For decades, Adirondack resource managers have blamed the yellow perch for the decline of heritage trout strains, believing that perch were introduced to Adirondack waters in recent times and have been displacing the native strains from their historic habitat.

But lake sediment core samples taken by Curt Stager and his students at Paul Smiths College yield DNA evidence showing that trout have been co-existing with perch for at least 2,000 years there. While perch are aggressive competitors and native trout are in decline, the reason for the change in balance likely lies in other factors yet to be determined.

Martha Foley: You do a lot of research taking core samples of lake bottoms. This is your thing, right? So now, you’re telling me some really interesting stories about sampling the lake bottoms right off the campus of Paul Smith’s College and some really cool information that’s coming from that, that is kind of surprising I think.

Curt Stager: It’s a really exciting time to be doing this kind of research because there are new methods that are being developed. By teaming up with other people, with other expertise - especially my colleague Lee Ann Sporn, who is a molecular biologist - we got to follow up on a brainstorm that came from my students.

We were taking sediment cores looking at quality changes through time, climate changes through time, by collecting these tubular core samples from the bottoms of the lakes, taking the layers of mud that accumulated over the centuries and analyzing what’s in it. The students were saying, “Well gosh, can’t you look at some other things? Like when an animal dies, doesn’t it’s DNA stay behind in the sediment?” And we started looking it up and it turns out it’s a new field in my area.

So we said well, "Gosh, Lee Ann can do this," so we teamed up and we found some really interesting things about the history of fish - and especially yellow perch in the Adirondacks - which turns out to be relevant to fish management today.

MF: Right, the narrative has been that the yellow perch is outcompeting some of the heritage trout strains, right? And we have a sentimental attachment to the heritage trout, so what do you do about these perch that are pushing them out?

CS: t’s a serious problem. We do have genetic varieties of brook trout that are unique to the Adirondacks and they are really having a hard time for multiple reasons. One of the ideas was that yellow perch weren’t here before and have moved in, and they take over the lake and out-compete the trout. That’s been the basis of a lot of the fisheries management to save the trout.

This idea that there were no yellow perch in the high areas of the Adirondacks is from old surveys done in the 1800s where people just didn’t find them. It would seem strange though, because perch are all over North America. Why wouldn’t they be here? But that was the assumption, and that made people think it was the perch killing off the trout.

Well it turns out that we went out on the lake in the middle of the winter, the students, Lee Ann and I drilled a hole in the middle of the ice and lowered the sampler through, pulled up a big pipe full of mud and carbon-dated it. It showed that there was 2,000 - actually a little more than 2,000 - years of sediment layers in there.

MF: Isn’t that fascinating? Your students must love this!

CS: Oh it was fun, and it was right in front of the student center, so people eating lunch could watch while they’re out there. Back in the lab, Lee Ann sampled top to bottom of the core and found yellow perch DNA all through the sediments for the last 2,000 years.

MF: So there goes that narrative of the perch versus trout?

CS: Well it sure looks like if you’ve been around for 2,000 years then you’re probably a native. Which is really interesting because then you can get a whole new set of questions. One of them is, if yellow perch are native to the Adirondacks as well, maybe there are native strains of yellow perch - just like there are native strains of trout - that we haven’t even been looking for yet. Maybe it’s a biodiversity resource we didn’t know we had.

MF: Well cool. The other question is, if the trout and the perch coexisted so nicely for 2,000 years, what’s happening now?

CS: That could be really useful information as well. If the trout, which had been in the lake before about the mid 1900s, were coexisting with yellow perch all those centuries, what has changed now so that the perch would take over? Maybe there is some other trigger or some other problem that we need to be addressing as well.

It could be anything from other species - like adding big predatory pike or bass to a lake - or water quality problems that make algae blooms that favor the yellow perch over the trout, or even climate change. It opens up a whole new set of questions that could be useful for preserving both the yellow perch and the trout.