SAN DIEGO — A toxic algal bloom spreading along the Southern California coastline has poisoned at least 130 animals in San Diego County since February, killing nearly half, according to rescue officials.
Stretching from San Diego to San Luis Obispo, the bloom has affected hundreds of animals, including whales, dolphins, sea lions, birds, and other marine wildlife that feed on fish exposed to high concentrations of domoic acid, a potent neurotoxin. This marks the fourth consecutive year the toxin has appeared along the coast, though its impact has been the most severe this year.
“This is the worst of the four years as far as animals that are sick and dying,” said Tracy Spahr, spokesperson for SeaWorld San Diego, via email.
The National Oceanic and Atmospheric Administration (NOAA) reported that all dolphins affected by domoic acid poisoning have either died or were humanely euthanized due to the severity of their symptoms.
As of May, SeaWorld’s marine rescue team, which oversees rescues across San Diego County beaches from Camp Pendleton to Imperial Beach, has rescued 64 California sea lions, six dolphins, 60 birds — including 50 pelicans — and one Guadalupe fur seal.
No whale strandings have been reported locally to date.
“The team will go out for rescues daily, so the numbers change often,” Spahr noted. She added that while call volume has slowed in recent days, the team continues to respond to animals showing symptoms of domoic acid poisoning.
SeaWorld also responds to sea turtles if needed, though no cases have been reported during this bloom. The San Diego Humane Society’s Project Wildlife assists with bird rescues, while the NMFS Southern Fisheries Science Center typically handles reports of deceased animals.
According to the Southern California Stranding Event Tracker, at least 56 animals have died from domoic acid poisoning in San Diego County alone. SeaWorld’s rescue hotline has received hundreds of calls over the past several months, with workloads for the rescue team tripling their normal pace for this time of year.
“This year is unprecedented,” said Jeni Smith, curator of SeaWorld’s rescue program, noting that the bloom began during winter rather than its typical summer onset, which is usually triggered by warmer waters.
While San Diego has reported high numbers, the impact has been more severe in other counties, including 203 cases in Orange County, 637 in Los Angeles County, and 528 in Santa Barbara and Ventura counties. San Luis Obispo County has reported 11 cases so far.
Experts believe the early onset of the bloom may have been fueled by factors like fertilizer runoff and debris from wildfires in the Los Angeles area earlier this year.
Domoic acid poisoning affects animals’ brains and hearts, often leading to lethargy and abnormal behavior.
“You might see them rolling around in the surf, or they could be experiencing seizures or tremors,” Smith said.
In some cases, poisoned sea lions have wandered into unusual areas, such as in front of restaurants or onto busy roads. In early April, one sick sea lion was rescued from a bike lane along Carlsbad Boulevard near Ponto Beach.
One visible sign of poisoning is a sea lion arching its neck and pointing its nose skyward. In severe cases, the animals may display aggression.
When affected by domoic acid, sea lions’ survival rate is about 50%. Despite the challenges, SeaWorld has returned 14 sea lions and eight birds to the wild this year.
If the bloom continues, the toxin may pose a risk to humans through the seafood supply. Domoic acid can cause amnesic shellfish poisoning, which can be fatal to humans if consumed. While seafood is routinely tested for safety, prolonged toxic conditions could harm the local fishing economy.
Despite the strain on resources, Smith encourages the public to report sick or stranded animals to the rescue hotline at 1-800-541-SEAL or via email at [email protected].
“Even if they look sick, that could change,” Smith said, urging people to keep their distance as the animals are protected and can behave unpredictably.
Reports of dead animals should be made to NOAA at 858-546-7162.
