The alewife, a type of river herring, wriggled against the current, a 10-inch streak that disappeared from view as it rounded a bend in the stream.

It was a normal springtime pilgrimage for the fish, which lives in the ocean but swims upstream to spawn. But this time it was happening in a surprising place — a waterway that was not here two years ago.

For more than a century, this place, called Tidmarsh Farms, was the site of a cranberry bog, a thick carpet of the fruit’s vines atop a bed of sand with straight water channels. But commercial cranberry farming, which began in Massachusetts, has flagged here in recent years as prices dropped and different farming methods emerged elsewhere. Unfolding here now is an ambitious project: turning a cranberry bog back into the coastal wetland it once was.

Economic shifts have left landowners and communities around the country trying to figure out what to do with fallow industrial space, from abandoned farmland to empty factories and warehouses. Experts say the project here shows one path for dormant cranberry bogs; four similar, smaller efforts already are underway in Massachusetts.

But they say this could also be a broader template for bringing back disappearing habitat that scientists say could be useful in an age of climate change.

“Lands like this can store floodwater or storm surges,” said Alex Hackman, a restoration specialist with the state who has overseen much of the work at Tidmarsh. “The ocean is going to push inland, and it’s lands like this — if we can protect them and re-naturalize them — that make for good places to receive that water in the future.”

After more than a year of intensive work, including seven earthen dam removals and a project to rebuild the stream that had not flowed uninterrupted since the 1800s, new life is returning to Tidmarsh after a century of industrial use. A walk through the property is a stroll back in time. Tadpoles and kestrels are turning up. Cranberries are withering. And the changes offer clues to a crucial question: What does it take for nature to come back?

In 1989, this was a thriving cranberry bog that produced 1 percent of Ocean Spray’s entire harvest. But technological changes enabled more efficient farming to take place elsewhere, including on dry land, and southeastern Massachusetts is now dotted with struggling cranberry bogs. Some farmers are seeking tax credits to renovate their bogs; a state report suggested ways to take advantage of the green space for those who choose to leave the bogs behind.

The owners of this land — Glorianna Davenport, a visiting scientist at M.I.T. Media Lab, and her husband, Evan Schulman, a financial services entrepreneur — decided to end the farming operation in 2010. They had already begun the process of getting protections for the land and finding state resources and federal money to pay for restoration.

Yet they had no idea, Ms. Davenport said, “what it would take to restore this to a natural, functioning wetland.”

In Europe, there have been efforts to bring back much older landscapes, called “rewilding.” And in the United States, the 1988 farm bill created incentives for preserving and restoring wetlands on former farmland. But Jeanne Christie, the executive director of the Association of State Wetland Managers, a nonprofit organization based in Maine, said it had been a difficult learning process.

Projects like the one at Tidmarsh, Ms. Christie said, could not come at a better time. Coastal wetlands — which she called “natural infrastructure” — have disappeared quickly under the pressures of development and agriculture.

But climate change has raised new questions about what precisely land should be restored to. A bevy of research unfolding here, through a project called the Living Observatory that has put sensors on the property to gather climate and environmental data, could help answer them.

“With changing average temperatures and precipitation, species moving in that weren’t there historically, folks are often wrestling with and pretty divided about, ‘How do we figure out what to do?’” Ms. Christie said.

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