Rare Sea Snakes, Tropical Fish Could Turn Up Along OC Coast During El Niño

Warmer waters could bring yellow-bellied sea snakes, tropical reef fish and other unusual visitors north to Southern California.

By Chris Lindahl, Patch Staff

Sep 17, 2026 11:55 AM PDT

One of the yellow-bellied sea snakes recovered from previous El Niño years. (Courtesy of the Natural History Museum of Los Angeles County)

From sea snakes to tropical reef fish, Orange County could see some unusual marine visitors in the coming months as warmer El Niño waters reshape conditions along the coast, according to the Natural History Museum of Los Angeles County.

Some unexpected species have already appeared. Hammerhead sharks have been spotted off Los Angeles, Orange and Ventura counties, while a whale shark was seen off Malibu and mahi-mahi, also known as dorado, were spotted near the Southern Channel Islands, museum officials said.

A longfinned bigeye caught off the Venice Fishing Pier has also been added to the museum's collection. The species is typically found from Baja California to Peru, according to NHM Ichthyology Curator Dr. Bill Ludt.

Previous periods of unusually warm ocean water have brought tropical species including damselfishes, pufferfishes and angelfishes north from Mexico, the museum said.

Beachgoers may also want to watch for yellow-bellied sea snakes. Only six have ever been collected in California, according to NHM Herpetology Curator Dr. Greg Pauly, and five washed ashore during El Niño years. The first was found in the fall of 1972.

The snakes normally range no farther north than the tip of the Baja Peninsula. Pauly said stranded sea snakes are most likely to turn up on Southern California beaches from October through January as cooling water makes them sluggish and winds or tides push them ashore.

El Niño can also affect more familiar animals. Reduced cold-water upwelling can limit food for seals and sea lions, while toxic algal blooms can increase the risk of domoic acid poisoning, which can cause seizures and other serious health problems.

Anyone who finds an unusual fish on shore can send a photo and contact information to nature@nhm.org. People who encounter a sick or dead seal or sea lion should keep their distance and call the NOAA West Coast Region Stranding Hotline at 866-767-6114.