LOS ANGELES — Sea lions and other ocean mammals in Southern California are falling victim to a poisoning event that a local expert calls the worst in recent memory. It is stranding the mammals along the coast as warnings are issued to beachgoers of the threat posed by animals that are transformed by their illness.

A surfer reported an attack by a sea lion that was "feral, almost demonic" as he was on his board off Ventura County on Friday. Rj LaMendola said the animal bit him as he surfed off Oxnard, shaking its head and dragging him off his surfboard. He said on Facebook that as he paddled away terrified, the sea lion continued to stalk him.

Ingesting domoic acid from harmful algal blooms can cause sea lions to have seizures or to crane their heads in a motion known as "stargazing." They can also fall into a comatose state. But experts advise people not to interact with animals believed to be sick because, without warning, they might aggressively lunge or even bite.

Meanwhile, local rescuers are struggling to meet the challenge.

As of Friday, at least 140 sea lions with symptoms of domoic acid poisoning had been taken in by the Marine Mammal Care Center in San Pedro, according to Chief Executive John Warner. At least 50 dolphins have also been stranded on area beaches, but because they almost always die from ingesting domoic acid, they are usually euthanized.

Domoic acid is a neurotoxin produced by harmful algal blooms that accumulates in filter-feeding fish, including anchovies and sardines. Those fish are then eaten by seals, sea lions and dolphins. Sea lions have a 50% to 65% survival rate when they're taken in for treatment in a timely manner.

Animals can be treated, but moving an ill sea lion to a facility can be difficult because an adult female can weigh up to 250 pounds and an adult male up to 1,000 pounds, requiring several people to move each animal.

A similar domoic acid event occurred in 2023 in California, resulting in the deaths of more than 1,000 sea lions.

A February algal bloom isn't common but also isn't unheard of, Warner said, adding that he can only recall one other stranding event this time of year from a few years ago.

Toxic algal blooms are also getting worse over time due to human activity that exacerbates the intensity, timing and scale of the stranding events, Warner said.

The warming of ocean temperatures caused by climate change, coupled with the acidification of the ocean due to nitrate runoff, have worsened toxic algal events, according to Warner. When it rains in L.A. County, the organic runoff flows into the ocean, which then feeds the algae.

"I liken it to a bloom put on steroids from human-caused factors that make these blooms worse every time we see them," Warner said.

Large domoic acid blooms usually happen every three to seven years, but Warner said that scientists expect to see these events happen much more frequently.

Treatment for affected animals includes tube feeding and IV fluids twice daily, which provides them with nutrition and medication until their seizures are under control, Warner said. Treatment also includes anti-seizure medication and sedatives, which also help with controlling seizures so they don't worsen in intensity and duration and result in permanent brain damage.

The longer the toxic blooms last, the more exposure the animals have, which increases the risk of permanent brain damage and makes it so they can't be released back into the wild, according to Warner. In those cases, when their behavior is no longer safe, the animals have to be euthanized.

The current algal bloom, which began about a month ago, has been worse for the center than the one that occurred in 2023, which Warner called the "worst domoic acid bloom in recorded history in Southern California."

Besides the higher number of sick sea lions taken in by the center overall, more male sea lions are succumbing to domoic acid poisoning compared with two years ago, Warner said. In 2023, the center took in about 130 sea lions and didn't have to take in any males.

"It takes a lot to take them down, and we're taking them in without them putting up a fight," he added. "That says a lot about the condition that they're in."

Male sea lions can be kept in the same pen when they're in a comatose state, but once they start waking up, they can become aggressive because of the neurological effects of the toxin. That puts capacity strains on the wildlife center because, at some point, every male sea lion will need its own enclosure.

The center could probably take in another 20 sea lions, as they continue releasing some animals that have already recovered, Warner said. They'll only be able to take in sea lions for another week or two, because the center still has to prepare for rescuing orphaned or stranded elephant seal pups during pupping season, which falls from February to late June.

"If these numbers keep up for another week or two, we're gonna be at the place where we have to leave animals on the beach," he said.

Currently, the center has two male sea lions in the same pen who will have to be separated. There are four small enclosures, a medium-sized enclosure and a large enclosure. Each enclosure can fit from three to five adult female sea lions, but only one male sea lion can be in an enclosure at a time.

"It's organized chaos," he added.

During the 2023 stranding event, the wildlife center took in 120 sea lions and five dolphins, Warner said. Dolphins are only rehabilitated if they're endangered species; they tend to experience intense stress hormones and trouble breathing when they're around people and out of the water.

There isn't much that can be done to lessen the blooms or clean them up; blooms usually last from four to eight weeks, Warner said. The 2023 stranding event lasted eight and a half weeks.

Because the Marine Mammal Care Center is a small nonprofit that relies on private philanthropy, Warner has been reaching out to cities and counties in the state to ask for their support to prepare for future stranding events.

"It's sort of a like in a fire, you don't hire your firefighters and personnel after the fire starts," he said. "We're not resourced to handle this volume on an ongoing basis. We're doing everything we can to meet the moment, and we can't do this without public and private partnership."

Although Angelenos may have learned over the years to stay at least 50 feet away from sickened marine animals and refrain from taking selfies with them, and to not put beached dolphins back into the water, tourists are a lot less educated about the proper protocol, Warner said.

People should call (800) 399-4253 to ask for rescue assistance if they see any stranded marine animals.

Dolphins, in particular, are skittish around humans and have a high rate of heart attack when they get scared.

"That's not the ending these animals deserve, and people need to leave them alone and not crowd around them," Warner said. "That's what we really need from the public. Selfies kill animals, so use your zoom, and stay away."

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