PORT TOWNSEND — Recreational shellfish harvesting has been closed on Discovery Bay after samples were found to contain elevated levels of marine biotoxins that cause paralytic shellfish poisoning, the state Department of Health announced Wednesday.

Danger signs have been posted at public access points warning people not to consume shellfish from this area, officials said.

Sequim Bay also is closed to all species of shellfish.

Mystery Bay and Kilisut Harbor, including Fort Flagler, have reopened to recreational harvest of all shellfish species except butter and varnish clams.

Butter and varnish clams are still closed in those bays due to the fact that they retain toxins longer.

Ocean beaches are closed for sport harvesting from April 1 to Oct. 31 each year.

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

The closure does not apply to shrimp.

Crab meat also is not known to contain toxins but the guts can harbor unsafe levels so they must be thoroughly cleaned.

Species that are not to be harvested are clams — including geoduck — oysters, mussels and other invertebrates such as the moon snail.

Symptoms of paralytic shellfish poisoning (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 potentially death.

Anyone experiencing these symptoms should contact a health care provider immediately, the state said. For extreme reactions call 9-1-1.

Toxins cannot be detected by sight or smell. Neither cooking nor freezing destroys biotoxins.

Recreational shellfish harvesters can get the latest information before they leave for the beach by visiting www.doh.wa.gov or calling 800-562-5632.

The emergency regulation hotline is 866-880-5431.