High PSP in Clams

Observation: The paralytic shellfish poisoning (PSP) results for Airport Beach, Sand Point, Alaska (butter clams collected 12/5/2014) had PSP toxin levels of 155 micrograms/100 grams. See the data on the attached graph or the Environment Alaska website. 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 following the July 13, 2014 PSP event. 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 have occurred in Alaska usually following warm winter rain events and stream flooding. 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. Forage fish, such as sand lance (AKA needle fish, candle fish, sand eels) can become toxic with PSP too. I recommend not eating dead or sick looking forage fish found on Alaska beaches and report these events to me. 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.