Short Wave - Spring ice is thawing earlier in lakes. What does that mean for life below the surface?

Episode Date: March 2, 2026

Lakes are freezing later, thawing earlier and experiencing dramatic temperature swings in between. And all that throws off the delicate balance of life below the surface. And that has a major impact on the roughly 1.7 million ice fishers in the U.S. who spend millions of dollars buying equipment and guide services each year. Producer Berly McCoy explains how scientists are tracking those ecological changes by getting out on the ice — to fish. Interested in more freshwater science? Email us your question at [e-mail] to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hi, shortwavers. Emily Kwong here with producer Burley McCoy and part two of her changing Lake Ice reporting. Don't worry if you haven't listened to the other episode. You don't need to. Appreciate this one. Definitely not, Emily. But quick recap, last episode we talked about how changing ice conditions are making it less safe to be on the ice, which is true where I live in Montana. Not only have there been warm spells, which make the lake ice less safe. This year, ice wasn't safe enough to walk on until the second week of January. Wow.

And Emily, you know how much I love to ice fish. Yes, you live for ice fishing season early. I know, and so far this year, that's been really tough here. So I recently went on an ice fishing trip with a fisheries biologist named Zach Feiner. I'll say I did see one guy catch one here yesterday, so they threw it back, so there at least one fish out there for us. Zach is in Madison, Wisconsin. Wait, you left your family in Montana to go fishing all the way in Wisconsin? In a heartbeat.

There's just no commitment more serious. But really, I wanted to get on the ice with Zach to talk about how lakes everywhere are losing ice and the impact that that's having on lake ecosystems from disrupting their food chains to lowering biodiversity, which could have a huge impact on your fishing way of life. Exactly. Me and about 1.7 million other ice. fishers in the U.S. Ice fishing is a huge industry that generates millions of dollars through equipment sales

and guide surfaces. I talked to David Van Lannan about how one of his favorite seasons, ice fishing, is shrinking. He grew up on a dairy farm south of Green Bay, Wisconsin, moved to Madison for work in 1971, and he says he's been fishing the area for decades. We've lost a good six weeks off of our ice fishing season since I started back in the 1980s. We used to start in December, end in April. Now we start in January and in March. Today on the show, how losing lake ice is affecting life below the surface.

And what that means for ecosystems and people who enjoy them? You are listening to Shortwave, the science podcast from NPR. Quick reminder, everyone, Shortwave comes out four days a week. That's Monday, Tuesday, Wednesday, and Friday. So to make sure you never miss an episode, look for the follow button on your podcast app and give it a top. Thank you so much. Okay, Burley, let's get into this. How was this reporting trip to go fishing in Madison, Wisconsin? It was packed. Zach picked me up at 5 a.m. Early bird gets the fish. I'm Burley. Can I throw my stuff in the back?

Get some donuts. Donuts are essential for ice fishing. They are essential. We drove about 15 minutes south to Lake Wabisa. to meet someone named Tom Seahash. He's a big walleye fisherman. He is the one who gave me the intel on this spot, and he's actually probably already down there. Because I wanted to catch a walleye. Is a walleye a fish? Yes, they are one of potentially dozens of fish

that are sensitive to changing lake ice. Their populations are doing okay right now in a lot of places, but biologists like Zach are keeping an eye on them because they spawn in the spring. Oh, yeah, that's when ice usually melts. Exactly. And so a big part of what Zach tracks is that timing of the ice freezing and thawing. And one of the parts of my research has really jumped out is that the timing at which the lake's thaw in the spring has gotten really variable. So, for example, in recent years, the earliest the lake has thawed has been in the middle of March.

And the latest the lake has thawed has been in the middle of May. So from one year to the next, it's a two-month-year. difference. That is a huge jump. What impact does that have on the fish? Yeah, Zach says it breaks down the normal process of what happens when a lake thaws. Can you describe that process? Yeah, it's kind of a domino effect. So in springtime, when a frozen lake starts to get more sun and warmer temperatures, that kickstarts algae blooms in the water that feeds little critters called zooplankton. And those zooplankton are a really important food source for some fish. But if there are these massive differences and when spring starts, it messes up the whole system.

All those events start to get scrambled up and mis-timed. So then your food web gets delinked or decoupled. And ultimately, you end up with not having enough food around to feed small fish. Zach's research has shown that in years with huge swings and when the lake thaws, they don't count as many young wallies the next fall. So fewer of them are surviving. Whoa. And the more that happens, eventually the less walleye there will be for people to catch and take home.

And the important thing to point out is that while I've seen this in walleye, lots of other species are seasonal spawners. They spawn in the spring or in the fall. So you could see these effects probably happening for a lot of different species. You know what I'm thinking about for some reason listening to this? Okay, my cat is so sensitive to the slightest changes in dinner being served by a half hour. And if it were a difference of months for his life cycle. I'm sure Zuka would screen. Yeah, yeah. I hope I'm not making like a false comparison here. It's just like I'm appreciating there's so much sensitivity for these species that a difference that could seem small to us is actually life or death to them.

