POULSBO — Marine biotoxins that cause paralytic shellfish poisoning — also known as PSP or “red tide” — have been detected in high levels in shellfish samples from multiple sampling stations on the eastern shore of Kitsap County, the state Department of Health and Kitsap County Health District report.

As a result, the health departments have closed shorelines for all species of clams, mussels and oysters on the east side of Kitsap County — from Point No Point in Hansville south to the Pierce County line near Olalla. This closure covers Blake Island, all of Bainbridge Island and all of the following bays, inlets and passages: Port Madison Bay, Miller Bay, Liberty Bay, Agate Pass, Rich Passage, Sinclair Inlet, Yukon Harbor, Colvos Passage and Dyes Inlet.

Samples of mussels collected on Aug. 1 from the Southworth ferry dock contained PSP toxin concentrations of 747 micrograms per 100 grams of shellfish tissue, the health departments reported. Beaches are closed when the toxin level exceeds 80 micrograms per 100 grams of tissue.

Warning signs have been posted at public beaches alerting people not to collect shellfish from the closure areas.

Shrimp and crab are not included in this closure, but crabs should be cleaned prior to cooking, and the “crab butter” should be discarded. Shellfish harvested commercially that are available in stores and restaurants are tested for toxin prior to distribution and are safe to eat, the health departments reported.

Marine biotoxins are not destroyed by cooking or freezing and can be life-threatening. People can become ill from eating shellfish contaminated with the naturally occurring marine algae that contains toxins that are harmful to humans. 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 potentially death.

Anyone experiencing these symptoms should contact a health care provider, the health departments reported. For extreme reactions, call 911.

In most cases, the algae that contain the toxins cannot be seen and must be detected using laboratory testing. The Health District reported it will continue to monitor shellfish at Kitsap County beaches, and will notify the public if the levels of PSP toxin become unsafe in other areas.

For current shellfish closures within Kitsap County, call 1-800-2BE-WELL, or visit www.kitsapcountyhealth.com.  For closures in other areas of Washington, call 1-800-562-5632, or visit www.doh.wa.gov/ehp/sf/biotoxin.htm.