California Algae Bloom Poisons Sea Lions, Dolphins | Weather.com
Sea Lions Rescued Amid Southern California Algae Bloom
At least 140 sea lions have been rescued on Southern California beaches since Feb. 20, and sick or lifeless dolphins and birds are also showing up amid what one expert says is the most damaging harmful algae bloom ever witnessed in the area.
It’s also the fourth year in a row the area’s sea life has been hit by a poisonous bloom.
“So far in 2025 what we’re seeing in Los Angeles County is worse than what we saw in 2023, which at that time was the worst ever recorded,” John Warner, chief executive officer of the Marine Mammal Care Center told us in an interview Monday.
Warner said the algae causes a type of poisoning called domoic acid toxicosis, which can lead to seizures, erratic behavior and lethargy. Sea lions and dolphins are the most affected, with the latter facing a higher death rate.
(MORE: Here’s How Hurricanes Are Changing Because Of Climate Change)
The care center, located in the Los Angeles area, treats sick sea lions with a combination of drugs and therapy to flush the poison out of their bodies. About 50% to 65% will survive to be released back into the wild, Warner said.
“Animals exposed to this year after year are not great candidates for being released,” he said.
The poison can also make sea lions more aggressive, which can pose a danger to humans. A surfer in the area was bitten by a sea lion Friday that was reported to have suddenly charged.
“Today, I endured the most harrowing and traumatic experience of my 20 yrs of surfing—an encounter that left me shaken to my core,” RJ
LaMendola wrote on Facebook.
LaMendola was treated at an area hospital.
(MORE: Hundreds Of Sea Turtles Rescued In Historic Florida Cold Snap)
Warner said these kinds of algal blooms and mass stranding events are happening more and more often.
“These are very difficult stories for people to hear and I know it sort of creates that feeling of wanting to hide under your covers because sometimes I feel that, too,” he said. “But what it’s really important for people to understand is that these are warning signs for our environment that is not doing well but can be corrected.”
Rescuers from the Marine Mammal Care Center near Los Angeles approach a stranded sea lion poisoned by a harmful algae bloom.
(Marine Mammal Care Center)Scientists say changing ocean conditions due to warmer temperatures are one reason the risk is rising. Increased run off and nutrient pollution also add fuel for blooms.
“I haven’t met anyone who wouldn’t agree that climate change and human activity exacerbates what were previously naturally occurring algal blooms,” Warner said.
(MORE: Hottest Year Yet Caps Off Hottest Decade Yet)
Last year was Earth’s warmest ever on record, the latest in a string of climate superlatives sending ocean temperatures to record highs, too.
This year’s Los Angeles-area wildfires may have also added more nutrients to the ocean in the form of ash and vegetation debris, he added. The long-term effects of the fires on ocean life remain unclear.
“Studying that is going to take time,” Warner said.
Weather.com senior writer Jan Childs covers breaking news and features related to weather, space, climate change, the environment and everything in between.