SALEM, Ore. — Oregon authorities have expanded shellfish fishing closures along the state’s entire coastline to include razor clams and bay clams, as already high levels of toxins that have contributed to an outbreak of shellfish poisoning continue to rise.
The Oregon Department of Fish and Wildlife said the new closures were due to “historically high levels” of a marine biotoxin known as paralytic shellfish poisoning. The measure, announced by the ministry in a press release on Thursday, came after government officials similarly closed the entire coast harvesting mussels last week.
Agriculture officials also closed an additional bay on the state’s south coast to commercial oyster harvesting, bringing the total of such closures to three.
Elevated levels of toxins were discovered in shellfish on the state’s central and north coasts for the first time on May 17, fish and wildlife officials said.
The shellfish poisoning outbreak has sickened at least 31 people, Oregon Health Authority spokesman Jonathan Modie said in an email. The agency has asked people who have harvested or eaten Oregon shellfish since May 13 to complete a survey intended to help investigators determine the cause of the outbreak and the number of people who have become ill.
Officials in neighboring Washington also closed the state’s Pacific coast to harvesting shellfish, including mussels, clams, scallops and oysters, according to a shellfish safety map prepared by the Washington State Department of Health.
Paralytic shellfish poisoning, or PSP, is caused by saxitoxin, a naturally occurring toxin produced by algae, according to the Oregon Health Authority. People who eat shellfish contaminated with high levels of saxitoxins usually start feeling sick within 30 to 60 minutes, the agency said. Symptoms include numbness of the mouth and lips, vomiting, diarrhea and shortness of breath, and irregular heartbeat in severe cases.
According to the health department, there is no antidote for PSP. Treating severe cases may require mechanical ventilators to assist with breathing.
Authorities warn that cooking or freezing contaminated shellfish does not kill the toxins and does not make it safe to eat.
Officials say the Oregon Department of Agriculture will continue to test for shellfish toxins at least twice a month, tides and weather permitting. Reopening an area closed due to biotoxins requires two consecutive tests showing that toxin levels are below a certain threshold.