The California Highway Patrol (just kidding – its the Public Health People in California) issued a public health advisory warning against the ingestion of Dungeness crabs because of higher levels of domoic acid in the crustaceans. Domoic acid is a naturally occurring neurotoxin associated with amnesic shellfish poisoning. It can cause all sorts of brain injury in humans that consume enough of it. It is produced by algae blooms and accumulates in shellfish, sardines and other small fish and cannot be destroyed by cooking or freezing. Scary stuff, kids.
One interesting tidbit – in 1961, California seabirds went crazy and attacked people, serving as the inspiration for the Hitchcock film “The Birds.” The birds in Capitola and Santa Cruz were thought to be under the influence of domoic acid. No kidding.