Creedence Clearwater Revival's "Fortunate Son" drifts from Karroll Tillett's workshop, a wooden shed about half a mile from where he was born.

Tillett, known as "Frog" to everyone here, has lived most of his 75 years on the water, much of it chasing summer flounder. But the chasing got harder and harder, and now he spends his time making nets for other fishermen at his workshop, at the end of a dirt path next to his ex-wife's house.

Ocean Shock: Fish Flee for Cooler Waters, Upending Lives in US South

The house is on CB Daniels Sr. Road, one of several named after two of the fishing clans that have held sway for decades in this small coastal town. Besides CB Daniels Sr. Road, there's ER Daniels Road and just plain Daniels Road. In Frog's family, there's Tink Tillett Road and Rondal Tillett Road.

Ocean Shock: Fish Flee for Cooler Waters, Upending Lives in US South

Once upon a time, these fishing families were pioneers. In the 1970s and 1980s, they built summer flounder into a major catch for the region. The 15 brothers and sisters of the Daniels clan parlayed the business into a multinational fishing company, and three years ago they sold it to a Canadian outfit for tens of millions of dollars.

Ocean Shock: Fish Flee for Cooler Waters, Upending Lives in US South

But for Frog Tillett and almost everyone else in these parts, there's not much money to be made fishing offshore here anymore.

Forty years ago, Tillett fished for summer flounder in December and January in waters near Wanchese, then followed the fish north as the weather warmed. In recent years, however, fewer summer flounder have traveled as far south in the winter, and the most productive area has shifted north, closer to Martha's Vineyard and the southern shore of Long Island.

Reuters has spent more than a year scouring decades of maritime temperature readings, fishery records and other little-used data to create a portrait of the planet's hidden climate disruption — in the rarely explored depths of the seas that cover more than 70 percent of the Earth's surface. The reporting has come to a disturbing conclusion: Marine life is facing an epic dislocation.

The U.S. North Atlantic is a prime example. In recent years, at least 85 percent of the nearly 70 federally tracked species there had shifted north or deeper, or both, when compared to the norm over the past half-century, according to the Reuters analysis of U.S. fisheries data. But this great migration is not just off the coast of America. Pushed out of their traditional habitats by the dramatically rising ocean temperatures and other fallout from climate change, summer flounder are part of a global disruption of marine species that threatens livelihoods, cultures and the delicate balance of the oceans themselves.

A mirror image of the flotillas of desperate people trying to escape deadly conflicts, this is a refugee crisis going on beneath the surface of the seas. And much of it has happened in the time it took a child to be born and graduate from high school.

Tillett, threading lead weights onto the bottom of a net, remembers the days of plenty up and down the Atlantic coast, catching summer flounder up north but knowing there were plenty more back home.

"Then, all of a sudden, everything starts moving that way, and nothing is left down here."

Few tourists traveling on Route 64 from the North Carolina mainland to the Hatteras beaches venture into Wanchese.

It isn't even a town, officially. The U.S. Census Bureau, however, says 1,600 people live here, many of them in one-story cinder-block homes, not the big beach houses on stilts, known euphemistically as cottages, a few miles away.

Most mornings, Danielses and Tilletts and Etheridges, another of the fishing clans, crowd the restaurant down by the marina.

Longtime flounder skipper Steve Daniels pulls up. Steve bought his first trawler in 1978 and started flounder fishing that summer. That was the year Wanchese fishermen decided there was money in the fish. In 1977, they had caught zero pounds. In 1978, they caught 12 million pounds, and in 1979, their catch approached 17 million pounds. And that doesn't count the millions of pounds they landed during the warmer months in Massachusetts, Rhode Island and New Jersey ports.

Over the years, however, the longer trips north needed to find the fish, among other factors, made the fishing increasingly unprofitable.

"There ain't no flounder around here no more — they all up there in Rhode Island," Steve says. "I got the hell out of it three years ago."

In the early 1990s, summer flounder stocks were on the verge of collapse after being overfished in the 1970s and 1980s, primarily by Wanchese and other North Carolina fishermen.