The yearly quarantine of all mussel species harvested publicly on the California coast came a month early this year and is now in effect. California Department of Public Health (CDPH) has found elevated levels of both domoic acid and paralytic shellfish poisoning in mussels. Poisoning from eating these mussels can be very severe, so make sure you avoid them. Cooking does not reliably eliminate the toxins.
Symptoms can start to show up as early as 30 minutes after eating the mussels, but it could take up to 24 hours.
The quarantine will run through October 31, and it covers all sport harvested mussels along the coast of California in all bays, all harbors and all estuaries. Commercially harvested shellfish however, are not included in the quarantine. These are certified by the state and are subject to strict requirements.
For more info, you can contact the CDPH at the shellfish information line 800.553.4133.