conducting tests only once a month. In addition to water, Wickman also measures conditions like temperature and salinity. This information is then provided to Sound Toxins, a Washington-based monitoring program focused on algal bloom events.
“We identify everything we can,” said Wickman. “They’re using it as a way to track different species coming through.” The hope is that a pattern for algal activity can be identified, which could be used to better predict and react to such blooms. “Someday, maybe, we’ll be able to see the differences, what’s going on in that area.”
For ongoing data on Southeast Alaska’s shellfish, Southeast Alaska Tribal Ocean Research maintains an up-to-date list of test sites online, as well as any warnings associable with local shellfish. The page is at http://www.seator.org. On its Facebook page, Wrangell Cooperative Association’s IGAP also posts updates as well as a “plankton of the week” highlight.
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