Paralyzing nerve toxin found in recreationally caught shellfish, most dangerous levels in 20 years

An unseasonably warm winter is putting a pause on the Bay Area’s recreational seafood catch, bringing elevated levels of a toxin found in shellfish much earlier in the year than usual.

The California Department of Public Health warned residents in Marin, San Francisco and San Mateo counties to refrain from harvesting and consuming mussels, clams, oysters and other bivalve shellfish due to harmful levels of paralytic shellfish poison.

The warning only applies to recreational harvests, as commercially harvested shellfish are regularly screened for toxicity levels before sale.

Paralytic shellfish poison, also called PSP, is a biotoxin produced by algae.