Sea lions, dolphins, now a whale: Ocean giant is latest victim of SoCal's toxic algal bloom

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22-04-2025

A minke whale that was swimming in Long Beach Harbor earlier this month died from domoic acid poisoning associated with a toxic algal bloom that has stricken many other sea creatures, according to officials.
Michael Milstein, spokesperson for the National Oceanic and Atmospheric Administration's West Coast regional office, said test results showed the whale had high levels of domoic acid in its urine at the time of its death.
"This is consistent with the many other marine mammals we have seen affected by domoic acid produced by the harmful algal bloom off Southern California first detected in February," Milstein said in a statement. "The tests are taking longer since the lab is processing so many."
Domoic acid is a neurotoxin produced by harmful algal blooms that accumulates in filter-feeding fish — including anchovies and sardines — which are then eaten by seals, sea lions and dolphins.
This is the fourth consecutive year there has been a domoic acid event, but this year's started much earlier than previous ones, according to Milstein. The algae bloom was the result of an upswell in the ocean that brought up enough nutrients to the surface to allow the algae to thrive, he said. Other experts also point to climate change and the runoff from the recent fires in Palisades as contributors to the algae bloom.
Hundreds of sea lions and dolphins have been affected so far, Milstein said.
"This has probably been the most severe, particularly this early in the year," he said. "How long it continues is the question."
Read more: More than a dozen sea lions along the Malibu coast are reported sick. What's making them ill?
The 24-foot-long minke whale was swimming in the harbor for several days and officials had tried to push it out to sea, only for it to come back, Milstein said. The whale, which is male, was then found dead April 3.
Minke whales are considered the smallest of the great, or baleen, whale family, and can grow to more than 26 feet long and weigh as much as 14,000 pounds, according to NOAA.
There are about 900 minke whales off the coasts of Oregon, Washington and California. They're protected under the Marine Mammal Protection Act.
Last week, a dead gray whale was also found washed ashore on Huntington Beach. The Pacific Marine Mammal Center in Laguna Beach is performing a necropsy to determine the animal's cause of death.
Although most of the marine mammals affected by domoic acid toxicity are California sea lions, other animals are also susceptible to its effects, according to the Marine Mammal Center.
Read more: Trump administration cuts to NOAA threaten efforts to save sea lions from toxic plankton
Domoic acid has been found in blue and humpback whales, as well as Guadalupe fur seals, which is a threatened species.
Ingesting domoic acid from harmful algal blooms can cause sea lions and other animals to have seizures or to crane their heads in a motion known as 'stargazing.' They can also fall into a comatose state. Experts advise people not to interact with animals believed to be sick because they might aggressively lunge or even bite.
Milstein said it's unlikely that the domoic acid event will have a significant effect on the overall population of marine mammals off the Western coast.
"There's a silver lining to the incredible productivity of the California ecosystem," he said. "On one hand it is feeding the algae bloom, but it's also responsible for the incredible diversity of species we're fortunate to have off the West Coast. These species are pretty strong and resilient and they have shown that over the year."
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This story originally appeared in Los Angeles Times.