Razor clamming has been closed on Clatsop Beach because of elevated domoic acid levels, the Oregon Department of Agriculture announced Thursday.

The immediate closure applies to recreational and commercial harvesting of razor clams and mussels on beaches and ocean spits from the mouth of the Columbia River at Astoria to Tillamook Head, south of Seaside. The closure cuts just two days off the season. The Oregon Department of Fish and Wildlife was scheduled to close Clatsop Beach Saturday for a seasonal summer conservation closure which runs each year from July 15 to Sept. 30.

Clams harvested before Thursday's closure are still considered to be safe and do not need to be destroyed, ODA officials said.

Razor clamming is still open for the rest of the Oregon coast, as levels of domoic acid are well within the safe range. A shellfish license is required to harvest shellfish.

Domoic acid is a naturally occurring toxin produced by marine phytoplankton or algae. Eating shellfish contaminated with it can cause illness ranging from mild to fatal. Domoic acid cannot be destroyed by cooking, adding baking soda or any other method.

Updates on shellfish toxin closures are at ODA's Shellfish Safety Hotline, (800) 448-2474 and online at oregon.gov/ODA by clicking on the link called shellfish closures. For more information on Oregon's razor clams, visit http://www.dfw.state.or.us/MRP/shellfish/razorclams