Beginning May 1 and continuing through at least Oct. 31, the California Department of Public Health (CDPH) is advising consumers not to eat sport-harvested mussels along the California coast.

The annual warning, which applies to all species of mussels, is in effect to protect the public against poisoning that can lead to serious illness, the Health Department said.

Commercially harvested shellfish in restaurants or from fish markets may be safely consumed. These are not included in the annual safety warning because commercial harvesters in California are certified by CDPH and subject to strict testing requirements to ensure that all oysters, clams, mussels and scallops entering the marketplace are free of toxins.

The state’s annual mussel warning is designed to prevent paralytic shellfish poisoning (PSP) and domoic acid poisoning, also known as amnesic shellfish poisoning, in people who might otherwise consume harvested mussels that have not been tested.

Both of these syndromes are from naturally occurring toxins linked to plankton consumed by shellfish, including mussels and clams. Cooking does not destroy the toxins.

Early symptoms of PSP include tingling of the lips and tongue, which may begin within minutes of eating toxic shellfish. These symptoms are typically followed by a loss of balance, lack of muscular coordination, slurred speech and difficulty swallowing, according to health officials.

In severe poisonings, a person may experience trouble breathing, confusion and disorientation, and medical attention should be sought immediately.

To minimize potential health risks, sport harvesters should avoid eating mussels that are recreationally harvested during the summer months beginning May 1.

For more about the quarantine, PSP and domoic acid visit the CDPH Annual Mussel Quarantine – Frequently Asked Questions web page.

For updated information on quarantines and shellfish toxins, call the CDPH Biotoxin Information Line, 800-553-4133.