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Sea lions have been attacking people at the beach in Orange County who get too close and marine wildlife experts believe the mammals may be acting aggressively after being sickened by poisonous algal blooms.

At the entrance to Dana Strands Beach in Dana Point is a warning to visitors about an aggressive sea lion in the area, one of at least three beaches where people have been bitten in the last several days.  

“We’ve actually seen a number of surfers in the water that have been bit by sea lions and those sea lions are more likely to be sea lions that have had a seizure and are completely unaware of their surroundings, just erratically swimming and then they bump into somebody and bit somebody,” Dr. Alissa Deming of the Pacific Marine Mammal Center told KTLA.  

Deming also said the aggression in the sea lions is likely related to the dramatic increase in sick marine mammals needing rescue because of a toxic algal bloom in Southern Californian waters in recent weeks. Through the food chain, domoic acid from the alga gets into the sea lions and causes all kinds of health problems.  

Aggressive sea lions in Orange County
A warning posted at the entrance of Dana Strands Beach in Dana Point about aggressive sea lions on June 27, 2023. (KTLA)

“Domoic acid is a neurotoxin that impacts the brain, your hippocampus in particular, and that results in seizure activity, and those seizure activities can result in animals acting anywhere from completely comatose and unresponsive to very hyperactive, confused and disoriented,” Deming explained.  

This is one of the reasons officials are warning the public to take extra precautions with marine mammals if they’re visiting the beach this coming holiday weekend.  

“I think it’s very important to let the public know that the best thing they can do for these animals is to give them their space,” Deming said. “These are wild animals and they’re very sick and they can be startled very easily because they’re kind of out of it. Although they’re really cute and they may seem like they wouldn’t want to hurt you, they could if you shock them, give you a bite and that would be almost the equivalent of being bit by a bear.”  

The same toxic algal bloom is affecting dolphins, with reports of at least two dolphins washing up onshore in Orange County. In those cases, experts also say people should not attempt to push the dolphins back into the water, but instead call for animal care and control services.