50% reduction in lake trout stocking comes after growing research that wild lake trout are sustaining population
By Zachary Matson
Fisheries managers in New York and Vermont plan to halve the number of lake trout stocked in Lake Champlain this fall as researchers continue to find growing evidence of a sustainable wild-reproducing population.
The plan is to stock around 41,000 lake trout raised at a Vermont hatchery in the fall, down from 82,000 last year, the New York Department of Environmental Conservation announced Wednesday.
A management cooperative of New York, Vermont and federal officials and lake researchers in 2021 cut out the use of around 30,000 lake trout raised at a New York hatchery, in an earlier step to lower stocking levels.
The recent stocking reduction is another sign of the growing strength of a reintroduced lake trout population in the nation’s 13th largest lake. Recent studies have found wild populations ranging up to nearly 10 years old, after decades of limited success.
Ellen Marsden, a University of Vermont fisheries biologist who studies Lake Champlain’s lake trout, said the wild lake trout population has made major strides in the past decade and appears primed to sustain itself.
“This isn’t just a flash in the pan,” she said. “This is sustained natural recruitment.”
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After decades of stocking, including formal efforts that commenced in the 1970s, around 2012 lake trout hatched in the lake finally started to make it through the first year of life after and survive into the juvenile state. Those juveniles have now started to age into reproductive maturity and continue to survive. Hatchery fish have clipped fins, so researchers look for fish without those clipped fins as an indicator that they were offspring successfully hatched within the lake ecosystem. The wild fish are constituting a growing share of different age classes.
One 2022 paper from Marsden’s lab found “higher adult survival rates and greater longevity than previously estimated” among the wild populations and an “upwards shifting age structure.”
By cutting the number of hatchery fish released into the ecosystem, the wild populations will have less competition for the lake’s food and habitat resources. A DEC fisheries biolgist said the stocking announcement “reflects positive changes.”
“We are allowing the wild fish the space and habitat needed for continued success, while continuing to support the recreational fishery,” DEC Regional Fisheries Manager Rob Fiorentino said in a statement.
Bill Wellman, a longtime member of Trout Unlimited working in the Champlain region, called the lake trout restoration a “success story” and said he thought most anglers would see the stocking reduction as a positive sign.
“It’s a success for conservation and it’s a success for anglers,” he said.
Major mysteries about the lake trout recovery and its future remain. For example: researchers are still trying to figure out where the wild fish are spawning. And the lake trout success could be undone by other threats like invasive fish or even the fish’s own success. Marsden said there is a need to resume a study of the lake’s forage fish that was suspended in 2015 to better understand the health of the fish the lake trout feed on.
After the decision to eliminate the New York-raised fish, a postdoctoral researcher in Marsden’s lab found evidence that the genetics of the wild lake trout was more closely linked to the New York strain. That strain, known as the “Seneca strain” was raised by collecting eggs from wild fish in Cayuga Lake and growing them on in a hatchery, releasing them as age-1 fish The Vermont fish are raised from a hatchery strain developed using the genetics of fish that survived after being stocked in Lake Champlain and are released into the lake at an earlier stage.
Marsden said the New York fish could have been more successful for a variety of reasons and that Vermont managers can alter their hatchery regime if necessary. She said the decision to suspend New York’s hatchery contribution was logistical and made before the genetics research.
“It was a perfectly sensible decision at the time,” Marsden said.
It may also be a moot point if the wild populations continue to sustain enough for managers to further reduce stocking levels. Speaking as a biologist and ecologist, Marsden said her ultimate goal would be to phase out stocking entirely if wild populations continue to succeed.
Lake trout appear to have a mixed relationship with some of the invasive fish species sharing the lake. Sea lamprey, an invasive parasite, wound Lake Champlain lake trout at higher rates than found in Great Lakes studies, Marsden said, but appear to be having a less negative impact in Lake Champlain. Lamprey control efforts starting in the 1990s likely contributed to the lake trout recovery.
While invasive alewife can prey on lake trout eggs and pass on a thiamine deficiency problem that impacts egg production in females, lake trout also feed on the energy-rich alewife. The timing of the apparent success of wild juveniles also coincides with the emergence of alewife in Lake Champlain, leading some researchers to suspect a positive relationship.
Managers and conservationists are eyeing the invasive round goby as a next potential threat to the Lake Champlain ecosystem. In other places, the quickly-reproducing gobies gather in huge swarms and feed on the eggs of fish like trout. But again, the dynamics of a growing and aging lake trout population could benefit from another food source. Over the longer term, climate change may also threaten important cold-water habitat for lake trout.
Funding for lake trout research and restoration will be part of an environmental trust fund required under the approvals for the Champlain Hudson Power Express, a transmission line that will lie on the bottom of Lake Champlain as it sends Canadian hydropower to New York City.
During a recent Lake Champlain citizen’s advisory meeting, Jim Lodge of the Hudson River Foundation offered an update. The foundation is the fund’s administrator.
The trust fund will spread $117.5 million over 35 years to projects the length of the transmission line, including Lake Champlain, the Hudson River and the Harlem River, near the project’s terminus in Queens. The fund parameters didn’t specify regional allocations.
“In some ways it sounds like a lot of money, as you’ll see when we get into projects and scope it doesn’t always seem like a lot of money,” Lodge said.
Lodge said the goal was to have a five-year implementation plan in place by the end of 2023. The trust fund was set up to focus its initial efforts on certain “priority projects” in the different regions.
In Lake Champlain, those projects include aquatic invasive species prevention and management, fish population and recreation studies and habitat restoration, which would receive the largest chunk of funding. Lodge described the initial investments as “data collection and analysis leading toward restoration.”