Thurston County has closed all of Budd Inlet near Olympia to recreational shellfish harvesting after tests found unsafe levels of the biotoxin that causes diarrhetic shellfish poisoning, or DSP. The county is warning harvesters that cooking the clams or mussels will not make them safe.
“Cooking does not destroy the toxin and does not make the shellfish safe to eat,” Thurston County Public Health and Social Services said in its Nov. 4 notice. The closure covers all shellfish species, including clams, mussels, oysters and scallops, and warning signs will be posted at the public beaches at Burfoot County Park.
That message targets a common belief. Many people assume steaming or boiling shellfish kills anything harmful, which is true for many bacteria but not for marine biotoxins. Freezing does not destroy the toxin either, according to the Washington State Department of Health.
Toxins That Survive the Pot
DSP comes from a naturally occurring algae called Dinophysis. When it blooms, shellfish filter it from the water and the toxin builds up in their tissue. The shellfish look, smell and taste normal, and laboratory testing is the only way to detect the toxin, according to the Washington Department of Health’s DSP guidance…