A blue mussel bed exposed at low tide on September 8, 2018, in Skagway.
Paralytic toxins have been found in shellfish collected at several beaches in the Upper Lynn Canal.
Advisories are currently in place for three Haines-area sites where shellfish has been collected and tested. Portage Cove and Taiyasanka Harbor have advisories for butter clams specifically, and Viking Cove has an advisory for all shellfish. Viking Cove was tested most recently.
Blue mussels collected May 12 at Nahku Beach also tested with very high levels of toxins and are cause to be cautious, said Skagway Traditional Council environmental coordinator Reuben Cash. The blue mussels Cash collected had paralytic shellfish toxin (PST) levels more than 10 times higher than the FDA’s safety limit, according to testing done by Southeast Alaska Tribal Ocean Research (SEATOR).
“Levels that high are much more likely to be a widespread event,” Cash said adding that historical wisdom that “summer time months are not a time for collecting shellfish” is a good rule of thumb. The risk isn’t just for people: pets can also be affected.
“I would advise people not to let their dogs munch down on anything when PST levels are this high,” Cash said. A dog from Skagway recently got sick from eating shellfish, and the vet in Whitehorse confirmed it had consumed paralytic toxins, he said.
This spring was the first time since 2021 mussels were collected at Nahku Bay, Cash said the tribe decided to sample after a phytoplankton bloom occurred in the bay.
“We were able to test the shellfish just after the bloom had subsided,” Cash said.
Then, he said something more unusual happened. As sampling continued, the toxin levels increased exponentially until the May peak, although additional phytoplankton wasn’t seen. Cash said he didn’t know the exact cause, whether wind blew in more phytoplankton, there was another bloom that wasn’t spotted, or other factors entirely.
“We’re not entirely sure,” he said. “It’s a very site-specific, location-specific event.”
Paralytic shellfish toxins are a group of more than 20 different toxins made in a type of phytoplankton that naturally occurs in Alaskan waters called Alexandrium.
When shellfish eat that phytoplankton, they also ingest and accumulate the toxins. Then, when humans eat the contaminated shellfish, they are poisoned, said SEATOR director Kari Lanphier.
Cash said molluscan shellfish like clams, oysters, mussels, snails and whelks can all accumulate the toxins and be dangerous for people to eat. Some of those are riskier than others: butter clams can hold the toxins for more than a year, Lanphier said. “You can’t boil them out, you can’t freeze them out.”
For shellfish like crab and shrimp, which are categorized as crustaceans, the toxins accumulate in the gut. The guts are unsafe, but once removed, the rest of the animal is safe to eat.
SEATOR is a tribal consortium that does environmental data collection. The consortium’s PST testing is done in the Sitka Tribe of Alaska’s environmental lab, Lanphier said. Results from shellfish collected by tribes throughout Southeast Alaska are published on SEATOR’s website to help the public know where PST is present and avoid eating unsafe shellfish.
The testing is often done on blue mussels because they are filter feeders, and can consume 50 gallons of water per day, so if Alexandrium is in the water column, they’ll find it, Lanphier said. But the lab tests a wide range of shellfish.
Although three sites are tested regularly in the Haines area, Chilkoot Indian Association’s Liam Cassidy said harvesters who collect shellfish can have SEATOR test a sample of about 20 shellfish before deciding to eat them.
Cassidy said he can send them in for testing, and the collector doesn’t have to reveal the location where they were harvested.
Lanphier said individuals can also send fresh or frozen shipments directly to SEATOR for testing. Once the shellfish gets to the lab, the turnaround time for results is about two days, she said. Testing at any site of collection is the most reliable way to stay safe, she said.
Individual reactions to consuming PSTs can vary depending on how the individual metabolizes the toxins, but it can be fatal.
“Alaska has had deaths,” Lanphier said.