Thousands of dead anchovies wash ashore, fall from sky in Bay Area's Marin County

MARIN COUNTY, Calif. -- The Bolinas Lagoon shore in Northern California's Marin County was seemingly painted silver by a school of anchovy.

Photos and video shared with San Francisco's KGO-TV show the mass die-off event that happened earlier this week.

"This is just one of those times where we kind of get to see just the sheer number of the size of these schools of fish," Marin County Parks Dir. Max Korten told KGO. "So it's kind of amazing."

Amazing and a mystery! There's still uncertainty about why the thousands of fish ended up here.

Referencing biologists, Korten explained, "What likely happened is, you know, some kind of predator out in the ocean encountered a school of anchovy somewhere near the mouth of Bolinas Lagoon."

He said this possibly pushed the anchovy more toward the shallow water, where they sucked up the limited oxygen and suffocated.

Volunteer researcher, Jim Ervin, said while that ending is likely, he believes something else may have attracted the anchovy to the lagoon.

"Hungry anchovies go where the food is," Ervin shared.

A current volunteer researcher at the Otolith Geochemistry and Fish Ecology Lab at UC Davis, Ervin retired after 27 years with the City of San Jose's Environmental Services Department in 2018. He was also a compliance manager for the San Jose-Santa Clara Regional Wastewater Facility.

Ervin told KGO, this La Nina year is generating more food production and the foraging fish are following. He explained the cool water is bringing in more anchovy than we've seen in the last 10 years off our coast and in the Bay.

The abundance is good news for seabirds. It's interesting news for anyone seeing anchovy far from water.

"People might not want to visualize this, but I think they're barfing," Ervin said. "I think they're flying over, just can't take it anymore, gotta release. I would imagine."

He continued, "They're feasting so much. There's more fish than they know what to do with."

As more is done to determine what led to the mass die-off, officials say don't panic. Similar mass die-over events have happened several times over the last few decades.

"My biggest words of assurance, I guess, is that anchovy populations boom and bust," Ervin shared. "And we're in a boom year. Then things like that, they drive 'em into the shore and unfortunately they do themselves in sometimes."

Ervin said there is a lot to be learned from the anchovy that washed ashore. Specifically, information about genetics.

"As they grow up, do they stay in the Bay? Or do some of them actually migrate out to the ocean and join the greater population," he questioned.

Korten with Marin County Parks described Bolinas Lagoon as a pretty fragile ecosystem and is encouraging anyone wanting to see the anchovies, to be mindful of the environment.

"It's a home to a really abundant amount of marine life," he said. "We just asked if anybody goes near there, just use caution and not to disturb the animals, the seals and things that make their home there."