Officials issue shellfish advisory

Toxins pose danger in sport-harvested Sonoma Coast bivalves

Jackie Sones, Bodega Marine Reserve research coordinator, hikes along an area of the Sonoma Coast hit hard by a mussel die-off during the 2019 heatwave. State and county officials in April 2026 have warned against eating sport-harvested bivalve shellfish, including mussels, due to the presence of naturally occurring, poisonous toxins circulating in the ocean off the coast. Kent Porter — The Press Democrat, 2019

A family searches for clams on Doran Beach in 2015. Health authorities have advised people not to eat sport-harvested bivalve shellfish, including clams, from the Sonoma Coast due to the detection of high levels of naturally occurring poisonous toxins in the species. Charlie Gesell— For Sonoma magazine

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By Martin Espinoza

martin.espinoza@pressdemocrat.com

High levels of naturally occurring toxins circulating in the ocean off the Sonoma Coast have led public authorities to recommend people not eat sport-harvested mussels, clams, scallops or oysters from the area.

The state warning, first posted April 9 and reiterated this week by Sonoma County’s health officer, comes ahead of the regular May 1-Oct. 1 statewide ban on sport-harvested mussels due to higher seasonal levels of some ocean toxins.

The new warning covers all bivalve shellfish harvested by recreational anglers and foragers along the Sonoma Coast.

A similar state warning against eating sport-harvested bivalve shellfish from the Marin and San Mateo coasts was issued on March 30.

Naturally occurring paralytic shellfish poisoning, or PSP, toxins can cause severe illness or death in humans.

Dr. Michael Stacey, Sonoma County’s health officer, said dangerous levels of those toxins have been detected in mussels from the county’s coastline. Cooking does not destroy the toxins, he noted.

Commercially caught shellfish, sold in restaurants and supermarkets, are considered safe to eat because they are regularly tested.

“It’s safe to eat in a restaurant or to buy mussels and shellfish commercially,” Stacey said. “The warning is just that you should not go out to the beach and harvest your own.”

The poisonous toxins are produced by algae and affected by warm water temperatures and an changing ocean climate. The toxins accumulate in shellfish without harming them, he said.

The symptoms of PSP poisoning can occur fairly soon after eating them, he said. These include getting a tingling sensation on your fingertips, nausea, vomiting, loss of coordination, possibly difficulty speaking or swallowing.

“The reason it’s called paralytic shellfish poisoning is because it does affect muscles,” Stacey said. “In very severe cases, you might get some muscle paralysis, which can affect the muscles related to breathing…at that level it’s absolutely a medical emergency.”

Anyone who has eaten shellfish and is experiencing symptoms should go to an emergency room before the symptoms advance to difficulty breathing or possible asphyxiation.

In addition to the current advisory not to eat sport-harvested shellfish from the Sonoma, Marin and San Mateo coastlines, a state advisory warning the public not to eat sport-harvested razor clams in Humboldt County, due to high levels of naturally occurring domoic acid, has been in effect since May 2024.

Domoic acid is also accumulates in clams and other shellfish, including crab, and can cause illness or death in humans, according to state public health officials. Like PSP toxins, cooking does not destroy domoic acid.

Under state law, only state-certified harvesters or dealers are allowed to sell clams, mussels, scallops or oysters commercially.

You can reach Staff Writer Martin Espinoza at 707-521-5213 or martin.espinoza@pressdemocrat.com