(bright music) - Welcome to "Prairie Sportsman," I'm Bret Amundson.

Today we're in Northern Minnesota on a small but deep lake crappie fishing.

Most of the fish are 30 to 50 feet deep.

If you're gonna target crappies that deep, there's some important things you need to know, and in this episode we're gonna tell you what those are.

(vibrant music) - We heard kind of loud and clear from our panfish anglers that the next thing they'd like us to focus on is crappie.

And we realize that, you know, crappie are found throughout the state of Minnesota, but they live in a huge variety of habitats.

So we're trying to little learn a little bit more about their biology and about how different like environments might affect angling.

So we're out here on a deep lake today, and we wanna understand how does deep water angling impact the crappie population, and what kind of guidelines can we come up with for anglers to help them make a more informed decision when they're out on the water?

- [Bret] With basing crappie fishing being popular among anglers, we wanted to know what effect Barotrauma might have on these fish.

- Barotrauma has been an interesting topic.

There's been a lot of discussion about it, and we're gonna figure out some best practices here.

- Bret] So what is Barotrauma?

Barotrauma and fish is similar to the bends in humans.

When a fish comes up from deep water, it goes through a change in pressure.

This change can cause internal damage to the fish, sometimes it's visible, sometimes it's not.

Visible changes include bulging eyes, an expanded swim bladder that pushes the stomach into the mouth, bleeding gills or gas bubbles under the skin.

Sometimes a released fish struggles to swim to the bottom, and even if they do, they still may not survive.

We're on a lake in northern Minnesota right now and we are doing some research for the Minnesota Department of Natural Resources.

We're out here with Lindner Media, "AnglingBuzz."

We're trying to catch some crappies right now and determine the effects of Barotrauma in various stages of natural fishing.

So, we've got different methods of fishing, we've got shorter handling times, we've got different ways to hold the fish.

A bunch of different methods we're gonna learn about, but first we gotta catch some fish.

- One of the things that I think is neat about the work that they're doing out here is that this was really driven by stakeholders.

So, Minnesota has a number of work groups, typically species specific.

So the panfish work group had been raising concerns about this for quite some time.

So they were to do some collaboration with the DNR and develop a preliminary study or a pilot project last year to dive into this to see how it might work.

And then this year now they're doing a little bit more of a refined approach to the study.

- So we kind of expanded on last year's work.

The main point of last year's work was just to see if something like this can even be done in the wintertime.

We wanted to see if we could even come out and set net pans, could we catch enough fish?

Could we keep gear from freezing in?

And we found out that we could, and we were able to do it on three different lakes with three different depth trials, which started to provide some provocative information that we wanted to continue to follow up on.

- [Bret] This year, they're using three different methods to study the effects of Barotrauma on crappies.

- In the first method that we're using is catching fish and holding them in pens like we did last year.

- [Bret] Two transport snowmobiles were on standby as anglers fished.

- Fish.

- [Bret] While this wasn't a private lake we were on, there was no public access.

- Jeremy!

- [Bret] And the area residents welcomed us for our study.

(snowmobile engine running) - Fish!

(crew chatting) I got one.

(snowmobile engine revving) Whew, there we go.

- [Bret] One thing I also wanna mention is you guys took great steps to really reduce the fish handling time.

- We did, yeah.

We were able to get these fish, we were actually shuttling them over to the net pens using snowmobiles.

So, a lot of times we were, from the time the fish was caught to the point where it was in the pen was around 30 seconds.

So, we were moving pretty fast.

We made a real effort to cut that handling time down.

- [Bret] The second method also utilized a holding pen, but biologists used a weighted contraption known as a descending device to quickly get fish back down to the depth that they were caught at.

- The first pan we just put fish in much like we did last year, released them directly into the pen.

The second pen, we actually wanted to see if we use the descending device, if that would've much of an impact, for a couple different reasons.

First, we hear anglers ask us questions about descending devices or fizzing to see if there's safer ways to release a fish.

So we could evaluate that, but we could also try to eliminate any confounding factor of the pen itself.

Last year we observed that some fish had trouble getting to depth because they'd run into that net.

So we thought, "Well, if we place them there," "that kind of eliminates that risk to the fish," which should give us a little better question, or a little bit better answer, I should say.

(gentle music) - [Bret] The third method involved an angler catching fish.

In this case, Jake Wallace from "AnglingBuzz".

As soon as the fish came outta the water, it was quickly unhooked, given a quick once over, and rated on a scale for Barotrauma symptoms and then released to minimize as much handling time as possible.

