Warning issued for recreationally harvested mussels from California coast

The California Department of Public Health issued a quarantine order Wednesday warning that mussels gathered by recreational harvesters from California’s ocean shore should not be consumed by humans for the next six months.

The quarantine area extends from the Oregon border to the Mexican border, including all bays, inlets and harbors in Los Angeles County. The Los Angeles County Department of Public Health conducts daily syndromic surveillance to identify cases of illness due to ingestion of mussels and other bivalent shellfish and works with the state by collecting shellfish for testing.

During the quarantine season, mussels may concentrate naturally occurring toxins that are highly poisonous to humans including paralytic shellfish poison and domoic acid biotoxins in bivalve shellfish, including mussels, clams, oysters and scallops.

Shellfish toxin levels do not have predictable cycles and can increase rapidly. Prevention of human illnesses requires the annual quarantine, combined with year-round surveillance, public education, shellfish advisories and commercial closures as needed. Cooking does not destroy the toxins.

The advisory does not apply to commercial shellfish from approved sources.

Mussels may be used or sold for use as bait when displayed and sold in containers labeled in boldfaced type letters at least one-half inch in height as follows: MUSSELS FOR BAIT ONLY, UNFIT FOR HUMAN FOOD, according to LA County health officials.

Symptoms of domoic acid poisoning, also referred to as amnesic shellfish poisoning, can occur within 30 minutes to 24 hours after eating toxic seafood.