Quartermaster Harbor has been closed for shellfish harvesting after unsafe levels of Diarrhetic Shellfish Poison (DSP) were detected there.

The closure by the state state Department of Health includes harvesting for clams, oysters, mussels, oysters, geoduck and scallops. Advisory signs will be placed at beaches warning people to not collect shellfish there.

Although DSP, a toxin produced by naturally occurring algae, has been a problem in European countries for some time, this is an emerging health threat for Washington, according to an announcement from Public Health — Seattle & King County. Anyone who eats shellfish contaminated with DSP is at risk for illness.

DSP poisoning symptoms include nausea, vomiting, abdominal pain and diarrhea, with diarrhea being the most commonly reported symptom. Symptoms may appear within minutes of eating contaminated shellfish or may take several hours.

Many other Vashon beaches are open to shellfish harvesting, though all island beaches are currently closed for butter clams and varnish clams. Some beaches, particularly on the west coast of the island, are closed due to pollution.

Shellfish harvesters are advised to call the DOH Biotoxin Hotline at 1-800-562-5632 or visit the DOH before harvesting shellfish anywhere in Puget Sound. See www.doh.wa.gov/CommunityandEnvironment/Shellfish and click on “Clickable maps.”