With improved fish passage, Maine is seeing a record number of river herring

Scientists say many more alewives and blueback herring have made their way into Maine’s waterways this year — a recovery they attribute to dam removals and habitat restoration.

Sean Ledwin, the director of the Bureau of Sea-Run Fisheries and Habitat at the the Maine Department of Marine Resources, said several rivers are seeing strong runs again this year, after record counts in 2023.

Ledwin said more than 6 million fish have been counted at Benton Falls, along the Sebasticook River (a tributary of the Kennebec River) — far more than last year. More than 3 million have been counted at China Lakes.

“And I had a chance to go out there this spring, and you couldn’t see far enough to see where the alewife run ended,” Ledwin said. “So there were millions of more alewives that didn’t even pass the project. So probably, you know, 15, 20 million alewives in that river system, which is pretty spectacular.”

More than 5 million river herring were counted at the Milford Dam, on the Penobscot.

Ledwin said the bountiful runs demonstrate the positive effects of fish passage projects, including a recent dam removal at Meddybemps Lake in Washington County.

“If you can get [alewives] into their habitats, which is slow ponds and lakes, they can really explode in population,” Ledwin said. “So usually the limiting factor is just getting access to the habitats, and then they kind of take it from there.”

Alewives are an important food source for many birds and for other fish, and Ledwin said the presence of more alewives can serve as a barrier to protect endangered Atlantic salmon from predators.

Ledwin expects alewife counts to continue to grow, thanks to $70 million in new federal funds to remove more dams and improve habitat across the state.