Burley McCoy

We drove about 15 minutes south to Lake Wabisa to meet someone named Tom Sihash.

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.

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

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.