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Researchers have found that fish species populations are shifting their range further north as the ocean warms. File/Andrew J. Whitaker/Staff

Shrimp boats from North Carolina pulled up to the McClellanville dock last week, loaded down with catch.

They had been trawling unrestricted ocean waters along the North Carolina-Virginia state line — in other words, hauling in shrimp that spawned in the Chesapeake Bay.

Until a few years ago that was unheard of: The bay just didn't produce shrimp. It's too far north.

But fish species are shifting their range as seas warm — four times faster than land species, according to a recent study.

The concerns are for a lot more than shrimp. It's deep-water finfish as well as surface roamers, species like wahoo, snapper, grouper and cobia. Those are among the most sought after game and seafood fish, and the rules for all of them are under review.

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Southeastern shrimp species have moved their range as far north as Chesapeake Bay. File/Grace Beahm Alford/Staff

As the waters warm this spring, the near-shore shrimping grounds will open. More of the half-million licensed recreational anglers in South Carolina will crank up boat motors and head out. Commercial boats are out there already. While the pressure on species from overfishing is a long-recognized and long-regulated issue, now there is a new one: How long will this fish even be there?

Anxiety is starting to churn in fishing communities over what will happen to their livelihoods or hobbies. The value to South Carolina of its rich shrimp and finfish waters has been estimated at $44 billion per year in recreational and commercial uses combined.

"Yellowfin tuna — we used to pack a good deal of it," said Rutledge Leland, of Carolina Seafood, which operates at the McClellanville dock. "I can't remember the last time I saw yellowfin tuna. They see more of it off North Carolina."

For regulators, the question now is what to do about it. Federal fish management councils set the catch rules by region.

"We're seeing the boats beginning to travel farther north to continue to catch the fish they were catching," said Franklin Schwing, a science division chief for the National Oceanic and Atmospheric Administration. Schwing was one of a number of researchers who took part in the study.   

The councils have started working jointly on rules for "shifting species," fish that used to be exclusive to one region but are now rapidly crossing into others. At its meeting earlier this month, the South Atlantic Fish Management Council brainstormed with both Mid-Atlantic and New England council directors. 

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South Carolina's recreational and commercial fishing combined value is estimated to be at $44 billion. File/Andrew J. Whitaker/Staff

The Southeast region hasn't seen the dramatic shifts in range that the cooler-water Mid-Atlantic and New England regions have, said Mel Bell, a member of the management council and the S.C. Department of Natural Resources fisheries management director.

"But we might be starting to see more of it now," Bell said. "We draw these nice (jurisdiction) lines but the species don't pay attention to our lines. We're trying to stay ahead of it."

The recent study found 80 percent of more than 1,700 ocean species worldwide are shifting range in response to warming waters, as well as four times faster than land species. The study is what's called a meta-analysis, or an evaluation of a number of more regionally focused studies to find consistent patterns.

The fish evidently are trying to stay in waters they are comfortable in, Schwing said. Unlike land species, which can tolerate wide temperature variations, for ocean species a few degrees affecting its food can make a live-or-die difference.

"I think we were surprised at first how fast they were moving," Schwing said. "But when we look at how fast the ocean environment is changing, I guess it wasn't a surprise."

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Reach Bo Petersen at @bopete on Twitter or 843-937-5744.

Science and environment reporter. Author of Washing Our Hands in the Clouds.

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