Yeah, especially if the food is just no longer there anymore. And this is true for lakes outside of Madison as well. Scientists are really just kind of starting to study this. So in our last episode, we talked about how many lakes have already lost weeks of ice coverage each winter season. And thousands are predicted to stop for. warming ice entirely before the end of the century. And these are lakes where the ecosystems have evolved to be icy in the winter. Yeah, I've been wondering about this ever since your last story. What is the ecological impact for organisms that have adapted to live in an icy lake? Yeah. I mean, walleye are this cool water species that could really suffer in the coming years as the climate continues to warm. And they're one of many where this could happen, right? I really wanted to experience being on a walleye lake while they're still around and doing okay. So back at Lake Wabisa, we unloaded the fishing gear from the car in the neighborhood

cul-de-sac with just one house near the end of the road. We're headed through here, the joys of urban ice fishing. I followed Zach through the dark to a tall chain-linked fence next to the house while he pulled the sled that had all the gear in it. After a few minutes, the tree-lined path opened up to a dark, open, expanse with one green light in the distance. This is Tom? Yep, I think so.

How great Gatsby of you. What was the green light? This is a headlamp. So we had our headlamps on. We walked out into the lake. Early? I'll see your face without a spotlight in my eyes later. Oh, yeah. Sorry about that.

No, no. Everybody's got one. All the cool kids are wearing. Yeah. Zach sets up his insulated pop-up tent and drill some holes in the ice to fish through. We've got some electronic machines to help us out. One is sonar that can tell you if something is moving in the water and where. Another is an underwater camera.

Both of these things help you find fish. So I'm picturing you all standing in the dark on this icy lake and there's a line down in the hole. And you're like waiting? We're watching the sonar because it looks like there's something down there. Does it look like it's still there? It doesn't, unfortunately. It's a problem with fish.

They move. But eventually. There it is. Oh. We're going to find out. Got one. Yep. Blue gills.

Oh, a blue gills fish, so not a walleye? A blue gill, yeah. Not a walleye. Texas bluegill are a warm water fish and one that will probably do better in waters like these as climate change continues. So I take the fishing pool, give it a try. Hey, game on. Fish on. All right.

Oh, new species. Oh, okay. I've never caught crappie before. Crappy, not a bad word. Just a different type of fish. Also, a warm water fish, actually. And now, as an avid ice fisher, I'm always looking for reasons why I'm not catching the fish that I want to catch.

So I ask Zach if changing ice from year to year could be the reason we're not seeing walleye today. It could be one of the reasons why. Yeah, yeah. Yeah, I mean, it's, uh, It's tough. There's a lot of lakes where walleye have declined really significantly, and now the only reason they're walleye in there is because we have to stock them. Stocking, yes, I learned about this the one time I went ice fishing in Maine. Stockings where humans are putting young fish in the lake.

Yeah, often thousands to keep up their numbers. It's done for conservation and for people like me who like to fish. And it happens in a ton of places, including the lake I fish in the winter. Now, Zach says the question becomes, when do people stop stocking if a lot of those fish are just going to die? Right. Like, are you setting them up for doom if you're putting them in a lake that is inhabitable for them? Right. Like, if ice keeps shifting rapidly and significantly knocking down walleye populations, how long should people continue adding them back? And maybe, for example, switch to supporting warm water fish that people like to catch that would thrive in these warmer waters. If you have this traditional connection to the walleye, maybe that's a harder change to accept her to deal with. This would be a big change for the fishing community to ask someone to do something that they've done their whole life differently.

I guess climate change asks that of all of us. Does Zach have any idea, though, how people are going to handle going for warm water fish instead of these cold favorites? Yeah, he says through surveys he's found people have definitely noticed a change in lake ice, which is a big first step to get people to think about then how to move. make changes. When you're faced with what to do about climate change, especially with regard to fish or other things, like, it's hard to control the amount of a carbon in the atmosphere, right, at the local level. But you can think about the things you can control. Maybe that means you make different harvest decisions. You keep fewer walleye. Maybe you decide to go fish for something

else, right? That might be more resilient to harvest, like a largemouth bass or a bluegill that are more of a warm water fish. This story is reminding me how people who fish and people who hunt are actually paying often more attention to the environment than most. So it's cool to be hearing this from them directly, you know? Yeah, that's so true. And Zach says it may also get people to think about what else they can do to help lake systems, like protecting the habitat that certain fish like, like walleye. As for you, fisher burly, did you ever get any walleye? I did, but not the way I wanted. I'll have the fried walleye. You got one served to you a different way on a plate.

I did. It was lovely. It was delicious. I had it with some fried cheese curds. So no wallet. I'll just have to go back. And maybe it'll be for a different kind of fish. If you liked this episode, do us a favor and share it with a friend because your vote of confidence is actually what ensures we can keep making this program.

I also suggest you check out part one of Burley's changing. Lake Ice series and gorgeous photos from Burley's fishing trip. We will link to them both in our show notes. This episode was produced by Rachel Carlson, edited by our showrunner Rebecca Ramirez, and fact-checked by Tyler Jones. The audio engineer was Kwayze Lee. I'm Emily Kwong, and I'm Burley McCoy. Thank you for listening to Shortwave from NPR.