This story was originally published by Inside Climate News and is reproduced here as part of the Climate Desk collaboration.

For a few weeks each summer, the Sebasticook River in Benton, Maine, is paved with flashing silver scales, so thick it seems you could almost walk across. The alewives have returned for their annual migration.

On a mid-May weekend, Benton held its annual Alewife Festival on the riverbank. With the tunes of a local steel drum band in the background, families made fish-themed crafts, sampled smoked alewives, and watched the migration in progress. Below Benton Falls Dam, fishermen hauled alewives into their boats one full net at a time.

Looking at this scene, it’s hard to believe that 35 years ago, fewer than 800 alewives were making this trip upriver. Last year, they numbered 9 million.

The story of Maine’s alewives is a conservation success decades in the making—and unmatched on the rest of the Atlantic coast.

Like Benton, several Maine towns hold spring festivals or 5K runs to celebrate the alewives’ return. In the coastal town of Penobscot, it’s the biggest event of the year, according to Bailey Bowden, who heads the local alewife committee.

Bowden, age 60, is a ninth-generation resident of Penobscot, population 1,100. He first learned about alewives from older relatives when he was around five years old. There’s something special about this fish, he said.

“It’s pretty impressive to see a brook full of fish, thousands and thousands of these fish that you can just reach down into the water and catch them with your hands,” said Bowden, who sports a dark ponytail and a gray beard under his Alewife Harvesters of Maine cap.

The alewife, or river herring, doesn’t sound like a source of such enthusiasm. The name supposedly comes from the fish’s rotund silver bellies, an unflattering comparison to female tavernkeepers.

The species lives mostly in the Atlantic Ocean, from Newfoundland to South Carolina, but in early summer the adults migrate as far as 100 miles inland to spawn in ponds and lakes.

“This is a right that towns have had forever…It was a pretty big slap in the face to lose the right to harvest this fish.”

Alewives aren’t considered a game fish, though some people do catch and smoke them. But they are a linchpin for Maine’s river ecosystems—one that basically disappeared from many of those rivers for decades.

They act as a “biological conveyor belt” of nutrients between the ocean and inland waters, said Rustin Taylor, the executive director of the Alewife Harvesters of Maine. Seals, otters, bald eagles, ospreys, pollock, trout, and other carnivores eat alewives. The fish fed generations of Native communities and colonial and industrial American towns. The Passamaquoddy tribe’s name for the species, siqonomeq, translates to “the fish that feeds all.”

Today, lobster boats use alewives as a favorite and affordable bait, said Taylor, 47, who spent 12 years as part of a lobstering crew. “Maine fishermen are very lucky to have that resource,” said Taylor, whose home in Somesville, near Acadia National Park, overlooks the local alewife run, which he helps to steward.

Part of the alewives’ charm is that “they swim up right into the heart of your town,” said 32-year-old Anne Zegers, the sea-run fisheries monitoring coordinator for Manomet Conservation Sciences, and a coordinator of the Gulf of Maine River Herring Network.

Alewife festivals, Zegers said, are a chance to celebrate alewives’ role in local ecosystems and economies and to talk about conservation. Plus, their migration coincides with returning warm weather, which after a long Maine winter is reason enough to hold a party, she said.

Taylor recalls seeing alewives in childhood, “before they disappeared in Somesville” during his teenage years. “I remember being mesmerized,” he said.

But even then, he was only seeing a remnant of the tens of millions of fish that once made the annual trip up Maine’s rivers.

Beginning in the 1700s, dams created a series of aquatic roadblocks. Alewives can wriggle their way through shallows and rocky........

© Mother Jones