State wildlife officials investigating the die-off of thousands of anchovies in Marina del Rey over the weekend have concluded that the fish probably died because they sought refuge in the harbor, became trapped and used up all of the oxygen in the water.
During an aerial survey of area beaches last week, California Department of Fish and Wildlife staff noticed a large school of northern anchovies traveling offshore, spokeswoman Janice Mackey said in an email to the Los Angeles Times.
“We suspect these were the same ones later found in the harbor, and may have sought cover from a predator species,” Mackey said. “Once in the harbor, the fish school became trapped, and subsequently depleted all of the available oxygen in the water.”
The fish started floating up dead Saturday evening among docks and boats in Basin A of the harbor, near Bora Bora Way. By Sunday, stinking masses of fish carcasses blanketed the surface of the water in a small corner of the harbor, attracting hungry sea lions and pelicans.
A cleaning crew from the Los Angeles County Department of Beaches and Harbors scooped up more than 6 tons of dead fish, Mackey said, and wildlife officials collected samples to analyze in a lab.
“While the sight of so many dead fish may be startling to some, this is not considered to be too unusual,” Mackey said.
Similar conditions have caused other fish kills in recent years, including an incident three years ago that fouled the waters of Ventura Harbor with about 6 tons of sardines. A die-off of millions of small fish in King Harbor in Redondo Beach, also in 2011, was blamed on a lack of oxygen.