Marlin and wahoo are showing up off Southern California, and an olive ridley sea turtle nested there for the first time on record

Southern California anglers are hauling in striped marlin, wahoo and yellowfin tuna, fish that normally belong to the waters off Mexico, while two female olive ridley sea turtles have laid nests on Orange County beaches. NOAA Fisheries reports that both developments have arrived as forecasters put the odds of a very strong El Niño above 83 percent. The turtle nests, the first of their kind on the U.S. West Coast, made the autumn of 2026 unusual even for a region used to ocean surprises.

Kelvin waves and a marine heatwave set the stage

As of October, NOAA predicts a greater than 83 percent chance that it becomes a very strong event through the northern fall and winter of 2026 and 2027. NOAA Fisheries says the event is expected to persist into early spring 2027, and that the effects on marine ecosystems can last months or even years. The probability is a forecast, not a measurement of anything that has already happened.

NOAA forecasters announced in June 2026 that El Niño had formed in the tropical Pacific. Oceanographer Michael Jacox of NOAA’s Southwest Fisheries Science Center and Physical Sciences Laboratory describes Kelvin waves as a key part of El Niño’s development. They carry warm water eastward along the equator, and after reaching South America they turn into coastal trapped waves that travel north along the Americas, including the U.S. West Coast. As they pass, they can raise sea level and ocean temperatures and weaken the upwelling of cold, nutrient-rich water. Jacox notes that West Coast waters already carry high sea levels from marine heatwaves, and El Niño is expected to bring warmer-than-normal temperatures along the coast from fall through winter. The warm water is not only an El Niño story. A separate NOAA Fisheries review says a large marine heatwave has warmed parts of the West Coast over the past year and broken Pacific temperature records, and that two current heatwaves, NEP25A and NEP26A, are not directly related to El Niño.

Striped marlin, wahoo and yellowfin tuna north of the usual range

The NOAA Fisheries feature on El Niño and local fisheries states that fishermen in Southern California are already catching large numbers of wahoo, striped marlin and yellowfin tuna, species normally found off the coast of Mexico. The feature gives no catch totals, dates or specific ports, so the observation is best read as the agency’s summary of what the recreational and commercial fleets are reporting rather than a measured survey.

NOAA frames the sightings as the kind of change that earlier El Niño years brought. Drawing on past events, the agency lists more tropical and pelagic animals as likely on the West Coast, including whale sharks, manta rays, sea turtles, marlin, dorado and wahoo, along with shifting distributions of market squid and tuna. Its review of the 2014 to 2016 period recalls whale sharks and hammerhead sharks turning up off Southern California and albacore moving closer to shore as far north as Washington. Several of the listed changes are far less welcome than a good fishing season. The same list includes more emaciated California sea lion pups, a higher risk of harmful algal blooms and a possible increase in whale entanglement risk.

Two olive ridleys at Seal Beach and Huntington Beach

On September 16, 2026, an olive ridley sea turtle nested on a beach near Seal Beach in Orange County. Three days later a second nest appeared about eight miles away, near the Huntington Beach Pier. Dr. Cali Turner Tomaszewicz, a research biologist in the Marine Mammal and Turtle Division at NOAA’s Southwest Fisheries Science Center, used photo identification, comparing body shape, barnacle number and placement, and scute patterns, to show that two different females were responsible. NOAA’s account of the first-ever olive ridley nest in California calls it “the first-ever recorded nest for any sea turtle species on the U.S. West Coast.” That record is the claim the evidence supports: a first documented nest, in NOAA’s records, for any sea turtle species on the U.S. West Coast. It does not mean turtles never nested there in earlier centuries, only that nothing was documented before.

An inter-agency team collected the eggs on September 25 and moved them to the Aquarium of the Pacific in Long Beach as a precaution. The partners include the U.S. Fish and Wildlife Service, the cities of Huntington Beach and Seal Beach, the U.S. Navy, the California Department of Fish and Wildlife, the Bolsa Chica Ecological Reserve, California State University, Long Beach, and the Surfside Colony Community Organization. The number of eggs is not stated, and NOAA says it is unknown whether they were fertilized or are viable. Incubation typically lasts 45 to 60 days, and any hatchlings would be released on the beaches where the eggs were laid.

A warm season is not a new range

The closest known olive ridley nesting is in the western Cape region of Baja California, Mexico, near Todos Santos, with a few scattered nests near Magdalena Bay. Mexican nesting runs roughly from July to December, and females typically lay two or three nests about two weeks apart. NOAA also notes that adult female sea turtles show high fidelity to the areas where they hatched, returning to nest about 15 years after hatching. A turtle nesting hundreds of miles north of that core is therefore well outside the usual pattern.

NOAA is open about the limits of the explanation. The agency says the exact reasons are uncertain, but that warm sea surface temperatures from ongoing marine heatwaves and the incoming El Niño are likely key factors, and it also points to the species’ nomadic, highly migratory habits and possible navigational errors. That is attribution with a hedge, and it should stay hedged.

One warm season does not amount to a permanent range shift. Past El Niño years brought tropical visitors north, and many retreated as the water cooled. Nests at the edge of a range add little to a population unless they hatch, the young survive and the females return, and for olive ridleys that return would take about 15 years. For now, two nests and a run of warm-water fish are documented events, and whether they repeat after El Niño fades will decide whether they mark a trend.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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