Beachgoers in Southern California be warned that sea lions are showing unusual signs of aggression as they continue to be exposed to toxic algae blooms.

Warning signs were posted on Salt Creek Beach and Strands Beach after two reports this week of sea lion-related injuries, an Orange County Parks spokesperson said.

The first incident occurred in Salt Creek on Monday, when a juvenile told lifeguards that he had been bitten while wading through the water. He was treated and released to a guardian, with advice to seek further treatment at an urgent care clinic.

A sign warning people of an aggressive seal or sea lion along the Dana Strands beach area in Dana Point, California, on Wednesday.Courtesy of John Kubota

Lifeguards at Strands Beach were alerted to another injury that night, but the person involved refused treatment.

Strands Beach closed Tuesday afternoon after reports of an aggressive sea lion surfaced, and it reopened Wednesday, the parks department said.

Sick animals

Aggression toward humans is not typical of sea lions, but the mammals are very sick right now due to toxic algae blooms offshore, said John Warner, executive director of the Marine Mammal Care Center, a nonprofit rescue organization. non-profit organization serving Los Angeles County.

the seaweed, Pseudo-nitzschia, is consumed by fish, which are then eaten by sea lions. The fish carry a neurotoxin called domoic acid that the algae produce, which essentially poisons the sea lions, Warner said.

«It literally affects their brains, and the behavior of sea lions, especially when domoic acid concentrations are quite high, changes dramatically,» Warner said. «They become symptomatic in ways that are just unpredictable in terms of their behavior, an aggressiveness that we don’t normally see.»

Trying to confirm the location.  Seals rest along the shoreline near the Dana Point area of ​​Los Angeles on June 25, 2023.
Seals rest along the shoreline in Los Angeles on Sunday.Los Angeles

The bloom has been traced to the waters of central California and the extreme north of southern California, where warm water and cooler water rising from the depths, called upwelling, can create Ideal conditions for algal growth.

NOAA Fishing said in a report this month Algae blooms are suspected of killing hundreds of California sea lions and nearly 60 dolphins in the first weeks of June.

bite reports

Justin Viezbicke, the stranding coordinator for NOAA Fisheries’ West Coast Region in California, said the department doesn’t track sea lion bites in part because of their rarity.

Similar bites have been reported in other regions of southern California, Warner said, including Santa Monica, but most appear to have been in shallow water.

Experts believe the mammals are so sick and scared that they attack humans who get too close in their vulnerable state, Warner said.

«None of this has been definitively investigated and flagged to my knowledge,» Warner said. «But putting 2 and 2 together, when you have this big algae bloom and domoic acid event, it’s pretty easy to connect the dots in a way that we’re comfortable assuming these are obviously connected incidents.»

Los Angeles County lifeguards this week urged bathers On Instagram stay at least 50 feet from sea lions. The post also encouraged anyone who sees a stranded sea lion to contact the Marine Mammal Care Center.

«Citizen vigilance is essential and thanks to the work @marinemammalcare been doing these past few weeks,» the post read.

Warner believes that people should not fear sea lions, but simply understand that approaching them at this time is not a good idea.

«Sea lions, you know, are the ubiquitous California ocean wildlife animal that people love. And this isn’t them,» Warner said. “So I don’t want this to turn into people watching sea lions like they do ‘Jaws.’ … This is not that sea lions suddenly become evil people-biters. I don’t want people to be afraid of these animals in the future. This is a really sad event.»

The Marine Mammal Care Center is working to rescue and treat sea lions affected by domoic acid exposure. Although there is no standard treatment, the center’s website says the animals are hydrated with fluids, anti-seizure medications and general nutrition that will not expose them to the toxin.