‘Big black clouds’ of thousands of anchovies flood CA harbor — and experts are concerned

Swarms of anchovies have invaded a California harbor, raising risks of a mass die-off, state officials reported.

“The anchovies are amazing,” longtime ocean swimmer Peggy Miles told the Santa Cruz Sentinel. “It’s like big black clouds in the water, and you don’t realize that it’s fish until you get there. Then, all of a sudden the cloud separates and they never touch you. It’s kind of like Moses crossing the Red Sea.”

But the influx of fish, which began last week, risks depleting the shallow water’s oxygen supply, Santa Cruz Harbor officials warned Aug. 29 on Facebook. That could cause a mass die-off of fish.

“This has occurred several times in the harbor’s history, with the last large-scale die-off occurring in 2014,” harbor officials said.

The 2014 die-off created a huge cleanup problem and a “foul fishy smell” along the coast, the Santa Cruz Sentinel reported.

The harbor turned on aerators to increase the oxygen supply in the water, officials said in a Sept. 1 news release.

Oxygen levels seem to have stabilized, officials said, but they asked boaters and other visitors to notify the harbor at 831-475-6161 if the swarms of anchovies return.

“We are on anchovy watch 24/7 when these fish come in here because we know how bad it is when they die,” Harbormaster Blake Anderson told the Santa Cruz Sentinel.

Santa Cruz is about 80 miles south of San Francisco.

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