PSP High in Clams

Observation: The paralytic shellfish poisoning (PSP) results in figure 1. for Sand Point, Alaska (butter clams collected 1/5/2015) had PSP toxin levels of 112 micrograms/100 grams. See the data on the attached graph or the Environment Alaska webpage. These levels are above the FDA limit for PSP which is 80 micrograms/100 grams, the red line on the attached graph. Since samples have been regularly collected we can see the gradual decline of PSP in butter clams and can make a prediction just based on our knowledge of PSP in butter clams and the trending data. The data clearly indicates a downward trend since the peak (July 13, 2014). Usually, a slow decline in PSP is common for butter clams in the winter, but remember, butter clams tend to maintain high PSP levels longer than other clams and mussels, and winter PSP events can occurred.

PSP levels will likely be different in adjacent beaches and will change with time. Littleneck clams usually do not reach as high of toxicity levels as butter clams and littleneck clam toxicity levels usually drop off quicker than butter clams. If you harvest/consume clams from Alaska beaches you should become familiar with all the clam species. Extreme caution should be taken when consuming any clams, cockles, scallops and mussels from Alaska’s beaches. Shellfish harvesters should be advised that PSP is a serious health risk when consuming personally harvested shellfish. Crabs feeding on toxic mussels, clams or fish (sand lance) can accumulate PSP toxin in their digestive system, so I recommend that before cooking, remove the back shell of the crab and clean out all the dark soft tissues that comprise the digestive system and crab butter. The same may be true for shrimp; the coon-stripe shrimp I sampled in the Haines area in 2014 had elevated PSP levels in their viscera (guts). Bivalves (clams, mussels, oysters, scallops) sold at wholesale and retail markets require PSP testing and are considered safe for human consumption, but crabs or shrimp are not regularly tested for PSP. The samples for this project (collected through the work of the Qagan Tayungin Traditional Council) are all analyzed by the Alaska Department of Environmental Conservation Environmental Health Laboratory. Note that the FDA limit for PSP is 80 micrograms/100 grams, the red line on the attached graph. The data collection for this project will continue to Fall 2015. Data tables are available at Environment Alaska's website.

Please note: Samples and analysis performed in figure 2. were provide through the efforts of the Qagan Tayagungin Tribe (QTT) in Sand Point, by Karis Porcincula, the tribes Environmental Coordinator, and she writes, "that the levels are still high and clams are unsafe to eat." For more information visit the QTT PSP Program website.

LEO says: Although the PSP levels are declining with each month; they are still high. How come?

Aleutain Pribilof Islands Association – Bruce replies, "The summer of 2014 saw a region-wide – Gulf of Alaska PSP event with high PSP levels reported from all my monitoring sites. The Haines site in Viking Cove had the highest PSP levels ever reported in Alaska. Sea otters and sea lions were found dead on beaches in the Aleutian Islands; they had high PSP levels. Sand lance, a small schooling fish, had elevated PSP levels all along the coast up to Deering in Kotzebue Sound. The PSP levels in Sand Point increased as part of this huge PSP event and is slowly lowering as the butter clams depredate or decontaminate themselves." Source: Bruce Wright, Senior Scientist, APIA, Inc.