Quartermaster Harbor is closed to all recreational shellfish harvesting after state health officials detected dangerous levels of Paralytic Shellfish Poison (PSP), according the Washington Department of Health.

The closure applies to all shellfish, including clams, oysters, mussels, scallops and other mollusks. Crabmeat is not known to contain the PSP toxin, but the guts can contain unsafe levels, according to Public Health – Seattle & King County. Crabs should be cleaned thoroughly and their guts discarded, the agency says.

PSP poisoning can be life-threatening and is caused by eating shellfish containing a potent neurotoxin. A naturally occurring marine organism produces the toxin, which is not destroyed by cooking or freezing. People cannot visually determine whether shellfish toxins are present — and thus the notion of a “red tide” is misleading, state health officiasl say.

Recreational shellfish harvesting can be closed due to rising levels of PSP at any time. Harvesters are advised to call the state health department’s biotoxin hotline at 1-800-562-5632 or visit the biotoxin website before harvesting shellfish anywhere in Puget Sound.