- There we go.

(snow crunching) - [Crew] Oh, we got one going.

- There he his.

- [Crew] We got a live one, here.

Jake really came back to the dock.

- [Jake] Team blue.

(chuckles) (crew chattering) He's just a little guy.

(crew laughing) (crew moans) - We got him.

- [Crew] It still counts.

- Yep.

- Right there at about 39 again.

- [Jake] Yep.

- How does his barrel, it doesn't look terrible.

- [Jake] Not bad.

He's got a rock in his stomach.

I'd say that's a two.

- [Dave] A two?

- [Jake] I was gonna write a two, that's what I think he looks like a (indistinct) (water splashes) There he goes, all right.

He looked like he went out and behind me.

- [Crew] That's him right there, huh?

He's still there.

(crew chattering) - And, I think, 35 feet under the ice.

Yeah, so we've been releasing fish with two forward facing sonar units to see if we can track the fish down to depth.

What they do, do they go down, do they go down the bottom?

Do they maintain or do they float up?

And we've had a mix of results so far.

We're still working on it, but interestingly, one of the groups over there doing it had one fish they caught in 48 to 50 feet come up stone dead.

It like came up the hole, it was dead and unreleasable, the second fish from 45 feet was released and went down and they tracked it with both units and it popped up right away and they never saw it again.

So we actually went over and looked at it with the aqua view camera and it's right underneath the ice, floated up dead.

So we're gonna go take a peek at that fish just to show the different variables that are involved with catching these fish outta deep water.

Some probably do well, some do okay and some die.

So, that's what we're trying to get to the bottom of here.

(bright music) - [Crew] Not fast when it means, I mean, it's just.

- [Crew] Yeah, he's still fighting it pretty good, right?

There he goes, doesn't he?

- [Crew] Right there.

- [Crew] Right there, yep, there he is.

(bright music) - [Bret] So that made it all the way down to the bottom and now it's working its way back up?

- He made it to almost 40 feet, and it's 55, yeah.

- [Bret] Okay.

- So, but he was down, there was another group of fish, and he got down just to them and now he's- (crew chattering) - He's gonna go quick now, I bet.

- [Bret] "Hey, guys, what are you doing?"

- "Hey, hey."

(crew laughs) - [Bret] "Where am I going?"

"Come back."

- [Crew] Yep, not looking good for yesterday.

(wind blowing) - [Crew] Oh, he just kicked there.

- [Crew] He did, wow!

(crew laughing) - [Crew] Yeah, it's not.

- [Crew] What'd he do?

- [Crew] "I think I can, I think I can."

- [Crew] He's working on up.

- [Crew] He was coming up, then he leveled off again at 20 feet.

- [Crew] Now he's going back down.

- [Crew] Wow, great course.

(chuckles) (crew chatters) - It's like he's got the life, he just doesn't have the... - It's amazing you can just see him.

You'd really think though, getting down to depths and getting back there.

- It should just equalize.

- You would think.

- And we saw a fish go right back down and seem to be with the school and be all right.

We saw a fish go right back down and then reach a certain depth and then kind of flutter down.

(chuckles) I mean, we saw it, and we saw fish float back up.

So, the technology will really show you a lot.

And I hope that whatever they learn from this study that the citizens and the license holders are able to say, "All right, this is the information we have."

"This is how we think we should manage the resource," "along with this information" "and input from the agency."

- [Bret] On day three, it was time to check the holding pens to see how the crappies were doing and employ an underwater drone.

(twinkling music) The underwater drone or ROV was deployed where Jake was fishing the day before.

The goal was to try to find the fish that he released to see if they'd made it to the bottom or if they'd floated up and died under the ice.

(pensive music) - How do you verify if the fish you immediately let go lived, right?

And thought, well some of them might sink to the bottom, but a lot of them we know float up and do they float up and sit under the ice and recover later?

Very possibly.

Or do they float up and die?

So we just thought, we caught a bunch of the fish we immediately released in one little area, so we just took the underwater ROV camera and we flew it around and we did find a number of dead fish, you know, came right up on them, and they were just stiff and dead under the ice.

So it was a percentage of what we actually re-released, so.

- [Bret] Since no one had been recently fishing in this particular area, it was clear that these were the fish that Jake had caught.

- [Jake] Yep, I don't see anybody walking now, but.

- [Dave] So that's the third fish we've seen.

- [Jake] Correct.

