Temperatures are rising in the San Juans, and so is the possibility of illnesses from shellfish consumption.

From June 15-July 16, all of San Juan County was closed for shellfish harvesting due to a high level of biotoxins. Eating locally reaped shellfish, like mussels, oysters or clams, at that time, could have resulted in sickness.

According to Kyle Dodd, the county’s environmental health manager, there were no local reports of illnesses from high levels of biotoxins in shellfish consumption this summer, or in the past three years. Today, the county is open to harvest shellfish, while nearby locations around Cypress Island is closed.

Shellfish are filter feeders, which means they strain small particles in the water to obtain food. Sometimes they keep poisonous residue, like biotoxins, in their tissue, which can make people sick when they are eaten. The biotoxins are formed as temperatures heat up, explained Dodd, and can cause such illnesses as Paralytic Shellfish Poisoning, which can lead to paralysis and even death.

According to the Washington State Department of Health, PSP cannot be prevented by cooking shellfish, though another illness involving shellfish, called vibriosis, can be avoided if shellfish are properly cooked. Vibriosis is an intestinal disease that can cause symptoms such as diarrhea and vomiting.

According to Dodd, there has been one confirmed case of vibriosis in the county within the last three years, in which the consumer purchased oysters from a retail store in the islands. Over the last three years, he said county staff have also investigated six other reports of foodborne illnesses from eating raw oysters, but they were not confirmed as vibriosis by lab results.

To ensure safe recreational shellfish harvesting, Dodd said county staff collect samples of mussels in nine local areas, every two weeks, from April through October. The samples are sent to the Washington State Department of Health for analysis to determine if the water the shellfish live in is safe. The local collection areas are Fossil Bay on Sucia; West Beach Resort on Orcas; Deer Harbor on Orcas; the University of Washington Friday Harbor Laboratories on San Juan; Cattle Point on San Juan; Mud Bay on Lopez; Barlow Bay on Lopez; and Odlin Park on Lopez.

Recreational closures, said Dodd, don’t always mean a nearby commercial shellfish grower will be closed as well. Commercial shellfish growers, said Dodd, can receive a separate clearing from the state by sending their own samples for testing.

Through education and caution, maladies related to shellfish consumption can be avoided, he assured.

“It is important to educate the public about ways they can protect themselves when harvesting and enjoying shellfish,” he said. “These illnesses can be very serious, but by checking for closures before they dig and properly cooking shellfish prior to eating, they are preventable.”

To check for closures before digging, visit www.doh.wa.gov/shellfishmap for an interactive map of harvesting areas or call the shellfish safety hotline at 1-800-562-5632.