BREMERTON —  Marine biotoxins that cause diarrhetic shellfish poisoning (DSP) have been detected in high levels in shellfish samples from the Brownsville Marina located in Port Orchard Narrows in Kitsap County.

As a result, the Washington State Department of Health and the Kitsap Public Health District have closed waters on the west shoreline of Bainbridge Island from the Agate Pass Bridge south to Point White, and on the east shoreline from Illahee State Park north to the Agate Pass Bridge, including all bays and inlets, to recreational shellfish harvesting for all species of clams, oysters, and mussels.

Samples of mussels collected on Dec. 9 from the Brownsville Marina contained DSP toxin concentrations of 17.5 micrograms per 100 grams of shellfish tissue. Shorelines are closed to harvesting when toxin levels exceed 16 micrograms per 100 grams of tissue.

An existing biotoxin closure for butter clams and varnish clams remains in effect on Kitsap County’s eastern shoreline from the Point No Point in Hansville south to the Pierce County line including all shorelines on Bainbridge Island and Blake Island.

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 toxins prior to distribution, and are safe to eat.

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. DSP symptoms can begin from 30 minutes to 12 hours after eating contaminated shellfish causing nausea, vomiting, abdominal pain, and diarrhea, with diarrhea being the most commonly reported symptom. Most symptoms subside within 72 hours.

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