The state Department of Health announced Tuesday that Paralytic Shellfish Poison was found in shellfish samples taken from the harbor, which is on Vashon-Maury Island.
According to state officials, eating the naturally occurring poison can be fatal. It's found in clams, oysters, mussels, scallops and other species of mollusks. The closure doesn't apply to shrimp or crab, but officials advice discarding the crab guts, or "butter."
PSP is especially dangerous because harvesters can't see it and it can't be destroyed by cooking or freezing.
Commercial beaches are sampled separately and commercial products should be safe to eat, according to the Department of Health.