Warm-water fish species appear in Southern California due to marine heatwave

Southern California anglers are seeing an unusual number of warm-water fish as rising ocean temperatures linked to El Niño and marine heatwaves bring species typically found farther south into local waters.

Fishermen working in Marina del Rey and Santa Monica are catching fish species, in larger sizes, that are rarely seen in the area. Tony Villanueva, a boat captain who has been operating out of the area for years, describes the haul as unprecedented. “Biggest yellowtail I've ever seen up here,” Villanueva told ABC 7.

Another captain, Alex Garcia, also said that anglers have been getting unusually large catches. “We've been catching a bunch of big bonito,” Garcia said. These species of fish are often seen in waters off Mexico, but now they are appearing along the Southern California coast. “People go on overnight trips and pay big money to go catch the fish that we're catching right here, right in our backyard,” Garcia added.

Ocean temperatures off Southern California have risen well above normal due to a marine heatwave overlapping with El Niño conditions. Dr Julia Coates, an environmental scientist with the California Department of Fish and Wildlife, told the broadcaster that warmer ocean conditions are driving these changes. “Right now we're experiencing warm water due to what's called a marine heatwave,” the scientist told the outlet.

She explained that the marine heatwave is bringing unusually warm water to Southern California, drawing tropical and pelagic species that typically inhabit deeper waters. These unusual conditions have resulted in these rare sightings for local anglers. “To see a hammerhead shark with yellowtails swimming around it was pretty cool.”

Boat captains who have spent decades fishing in the local waters have called it a rare event. “We had fish up to, like, 25, almost pushing 30 pounds. Unheard of here, unheard of. Dorado, catching dorado on the anchor right off Santa Monica,” Villanueva said. Garcia observed that water temperatures are significantly higher than normal. “The water temperature obviously is way higher than it usually is. It's like 76 degrees out there.”

The temporary abundance is exciting; however, it may upend local fishing economics. Coates added that warmer waters have boosted fishing opportunities; similar conditions in the past have had serious environmental consequences. “We saw a dramatic loss of kelp and kelp forests in Northern CA, that ecosystem was dramatically changed and has not yet recovered,” Coates explained, referring to the previous thermal anomaly.

Villanueva also commented on the effects of unusually warm water farther south. “Down south, the water's so warm that it's actually killing off some fish because the water's too warm.” Coates also cautioned against viewing the fish boom as simple good fortune. Between 2013 and 2016, Southern California experienced a similar collision of El Niño and extended marine heatwaves during an event called ‘The Blob’. Local fishing operators have plans to continue running trips despite expectations for high surf. “The fish are out there, it's a really cool time to get out on the water,” Garcia said.