SHIMADA-Underway (1).jpg

NOAA research vessel, Bell M. Shimada

(NOAA)

A massive toxic algal bloom has closed shellfish fisheries along the West Coast.

"It appears to be the largest we've seen in terms of severity and magnitude," said Michael Milstein, spokesman with NOAA Fisheries.

He said when the ocean is warm and not "mixing," algae grow and produce a toxin, which is then eaten by sardines, anchovy and other fish that feed on the algae.

Microorganisms known as plankton can accumulate the toxin, which then can poison birds and sea lions that feed on them.

California officials, he said, have warned against eating harvested mussels and clams, commercially or harvested anchovy and sardines, or the internal organs of commercially or caught crab taken from Monterey and Santa Cruz counties.

Oregon officials, he said, have halted all shellfish harvesting from the Columbia River south to Tillamook Head and closed the entire state coastline to razor clamming. Mussel harvesting north of Gold Beach has also been closed.

All coastal Washington beaches, he said, have been closed to razor clamming, at an estimated loss of more than $9 million in revenue for coastal communities in the past month alone.

He said Washington has closed the coast to Dungeness crab harvesting.

"That's the first time they've ever done that," he said.

Milstein said the bloom is a natural phenomenon and will dissipate when temperatures start to fall.

Meanwhile, federal biologists have embarked on a research expedition to examine the bloom.

"This is unprecedented in terms of the extent and magnitude of this harmful algal bloom and the warm water conditions we're seeing offshore," said Vera Trainer, with NOAA's Northwest Fisheries Science Center in Seattle. "Whether they're related we can't really say yet, but this survey gives us the opportunity to put these pieces together."

On Monday, a team of scientists set out from Oregon aboard the NOAA research vessel Bell M. Shimada to survey the algae bloom along the West Coast. They joined a previously scheduled research mission to assess the sardine and hake populations along the coast.

The scientists will examine levels of marine toxins and collect water and algae samples, hoping to understand what's happening. NOAA is working with the University of California-Santa Cruz, the University of Washington as well as the Quileute and Makah tribes in Washington.

-- Tom Hallman Jr.

thallman@oregonian.com; 503 232-5981

@thallmanjr

-- The Associated Press contributed to this report.