By Mary O’KEEFE

There have been recent reports of a harmful algae bloom occurring off the coast of Southern California. 

According to the West Coast Marine Mammal Stranding Network, partners reported over 100 calls a day of sea lions and dolphins affected by the algal toxin domoic acid, according to National Oceanic and Atmospheric Administration (NOAA).

Domoic acid is a naturally occurring marine neurotoxin made from certain algae. When it rains runoff from land, specifically urban and agricultural runoff, can increase nutrient input, which causes this type of algae to rapidly grow, according to 7seascollective.org.

“There’s actually two types of toxins that are being detected out in the water right now,” said Emily Yam, senior director of learning and public engagement at the Aquarium of the Pacific. “Domoic acid is the one that is making the news right now but there’s actually increasing evidence there’s a different toxin created by a different type of plankton. It is creating something called saxitoxin, which is also harmful to humans.”

Saxitoxin is a major cause of paralytic shellfish poisoning and harmful when consumed by humans. 

These two different types of toxins are adding to the complexity of the recent algae bloom. 

Yam said quite a bit is known about what is occurring with these toxin algae blooms because of the partners they work with including NOAA. 

“First and foremost, at the Aquarium of the Pacific we consider ourselves a messenger and supporter of our partners in this work, but we are not the ones [who] are actually collecting the damage,” she said. 

Aquarium of the Pacific does send support – equipment and personnel, for example – to animal care facilities that care for the sick animals. 

There is a ton of algae in the ocean all the time. 

“There’s this unseen world of plankton that are out there,” Yam said. 

The conditions in the ocean have to be just right for the algae to grow and when it starts growing it can quickly take off; that is what is contributing to these two blooms. 

“Neurotoxins can cause [in sea life] lethargy, foaming at the mouth, seizures, brain damage and death in animals, like sea lions and dolphins, when contaminated fish are consumed. [These types] of bacteria are also harmful to humans and can be contracted through ingestion of infected fish and shellfish. Infected shellfish, specifically, can cause amnesic shellfish poisoning. Coming into contact with infected water may also cause skin irritation, so proceed with caution when thinking about heading into the water,” according to 7seascollective.org.

“We have seen this most impactful in the ‘stranding’ of marine mammals and … most notably sea lions,” Yam said. 

Stranding occurs when a marine mammal is on the shore and unable to return to the water under its own power, is on shore and may be able to return to the water but is in need of apparent medical attention, is in the water but cannot return to its natural habitat without assistance or is dead on the beach or in the water, according to NOAA.

Yam added this is the fourth consecutive year when high levels of algae blooms, or algae populations, and the stranding of marine mammals is being seen. 

In 2022 there were a hundred [marine mammals] that were reported stranded. In 2023 there was over a thousand; in 2024 about 300 and then this year … as of last week … there were over 1,500, Yam said. 

“That’s so far this year,” she said. “I mean it’s only May … That’s pretty remarkable.”

On May 9 the California Dept. of Public Health (CDPH) released a mussel quarantine order effective May 1 through Oct. 31, 2025. During the quarantine, all species of mussels gathered from California’s ocean shore by recreational sport harvesters should not be consumed by humans. The quarantine area extends from the Oregon border to the Mexican border including all bays, inlets and harbors in Los Angeles County. The Los Angeles County Dept. of Public Health continues to work with CDPH and collect shellfish for testing.

This advisory does not apply to commercial shellfish gathered by approved sources.

Early symptoms of paralytic shellfish poisoning in humans include tingling of the lips and tongue, which may begin within minutes to a few hours after eating toxic shellfish. These symptoms are typically followed by a loss of balance, lack of muscular coordination, slurred speech and difficulty swallowing. In severe poisonings, complete muscular paralysis and death from asphyxiation can occur.

People consuming clams or scallops are warned to remove and discard the digestive organs or viscera and any other dark parts. Only the white meat of clams and scallops should be prepared for human consumption. Also, bivalve shellfish (scallops, oysters and mussels) should not be collected for food from any area subject to sewage or chemical contamination, according to the CDPH.

Although the Crescenta Valley is landlocked, many residents go to the beach and the hotter the weather gets the more people will go. It is important to know what to do if a sea lion, or any sea mammal, is found that is in distress. 

According to LA County’s Marine Mammal Care Center, the following steps are suggested when a potentially sick seal or sea lion is spotted:

• Give them their space. – Never approach marine mammals as they may be very sick. It is advised to keep at least 50 feet away.
• Take pictures with zoom – Again, don’t get too close! 
• Keep pets away. – They can scare the marine life and may get injured or get infected. 
• Call the rescue team! It knows what it is doing. People should take note of where they are and call the rescue team hotline. Hotline numbers: NOAA (866) 767-6114, West Coast Stranding Hotline (866) 767-6114, Marine Mammal Care Center (800) 399-4253.

Anyone who experiences gastrointestinal or neurological symptoms after eating mussels taken for human consumption by recreational sport harvesters from California’s ocean shore, should submit a Foodborne Illness Report and seek medical care. For additional information, call the shellfish hotline at (800) 553-4133 or go online to the CDPH Marine Biotoxin Quarantines and Health Advisories. 

For more information, visit 7seascollective.org and visit the Aquarium of the Pacific website at www.aquariumofpacific.org.