New research finds more genetic diversity in Adirondack brook trout

(NCPR) — Wild brown trout are one of the most valuable fish species in the Adirondacks, but they’re also one of the most difficult to catch, in part because their populations have plummeted in recent decades.

Zachary Matson, a reporter for the Adirondack Explorer, wrote an article in the current issue of the magazine about the history of wild brown trout in the park and what new research is revealing about the future of the species.

ZACHARY MATSON: There are historical accounts of early anglers pulling trout from streams and ponds left and right throughout the Adirondacks. The Adirondacks really are an ideal habitat for brown trout, they like that kind of cool water currents that we have everywhere. So I think everyone who has looked into this thinks brown trout have historically been all over the Adirondacks.

EMILY RUSSELL: You have a line in your article that is a really long list of things that have threatened the survival of wild brown trout in the park. Not just overfishing, but a few other things. I wonder if you could just put them all out there. Give me an overview of what these threats to wild brown trout were.

Brown Trout Show at the Wild Center. (Photo: Wild Center, Creative Commons, some rights reserved)

MATSON: Yes, brown trout are one of those species that are very sensitive to environmental changes and can signal challenges. Acid rain was obviously a big problem in the Adirondacks. And acidification has had a devastating impact on brown trout. A major lake survey in the 1980s found that by the late 1980s at least 40 lakes had been identified as having lost their entire brown trout population. These were lakes that were surveyed and found fish in the 70’s and by the late 80’s there were no fish there.

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Also things like deforestation have had a big impact, they reduced habitat, they warm the water when you lose tree cover and cause more runoff and sedimentation. Building dams throughout the park, hundreds of them, creates these warmer ponds rather than the flowing streams they like. Every kind of development, all that fishing, there was non-native wild fish that were put in lakes all over the Adirondacks that outcompete or eat the brown trout. So yes, they have faced many challenges and are still persevering.

RUSSELL: And now climate change, right?

MATSON: Right. There is a federal study that suggests that if we continue on the global carbon emissions path we are on now, there could be enough warming for brown trout to eclipse their entire habitat in the United States by the end of the century could lose the Adirondacks. So, yes, the challenge of climate change is truly an existential challenge for brown trout in the Adirondacks.

Anglers and members of Trout Power came together for a weekend in June 2022 to collect genetic samples at Great Camp Sagamore. (Photo courtesy of Adirondack Explorer)

RUSSELL: As such, there have been recent efforts to study trout populations in the park. Tell me about Trout Power and what you found in your research.

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MATSON: Trout Power is a non-profit organization made up of volunteer anglers who go to various locations in the Adirondacks and collect thin clips — they catch a fish and just flick a bit of its fin off its tail, and then they stick that in you Vial. Within that small thin clip, they can send it to a lab to analyze the genetic information of that fish. And then the researchers can examine – does this have the genetics of fish that was stocked, or does it have a genetic pattern that suggests it has more unique DNA, coming from a native variety that’s been around longer. So, for the first time, researchers really get a better view of how widespread the genetic diversity of different brown trout strains is throughout the park. And I think it goes beyond what people might have understood before, just how much diversity there really is in terms of the genetics of these fish.

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RUSSELL: What does this new research into the genetic diversity of wild brown trout in the Adirondacks say about the future of these populations? How tenuous is their future and how hopeful are researchers and anglers for the survival of wild brown trout?

Kurt Jirka and Alex Gatch maintain a fishing net to monitor the brown trout population in a lake in the fall of 2016.

MATSON: I think their future is still very delicate. And there are these much larger trends at play. But understanding the genetic diversity of the fish that are here now tells researchers that the more diversity there is, the more likely some of these strains of fish will be able to survive warming weather and warming patterns and whatever.

The researchers hope that if there is great diversity and it is protected from stocking and these other threats, if you restore streams there will be more habitat these fish rely on when you create access by removing barriers to cooler headwaters – if you’re doing things like that and you have that variety already there, maybe some of them won’t make it, but some of them might. Understanding this could also open different avenues to new conservation strategies. So the diversity is hopeful and I think it gives some sense that they might be able to survive what’s coming.

2022 Copyright Public Radio of the North Country.

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