Mussel samples indicate PSP risk at Shoemaker helipad

A recent reading on shellfish taken from around the Shoemaker Bay helipad has shown elevated risk of paralytic shellfish poisoning.

Blue mussel samples from the site were taken by the local Indian Environmental General Assistance Program office on June 12, and sent to the laboratory maintained by Sitka Tribe of Alaska the next day. The readings came back positive for saxitoxin, the underlying agent responsible for PSP in humans. As a result, residents are advised to avoid eating shellfish from that area for the time being.

Since last year Wrangell’s IGAP office has been monitoring shellfish species found at commonly used beaches, partnering with Southeast Alaska Tribal Ocean Research in Sitka to test for several harmful contaminants. It has previously reported elevated levels of saxitoxin in butter clams gathered from beaches around Shoemaker Bay and Pats Landing, cautioning the public to avoid eating that species from those sites for the present. Specimens at Zarembo Island also came back with dangerously high levels.

Saxitoxin is produced by the phytoplankton Alexandrium, large blooms of which can taint nearby waters. Area filter feeders like clams and oysters absorb the toxin, which can be transmitted to humans upon ingestion. Symptoms of PSP tend to begin with numbness of the oral membranes, and severe cases can entail nausea, vomiting, neurological effects, paralysis, respiratory failure and ultimately death.

Different species absorb but also relinquish such toxins differently than others. Wrangell IGAP technician Kim Wickman explained blue mussels do so relatively quickly, which makes them a particularly good indicator species with which to gauge current water conditions at local beaches. When the mussels test positive for toxicity then, it means other species are likely affected as well, and may be so for longer. Of the local species, butter clams tend to take the longest to pass the toxins.

Once collected, specimens are sent live to the Sitka laboratory to be examined and measured. For a sample of blue mussels between 80 and 130 need to be collected to produce a reliable measure.

Test samples are taken on a weekly basis, providing an up-to-date picture of the health of available shellfish. Wrangell Cooperative Association, through its IGAP, is one of 14 other tribal organizations participating in the toxins monitoring project for Southeast Alaska. Results for this wider area are posted on SEATOR’s website, at http://www.seator.org/data.