‘I’ve never seen it this time of year’: Anchovy die-offs this winter surprise Santa Cruz harbor community

Senior Deputy Harbormaster John Haynes said he never expected to see an anchovy die-off during the winter season at the Santa Cruz Harbor.  

But this January, he saw it for the first time. Actually, he’s seen multiple die-offs between then and the end of March.

“I’ve never seen it this time of year,” he said, Wednesday. “It’s very unusual to have a lot of anchovies close to shore in the wintertime. I never would have expected it at all.”

Last week was the most recent die-off at the harbor, and Haynes said that as recently as Sunday there were still a lot of birds hunting for anchovies. By Monday, he said there were far fewer, and by Wednesday there was hardly wildlife in the harbor. 

Haynes, who has worked at the harbor for nearly 14 years, said anchovy die-offs typically happen in the summer, but in recent years, they’ve been happening further into the fall. It’s normal for schools of anchovies to swim into and out of the harbor throughout the year, but it’s typically July through October that the larger numbers come in from the bay. 

During the summer months, Haynes said the warmer water doesn’t hold oxygen as well. He thinks the colder water right now could be helping to keep the anchovies from dying in larger numbers because it’s holding more oxygen. He added that the dead anchovies are mostly being killed and eaten by birds, seals and sea lions, as opposed to dying from the lack of oxygen. 

“The amount of birds we’ve been getting is really impressive, it looks like a swarm of flies,” he said. 

Because the dead fish aren’t piling up as much as they have in prior die-offs, harbor staff  haven’t had to do any cleanup. Haynes said without doing a cleanup and scooping up the anchovies, they don’t have an accurate estimate of how many pounds, or tons, of anchovies have been coming into the harbor during these die-offs. 

“We’ve had enough birds show up that they’ve been able to eat the dead fish,” he said. “So the smell hasn’t really been lingering more than a day or two after.” 

During larger die-offs, staff at the harbor operate aerators – machines that pump oxygen into the water – to help keep oxygen levels high enough so that fewer anchovies die. But after using the aerators so much last year, the machines are in need of repairs and parts need to be replaced. Haynes said staff are still waiting for parts and they’re not sure when they’ll have the aerators available. 

Because the die-offs haven’t been as severe these past few months, he said they haven’t incurred any damages or costs. 

Haynes said harbor staff have noticed a pattern with these die-offs these past few months, in which the weather gets warmer for a few days and the anchovies come closer to shore, and into the harbor. Then, the weather gets stormy and cold and they clear out. He’s preparing for another influx of anchovies in the coming days as the weather is forecast to warm up.  

“If the current trend happens, we’re going to have a doozy of a summer,” he said. 

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