Wildlife Watch: Biologists see improved health in Lake Champlain trout

Published: Nov. 23, 2021 at 2:49 PM EST
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BURLINGTON, Vt. (WCAX) - The state will start stocking fewer trout in Lake Champlain. Biologists say it’s a sign of a healthy population and a healthy lake.

The lake trout is native to Lake Champlain, but the fish was almost completely eradicated by overfishing and habitat destruction in the 1800s.

To help the population recover, the state started a program to restock the fish in the late 1960s and ‘70s.

“That program has continued. There were little starts and stops in the early years but from the ‘80s on it’s been continuing,” said Bernie Pientka, a fisheries biologist with the Vermont Department of Fish and Wildlife.

Each fish the state stocks in the lake is marked so the fish can be identified.

“So over those years we were stocking, all the fish we stock have a fin clip and we rotate the fin clip for different ages. So the fish out there we would see that after being out there for multiple years, we would see evidence it came from the hatchery as a source,” Pientka said. “For the most part, we had evidence that the fish we were seeing in the lake-- anglers were catching them-- are fish that were clipped from a hatchery source.”

The state works with many partners including Ellen Marsden, a University of Vermont professor in wildlife fisheries. In her research with students at UVM, Marsden started to notice fish that weren’t stocked.

“In 2000, 2001 we have seen multiple sightings of lake trout spawning successfully. That they are hatching successfully these little fish and never saw them again,” Marsden said.

But within the last decade, they started to see more and more fish. This was happening at different spawning points where the stocked fish were usually going.

“This was happening new and we traced it back. It started in about 2012. Suddenly we have natural reproduction producing fry live through the first winter of their lives. And at that point, they got it made. Their survival rate is going to be good,” Marsden said.

It is good news to these biologists.

“Jumping up and down and screaming on the boat. You didn’t hear us out there?! This was incredibly exciting to suddenly see not just accidentally, oh, there’s one small fish that doesn’t have its fins. I think we had a dozen on the deck that first day in the catch. Oh, this is big. This is something big,” Marsden said.

“It’s really exciting news,” Pientka said. “We have been working on lake trout for over 60 years on Champlain and this is a huge change. I mean, this was the initial goal of the stocking was to create a natural reproducing population.”

And it’s not a fluke.

“So we do it again the next year and we did it pretty much every two weeks throughout April through November to see where they were, what depth, what part of the lake. But it’s continued. In ‘16, the proportion of unclipped fish, in 2017 the numbers went up again. By ‘18, we were like at 56% of juveniles this little were unclipped. OK, this is a sustained recruitment we call it of these wild fish surviving against the population,” Marsden said.

Now, the state says they will be stocking one-third fewer lake trout into Lake Champlain.

“We are not just doing the cutoff and walking away; we are continuing to monitor the situation, we are continuing to evaluate it,” Pientka said.

But what does this say about the overall health of the lake? These biologists acknowledge things like cyanobacteria and invasive species remain concerns for the lake’s future but they say if the lake is stable enough to see reproducing trout, it’s a sign it is healthy.

“A healthy lake trout population is absolutely a healthy lake. We have always known that’s the goal. The state has been stocking them since the ‘60s. Come on, can we get some good results here? This is the good news. That’s what they were trying to do all along. From a researcher standpoint, great. Why did that happen now? We have to try to figure out what went right and it’s a nice position to be in. Usually, it’s like, oh, what went wrong? Now, suddenly after five decades, it’s what went right,” Marsden said.

A step forward in creating a healthy trout population within Lake Champlain.

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