Pulled by an instinct only a concrete dam could thwart, Atlantic herring and shad once surged up the Catawba River each spring by the millions.

Soon the fish will again be able to fulfill their destiny: to spawn in the river where they once hatched.

A new agreement between Duke Energy and the U.S. Fish and Wildlife Service will turn the fish into hitchhikers. They will be trapped at the base of South Carolina's Lake Wateree dam, which has stopped their way upstream since 1919, and trucked around it.

Their offspring, the plan goes, will eventually reclaim the river's longest remaining free-flowing stretch, the 30 miles below Lake Wylie.

A truck ride will be an inglorious end to epic migrations that begin as far away as Nova Scotia. But it's part of a broader plan to return long-gone natives to the Santee River basin, which stretches to the sea and includes the Catawba.

Biologists are trying to rebuild a bit of the natural world, and a key piece of Carolinas history, that dams drowned nearly a century ago.

As part of that plan, S.C. Electric & Gas has agreed to build fish passages near Columbia that will help shad and herring find their way to old spawning beds in the Broad River, and eventually into North Carolina.

Closer to the Atlantic, where shad and herring spend most of their lives, South Carolina's state-owned utility Santee Cooper will expand fish passages on the Santee that date to the 1940s.

And on the Pee Dee River, east of Charlotte, Progress Energy agreed last year to a similar truck-and-transport plan for shad and American eels. Shad once migrated up the Yadkin as far as North Wilkesboro, in the N.C. foothills.

These efforts will help prop up species once so abundant that historical accounts read like tall tales. Centuries of dams, pollution and overfishing have beaten the fish down to a smidgen of their former bounty.

Now they're a depleted link in the food chain for the ocean fish and seabirds that feed on them. Next time you bite into a lovely tuna steak, thank the lowly herring that grew it.

The decline of the shad

Each May, the Great Falls of the Catawba exploded in a silver flash: the shad run.

As late as the 1890s, great schools leapt up the four-mile-long cascade, 45 miles south of Charlotte. Trapped by the thousands, the fish were the centerpiece of the annual “shadfest,” a riverside revelry of gambling, fistfights, horse racing and gorging on firm, sweet fish.

Long before that, historians say, the annual shad and herring runs influenced where the Catawba Indians built their villages.

To the Europeans who settled the East Coast, the fish were a gift from God. Easy to catch during their river runs, and free for the taking, the fish were dried or salted away in barrels for winter.

Their decline began with the grist mills that began damming Piedmont streams in the 1780s, said Prescott Brownell of the National Marine Fisheries Service in Charleston.

The mills began a pattern followed late in the 19th century by impassable hydroelectric dams like Wateree. Shad and herring populations crashed.

Despite steep declines after 1900, fishermen on N.C.'s Albemarle Sound still hauled in nearly 11.9 million pounds a year from 1890 to 1970. Last year the statewide commercial catch totaled about 300,000 pounds.

A way around the dams

Their revival on the Catawba stems from Duke's renewal of its federal hydroelectric license. The Fish and Wildlife Service, charged with protecting rare species, may require fish passages.

Under an agreement with the federal agency and state wildlife agencies, Duke and S.C. Electric & Gas will pay for fish passages to move American shad, blueback herring and American eels from the Atlantic up the Santee River and then the Catawba.

Duke expects to spend more than $10 million to route the fish and eels around the Wateree dam. It will start in 2018 after a 10 years of research.

Unlike shad and herring, eels are born at sea but spend their lives in freshwater rivers. Dams doomed all three.

Because eels can slither up inclines, low ramps will eventually be built for them at all 11 of Duke's Catawba dams.

The fish will be trapped at the dam, trucked in tanks and released into Lake Wateree, the southernmost of the Catawba reservoirs. Eggs laid by migrating females will be boosted by young fish raised in hatcheries and released into the wild.

Over time, if improved fish passages downstream increase the number making their way up the river, they will be released into the free-flowing waters north of the lake.

If nature and engineering work as planned, the young fish will bond to the chemistry of their new native waters like a baby to its mother's scent. They will tumble through the dam's big turbines and swim to the sea.

And before they die, a deep urge will turn them toward the Catawba, dodging dams and fishing nets, to a place we would call home.