Alewives, or river herring, are making their usual spawning migration to Maine in unusually high numbers this year, thanks in part to restoration efforts and the removal of dams on the Penobscot and Kennebec Rivers.
Because they serve as a food source for several fish species as well as eagles, ospreys and other animals, alewives’ success is seen as an indicator of the health of Maine rivers. And one small stream in Bradley is expecting to see more than a million of the fish return over the next several weeks.
Even before visitors reach the Leonard’s Mills Maine Forest and Logging Museum on Blackman Stream, they get the sense that something fishy is going on. That’s because you can smell the tens of thousands of alewives in the current before you can see them.
Josh Royte, a conservation scientist with the Nature Conservancy, steps to the edge of the bank for a better look. Hundreds of fish are being channeled into a fishway to make their way upstream.
“That site is chocked with fish waiting for their turn to come up, you can see their dorsal fins sticking out of the river for hundreds of feet out into the river. You can see nothing but the fins of these fish sticking out waiting to come up into Blackman Stream,” he says. “So it’s pretty exciting and there’s a lot more fish still to come.”
Like other fish species that spawn in fresh water but live in the sea, alewives are imprinted with an internal guidance system that leads them back to the bodies of water where they were born. In Bradley, Royte says the fish are descendants of alewives that that were born in nearby Chemo Pond four years ago.
It’s all part of an effort to restore sea-run fish to Maine rivers. Supported by Maine’s Indian tribes, conservation groups such as the Nature Conservancy, the Atlantic Salmon Federation and many other partners, the project is succeeding, Royte says. They’re showing up in numbers not seen in about 200 years.
“After some really spectacular world-class dam removal projects and fish passage projects like this one on Blackman Stream, the fish are coming back and they’re coming back in numbers that are astounding,” he says.
Seven years ago there were zero alewives in Blackman Stream. Last year, the fish counting tubes set up at the end of stream’s fishway recorded more than 600,000 of them.
Ray “Bucky” Owen, former commissioner of the Maine Department of Inland Fisheries and Wildlife, is among those who takes a special interest in the alewife restoration effort in Bradley. He closely monitors how the fish are proceeding near the fishway, paying particular attention to where large numbers of the fish gather and circle for hours as they attempt to find an opening that will lead them to the spawning waters.
Owen says that’s another area of the stream that could use some attention.
“It’s a little hard to see them, but that whole pool is filled with alewives and they’re thinking about putting one more pool down here that will attract, because there’s more flow coming through there and they tend to react to flow than here at the fishway,” Owen said.
The fish jump as Graham Gillette, a fisheries biologist with the National Oceanic and Atmospheric Administration, lowers his dipping net into the pools to scoop up 20 or so of the fish, which average around 12 inches long and weigh a little less than 12 ounces. He drops the flopping fish into a bucket and checks to see how they’re doing.
“Alewife primarily run during the day, so at nighttime, these falls, they won’t be filled with fish,” he says. “They’ll all back down into a deeper pool where they can rest and regain some strength to make the attempt the next day.”
“I can see a fin right there,” says Nate Vann of Colorado, one of dozens of kids visiting the Leonard’s Mills Museum.
Vann is mesmerized by the undulating forms that have turned Blackman Stream as black as its name, and he says he’s already learning a lot about how alewives fend off predators on their journey up the Penobscot River to Bradley.
“They have the same colors and those colors help them camouflage, so what they’ll do is if they want to hide from predators, then they can camouflage on the floor on these rocks,” he says.
The alewife spawning run is expected to continue for the next 2-3 weeks. And Royte says that with nearly 400,000 fish counted already, Blackman has established itself as the biggest-producing alewife stream per acre in North America.