In an alarming trend along the Southern California coast, sea lions, typically known for their playful nature, have turned aggressive, attacking humans in a series of rare and disturbing incidents. Experts believe the culprit may be a deadly neurotoxin triggered by toxic algal blooms, also known as red tides, which are wreaking havoc on marine life.

On March 30, 15-year-old Phoebe Beltran was swimming in Long Beach during tryouts for the Junior Lifeguards cadet program when a sea lion suddenly attacked her. “I was just so scared, so shocked, but I still felt the immense pain on my arms, like, over and over again,” she told local media. Despite bite marks, bruises, and scratches, Beltran did not require stitches.

Just days earlier, on March 21, surfer RJ LaMendola was bitten off the coast of Oxnard in Ventura County. The sea lion, he recalled in a social media post, “erupted from the water” and charged at him with a “feral, almost demonic” expression. The incident, he said, left him “shaken to his core.”

These attacks, though rare, come amid a surge in domoic acid poisoning among sea lions—caused by harmful algal blooms proliferating off the Southern California coastline since late February. The toxin affects the animals’ neurological systems, leading to disorientation, seizures, and sometimes aggressive behavior.

“The sea lions are coming in almost comatose by the time they’re stranding,” said John Warner, CEO of the Marine Mammal Care Center in Los Angeles. “Volume-wise, it’s definitely the worst we’ve ever seen.”

Climate Crisis Feeding the Bloom

The red tide events are intensifying, with Warner pointing to human-induced climate change as a major factor. Warmer, more acidic ocean waters and nitrogen-rich runoff from agriculture have created ideal conditions for the toxic algae to thrive and infiltrate the food chain. As small fish consume the algae, the toxins work their way up to larger predators like sea lions, dolphins, and marine birds.

Upwelling—a process where cold, nutrient-rich water rises from the ocean depths—has further exacerbated the bloom. “There’s just a huge amount of food everywhere in the water table,” Warner explained.

Impact on Wildlife Is Devastating

Since the beginning of this year, more than 2,000 calls have flooded the Marine Mammal Care Center’s hotline, a five-fold increase over normal conditions. Of the 240 animals treated by the end of March, 80% were pregnant sea lions. Many are forced to expel their fetuses due to the toxicity, raising concerns about long-term population health.

Sea lion pups and elephant seal pups are also stranding at higher rates, and the recovery process is proving slower and more challenging this year. A triage site has been set up to accommodate around 25 additional animals as the center runs out of space and resources.

Sadly, for dolphins, the outlook is even grimmer. Over 70 dolphin strandings have been reported in Los Angeles County alone in 2025—many already deceased. “There’s no rehabilitation that’s going to work with dolphins,” Warner said. “The best thing we can do is humanely euthanize them.”

What the Public Needs to Know

Marine experts urge the public to maintain a minimum distance of 150 feet from sea lions and seals spotted on beaches. Interaction with sick or disoriented animals can lead to injury or distress—for both humans and the animals.

While efforts to rehabilitate affected sea lions continue, the root causes—rising ocean temperatures, pollution, and climate change—remain broader challenges that require long-term environmental action.

“When they are affected with this toxin, they’re out of their minds,” Warner said. “They’re scared, disoriented, and really don’t understand where they are. That’s when some of these dangerous encounters can happen.”

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