As the heat wave reaches Southern California for summertime, more Orange County residents are heading for the beaches.

But rising temperatures are also pushing other creatures onto local beaches: sick and sometimes aggressive sea lions.

Off the California coast, toxic algae blooms — a rapid increase in harmful algae caused by a combination of water runoff and rising temperatures — are poisoning sea lions and dolphins, causing stranded marine animals onto local beaches.

Dozens of sea lions affected by the toxic algae have been seen attacking beachgoers or washing up dead on shore due to the poisonous blooms, which produce a harmful domoic acid neurotoxin.

The algae, which thrives in warmer climates, cause these mammals to undergo seizures and brain injuries as a result of ingesting the toxin during this massive bloom event up and down the coastline.

Sea lions and dolphins usually get infected by this algae when they consume fish that have come into contact with the domoic acid.

The Pacific Marine Mammal Center is a nonprofit that rescues stranded sea lion on Orange County beaches and releases them back into the wild after they’ve recovered from their ailments, typically malnutrition or dehydration.

The capacity for the center’s hospital in Laguna Beach is filling while more of these mammals wash up on beaches and the rescue team is sent to transport them to its facility.

Alissa Deming, director of clinical medicine at the center, said right now is the worst they’ve ever seen marine mammals affected by this algae.

“In any given year, we would probably have about 10 to 15 adult animals,” Deming said in a phone interview earlier this month. “During this event, we have responded to over 100 animals.”

Dr. Alissa Deming, Director of Clinical Medicine, at the Pacific Marine Mammal Center on July 26, 2023. Deming provides medical care to all marine mammals that strand alive on Orange County’s beaches, including the sea lions seen behind her. Credit: ERIKA TAYLOR, Voice of OC.

The problem got so bad that the center had to build four extra pens in an emergency expansion to their animal hospital earlier this summer just to accommodate the stranded sea lions in Orange County.

“​It was very expensive for us — it was not cheap,” Deming said. “This whole bloom has completely blown our budget.”

Last year, the Pacific Marine Mammal Center wrote a budget of $5 million, according to chief executive officer Glenn Gray. Gray said their work would not be possible without their 250 active volunteers, many of which are working 18-hour days due to the bloom.

The center’s rescue team is deployed after receiving calls to its hotline with reports of a stranded sea lion or other marine mammal. 

A view of a Pacific Marine Mammal Center rescue team vehicle from inside “the barn,” where animals are treated. Credit: ERIKA TAYLOR, Voice of OC.

Animals with domoic acid poisoning receive anti-seizure and anti-inflammatory medication for about five days. After around two weeks of observation, the mammals are released back to the sea if the treatment is successful.

The seizures from this toxic algae can cause permanent brain damage or death if not treated in time. Deming said about a third of the sea lions called into the center have already died. If the animals don’t respond well to treatments, they could be left permanently epileptic and are usually euthanized.

Sea lions and other marine mammals that wash ashore on Orange County’s beaches are treated back at the center, which is nestled in the rolling hills of Laguna Canyon along the rural highway 133. 

Signage at the Pacific Marine Mammal Center on July 26, 2023. The center is located at 20612 Laguna Canyon Road, and is open to the public daily from 10 a.m. to 4 p.m. Credit: ERIKA TAYLOR, Voice of OC.
A sea lion stretches in the sunlight at the Pacific Marine Mammal Center on July 26, 2023. Credit: ERIKA TAYLOR, Voice of OC.

When sea lions and other marine mammals in the facility are deemed healthy, they are released back to nature. Earlier this month, the center released two young sea lions who had made a full recovery.

Gray encourages people to come to the center to learn more about the connections between marine mammals and humans.

“People need to come to grips with the idea that we are not being friendly to the ocean,” Gray said. “The ocean is 70% of our home, and we need to take better care of it. We are seeing the first-hand effects of climate change on our shores.”

The center continues to welcome visitors despite being overwhelmed by the toxic algae bloom.

The inside of “the barn” at the Pacific Marine Mammal Center on July 26, 2023. The barn holds some indoor animal pens, alongside an x-ray station. Credit: ERIKA TAYLOR, Voice of OC.
Jill Andersen, 65, with her grandchildren Carter Hemingway, 4, and Sutton Hemingway, 3, at the Pacific Marine Mammal visitor area. Credit: ERIKA TAYLOR, Voice of OC.

Jill Andersen visited the center with her two grandchildren earlier this month to teach them more about the ocean.

“My grandchildren love to visit the center and see the animals — it’s one of our fun adventures together,” Anderson said. 

Although she had not seen any marine mammals on the beaches herself, she said she was aware of what was happening on Orange County’s coast.

“It’s really unfortunate what is happening to them now.”

Release team members unload the sea lion yearlings for release at Aliso Creek Beach on July 26, 2023. Credit: ERIKA TAYLOR, Voice of OC.
A member of the release team holding a sign that says “Quiet Please” at the release of two sea lions on July 26, 2023. Attendees needed to be quiet in order to avoid confusing the sea lions. Credit: ERIKA TAYLOR, Voice of OC.
A Pacific Marine Mammal Center (PMMC) sea lion release at Aliso Creek Beach on July 26, 2024. Aside from the affects of the poisonous algae blooms, sea lions can be injured through entanglement, plastic injection, bow strikes, and other human activities, according to the PMMC . Credit: ERIKA TAYLOR, Voice of OC.
Children examining a tiger shark jaw bone at the Pacific Marine Mammal Center on July 26, 2023. Credit: ERIKA TAYLOR, Voice of OC.
A child playing with interactive signage at the Pacific Marine Mammal Center on July 26, 2023. Credit: ERIKA TAYLOR, Voice of OC.

Angelina Hicks is a Voice of OC Reporting Fellow. Contact her at or on Twitter @angelinahicks13.

Erika Taylor is a summer Voice of OC Photojournalist Intern. Contact her on Instagram @Camerakeepsrolling.


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