An estimated “several hundred dead fish” were found floating in the Malibu Lagoon on Thursday morning, following a mass die-off that was being investigated by California State Parks scientists this week.
California State Parks Angeles District Superintendent Craig Sap said the cause of the mass die-off was still under investigation and could take several days to confirm. The working theory was that high water temperatures caused hundreds of fish to die, either Wednesday or early Thursday morning.
“From what Jamie—the environmental scientist that was down there— [said], it’s probably … because it was 28 degrees celsius,” Sap said  in a phone call with The Malibu Times Thursday afternoon. That means the water temperature in the lagoon was measured at a little over 82 degrees Fahrenheit. “It may be related,” Sap said, later adding, “dissolved oxygen seems fine, but that’s all they can come up with at this point.”
Though fish die-offs have occurred in and around Malibu in the past, Sap said this was the largest he could recall seeing in his years working for the state.
“I’ve seen—not to this degree—but historically, I’ve seen this happen before. I can’t recall how long ago, but I’ve seen some die-offs,” Sap said.
Most of the fish found floating belly-up in the lagoon were mullets, with some other, catfish-type fish, Sap said. “I don’t think there’s any steelhead or anything like that,” the director said. Southern California Steelhead Trout, a subspecies of steelhead found in waterways between Santa Maria and San Diego, have been considered endangered since 1997.
As for what can be done to clean up the lagoon, Sap said the state was working on a solution—and meanwhile, “the birds are having a field day” eating the fish floating in the shallow water.Â
“We’re going to keep an eye on it,” Sap said. “If we need to remove some of them—if we can—we’ll look into that.”
The Malibu Lagoon underwent a controversial restoration project in 2012 and 2013. Since then, scientists have touted successful reintroduction of local plant and animal species, but locals have raised concerns over alleged failures in the project. One common complaint is the lack of breeches in the lagoon, meaning lagoon water is not mixing with ocean water.