After a brutal spring of toxic algae blooms turning some sea lions into sick, snarling seaside hazards, anxious beachgoers can breathe a sigh of relief as experts say the worst of the poisoning is over.
This week, the Marine Mammal Care Center in San Pedro said it had seen no new patients with domoic acid poisoning or any recent signs of Pseudo-nitzschia algae in Southern California waters.
“This was the longest, most toxic, and deadliest bloom we’ve ever experienced,” the center announced on social media. “Because of your support and advocacy, we got through it, and hundreds of marine mammals received a second chance at life!”
This year’s poisoning event pushed the center to its limits as it treated more than 400 marine animals, including scores of sick sea lions and dolphins.
It was also marked by several reports of aggressive sea lions attacking people in the water.
A 15-year-old girl was bitten by a sea lion while completing a swim test for her Junior Lifeguards program in Long Beach at the end of March. A few weeks prior, a surfer was reportedly accosted by a “feral, almost demonic” sea lion that he said dragged him off his board in Oxnard and stalked him in the water.
The California coastline can experience large-scale blooms of algae called Pseudo-nitzschia australis when warm water combines with excess nutrients such as nitrogen and phosphorus. Researchers say that climate change and an increase in agricultural runoff, wastewater discharge and urban stormwater have increased the scale and frequency of these blooms in recent years.
Small fish including anchovies and sardines ingest the toxic algae, which then bioaccumulate in larger marine mammals that eat the fish.
Ingesting domoic acid 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. Experts advise people not to interact with animals believed to be sick because they might aggressively lunge or even bite.
Southern California saw another major poisoning event in 2023, which resulted in the deaths of more than 1,000 sea lions. If taken in for prompt treatment, poisoned sea lions have a 50% to 65% survival rate, according to the Marine Mammal Care Center.
Although the worst of this year’s crisis appears to be over, the center still has its work cut out to tend to the sick animals and prepare for the next bloom.
In order to meet the growing regional need, the center says it is expanding its hospital facility, increasing its rescue capacity and securing research funding to better understand toxic algae blooms.
