PORT TOWNSEND — Oak Bay, Port Ludlow and Mats Mats Bay have been closed to shellfish harvesting of butter and varnish clams because of the danger of potentially fatal paralytic shellfish poisoning, while all other beaches in Jefferson and Clallam counties remain closed to harvesting of all species of shellfish.

Elevated levels of the marine biotoxin that causes paralytic shellfish poisoning (PSP) was found in a recent clam sample from Oak Bay. Other species of shellfish are not affected on those specific beaches.

Toxins remain in butter and varnish clams for longer than other species, sometimes for more than a year after a bloom of algae containing the marine biotoxin has subsided.

But all other beaches on the North Olympic Peninsula are closed to harvesting of all species.

Those include Kilisut Harbor, including Mystery Bay and Fort Flager, and Discovery Bay as well as Sequim Bay and the Strait of Juan de Fuca beaches from Cape Flattery east to the Jefferson County line.

Ocean beaches are closed for the season.

PSP can be fatal. Illness is caused by eating shellfish contaminated with toxins from the naturally occurring marine plankton Alexandrium. Biotoxins are not destroyed by cooking.

Symptoms of PSP can appear within minutes or hours and usually begin with tingling lips and tongue, moving to the hands and feet, followed by difficulty breathing and paralysis. Anyone experiencing any of these symptoms after consuming shellfish should contact a health care provider immediately. For extreme reactions, call 9-1-1.

Shellfish harvested commercially are tested for toxin prior to distribution and should be safe to eat.

“All species” includes clams (including geoduck), oysters, mussels and other invertebrates such as the moon snail. All areas are closed to recreational scallop harvest.

The closures do not apply to shrimp. Crab meat is not known to contain biotoxins, but the guts or “butter” can contain unsafe levels. So cleaning the crab thoroughly and throwing out the “butter” is recommended.

During the warmer months, the naturally occurring Vibrio bacteria within shellfish is a concern. Hood Canal currently has a Vibrio bacteria warning. The public should cook shellfish from Hood Canal to 145 degrees internal temperature for 15 seconds.

The state shellfish safety map can be found at www.doh.wa.gov/ShellfishSafety.htm.

Recreational harvesters should also check Fish and Wildlife regulations and seasons at wdfw.wa.gov/fishing/shellfish or the Shellfish Rule Change Hotline 1-866-880-5431.