Scientists Uncover Mystery Behind Aggressive ‘Demonic’ Sea Lions Plaguing West Coast Waters
Toxic Algae Behind Aggressive Sea Lion Attacks in California
[Image: Aggressive sea lion in water]
California’s recent surge in sea lion attacks has been linked to toxic algae blooms, scientists reveal. Marine experts from Los Angeles traced the animals’ uncharacteristic aggression to domoic acid toxicosis, a neurological disorder caused by harmful algal blooms (HABs) along the coast.
The Science Behind the Toxin
The Marine Mammal Care Center confirmed that infected sea lions exhibited seizures and confusion after consuming fish contaminated with domoic acid. This toxin is produced by Pseudo-nitzschia, algae thriving in nutrient-rich waters due to seasonal upwelling. NOAA explains that strong winds push cold, nutrient-dense deep water to the surface, triggering algal overgrowth. While beneficial for marine life in moderation, these blooms become toxic when overpopulated.
“The sea lions are disoriented, terrified, and reacting to their sickness,” said John Warner, CEO of the Marine Mammal Care Center. By March, his team had treated 195 poisoned sea lions—four times more than in early 2024.
[Image: Algae bloom in ocean]
Caption: Pseudo-nitzschia blooms release domoic acid, which accumulates in fish and sickens sea lions.
Surge in Attacks
Victims described “demonic” encounters with agitated sea lions. Lifeguard trainee Phoebe Beltran, 15, was bitten during a swim test in Long Beach. “I felt something clamp my arm. I prayed it wasn’t a shark,” she told local media. Similarly, surfer Rj LaMendola recounted a March 21 attack that left him with PTSD. “The sea lion’s mind was warped by poison. It shakes me to my core,” he shared on social media.
[Image: Injured surfer]
Caption: Rj LaMendola called his sea lion encounter “the most traumatic experience” of his surfing career.
Rising Sea Lion Populations Amplify Risk
California’s sea lion population has exploded from 1,500 in the 1920s to ~250,000 today, increasing human-animal interactions. As HABs grow more frequent (now four consecutive years), so do risky encounters. Warner noted this year’s toxin seems particularly potent, with animals appearing “comatose” rather than just erratic.
Treatment Challenges
Vets treat affected sea lions with anti-seizure drugs, hydration, and tube feeding. While some recover within a week, survival rates hover at 50–65%. This year, even prolonged care hasn’t fully reversed lethargy in some patients.
[Image: Sea lion receiving treatment]
Caption: Rescued sea lions undergo intensive care, but recovery isn’t guaranteed.
Climate Connection
Scientists warn warming oceans may worsen HABs. “Something’s wrong in the ocean,” LaMendola stated, urging action. As blooms persist, coastal communities must balance wildlife safety with public health, highlighting the urgent need for ecological solutions.
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