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Atlantic Salmon Recovery: It Takes an Ecosystem


An interview with NOAA Fisheries biologist Rory Saunders

By Rich Press, NOAA Fisheries Science Writer | Posted: December 7, 2015
Follow Rich on Twitter: @Rich_NOAAFish



Atlantic Salmon. Credit: Hans-Petter Fjeld (CC-BY-SA)

When most people in the United States think of salmon, they think of Alaska or the Pacific Northwest. But although it’s hard to imagine today, salmon used to run in big numbers in New England as well. Atlantic salmon supported commercial and recreational fisheries for centuries, sustained Native American populations for millennia, and played a vital role in the region’s ecosystem since the glaciers melted away. Today, unfortunately, Atlantic salmon are highly endangered, and scientists are working to help bring them back from the brink.

One of those scientists is Rory Saunders, a NOAA Fisheries biologist in Orono, Maine. To help Atlantic salmon recover, two dams have recently been removed from the Penobscot River, and Saunders has been working with other scientists to monitor the effects of those dam removals on salmon and other species. In this interview, Saunders discusses what caused Atlantic salmon to become endangered and what we’re doing to help them recover. As Saunders notes, to bring Atlantic salmon back, we need to bring an entire ecosystem with them.

How endangered are Atlantic salmon?

Unfortunately, they’re in pretty bad shape right now. The Penobscot River typically has about 75 percent of the Atlantic salmon in the United States, and in the last few years we’ve seen only a few hundred animals returning to that river. But we’re doing everything we can to keep the numbers from dropping further and to hopefully rebuild them into a viable population.

How big a phenomenon were Atlantic salmon back in the day?

Historically, tens of thousands of Atlantic salmon would have returned to the Penobscot River every year. But for a bigger river, like the Connecticut, they would have numbered into the hundreds of thousands. No one alive today has ever seen Atlantic salmon running in big numbers like that in these rivers, and people sometimes forget that they used to range all the way down into Southern New England.


Rory Saunders (left) and Stephen Coghlan of the University of Maine conduct an electrofishing survey in a tributary of the Penobscot River to monitor changes in fish communities as restoration efforts proceed. Credit: Hirundo Wildlife Refuge/Gudrun Keszoecze.

What caused the decline in Atlantic salmon, and what challenges are they still facing today?

Pollution, overfishing, and dams were the main culprits in the decline of Atlantic salmon. The first two problems aren’t as significant as they once were. Historically, some U.S. rivers were very polluted, but they’re much cleaner now than they were 50 or 60 years ago thanks to the Clean Water Act and other laws. And as for overfishing, there used to be very big commercial and recreational fisheries for Atlantic salmon here. But today, of course, there’s no fishing at all for them in U.S. waters. 

Dams, however, are a different story. We estimate that there are over 600 dams in Maine alone—both big hydro-electric dams and many small, remnant dams—and these still pose a big challenge to Atlantic salmon.

Marine survival is also a major concern. Over the last 25 years or so, survival in the ocean has been markedly lower for Atlantic salmon, whether from the U.S. or other countries in their range. The ocean’s obviously a big place, and finding out where and when they’re hitting a bottleneck out there is a major focus of our science center’s research.

There is also some fishing for salmon off the coasts of Canada, Greenland, and parts of Europe, which have their own populations of Atlantic salmon. Since salmon from everywhere mingle in the ocean, some of our fish are caught in those fisheries, particularly off the west coast of Greenland. We’re working through the North Atlantic Salmon Conservation Organization to reduce the risks to U.S.-origin salmon. But other than that we don’t really have a lot of control over conditions in the ocean, so the best thing we can do is boost the number of young Atlantic salmon that leave our rivers in the first place.


Rory Saunders fishing for brook trout with his son Ian in Northern Piscataquis County, Maine. Credit: Alyson Saunders

In the last few years the Penobscot River Restoration Trust removed Veazie Dam, which was the lowermost dam in the Penobscot River, and the Great Works Dam, which was the next lowest. What effects have those dam removals had on salmon populations?

The effects we’re seeing vary from species to species. The short-lived species reproduce at a younger age so we’d expect them to turn around more quickly, and that’s exactly what we’re seeing. This year over 589,000 river herring made it past Milford Dam, which is now the lower most dam on the Penobscot. That’s up from about two thousand in 2011, so the dam removals have been a huge success story in terms of river herring.

We haven’t yet seen an increase in Atlantic salmon returns, but the return of smaller native species is good news for salmon because they provide benefits at different times in the salmon’s life cycle. For example, adult salmon eat sea-run rainbow smelt. Also, we think that the presence of other fish reduce predation on young salmon. And sea lamprey stir up the sediment when they spawn, which we think “conditions” the streambeds for juvenile salmon. So it’s becoming clear that if we want to get to salmon recovery, we need to bring along these other species as well.

What else are we doing to help Atlantic salmon recover?

Atlantic salmon are highly migratory, so much of what we’re doing is aimed at reconnecting ocean and freshwater habitats so they can complete their lifecycle.

Removing dams is part of that effort, but we’re also working with dam operators to make the remaining dams more fish-friendly. Recent research has shown that young salmon smolts making their way to the ocean can be injured during dam passage, and that if we make the dams safer for them, a greater number will survive the journey.

In addition to dams, undersized culverts [channels that allows streams to pass under roadways] are also a concern.  In downeast Maine, Project Share has improved over 150 culverts. That’s good not only for fish but also for other animals, like turtles and mink, that want to use streams as migratory corridors.

Are you optimistic about the future for Atlantic salmon?

I am cautiously optimistic because these animals are tremendously resilient. Ten thousand years ago there was a mile-high glacier sitting right here over my office, and the salmon came back as soon as the glaciers melted away. That resilience is built into their DNA, and if our rivers are clean and well connected, salmon populations will be OK. But we have to act quickly and face these serious challenges head on.