Fort Flagler, Kilisut Harbor, and Mystery Bay were ordered closed for recreational shellfish harvest Thursday after samples of shellfish were found to contain elevated levels of marine biotoxins that cause paralytic shellfish poisoning (PSP).

Officials with Jefferson County Public Health said signs warning of biotoxin danger have been posted at public access points to warn people not to consume shellfish from the area.

Health officials said the closure includes clams, oysters, mussels, scallops, and other species of molluscan shellfish.

Officials also noted that crabmeat is not known to contain the biotoxin, but the guts can contain unsafe levels. To be safe, the health department is reminding recreational crabbers to clean crab thoroughly and discard the guts (also known as the “butter.”)

Shellfish harvested for commercial sale are tested for toxins prior to distribution and should be safe to eat.

Health officials also warned that marine biotoxins are not destroyed by cooking or freezing.

People can become ill from eating shellfish contaminated with the naturally occurring marine algae containing toxins harmful to humans. Symptoms of PSP can appear within minutes or hours and usually begins with tingling lips and tongue, moving to the hands and feet, followed by difficulty breathing, and potentially death.

Anyone experiencing PSP symptoms should contact a health care provider immediately. People who have extreme reactions should call 911.

In most cases the algae that contain the toxins cannot be seen, and must be detected using laboratory testing.

Recreational shellfish harvesters can check the Washington State Department of Health Shellfish Safety Map at doh.wa.gov/ShellfishSafety.htm for an updated map of closed, open, or conditionally open public shellfish beaches, as well as marine biotoxin closure zones. People can also call the Department of Health Biotoxin Hotline at 1-800-562-5632 before harvesting shellfish anywhere in Washington state.

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