This is what’s making sea lions sick — and causing quite a stench in Pismo Beach

Dead fish have washed up on the sand in Shell Beach in recent days.
Dead fish have washed up on the sand in Shell Beach in recent days. jjohnston@thetribunenews.com

If you’ve been to or driven past Pismo Beach recently, you’ve most likely noticed a pungent odor.

That smell could be caused in part by an algae bloom — and the fungi are also hurting local sea lions. Residents and visitors in Pismo and Shell beaches have also seen dead fish washing up on the shore and brown water, which may also have something to do with the algae.

Large algae blooms first appeared in California in 1991, said Clarissa Anderson, executive director of the Southern California Coastal Ocean Observing System.

Then there was a lull until 1998, when Central California saw a mass blooming event that killed more than 400 sea lions.

Algae blooms have appeared off the California coast every year since then. And every year, “we’ve seen that the blooms are getting more and more toxins,” Anderson said.

Anderson said that her organization has been seeing a lot of algae blooms off of SLO County, and the forecasts for SLO County “have been pretty hot for the last month and a half.”

The organization uses a forecast model to monitor algae blooms off the coast of California. The forecasts are based off of a combination of satellite imagery and physical numerical weather models in the ocean. It’s not an exact representation of every algae bloom, but it’s a good frame of reference.

Anderson said she believes that what’s happening in the South County could be caused by two different types of algae. One of those blooms, which is called pseudo-nitzschia, contains a toxin called domoic acid.

When fish like anchovies feed on pseudo-nitzschia algae, domoic acid builds up in their bodies. And when marine animals like sea lions eat the fish, the toxin poisons them and can cause brain damage, seizures, disorientation and death.

In July, the Sausalito-based Marine Mammal Center rescued 69 sea lions in San Luis Obispo County, with most of those coming from the Oceano area, according to Dr. Shawn Johnson, the center’s director of veterinary science. Johnson said they believe the sea lions suffered from exposure to domoic acid.

Over the last month, most of the sea lions that have been rescued were adult females who are lactating, which means they have pups that they are caring for.

“The moms go out, they fed on a bunch of fish that were carrying the toxin, the toxin caused them to have brain seizures and illness, which caused them to wash up on the beach where we find them,” Johnson said. “Unfortunately, there’s a pup on the Channel Islands looking for its mom and won’t find her.”

Since the beginning of the year, the center has rescued 82 sea lions along the 600 miles of coastline stretching from San Luis Obispo County to Mendocino County.

The center treats the sea lions who are suffering from domoic acid toxicity for weeks at a time. But not all of them make it.

“Unfortunately, by the time we rescue them, some of them consume so much of the toxin that they can’t stop seizures,” Johnson said.

“They end up dying or we end up euthanizing them because we know they have severe brain damage and are never going to recover.”

This year, of the 82 rescued sea lions, 31 have died. And, according to the center’s website, they are seeing an uptick in suspected domoic acid cases in San Luis Obispo County, with volunteers rescuing a high number of sea lions in the area that show signs of the toxicity.

The presence of pseudo-nitzschia algae explains the sea lions. But it still doesn’t account for the noxious smell.

“We don’t typically smell (anything) related to (algal blooms) unless it’s a really enclosed harbor,” Anderson said, who was surprised that the smell was coming from the Pismo area and not from somewhere like Avila Beach.

However, a different kind of algae bloom, called dinoflagellate algae, creates a dense bloom, Anderson said. If there’s enough dinoflagellates around, people could smell the bloom as it decays.

And, though it’s uncommon, it’s possible that fish could be consuming enough of the pseudo-nitzschia algae that they are becoming disoriented and end up washing up on the beach, Anderson said.

Both dinoflagellate and pseudo-nitzschia blooms, which create red tides, aren’t necessarily harmful to humans.

The harm comes when people eat lots of fish that may have come in contact with domoic acid, such as sardines or anchovies. The California Department of Public Health monitors commercial seafood supplies, but recreational fishers depend on state-directed quarantines, which means there’s certain times of the year when people can’t fish for something.

But even though both types of algae blooms won’t necessarily hurt people, “when you have a lot of algal blooms along the coast, you can have a lot of bacteria in the water,” Anderson said. “It’s common knowledge that if there’s a big red tide, don’t go swimming.”

Gabby Ferreira: 805-781-7858, @Its_GabbyF

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