More than 50 sickened adult sea lions have been found on beaches in Southern California in the last few days, demonstrating symptoms indicating they had ingested food poisoned by a toxic algae bloom off Malibu.
Officials said the bloom produced by a species of marine plankton filled with a neurotoxin called domoic acid is considered an anomaly this time of year.
“These blooms should not be happening now,” said Dr. Alissa Deming, vice president of conservation and medicine and lead veterinarian at the Pacific Marine Mammal Center in Laguna Beach. “I don’t know what’s going on in the ocean. Starting in February is unreal.”
Domoic acid is produced by algae that is then eaten by small fish. When marine mammals, dolphins and sea birds eat the fish, it can lead to neurological impacts and cause seizures and aggressive behavior. Symptoms also include lethargy, dehydration and vomiting, and the animals can die.
Blooms typically start in spring when the sun is out longer, fueling the toxins’ growth. Recently, the blooms have been linked to ocean upwellings, where water loaded with rich nutrients from the deeper ocean is pushed closer to shore, sunlight stimulating the blooms. Blooms have been frequent the last four years, with marine mammal experts pointing to warming ocean temperatures, climate change and human activities as causes.
In 2023, a June bloom off Santa Barbara killed more than a thousand sea lions and dolphins and created a crisis along the Southern California coast while draining the resources of marine mammal rescue centers.
The animals found onshore in recent days – many in good body shape and pregnant, rescuers said – are seizing and acting listless or unresponsive, even when people are close by. Lifeguards and park rangers from Ventura to Orange County are on the lookout for more sickened animals and are cautioning the public to stay away.
The largest number of animals have been found along beaches in Malibu, which has overloaded resources at the California Wildlife Center there, said John Warner, CEO of the Marine Mammal Center Los Angeles.
Many of the animals found by CWC staff have been taken to Warner’s MMCLA in San Pedro. He said, as of Thursday, Feb. 27, his center had taken in at least 17 live animals and responded to rescue requests where animals were near death on the beach. Five sea lions have died. Of those rescued, all but one are female, and all but two are pregnant.
Affected sea lions have also been found in the Pacific Palisades, Playa Del Rey, Dockweiler Beach, Palos Verdes, Santa Monica and Redondo Beach. Reports of more being found in Malibu are coming in daily, Warner said.
“This is four years in a row of domoic acid toxicosis showing up in our sea lions in Southern California and the worry that we have is what toll this might take on breeding populations,” Warner said. “We’re also looking at our preparedness and readiness should this become a larger event. We learned a lot from the bloom in 2023.”
The domoic acid event impacting adult animals comes just as centers are gearing up to rescue pups born last summer that often come in dehydrated and ill this time of year because of a lack of food sources. The San Pedro center has 19 pups already, and in Laguna Beach there are six, so far. None are affected by the toxin, officials said.
The Pacific Marine Mammal Center began getting reports on Friday, Feb. 21, of sickened adults along the Orange County coast. Its rescue team was called to Bolsa Chica State Beach for a dead dolphin, Dr. Deming said. Within hours, the team was called again when lifeguards saw a seizing sea lion.
“We rescued the animal and gave it anti-seizure medication,” Deming said. “She passed away in 30 minutes.”
On Monday, PMMC was called again when lifeguards observed another animal in distress in Newport Beach. Deming said her team had just been training with lifeguards in the last week to refresh them on what to do during the busy pup rescue season – often at its peak in March and April – and what to do if a domoic acid bloom happens.
“They had already set up barricades and rescued a robust and beautiful animal,” Deming said of the pregnant female sea lion the center has named Weaver. The mother will likely not be able to keep her fetus, though, for her own health, Deming added.
“She probably (also) has a pup out on the islands – San Miguel Island is a huge sea lion rookerie – and it’s a bit early for a baby sea lion to be weaned,” Deming said. “There’s a concern that if she does have a pup (already), it won’t do well. This impacts both a sea lion on the islands and next year’s pup that should be born.”
While Deming, like Warner, is unsure of what has prompted the present bloom, which are often triggered by a flush of polluted runoff during rain events, she said she worries about the flame retardant used to fight the recent Palisades and Eaton fires.
“That raises concerns, but a lot of work needs to be done to see if that’s doing it,” she said.
Clarissa Anderson, director of the Southern California Coastal Ocean Observing System, has been keeping tabs on toxic algae blooms off the coast and agreed the timing of this bloom is on the early side.
Typically, the cycle is spring and summer because the blooms are tied to spring upwelling in the ocean, she said.
What was interesting during the massive 2023 toxic bloom, Anderson said, was she saw very little evidence of the toxin at shore sampling stations. She’s seeing a similar pattern now indicating the animals are catching their prey further offshore.
“Our satellite model is showing heightened probabilities (of domoic acid) in Southern California from Santa Barbara south,” she said. “So, there’s reason to believe we’re having a domoic acid event.”
She said one way to learn more is to get on a vessel and do offshore sampling. That would be an ideal way to help the centers prepare for what could come at them. But recent funding cuts impacting the National Oceanic and Atmospheric Administration are making research like that less likely, she said.
And, while she doesn’t think it’s too likely, she said she doesn’t completely discount the notion that runoff may have carried fire retardant from the recent fires and fueled a bloom that may have already been developing.
“It’s possible, we have seen some blooms respond to ash during the Thomas fire in Santa Barbara,” Anderson said. “We don’t have a lot of data to understand the mechanism on how those two things were really a cause and an effect. … It’s hard to speculate and without going out there and doing studies, I don’t want to speculate.”
Anderson said a California Cooperative Oceanic Fisheries Investigations research vessel was recently out during the fires and collected a lot of plankton and ash samples. She said she expects to see good data from that.
The rescued animals are also being tested to help provide answers.
“My gut feeling is this is an oceanographic feature,” Anderson said, “but it doesn’t mean if you had a lot of ash in Malibu, it couldn’t stimulate it or help a bloom.”