A local biologist has been nationally recognized for his efforts to restore the Atlantic salmon population in Lake Champlain after the fish disappeared more than a century ago.

Essex’s Bill Ardren, a fish biologist with the U.S. Department of Fish and Wildlife, earned that agency’s Rachel Carson Award for Exemplary Scientific Accomplishment, which recognizes scientific contributions and real-world results in the face of conservation challenges.

The award is named after an aquatic biologist whose scrutiny of the widespread use of chemical pesticides famously led to a ban on the use of DDT in the U.S.  It’s one of three science awards the U.S. Fish and Wildlife Service distributes annually.

Ardren, who received the award at a national conference last week in Denver, said he’s humbled and honored to be associated with Carson.

“I really had to take a step back and think about the things that we’re doing, and how that could relate to such to such a major accomplishment,” he said.

Salmon disappeared from land-locked Lake Champlain in the mid-1800s due to overfishing, agricultural runoff, development and dam construction, which prevented the fish from swimming upstream, according to the federal wildlife department.

Salmon restoration efforts in Vermont have been ongoing for decades, with fish produced in both state and federal hatcheries prior to being stocked by the tens of thousands in Lake Champlain waterways every year.

But it wasn’t until 2016 that biologists documented the first natural reproduction of salmon in two of tributaries – the Winooski River and the Boquet River in New York – thanks in part to Ardren’s work.

“I feel like the contribution I made coming in was to help identify some gaps in our knowledge about the salmon’s biology and how we could use science to help those fish survive better,” he said.

Ardren’s research identified ways biologists can encourage more salmon to make the migration trip upstream while also finding some best practices for introducing the fish into the waterways.

Ardren is pictured in the field (Courtesy photo)

Once hatched, salmon stay in waterways like rivers or streams for about two years, then swim out into the lake until eventually returning upstream to spawn, which is why lakes need streams with enough spawning and rearing habitat to sustain a naturally reproducing population.

But the annual migration from Lake Champlain has been a challenging one due to physical barriers, and while human intervention has helped overcome these obstacles, biologists were surprised to see so few fish return each year.

Ardren’s research helped identify ways biologists can encourage more salmon to make the migration trip while also providing some best practices when introducing the fish into the waterways.

For example, when one project identified a chemical odorant that salmon cue in on for spawning grounds in the wild, Ardren suggested changing the hatcheries water sources from well water to brook water during a specific time of year. The changes allowed young salmon to be exposed to the chemical cues early on and better find their way back to the waterways as adults.

As a result, Ardren said, returns in rivers have been three to five times higher than previous rates.

Another project came with the help of Brett Towler, a hydraulic engineer also honored at last week’s national conference. The two collaborated with Green Mountain Power to modify a structure at a hydropower dam, which fish need to pass through when heading back downstream, allowing a greater percentage of fish to make it back to the lake.

Ardren’s recognition comes during the international year of the salmon, a project launched by the North Pacific Anadromous Fish Commission aimed at raising awareness of “what humans can do to better ensure salmon and their varied habitats are conserved and restored against the environmental variability,” reads the NPAFC website.

The project features events around the U.S. and more than a dozen other countries. Here, the Lake Champlain Fish and Wildlife Conservation Office is planning a series of events, including a collaboration with the Lake Champlain Maritime Museum, which will have a museum replica canal boat touring the lake to talk about landlocked salmon.

For Ardren, meanwhile, the work continues; he has a project planned for this fall that will further illuminate the migration patterns of adult salmon. Beyond his personal interest, Ardren said the the fish play an important role in the overall effort to restore Lake Champlain’s aquatic ecosystem.

“A lot of things have to go right for salmon to be able to complete their life cycle,” Ardren said. “So they’re a really good indicator species of how well we’re doing in terms of restoration.”

This story has been updated to reflect the correct spelling of Bill Ardren’s name. We sincerely regret the error.