Toxic algae is making sea lions on Southern California beaches aggressive and unpredictable: It's the ‘new normal,' marine mammal expert says

• An algal bloom near southern California beaches is causing sea lions to act unpredictably.
• It's also causing the sea lions to give birth to stillborn pups, a marine mammal expert said.

A toxic algal bloom causing sea lions on Southern California beaches to act unpredictably is expected to be the "new normal," a marine mammal expert told Insider.

For the past month, beachgoers have spotted sea lions across Southern California's coastlines — from Ventura to San Diego counties — exhibiting peculiar behavior.

Sea lions popping up in "crowded human environments" like beaches is already outside the norm, John Warner, CEO of Marine Mammal Care Center in Los Angeles, told Insider.

But the pinnipeds have also been showing up on shore acting in strange ways: bobbing their heads side to side or extending them backward, foaming at the mouth, and, in some cases, acting aggressively against beachgoers. One woman shared a Facebook post describing a run-in with a sea lion that bit her while she was on a 5K swim.

"We're seeing them everywhere, every day, and it's because they are sick," Warner said.

The cause is a toxic algal bloom that experts have told Insider is the "worst outbreak" in Southern California yet. Fish, especially sardines and anchovies, feed on the neurotoxin-producing algae and eventually poison large marine mammals with domoic acid when they're consumed, Warner said.

This toxin then causes the sea lions to behave strangely, coming to shore in crowded areas and in many cases exhibiting symptoms of a seizure. Many sea lions and dolphins have also died after being poisoned by domoic acid.

The National Oceanic and Atmospheric Administration (NOAA) Fisheries said the Channel Islands Marine & Wildlife Institute, which is headquartered in Santa Barbara, received more than 1,000 reports of sick and dead marine mammals between June 8 and June 14, USA Today reported.

Warner told Insider his organization has become overwhelmed with marine mammal patients in the past few weeks, putting a strain on the center's resources.

The CEO said the facility currently has about 120 patients; 80 of which are sea lions impacted by domoic acid. A triage center was set up nearby with the help of the Los Angeles Unified School District, he said.

As marine life agencies scramble to aid the sea lions, Warner said the issue with the toxic algal bloom is not expected to be resolved anytime soon.

All across the US, algal blooms have grown out of control, and the top contributing factor is warming ocean temperatures, according to the Environmental Working Group.

NOAA announced in a monthly climate call that ocean temperatures reached record highs in May, ABC News reported.

"This is creating a situation where these (algae) blooms are bigger, more intense, and longer lasting than we've seen," Warner said. "And it is expected that this will become a new normal."

Warner added that the abundance of toxic algae arrived "at the worst possible moment for sea lions."

A majority of sea lions in California are born in June due to a unique, shared biological phenomenon, Warner said. And the toxic algae has plagued the rookeries of California's Channel Islands — one of the most populous breeding grounds for sea lions.

"The Channel Islands are an absolute, essential, important ecosystem for California sea lions, and it happens to be smack dab in the middle of this unprecedented toxic algal bloom," he said.

Due to the algae, Warner reported that some of the sea lions are giving birth on beaches in Los Angeles and a lot of the pups are stillborn.

In addition, late June to early August is breeding season for the California sea lion, according to NOAA. This means the males are coming, Warner said.

"These are sea lions that weigh anywhere from 300 to 700 pounds," Warner said. "If they start coming up on beaches with domoic acid poisoning — that is something we can't deal with. They're too large and too aggressive and become even more of a public safety issue."

There's also the potential risk of the algal bloom coming close to shore, impacting other pinniped species such as harbor or elephant seals, according to Warner.

"We're really crossing our fingers that those two additional impacts don't happen," Warner said. "The warning needs to go out that, if that happens, this situation becomes even more precarious."

Warner said that the main course of action for the general public is to leave the sea lions that come to shore alone and to notify a lifeguard or call a nearby marine mammal agency such as the Marine Mammal Care Center.

Sometimes, the sea lions are able to flush the acid out of their system if they get enough rest in a stress-free environment, Warner said.

"It's sad to watch an animal suffer, and we can't be at every single animal immediately — sometimes for a couple of days given the sheer volume right now — and it's tough," he said.

The Marine Mammal Care Center is also accepting volunteers and donations.