Thousands of dead anchovies wash up on California beach. Here’s what happened

Beachgoers near the Cayucos Pier were faced with a startling sight on Wednesday — masses of dead anchovies washed up on the shore, driven there by a feeding frenzy in the ocean nearby.

According to Danna Dykstra-Coy, who captured video and photos of the scene, the swath of fish stretched out on both sides of the pier, reaching north to about D Street.

She estimated that there were perhaps thousands of the anchovies on the beach, with many more still swarming in the surf.

That school of fish attracted many seabirds, Dykstra-Coy said.

“Massive balls of bait fish were chased by hordes of brown pelicans on a feeding frenzy to shore,” she told The Tribune in an email. “Many anchovies attempting to escape the stream of dive-bombing birds ended up on the beach.”

When a school of bait fish like that gathers in a tight sphere, usually to avoid nearby predators, it also attracts sea mammals, including whales and dolphins. At that point, it’s called a bait ball.

In 30 years of living in Cayucos, Dykstra-Coy said it was the first time she’s seen such a phenomenon there.

Apparently, die-off incidents like that happen when too many fish try to occupy too small an area of water and wind up depleting the oxygen in the sea.

While uncommon in Cayucos, bait-fish die-offs happen occasionally elsewhere.

In July, Bay Area newspapers reported about a similar incident in a Bolinas lagoon.

The San Francisco Chronicle story said about the die-off that “anchovies swim in schools, and the theory is that a large one was pushed into the lagoon by birds and then trapped by its sand bar. With so many fish stuck in a relatively small body of water, there wasn’t enough oxygen, which killed the fish and stranded them on shore, said Samantha Haimovitch, a superintendent with Marin County Parks, which manages the lagoon.”

The Tribune has reached out to the state Department of Fish & Wildlife, State Parks and Cal Poly biologists but had not heard back by the time of publication.

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