What's behind the dead fish at Malibu Lagoon, Ormond Beach? Scientists look for answers
Cheri Carlson
A few weeks before dead fish started showing up in Malibu Lagoon, hundreds were found dead at Ormond Beach in Oxnard.
Researchers from CSU Channel Islands worked with The Nature Conservancy, the California Department of Fish and Wildlife and others to try to figure out what caused the local die-off, which started in late July.
Not the first fish kill
It's not the first time a fish die-off has shown up in the area. In recent years, several small incidents have happened, some tied to pesticide spills, said professor Sean Anderson.
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This time, groups got there quickly and collected fish. Necropsies were performed in the Camarillo university's lab with help from a state fish pathologist.
Samples were sent to the state Wildlife Investigations Lab for testing. On Tuesday, as news spread about another die-off miles down the coast in Malibu, the results came back.
They were negative. “That rules out a chemical toxic exposure,” Anderson said.
Chemical exposure ruled out
That means something else was to blame, likely physical stress. And, it could be a similar cause of the die-off at Malibu Lagoon, too.
Right now, Anderson and others are leaning toward heat and low oxygen levels as the likely culprits.
An algal bloom could lead to low oxygen levels, but they saw no evidence of that happening near Ormond.
But the weather had been hot.
“Oxygen is super dependent on the temperature of water,” Anderson said. Colder water is called oxygen rich. Warmer water is oxygen poor.
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At Ormond, most of the dead fish that initially showed up are long gone.
But there is still a lot of data to study, Anderson said.
Finding a cause for dead fish
He and his students plan to dig into atmospheric records to get more details about whether it really was “exceptionally warm” during the lead-up to finding the dead fish. He also would like to put some sensors in the water.
First up is to look at toxicology data from the Malibu fish to confirm the die-off also wasn’t the result of some kind of toxic exposure.
Dead fish started showing up floating in the lagoon last week. Officials have said that came after several consecutive days of warmer-than-usual temperatures.
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