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

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 https://www.npr.org/people/985775371/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 [email protected] mailto:[email protected]. Listen 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 http://plus.npr.org/shortwave. See pcm.adswizz.com https://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 https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:00Speaker 00

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• 0:19Emily Kwong?

  You're listening to Short Wave from NPR.

• 0:24Emily Kwong?

  Hi, Short Wavers. 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 to appreciate this one.

• 0:36Speaker 02

  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.

• 0:54Emily Kwong?

  Wow.

• 0:54Speaker 02

  And Emily, you know how much I love to ice fish.

• 0:57Emily Kwong?

  Yes, you live for ice fishing season, Burley.

• 1:00Speaker 02

  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 Finer.

• 1:08Speaker 03

  We'll say I did see one guy catch one here yesterday. So they threw it back. So there's at least one fish out there for us. But.

• 1:16Speaker 02

  Zach is in Madison, Wisconsin.

• 1:19Emily Kwong?

  Wait, you left your family in Montana to go fishing all the way in Wisconsin?

• 1:23Speaker 02

  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.

• 1:38Emily Kwong?

  Which could have a huge impact on your fishing way of life.

• 1:42Speaker 02

  Exactly. Me and about 1.7 million other ice fishers in the US. Ice fishing is a huge industry that generates millions of dollars through equipment sales and guide services. 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.

• 2:07Speaker 04

  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, end in March.

• 2:21Emily Kwong?

  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 Short Wave, the science podcast from NPR.

• 2:45Speaker 00

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• 3:42Emily Kwong?

  Quick reminder, everyone. Short Wave 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 tap. 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 5:00 AM. Early bird gets the fish.

• 4:08Speaker 02

  I'm Burley.

• 4:12Speaker 02

  Can I throw my stuff in the back?

• 4:15Speaker 03

  Some donuts.

• 4:17Emily Kwong?

  Donuts are essential for ice fishing.

• 4:19Speaker 02

  They are essential. We drove about 15 minutes south to Lake Wabisa to meet someone named Tom Seehash.

• 4:26Speaker 03

  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.

• 4:34Speaker 02

  Because I wanted to catch a walleye.

• 4:37Emily Kwong?

  Is a walleye a fish?

• 4:38Speaker 02

  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.

• 4:52Emily Kwong?

  Oh, yeah, that's when ice usually melts.

• 4:54Speaker 02

  Exactly. And so a big part of what Zach tracks is that timing of the ice freezing and thawing.

• 5:00Speaker 03

  And one of the parts of my research that has really jumped out is that the timing at which the lakes thaw in the spring has gotten really variable. So, for example, the earliest 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 difference.

• 5:23Emily Kwong?

  That is a huge jump. What impact does that have on the fish?

• 5:27Speaker 02

  Yeah, Zach says it breaks down the normal process of what happens when a lake thaws.

• 5:31Emily Kwong?

  Can you describe that process?

• 5:32Speaker 02

  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 in when spring starts, it messes up the whole system.

• 5:54Speaker 03

  All those events start to get scrambled up and mistimed. So then your food web gets delinked or decoupled. And ultimately, you end up with not having enough food around to feed small fish.

• 6:04Speaker 02

  Zach's research has shown that in years with huge swings and when the lake thaws, they don't count as many young walleyes the next fall. So fewer of them are surviving.

• 6:13Emily Kwong?

  Wow.

• 6:14Speaker 02

  And the more that happens, eventually the less walleye there will be for people to catch and take home.

• 6:19Speaker 03

  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.

• 6:30Emily Kwong?

  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, like.

• 6:42Emily Kwong?

  And, and if it were a difference of months for his life cycle.

• 6:47Speaker 02

  I'm sure Zuko would scream.

• 6:48Emily Kwong?

  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.

• 6:59Speaker 02

  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 forming ice entirely before the end of the century. And these are lakes where the ecosystems have evolved to be icy in the winter.

• 7:25Emily Kwong?

  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?

• 7:33Speaker 02

  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 a neighborhood cul-de-sac with just one house near the end of the road.

• 7:56Speaker 03

  We're headed through here to the joys of urban ice fishing.

• 8:00Speaker 02

  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?

• 8:16Speaker 03

  Yep, I think so.

• 8:17Speaker 02

  How Great Gatsby of you. What was the green light? This is a headlamp. So we had our headlamps on. We walked out onto the lake.

• 8:26Speaker 06

  Early? I'll see your face without a spotlight in my eyes later.

• 8:31Speaker 02

  Oh, yeah, sorry about that.

• 8:32Speaker 06

  No, no, everybody's got one. All the cool kids are wearing them.

• 8:35Speaker 02

  Yeah. Zach sets up his insulated pop-up tent and drills some holes in the ice to fish through.

• 8:44Speaker 02

  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.

• 8:54Emily Kwong?

  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?

• 9:00Speaker 02

  We're watching the sonar because it looks like there's something down there.

• 9:05Emily Kwong?

  Does it look like it's still there?

• 9:09Speaker 03

  It doesn't, unfortunately. That's the problem with fish, they move.

• 9:13Speaker 02

  But eventually.

• 9:18Speaker 03

  We're gonna find out. Got one.

• 9:24Speaker 03

  Yep.

• 9:26Speaker 03

  Bluegills.

• 9:28Emily Kwong?

  Oh, a bluegill's fish, so not a walleye?

• 9:32Speaker 02

  A bluegill, yeah. Not a walleye. Zach's 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 pole, give it a try.

• 9:45Speaker 07

  Hey, game on. Fish on.

• 9:49Emily Kwong?

  All right.

• 9:49Speaker 07

  Crappy. New species.

• 9:51Emily Kwong?

  Oh, OK. I've never caught a crappy before.

• 9:54Speaker 02

  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.

• 10:13Speaker 03

  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.

• 10:27Emily Kwong?

  Stocking, yes. I learned about this the one time I went ice fishing in Maine. Stocking's where humans are putting young fish in the lake.

• 10:35Speaker 02

  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 gonna die.

• 10:53Emily Kwong?

  Right, like, are you setting them up for doom if you're putting them in a lake that is inhabitable for them?

• 10:58Speaker 02

  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.

• 11:13Speaker 03

  If you have this traditional connection to walleye, maybe that's a harder change to to accept or to deal with.

• 11:18Emily Kwong?

  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?

• 11:34Speaker 02

  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 make changes.

• 11:44Speaker 03

  When you're faced with what to do about climate change, especially with regard to like fish or other things, like it's hard to control the amount of like 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.

• 12:09Emily Kwong?

  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?

• 12:19Speaker 02

  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.

• 12:29Emily Kwong?

  As for you, fisher burly, did you ever get any walleye?

• 12:34Speaker 02

  I did, but not the way I wanted. I'll have the fried walleye.

• 12:42Emily Kwong?

  You got one served to you a different way, on a plate?

• 12:45Speaker 02

  I did. It was lovely. It was delicious. I had it with some fried cheese curds. So no walleye, I'll just have to go back. And maybe it'll be for a different kind of fish.

• 13:00Emily Kwong?

  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 Burleigh's Changing Lake Ice series, and gorgeous photos from Burleigh's fishing trip. We will link to them both in our show notes.

• 13:19Speaker 02

  This episode was produced by Rachel Carlson, edited by our showrunner Rebecca Ramirez, and fact-checked by Tyler Jones. The audio engineer was Kwesi Lee.

• 13:28Emily Kwong?

  I'm Emily Kwong.

• 13:29Speaker 02

  And I'm Burleigh McCoy.

• 13:30Emily Kwong?

  Thank you for listening to Short Wave from NPR.

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