(upbeat music) - [Narrator] Welcome to the age of humans.

(upbeat music continues) (upbeat music) - These guys didn't sprout wings and fly over from Southeast Asia, we brought 'em here so we made the problem, we gotta, we gotta fix it.

(upbeat music continues) - Strangers in paradise.

It's a story about biology but it's also a story about perception and labels that spans both biology and culture and a lot of interesting and surprising ways.

(upbeat music continues) - After habitat destruction, the leading cause of species decline across the globe, are invasive species.

We've heard a lot about these kinds of stories but our show takes sort of a different perspective on it.

(upbeat music continues) - It's very easy to be like, invasive species bad, native species good, you know?

Like a kind of a binary approach to the world.

- [Nate] It sort of treats invasive species as an extension of ourselves.

How did these species get there and why can't we solve the problem?

- So the myna bird that is here is it a native species or is it an invasive species?

- So there you go, there's the million dollar question.

(upbeat music continues) - When you dig a little bit deeper, it really is a story about how we decide as a species what belongs and doesn't belong in wild ecosystems and how subjective those judgments can be.

(upbeat music continues) - What deserves to be saved and protected versus what deserves to be eradicated, right?

I mean, these are all really, really big questions that show us a lot about who we are.

(upbeat music continues) - The topics for invasive species read like, almost like a carnival adventure list, where you're like, huh okay, python hunting, horse roundup, carp derby.

- We filmed this amazing sequence with these invasive silver carp jumping out of the water and self-proclaimed rednecks, trying to catch them in midair with nets.

(fisherman laughing) From motorboats, you know speeding along the Illinois River.

- We had like, I think a really touching conversation in a lot of ways.

We had a lot of fun together and I got absolutely beat up by fish, which I didn't think was ever a thing that would ever happen to me.

(upbeat music continues) - So when they get spooked, one of the ways they escape from predators is just like fling themselves outta the water.

Very useful, probably for them, but it's very not helpful for people that wanna recreate on these waterways.

These fish will mess you up.

I got to experience it firsthand.

I was in a boat.

Everybody has like face masks on and you totally think it's overkill.

You're like, what are these people doing?

You hit these pockets where they just start jumping and these fish just start running into people's faces, hitting them on the back.

And so I'm right in the middle of this mess and there are fish coming at every direction.

It is totally insane.

(upbeat music continues) - My job on this shoot was to handle the high speed camera and to try to get specific shots of like fish jumping out of the water, people catching fish in nets, and so it was like a lot of trial and error.

There must be terabytes of absolute garbage that our editors had to go through.

I feel so sorry for them.

(upbeat music continues) - I still find fish goo in my equipment like six months later.

The thing about Febreze is it just covers up the fish smell, so I know it's still there.

It's never gonna go away.

(upbeat music continues) - You know, the pua'a has been a part of our oral traditions of our history, of our genealogy.

It is an integral part of our story.

(upbeat music) - I think one of the things that audiences are gonna notice about this episode is that more than I think any other episode it sort of embraces this gray area where the right answer depends completely on the way you see the world.

I think you're gonna be left feeling sort of conflicted on on the way you look at invasive species.

- You know, invasive species are not villains.

We project so much onto them.

We use the language of war to talk about them, that they're invading.

We're at war with invasive species.

It's a battle for, you know, this ecosystem and yet they're just wild animals trying to survive.

- I hope people leave having learned something fun but also feeling like, hmm, I don't know what the solution is here.

The solution's complicated and maybe we should go back and consider our values.

(upbeat music continues)