Crab and clam fisheries in at least two western states have been closed down out of concern over an exceptionally large mass of toxic algae in Pacific Ocean waters off the U.S. West Coast.
The bloom of algae known as Pseudo-nitzschia, the largest in more than 10 years, stretches from central California to Washington and may extend into Alaskan waters, officials say.
Officials in Washington and Oregon have closed coastal areas to crab and clam harvesting because of the bloom.
Such blooms are common in the spring, but this one is extremely large with extremely high concentrations of a natural toxin called domoic acid, scientists with NOAA say.
Samples taken off the coast of California's Monterey Bay and the central Oregon coast revealed the highest concentration of domoic acid ever recorded, they say.
Such blooms and concentrations of domoic acid are commonly referred to as a "red tide."
While a red tide bloom doesn't pose a health risk to people who eat commercially-caught fish, most of which don't feed directly on algae, crabs or clams caught and eaten by recreational fishers can present a significant risk, possibly causing seizures and even death, experts say.
There is concern because the current bloom is "geographically quite extensive," says Vera Trainer, an oceanographer with the Marine Biotoxins Program at NOAA's Northwest Fisheries Center in Seattle. "We have reports of high domoic acid levels from Monterey Bay, California, all the way up to Homer, Alaska."
"This is unprecedented in terms of the extent and magnitude of this harmful algal bloom and the warm water conditions we're seeing offshore," she says. "Whether they're related we can't really say yet, but this survey gives us the opportunity to put these pieces together."
Among the potential victims of the toxin are California's sea lions, which can display symptoms of "sea lion sickness" after eating contaminated fish.
The toxin becomes stronger as it moves up the food chain, explains Scott Kathey of the Monterey Bay National Marine Sanctuary.
"By the time you get to the higher level predators, like a sea lion, it's already been concentrated through all these fish on the ladder to the sea lion," he says. "The visible aspects will be, like, the shakes, their behavior becomes very erratic. They can't focus on feeding, so they get dehydrated, malnourished, and then they essentially starve to death."
There are fears the current bloom could result in a mass die off, something that has occurred in previous red tides.
"It's sad to see, because you can tell they are in distress, and there is not much we can do about it," Kathey says.
