More butter clams carrying PSP risk

A new sample site shows more butter clams carry the risk of paralytic shellfish poisoning for consumers, according to a report released last week.

Since last year Wrangell Cooperative Association's Indian Environmental General Assistance Program (IGAP) staff have been collecting samples of various bivalves from the beaches around Shoemaker Bay on a weekly basis. It added a new site further south to its monitoring, near Pats Landing. It was here that the butter clam samples showed unsafe concentrations of saxitoxin, which causes PSP.

PSP can be fatal, causing paralysis in humans. It begins with a numbness of the oral membranes, and severe cases can include nausea, vomiting, neurological effects, respiratory failure and ultimately death. The saxitoxin which causes the illness is produced by Alexandrium phytoplankton, which can bloom in large enough numbers to taint nearby waters. It ends up in filter feeders such as clams and oysters as a result, and can take upward of two years to pass. Of the varieties being tested in Wrangell, butter clams can take the longest to filter out such substances.

Like its warning issued after finding similar readings in Shoemaker samples last August, the announcement is precautionary. Other species sampled at both sites have been found to be safe. So long as they're not being added to, saxitoxin levels eventually recede over time, as is the case at Shoemaker.

For saxitoxin, the Food and Drug Administration sets a safety threshold of 80 micrograms per 100 grams. The samples at Pats Landing showed a reading of 115. Different species filter through toxins at various rates, and levels can drop rapidly. Readings from Shoemaker samples that read 212 in August had dropped to 104 by around Thanksgiving.

Samples are tested by Sitka-based Southeast Alaska Tribal Ocean Research, which posted the alert on its website at http://www.seator.org/data. The site collects updated data from 28 different sites in 16 communities around Southeast, focused on saxitoxin, domoic acid and other harmful toxins to be found in shellfish.

The SEATOR program and its laboratory were established by Sitka Tribe of Alaska in order to give local shellfish harvesters a way to test clams and other shellfish important to subsistence. Previously the only lab in the state capable of such testing was in Anchorage, and catered primarily to commercial fisheries.

In 2013, the Southeast Alaska Tribal Toxins network was started to coordinate and share information between the region's tribal governments. Wrangell's IGAP began collaborating with SEATT last April, beginning with its monitoring at Shoemaker Bay.