The West Coast is in the midst of an unprecedented toxic algal bloom, but marine life off the San Luis Obispo County coast has so far avoided the outbreak.
Starting this month, marine researchers began recording some of the highest concentrations of the natural toxin domoic acid ever observed in Monterey Bay and off the central Oregon coast.
Domoic acid is a toxin that is produced by some algae blooms, which are often referred to as red tides. When present, the toxin accumulates in the tissue of sardines and anchovies as well as mussels, clams and other marine filter-feeding organisms.
This poses a threat to seals and sea lions, which feed on sardines and anchovies. People can also be poisoned if they eat those two bait fish species as well as recreationally harvested shellfish.
Sign Up and Save
Get six months of free digital access to The Tribune
Health officials have imposed harvest closures in various places in all three West Coast states, the closest being in Monterey and Santa Cruz counties. However, local fishermen and biologists say toxic algal blooms have not yet caused any problems in San Luis Obispo County.
“As we speak, we have received no seafood warnings,” said Mark Tognazzini, a Morro Bay commercial fisherman and seafood merchant and restaurateur. “The only issue is the Morro Bay oyster beds.”
He said domoic acid has not been detected in Morro Bay oysters, but the weekly testing of the beds has been increased to twice a week out of an abundance of caution. Commercially harvested shellfish is considered safe because it is subject to this kind of frequent mandatory testing to monitor for toxins.
Similarly, local wildlife biologists and wildlife rescuers say they have not seen an increase in the number of marine mammals suffering from domoic acid poisoning. The toxin causes brain damage and seizures in the animals.
Small-scale toxic algal blooms occur most summers, particularly when sea temperatures are warmer, said Laura Sherr, spokeswoman for the Marine Mammal Center in Sausalito. “It is something that always exists,” she said.
So far this year, six seals suffering from domoic acid poisoning have been rescued from beaches in San Luis Obispo County, which is not considered an unusually high number. This compares to 36 seals rescued in Monterey County, where the domoic acid outbreak is severe.
“It doesn’t seem like domoic acid exposure has really kicked in here in Central California,” said Mike Harris, a biologist with the California Department of Fish and Wildlife.
Meanwhile, the fisheries division of the National Oceanic and Atmospheric Administration has stepped up its monitoring of domoic acid levels. The NOAA research vessel Bell M. Shimada set sail earlier this month from San Diego for a research cruise up the West Coast to Vancouver.
Along the way, scientists will assess sardine and hake populations and examine levels of marine toxins and the organisms that produce them. The journey will take all summer to complete, said Michael Milstein, a spokesman for NOAA Fisheries.
The ship first encountered elevated domoic acid levels in the Santa Barbara Channel. This is similar to the last severe domoic acid outbreak in 1998. That year, the Santa Barbara Channel and Monterey Bay were the state’s two hotspots.
“It will be interesting to see how the summer progresses,” Milstein said.