New research finds more genetic diversity in Adirondack brook trout
(NCPR) - Wild brook trout are one of the most prized species of fish in the Adirondacks, but they’re also one of the hardest to catch, in part because their populations have plummeted in recent decades.
Zachary Matson, a reporter for the Adirondack Explorer, wrote a piece in the current issue of the magazine about the history of wild brook trout in the park and what new research finds about the future of the species.
ZACHARY MATSON: There are historical accounts of early anglers pulling out trout left and right from streams and ponds all throughout the Adirondacks. The Adirondacks are really ideal habitat for brook trout, they like these sorts of cool water streams that we have all over the place. So, I think everyone who's studied this thinks that brook trout, historically, were all over the Adirondacks.
EMILY RUSSELL: You've got a line in your piece that's a really long list of things that have threatened the survival of wild brook trout in the park. Not just overfishing, but a bunch of other things. I wonder if you could just kind of lay them all out there. Give me an overview of what those threats have been to wild brook trout.
MATSON: Yeah, brook trout are one of those species that's very sensitive to environmental changes and can signal challenges. Acid rain was a major problem, obviously, throughout the Adirondacks. And acidification of waters had a devastating impact on brook trout. A major lake survey in the 1980s found that by the end of the 1980s, there were at least 40 lakes that were identified as having lost their entire brook trout population. These were lakes that were looked at in the 70s and they found fish, and by the late 80s, there were no fish there.
Also things like logging had a big impact, it reduced habitat, it warms the waters when you lose that tree coverage and causes more runoff and sedimentation. The construction of dams throughout the park, hundreds of them, creates these warmer ponded waters rather than the flowing streams that they like. Any kind of development, all the fishing, there have been non-native game fish that have been put into lakes every which way throughout the Adirondacks that out-compete or eat the brook trout. So yeah, they've faced a lot of challenges and are still hanging on.
RUSSELL: And now including climate change, right?
MATSON: Right. There's a federal study out there that suggests that if we continue, globally, the carbon emissions path that we're on now, there could be enough warming that brook trout could lose all of its habitat in the Adirondacks by the end of the century. So, yeah, the climate change challenge is really an existential one for brook trout in the Adirondacks.
RUSSELL: So there's been an effort recently to study trout populations in the park. Tell me about Trout Power and what they've found in their research.
MATSON: Trout Power is a nonprofit organization made up of volunteer anglers who go out to different locations in the Adirondacks and collect thin clips— they catch a fish and they just snip a little bit of its fin from his tail, and then they put that into a vial. Within that little thin clip, they can send it to a lab to run the genetic information of that fish. And then researchers can study— does this have the genetics of fish that was stocked or does it have a genetic pattern that suggests it has more unique DNA that is from a native strain that's been around longer. So really, for the first, time researchers are starting to get a better handle on just how widespread the genetic diversity of different strains of brook trout are throughout the park. And I think it is going beyond what maybe people previously understood in terms of how much diversity there really is in terms of the genetics of these fish.
RUSSELL: What does this new research about the genetic diversity of wild brook trout in the Adirondacks say about the future of those populations? How delicate is their future, and how hopeful are researchers and anglers about the survival of wild brook trout?
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, is telling researchers that the more diversity there is, the more likely some of those strains of fish are going to be able to survive warming weather and warming patterns and what have you.
Researchers are hopeful that if there is a great amount of diversity, and that that's protected against stocking, and these other threats, that if you restore streams so that there is more of habitat that these fish rely on, if you create access by removing barriers to cooler headwaters— if you do those types of things, plus you have this pre-existing diversity, some of them might not make it, but some of them might. Understanding that could also open up different paths to new conservation strategies. So the diversity is hopeful and I think it does offer some sense that they might be able to survive what is coming for them.
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