On a gray October day, state marine biologist Jennifer Noll is wading through the cold, clear waters of the South Branch of the Sandy River in search of redds, the rocky nests in which Atlantic salmon have laid their eggs.
She happens upon a spot in the riverbed where the gravel has been excavated.
“So we just found an Atlantic salmon redd," Noll says.
It’s an oblong depression with a downstream hump where a female salmon deposited her eggs.
"It's fairly large, it’s probably a meter and a half to about two meters long and maybe a meter wide,” Noll says.
The Sandy River is an improbable salmon stream, because it's blocked by four dams. But biologists say the salmon population is growing in this tributary of the Kennebec River. And the river's cold water could provide a refuge for the endangered species as the climate warms.
Dams have impeded upstream migration on the Kennebec since the Civil War era. So to get here, these fish had to be trapped last summer at a dam on the Kennebec in Waterville. Noll and her colleagues then trucked them upriver past the four dams.
And that’s just the last leg of an ambitious journey. John Burrows of the Atlantic Salmon Federation, who’s tagging along with Noll, says the juvenile fish will spend three or four years in the river, then make the treacherous trip back out to sea.
“They're going to leave this river, swim about 175 miles down the Sandy, down the Kennebec to the Gulf of Maine, then they're going to keep swimming," Burrows says. "Most of them will go to Greenland, several thousand kilometers away. They’ll spend two winters in the ocean, growing into big salmon, then they are going to come back, after about two years there, and make the journey upriver.”
Every part of the journey is fraught. Still, conservationists are encouraged by recent returns. Eighty adult salmon made it to the Sandy River and its tributaries last year. This year, that number nearly doubled.
And Noll says part of the reason may be that the Sandy River has something that salmon will need in the coming years: cool water temperatures.
“So the Sandy River has really great climate resilience, at least that’s what it’s showing so far," Noll says. "Temperatures will be favorable for salmon for quite a few years. At least that’s what’s predicted."
Burrows says rebuilding the salmon population will require getting them to cold rivers like this one, and he says that means removing some of the dams on the Kennebec. But that's not likely to happen soon, because of a recent shift in the political and regulatory landscapes.
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David Heidrich of Brookfield Renewable, which operates the four dams, cites an opinion by federal regulators in March that finds while the dams may adversely affect Maine salmon, they are not likely to jeopardize their existence.
“That's another important indicator, not only to Brookfield and to the state, but also that those that may be interested in salmon recovery that the hydroelectric dams can coexist with migratory species," Heidrich says.
Whatever the fate of the dams, all parties agree that fish passage needs to improve.
John Kocik, of NOAA Northeast Fisheries, says to rebuild the population salmon will have to be established in cold waters like the Sandy River and the upper Penobscot watershed, and in other habitats as well.
“We want to get redundancy in the habitats that they’re in, from coastal rivers to headwaters, higher elevations," Kocik says. "So we’re trying to build a portfolio that has the different genetic populations, and also the different types of habitats that Atlantic salmon used for generations.”
The federal goal of a self-sustaining run of 6,000 wild adult salmon returning to Maine rivers would bring an end to protections under the Endangered Species Act. But Kocik says the dramatic efforts to protect the fish since they were listed in 1999 have mostly served to stabilize their numbers, and stop the decline.
But as they wade through the cool waters of the Sandy River, Noll and Burrows witness evidence of life.
Two large salmon blast by in shin-deep water.
“That just jumped me!" Noll says. “It never gets old, I continue to get jumped by salmon and fish all the time, and it’s like the highlight of my trip, the highlight of my year.”
Burrows says that kind of sighting makes him optimistic.
"The species is resilient," he says. "And if you get them to the habitat, they’ll take care of themselves. And so it’s hard not to come up here and feel hope for the future. Because it's a beautiful river, it's phenomenal habitat, it’s cold. And we’re seeing signs of fish everywhere.”
