Extreme Heat Likely Cooked 2,000 Fish to Death in Malibu Lagoon

By Kimberly Hickok, Reference Editor | August 30, 2018 07:02am ET

Some fish just can't take the heat. And unfortunately, that's probably why an estimated 2,000 striped mullet (Mugil cephalus) suddenly died in Malibu Lagoon and Malibu Creek in Southern California last week.

There are several species of fish that live in the coastal inlet of Malibu Lagoon, including the Southern California steelhead trout (Oncorhynchus mykiss irideus) and the tidewater goby (Eucyclogobius newberryi). But the striped mullet was the only species to go belly-up.

The precise cause of the mass fish mortality is still unclear, but California State Parks officials are working to find the answer. So far, the most plausible explanation is the higher-than-average water temperatures in the lagoon: 80 to 82 degrees Fahrenheit (27 to 28 degrees Celsius). [The 5 Most Mysterious Animal Die-Offs]

Those temperatures are thought to be the upper limit in which striped mullet can survive, California State Parks officials said in a statement. High water temperatures can also decrease the amount of dissolved oxygen in the water and may promote increased bacteria and algal growth. But striped mullet are generally tolerant of low oxygen levels, so that's probably not the culprit in this case.

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