MILFORD, Maine — A year ago, while fisheries biologists were monitoring the most dismal return of Atlantic salmon to the Penobscot River in at least 35 years, Richard Dill admits he began to wonder about the role a brand new fish lift was playing.
“We were anticipating a low run, based on what we had seen the past couple of years,” said Dill, a biologist who works for the Maine Department of Marine Resources’ Division of Sea-Run Fisheries and Habitat.
But week by week the number of returnees wasn’t just low, it was historically low, as he and other experts tinkered with flow regimes at a new fish lift at the Milford Dam. That lift took over the role of a Veazie Dam fishway that had been the first upstream barrier to fish passage — and the salmon-counting station — since 1978.
But while the dam’s owners — Brookfield Renewable Energy Group — and DMR biologists struggled to find out whether salmon were just avoiding the new lift, they found evidence to the contrary.
“[Brookfield and the University of Maine] were conducting passage studies, so we were taking salmon [that did make it to the lift] and putting them back downstream,” Dill explained.
The object of the study was to count how many fish would continue their trip upstream and end up in the fish lift a second time.
“They weren’t returning quickly, or as quickly as we would have liked, but at the end of the season I think we passed 95 percent of those [through the lift a second time],” Dill said. “So [originally] there were some questions — was it the facility [that was to blame for low returns]? — but I don’t really think it was. It was just a really low salmon year everywhere.”
On Wednesday, Dill said 105 more fish have been tagged and monitored this year, and 85 already have made it back through the fish lift. Better yet, biologists already are on their way toward doubling last year’s return total, as 457 Atlantic salmon have returned thus far.
The Milford Dam fish lift project took about 18 months to complete, and construction finally wrapped up in July of 2014. The improved fish passage was a component of the Penobscot River Restoration Project, which called for the removal of two dams and an a fish bypass farther upstream, in Howland. The project has opened up hundreds of miles of upstream habitat to fish that were unable to pass barriers before the dams were removed.
Fish are drawn to an “attraction flow” of water they seek out and end up swimming into a cage where they can be monitored through a window and via an underwater camera.
American shad are counted and allowed to swim straight through the fish way, according to Dill, while Atlantic salmon and river herring are lifted in a water-filled elevator and sorted. The river herring have been stocked in upstream lakes and ponds, while many of the salmon are taken to Craig Brook National Fish Hatchery to serve as broodstock for the next generation.
The water-filled “hopper” holds 5,000 gallons and is automated. On Wednesday, it was set to lift fish every 20 minutes, with crews standing by, ready to react.
The versatility of the new facility is impressive, Dill said.
“The primary reason for this TV is to prevent crushing a fish [when the gate swings open],” Dill said as he watched fish through the viewing room window. “But it also allows us to see what’s coming, so then we can operate the gate so we can let shad swim by. But if we see a salmon swimming up, we can [close] the gates and capture it.”
In one major way, the new fish lift is a huge improvement from the former fishway at Veazie, biologists said.
“Shad never used to use the fishway,” DMR biologist Mitch Simpson said. “I think we had 16 shad over the past 30 years at Veazie, and we’re up to over 1,200 here [this year alone].”
In addition, biologists have lifted, sorted and transported 587,361 river herring at the Milford Dam this year.
Beginning in April, Kevin Job joined the crew at the dam as Brookfield’s lead fishway technician. He works side by side with DMR biologists and helps monitor the flow that all hope will attract fish into the fish lift.
That’s not always a simple task. A few days ago, the Penobscot was running at 8,000 cubic feet per second at the dam. After Tuesday’s thunderstorms, that level rose to 20,000 cubic feet per second.
“There was one day when [the water below the dam] dropped a foot and a half in one day,” Job said. “We’re constantly adjusting this flapper gate just to make sure the attraction [flow] doesn’t get lost during the day or it doesn’t get too much.”
The theory? Salmon and other fish are attracted to water flowing at a specific rate. Too high and they have to work too hard. Too low and they turn around and look elsewhere. The goal of technicians and biologists is to make the flow at the fishway the most attractive on the whole river.
“There were a lot of experts we talked to [last year] … and sometimes that was on a daily basis, when we weren’t catching many fish,” Dill said. “I think we’ve proven through what we did last year to what we’re doing this year that we have it figured out now.”
Kevin Bernier, Brookfield’s senior compliance specialist, is proud of the job his company is doing to help migrating fish move through their power generation dam.
“Brookfield has pretty strong environmental policies,” Bernier said. “We protect natural resources; we protect the environment.”
And after the Veazie Dam was demolished, the role the new Milford facility plays became essential to the ongoing salmon conservation effort, according to Dill.
“Without this sorting facility, we wouldn’t be able to collect our sea-run broodstock for the Penobscot,” Dill said. “This is the only river [in Maine] where there’s a sea-run broodstock — where the fish have gone out to the river, had that experience, and then come back. On the rest of our rivers, we collect parr — 1- or 2-year-old fish — in freshwater, then they’re held at the hatchery for a couple of years. … So this facility is vital to the Penobscot project.”