Up and down the West Coast, ichthyologists—professional fish nerds—can barely contain themselves. Whale sharks normally in the Sea of Cortez have been seen as far north as Malibu. Spotter planes have photographed giant manta rays flapping their way north. Sport fishermen who normally have to travel to Baja for wahoo and blue marlin are now catching them by the boatload off the coast of San Diego. And a rainbow of reef fish that are hundreds of miles beyond their normal range are poking around the piers of Southern California.

Mike Couffer, a semiretired biologist from Newport Beach, has been scuba diving nearly every day to see the mohawk-style fins of star-studded grouper, tiny iridescent orange creolefish, three-banded butterflyfish, and other exotic fish hardly ever seen in this area. “It’s just nuts, what’s going on out there,” he told me. The balmy waters produced during this year’s El Niño have essentially imported a whole ecosystem from Mexico. In recorded history, “this is the most profound movement of tropical fishes into California that anyone’s ever seen,” Milton Love, a research biologist at UC Santa Barbara’s Marine Science Institute, told me.

From his office window, Owyn Snodgrass, a NOAA Fisheries research biologist, can see the Scripps Pier in La Jolla. He told me that his father, a former aquarium curator, used to drop a probe twice a day off that pier to take the temperature of the Pacific Ocean, contributing to a daily record that stretches back to 1916. This year, an extraordinary amount of warm water has built up in the equatorial Pacific and beyond, driving what promises to be the most intense El Niño ever recorded.

When Snodgrass and I talked on Tuesday, the water temperature at the pier was 75 degrees, 11 degrees warmer than the daily average and the warmest November 3 ever recorded. This would have surprised him more if daily records hadn’t already been broken 65 times this year. As we spoke, Snodgrass was keeping an eye on a livestream showing the water under the pier. He watched a razor surgeonfish swim by. “That has never been documented in California waters,” he said.

Snodgrass is one of a handful of scientists who are sifting through social-media posts and reports from fishermen and scuba divers to verify and document the species among the profusion of tropical immigrants that rarely make it this far north. That’s not always so simple. People have sent in photos with dubious dates or locations. But the group thinks that it has already identified about 10 species new to the state. A fisherman on the Venice Pier in Los Angeles pulled up one in August—an 11-inch nocturnal orange fish with big eyes, known as a longfin bigeye—that typically lives hundreds of miles away, in Mexico. It’s now preserved in alcohol at the Natural History Museum of Los Angeles County.

Snodgrass has also been collecting the heads of monster tuna to find out where they came from. In the past month, he said, fishermen have caught four bluefin tuna that each surpassed the previous California record for biggest caught by rod and reel. One of them, a 650-pounder, beat the record by more than 200 pounds. Big fish from the south started showing up earlier in the year, following the warmer waters in search of food; many of the smaller reef fish showing up more recently wafted in on the currents as eggs and larvae. They’re only now big enough to be easily identified, and, when the period of warm water subsides some months from now, “most of them probably will just die,” Love said.

But some could gain a foothold here. During the 1983 El Niño, Love said, tropical triggerfish made their way to California, and they can still be found in the state. And as average ocean temperatures keep rising, tropical fish will be more comfortable living at these latitudes. This season’s El Niño is like a preview of the future—wrecking-ball tides of higher sea levels, the exotic species that will find new homes, the endless new temperature records. “A little foreshadowing,” Greg Pauly, the curator of herpetology at the Natural History Museum, told me.

For some of California’s more familiar life forms, the conditions this year have been deeply alarming. April Ridlon, the director of science at the Monterey Bay Aquarium, in Monterey, has deployed extra divers to monitor kelp forests that can suffer in warmer temperatures, deprived of nutrients from cold upwelling waters. Just over a decade ago, amid the marine heat wave known as “the blob,” which coincided with another El Niño, Central California lost more than half of its kelp forests, she says, and Northern California lost even more.

In some areas, the kelp has still not returned. She expects to lose kelp now, too, which means potentially losing populations of hundreds of other species that rely on them for habitat and nursery grounds. These could include animals that we eat—rockfish or Dungeness crab or abalone—as well as those we tend to care about keeping alive, such as the sea otters who wrap themselves in kelp strands when they sleep.

If this is our future and we are just glimpsing it now, at least it has offered a few moments to savor. On Sunday afternoon, Ali Steele, a 40-year-old producer, rode her bike to San Buenaventura State Beach, in Ventura, to look for driftwood. “Beachcombing like an old lady,” she told me. On a quiet stretch of rocks and dunes, she noticed a turtle half-burrowed in the sand, laying eggs. “She was very visibly straining and then resting. Then straining and then resting. And then digging and then straining and then resting,” Steele said.

As she watched this long ritual, she started to cry. She stayed near the turtle until the sun went down. It felt to her like a gift from the universe.

She didn’t realize then just how rare it was. Sea turtles usually don’t nest on the California coast. But earlier this year, for the first time, two olive ridley sea turtles laid eggs on beaches in Orange County. The closest major nesting beach for this endangered species is nearly 1,000 miles south, on the Baja California Peninsula in Mexico, where the turtles usually return after nearly two decades out at sea. Whatever sent them off course, Jeffrey Seminoff, who leads NOAA’s marine-turtle ecology and assessment program, told me, “it certainly has something to do with the extremely warm waters.”

Concerned about incoming storms, federal officials carefully moved those turtle eggs—204 of them—to be incubated at the Aquarium of the Pacific, in Long Beach. The olive ridley turtle that Steele observed on Sunday near the Ventura Pier was the third nesting sea turtle ever seen in California, and the one farthest north. Authorities have put an enclosure around the nest to protect it, but so far, they have decided not to relocate the eggs, even though tides could threaten the site in the 45 to 60 days until they might hatch.

The turtle eggs at the aquarium could hatch any day. If they do, federal officials will try to rush the hatchlings to the beach and send them on their way. If they happen to make it out there in the ocean, 20 years from now, these turtles might even come back to a warmer California and find the place more suitable to their needs than the California that we have known.