EVERETT — The state Department of Health has closed Port Susan and Possession Sound for the recreational harvest of all species of shellfish because of a spread of marine bio-toxins that poison shellfish.

The closure includes clams, oysters, mussels, scallops and other species in central Puget Sound. Shellfish harvested commercially are tested for toxins prior to distribution. Crab meat is not known to contain the bio-toxin but the guts can contain unsafe levels, the Snohomish Health District reported Friday. To be safe, clean crab thoroughly and discard the guts, which are sometimes referred to as “crab butter.”

Marine bio-toxins that cause Paralytic Shellfish Poisoning (PSP) 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 begin with tingling lips and tongue, moving to the hands and feet, followed by difficulty breathing and potentially death. Anyone experiencing those symptoms should contact a health care provider immediately. For extreme reactions, call 911.

In most cases, the algae that contain the toxins cannot be seen and must be detected using laboratory testing. That is why recreational shellfish harvesters should check the Washington Shellfish Safety Map or call the Biotoxin Hotline at 866-562-5632 before harvesting shellfish anywhere in Washington. Recreational harvesters should also check Fish and Wildlife regulations and seasons at www.wdfw.wa.gov/fishing/shellfish, or call the Shellfish Rule Change Hotline at 866-880-5431.