The mussel quarantine is a yearly event that happens due to dangerous levels of biotoxins that may be present in mussels gathered by the public anywhere on the California coast, including bays, inlets and harbors. The quarantine applies only to sport-harvested mussels; commercially grown mussels from certified companies are not included in the quarantine. The annual mussel quarantine is in place to protect the public against paralytic shellfish poisoning (PSP) and domoic acid poisoning (DAP), also known as Amnesic Shellfish Poisoning.
The annual quarantine is normally in effect from May 1 through October 31. However, the California Department of Public Health (CDPH) may begin the quarantine early, or extend it, if monitoring results indicate the presence of dangerous levels of biotoxins outside of the normal quarantine period. The May through October quarantine period encompasses more than 99 percent of all PSP illnesses and deaths reported in California since 1927. The mussel quarantine is in effect from the Oregon border to the Mexican border. All bays, inlets and harbors are included.
The annual quarantine is in place so the public does not collect mussels during this high-risk period for marine toxins. The occurrence of biotoxins in mussels is unpredictable and they can increase in concentration very rapidly. Therefore, the annual quarantine period provides the best approach for protecting the public from these potentially deadly biotoxins.
These toxins are very dangerous and have been responsible for many deaths worldwide. Since 1927, there have been 542 reported illnesses and 39 deaths attributed to PSP in California. Death can occur within 30 minutes of consuming toxic shellfish.
There are no known antidotes to the toxins found in mussels. Cooking does not reliably destroy the toxins.
For additional information about the mussel quarantine: Mussel Quarantine Frequently Asked Questions section.
CA Dept. of Public Health Mussel Quarantine Announcement