Sea creatures keep dying in California waters. Now researchers have an answer

Paloma Chavez, The News Tribune (Tacoma, Wash.) on Apr 24, 2025

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Sea creatures keep showing up dead in California waters, and researchers may have an answer as to why.

It has to do with their food.

One of the largest algae blooms in Southern California has been linked to the death of two whales, a humpback whale and a minke whale, according to an April 23 news release by the Pacific Marine Mammal Center (PMMC).

On Jan. 24, the female humpback was seen dead in Huntington Beach, and on April 6 the male mink whale was stranded dead after showing abnormal swimming patterns in Long Beach, officials said.

Small fish and sardines can create domoic acid, and test results showed both the humpback and mink whales had high levels of the neurotoxin in their stomachs and urine, officials said.

“We typically see mass strandings of California sea lions, with occasional dolphins, during domoic acid events,” Dr. Alissa Deming, veterinarian and vice president of conservation medicine + science at PMMC, said. “This bloom is negatively affecting record numbers of sea lions and dolphins — and now multiple whale species. The scale of this mortality raises serious concerns about ocean health.”

Their causes of death were determined to be domoic acid toxicosis, officials said.

Although two other whales were seen stranded dead and may be linked to the same toxin, their lab results are still pending, officials said.

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