A new hope surfaces for salmon restoration
This is the second feature in a five-part series that follows an Atlantic salmon on its journey upstream to spawn in a tributary of Lake Champlain driven by its instincts (and a pickup truck). Learn why this species disappeared from the lake in the 19th century, and how it is making a comeback today thanks to collaboration by partners in the basin.
“Welcome to the Winooski River!” U.S. Fish and Wildlife Service Fish Biologist Nicholas Staats beamed as he shook my hand on the walkway atop the Winooski One Dam in Winooski, Vt. Behind him, a white board announced that 75 salmon had been lifted to date this season. I was about to find out what that meant.
“I’ve got fish in here,” Staats said, tapping the metal hopper that serves as the “lift” — an elevator that fish swim into at the base of the dam for a ride to the top. “I’ll be taking them out of the box with my net,” he said, warning, “They’re going to splash; they’re going to wiggle.”
Staats scooped a fish from the hopper, weighed it, and set it on a table for an assessment while dam operator Jon Clark, who collaborates with the Service, recorded the data. Then he placed the fish in a tank in the back of a pickup truck to be shuttled upstream, just like the salmon I encountered in the Boquet River on the New York-side of the lake.
There are an estimated 442 dams and 13,822 culverts in the Lake Champlain Basin, not including its Canadian tributaries. For the local, state, nonprofit, and federal partners who are working together to bring Atlantic salmon back to the basin, these obstacles have become primary targets for advancing the restoration program toward a goal that once seemed unreachable: natural reproduction. If salmon cannot move up and downstream for seasonal migrations, they cannot complete their natural life cycles. End of story.
So wherever possible, dams and culverts are being removed to open access to upstream habitat, as in Willsboro, N.Y., where partners joined forces to take down an obsolete dam on the Boquet that last powered a paper mill long ago.
But some dams still play important roles in their communities; Winooski One generates 30 million kWh of hydropower annually — enough to power more than 2,700 homes for an entire year. Removing it is neither feasible, nor desirable. So what’s a salmon to do? Take the elevator, of course.
Established in 1993 in cooperation with Burlington Electric and Green Mountain Power, the “Trap and Truck” fish passage program gives salmon access to more than 20 miles of habitat in the upper Winooski and its tributaries. Like the removal of the Willsboro Dam, it’s another great example of the collaboration taking place around the basin to get salmon beyond barriers. It’s also a great photo opp for local media. “I think there are about 40 pictures of Nick holding a salmon at the lift,” joked Bill Ardren, Senior Fish Biologist at the Service’s Lake Champlain Fish and Wildlife Conservation Office. Make that 41.
But now partners have another reason to consider the operation a success, and an indication that the restoration program is moving forward. “This summer we documented natural reproduction from the fish that were brought upstream in the Winooski for the first time in probably 200 years,” said Ardren.
For biologists, this is a triumph. For anyone else, it sure sounds like a good thing, but it probably demands a little context. When the salmon restoration effort got underway in the 1970s, there were no salmon left in the lake. Zero. Going from zero to a viable fishery required seeding the lake with salmon, and then letting nature do its thing.
The Service worked with the Vermont Department of Fish and Wildlife to start raising salmon from a strain originating in Sebago Lake, Me. — home of one of the last remaining native populations of landlocked Atlantic salmon in the United States. Today salmon are produced in both state and federal hatcheries in the Lake Champlain Basin: the Dwight D. Eisenhower National Fish Hatchery in North Chittenden, Vt., the White River National Fish Hatchery in Bethel, Vt., the Ed Weed Fish Culture Station in Grand Isle, Vt., and the Adirondack Fish Hatchery in Saranac Lake, N.Y.
“We work together to share the fish production and other work on the lake, such as sampling and assessment, so we know how our fish are doing out there,” explained Henry Bouchard, the manager of the Eisenhower hatchery, which produces 130,000 salmon for Lake Champlain every year (including my salmon).
At this point, it would be appropriate to ask: If hundreds of thousands of salmon have been stocked in Lake Champlain since the 1970s, why didn’t partners find a single natural-born fry until 2016? Shouldn’t nature have been doing its thing by now?