(gentle music) - So right now Mike has the underwater drone out and they're just looking for dead crappies that have floated up under the ice and are trapped and they're finding all sorts of fish under there.

In fact, when Jeremy was walking around, he found one that actually floated up into the hole and is frozen into one of the holes now, but they've got some forward facing sonar that they're using to track the drone underwater.

And then Jeremy's walking up on top of the ice and following the drone from the forward facing sonar guys.

And I'm marking where they're finding all these dead fish and I think it's been four or five now or something like that they found.

(gentle music continues) So far 40 fish caught that you released with the forward facing sonar.

- Yep.

- [Bret] And we found in just, what, 10, 15 minutes, if that?

- Six under the ice and one in a hole.

- [Bret] So seven dead ones.

- And that's pretty, and our field of view is not that big, but that's a lot of dead fish, you know.

- Yeah, you know, and I mean it does replicate actual real world immediate release fishing conditions where sure these fish swim down, but some percentage of them, don't make it.

- After a comprehensive search of the area, it was time to go back and check the pens and try to get some preliminary results.

We had live scopes and Lowrance units and Humminbird units all over the place.

When you saw that part of the research, that part of the study, was there anything that surprised you or anything that you saw there that stood out?

- Yeah, you know, the crews actually working up the fish right now, so, you know, we're gonna have to dig into the numbers, but just general observation, you know, it seemed like about a third of the fish were floating in each of the net pens, so it didn't seem like the descending device made much of a difference.

Both of those pens looked the same.

And interestingly enough, when the crew came out today and used the underwater drone, they found that about a third of the fish that were captured yesterday, they actually found pinned up underneath the ice.

So it seemed like, regardless of which method was used, we were finding a similar number of fish that were, that weren't able to, to maintain their depth and were pinned up near the surface.

And then both in, in the pens, in both pens, and also just out here on the open ice, we observed some fish that had, you know, apparently died and actually sank to the bottom.

So some fish seemed to be released and they swim down and they do just fine.

Some fish are released and then end up floating back to the surface and some fish seem to swim down to depth only to find themselves laying on the bottom.

So there's definitely different things that are going on with each individual fish.

- And these were some deep waters that we were fishing in.

- They were.

- Deeper than last year.

We don't have final numbers or final tallies on any of this stuff yet.

This is just kind of observations that we've had on what these fish have have experienced out here today.

But it was really interesting taking that underwater drone out there and seeing those fish pinned up against the bottom of the ice.

I mean, it's something you hear about, but without that sort of tech, it's hard to actually see it.

- Yeah, and you know, and I'm as guilty as anybody when I've been fishing, I release the fish and say, "Well, that fish swam down."

"I'm sure it was fine."

So, it was extremely informative to be able to use the forward facing sonar and track these fish for, in some cases, we were able to track 'em up to five minutes or more.

And what we found is there was a delay between the point of that fish descending to depth and where it really started showing signs of trouble and floated back to the surface.

So I don't think that in most cases that mortality is instant.

It probably occurs after that fish, you know, at least makes an effort to return to depth.

But yeah, if you're, you know, I think that fish yesterday that was stone cold dead, I think that was caught like 50 feet of water.

You know, obviously some fish are just instantly killed.

But probably that delayed mortality is, you know, more common.

- And I think it's also important to note that this research is ongoing.

Like, you're gonna continue to do this, you're gonna continue to try different methods and try to get the best results possible.

That's the bottom line.

You're just trying to find the best results.

- Yep, absolutely, yep.

So we're hoping to add a little bit more precision where we can come up with some, you know, somewhat precise estimates of mortality at given depth, but it'll take more data and more time to do that.

- We're not trying to say something's right or wrong, we just want to know if something's happening to let other anglers know so that when they're going out they have it in their mind that, "Hey, you know, for these crappies," "if you're fishing them super, super deep," "there's probably a good chance" "there's gonna be some dying."

I mean, I don't know about you, but I run into a lot of guys out on the ice that it doesn't even enter into their mind that they're killing a fish.

- They don't know about it.

- This is my opinion, but what I've seen doing this fishing and with this research that it makes a lot of sense to me that if you are going to target fish in deep water, it's probably best again to just use this as a harvest opportunity, not necessarily recreational fishing to see how many can put on top of the ice, or how many can catch and let go.

- [Bret] All the fish that were kept in the pens were either sent to the lab for necropsies or sent home with some of the anglers for fish fries.

We learned a lot about Barotrauma, but more information about this study will be coming out in the future, and of course more studies will continue next winter.