Officials Warn Against Harvesting Mussels, Clams

Fearing an outbreak of sometimes fatal poisonings as the weather grows warmer, the California Department of Health Services declared a ban on the harvesting of mussels, clams, scallops and other shellfish that feed off a toxic microorganism.

The annual May 1 to Oct. 31 ban is aimed at bivalve mollusks that feed on the Alexandrium catanella microorganism that causes paralytic shellfish poisoning (PSP) when eaten, Dr. Donald G. Ramras of the San Diego County Department of Health Services said.

Alexandrium catanella poisons the nervous system within a few minutes or hours of being eaten, sometimes causing muscle paralysis and even death, Ramras said. There is no known antidote to the poison, which cannot be destroyed by cooking, he said.

The taking of the mollusks--including all mussels, dark meat clams and native rock scallops--is banned along the entire California coast as the weather grows warmer and the organisms breed faster, Ramras said.

Special efforts are being made to inform new arrivals from Southeast Asia and the Pacific Islands, who like to harvest the mollusks. The Alexandrium organism rarely occurs in the waters off their homelands, Ramras said.

In California, the organisms are sometimes so plentiful that they turn the waters reddish-brown, creating a “red tide,” he said.

Last August, 11 nonfatal cases of paralytic shellfish poisoning were reported in northern Sonoma County, officials in San Diego said.

In 1989, two nonfatal cases were reported in Mendocino County, and, in 1980, a major outbreak of PSP occurred along the coast in Marin and Sonoma counties, with 98 cases--including two deaths--reported, officials said.

The quarantine does not apply to abalone, crab or shrimp because they do not feed off the Alexandrium catanella organism. Commercially sold bivalves are also not effected because they are closely monitored by state or federal authorities, Ramras said.