In the beginning, nature couldn’t do its thing. “It wasn’t until recent years that we even began to look for natural reproduction,” said Brian Chipman, a Fisheries Biologist for the Vermont Department of Fish and Wildlife who has been involved in the restoration program for 30 years. “In the 1970s and early 1980s, there really wasn’t any accessible spawning habitat for salmon,” he explained. No fish ladders or fish lifts, no trapping or trucking.
And then nature did start to do its thing, but it wasn’t the “thing” we wanted. By the late 1970s, scientists were seeing hatchery born salmon grow to a desirable size for the fishery, but they were also seeing a corresponding boom in the population of a parasitic fish in the lake called sea lamprey.
Try to imagine the worst thing possible, and you’ll probably be picturing a sea lamprey: snaky body, mouth like a suction cup, concentric rings of jagged teeth, and a rasping tongue. When sea lamprey find a host fish, “They use that suction-cup mouth to stick to its body, and scrape a hole through its flesh with their tongue,” explained Steve Smith, a Fish Biologist at the Lake Champlain Fish and Wildlife Conservation Office. Feel free to take a moment to shudder at that thought.
While sea lamprey is arguably native to Lake Champlain, the sudden influx of a food source that had been absent for more than a century caused its population to explode. Given that a single sea lamprey can kill the equivalent of 40 lbs of fish in a year, it’s easy to understand why an explosion of them would cause a problem.
If reestablishing a salmon fishery was the dream of the restoration program, sea lamprey was a waking nightmare. “The sea lamprey population was so high, and salmon survival was so low, that most of the hatcheries were just trying to grow fish quickly to get them into the fishery,” said Ardren.
In 1990, the Lake Champlain Fish and Wildlife Management Cooperative (a partnership of the Service, Vermont, New York State, and Quebec) launched a pilot program to experiment with established methods developed in the Great Lakes for suppressing sea lamprey. What started as an experiment has evolved into a cornerstone of the salmon restoration program: a strategic, long-term control program that involves tactical application of lampricide to kill larvae, and temporary barriers to trap adults during seasonal migrations, all guided by comprehensive assessments of sea lamprey throughout its lifecycle.
It took trial, error, and a lot of patience — learn more in a previous blog post about the evolution of the sea-lamprey control program — but it’s working. Wounding rates for salmon have dropped from 100 wounds for every 100 salmon to fewer than 20, and other fish species that are susceptible to sea lamprey attacks are rebounding as well, such as lake trout, walleye, and lake sturgeon.
“Since we have stepped up lamprey control in the last 15 years, we are seeing much greater salmon survival, much larger runs, and fishing on the lake has improved immensely,” said Chipman, pointing to the results from his 2015 survey of anglers fishing the main deep-water section of the lake shared by Vermont and New York. “According to those data, salmon are the most popular fish in terms of drawing anglers to that area of the lake.”
With the lamprey nightmare fading, the hatchery program began to adapt. “We started to focus more on the quality and condition of the fish, rather than size,” said Bouchard. “We wanted to produce a fish that was more vigorous and better adapted to the environment, which subsequently translates to greater adult survival.”
You’d think greater adult survival would translate to natural reproduction, but just as scientists started to get a handle on the sea-lamprey problem, something even scarier showed up in the lake: a small, unassuming fish called alewife. Looks can be deceiving.
Alewife were introduced to the lake around 2003, and gradually started to crowd out rainbow smelt, the primary food source for salmon. So salmon started to eat alewife instead, and therein lies the problem. Alewife are sort of like fast food — tasty, convenient, and nutritionally toxic — they carry an enzyme called thiaminase that digests the Vitamin B in the intestines of salmon, which can lead to neurological dysfunction and survival in adults and their progeny.
“It’s only recently that we’ve been getting salmon up river in large enough numbers to ask: Will they spawn? Now we also have to ask: Will the eggs hatch and produce young?,” said Staats.
As such, the discovery of a wild-born salmon fry in the Winooski River represents a new hope for natural reproduction, and scientists are optimistic. Cautiously optimistic. “It’s a good sign that some have survived, but if you find 20 young fry downstream of a salmon nest, you wonder if there were a hundred that didn’t survive,” said Staats.
More than just wondering, they are going to find out. Next week, learn about the research taking place in hatcheries and in the field to help salmon make it in the wild. Turns out my salmon has a pretty good shot.