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Sharks VS Orcas, Dolphins, & More! | 2025 Sharkfest MEGA Episode | National Geographic

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NARRATOR: From the depths...

The giants are stirring...

MAN: This is almost as big as the boat

NARRATOR: Great whites in Hawaii...

MAN: I poked my head above the water and say,

"Hey guys there's a shark under your boat."

NARRATOR: Tigers in French Polynesia...

ANDY: Holy smokes.

A lot of sharks here.

NARRATOR: Possibly the largest ever caught on camera.

KORI: She's the biggest shark I've ever seen.

ANDREW: This thing is so big.

NARRATOR: What's behind these unbelievable encounters?

MARK: Deep Blue is probably the most famous shark in the

world besides Jaws.

NARRATOR: And can a tiger from Tahiti challenge

Deep Blue's legendary status?

Hawaii, a tropical paradise...

Known for white beaches, stunning scenery and

abundant marine wildlife.

Many shark species call these waters home.

Tiger sharks, hammerheads and oceanic white tips are common.

But it's extremely rare to see a great white...

On January 11, 2019, that was all about to change.

Everyone on the island of Oahu was talking about a huge

sperm whale carcass near the shore, attracting sharks.

An unusual sight for most.

But for wildlife photographer, Kimberly Jeffries, and boat

captain and diver, Mark Mohler, it sounded

like a chance to capture some amazing photos.

MARK: So we heard about the whale on the news.

We had reports of tiger sharks, oceanic white tips,

even hammerheads.

We wanted to get out as soon as we could and by the time we

made it out, the whale had already washed ashore

right here at Sand Island.

KIMBERLY: That's exactly where it was.

It was beached right there on the sand next to the rocks.

NARRATOR: Kimberly is a professional wildlife

photographer and conservationist.

Capturing amazing images, above and below the surface.

She and her boyfriend, Mark, dedicate as much of their time

as possible to their true passion, photographing and

studying animals in the water.

On January 12th, the Department of Land and Natural Resources

tows the dead whale back into the ocean.

KIMBERLY: I heard reports that they had dropped the whale

carcass eight miles offshore.

And I was like, "Let's go check it out."

NARRATOR: The next morning, Mark has other plans.

So Kim, along with two friends, Andrew Gray and

boat captain, Danny Roberts, set off in search of the carcass.

ANDREW: We got about 100 meters off the whale and

started gearing up.

NARRATOR: This is the moment they've been waiting for.

A chance to see whatever might be lurking under the water,

scavenging on the giant carcass.

ANDREW: And at that point, tiger sharks started swimming

up to our boat and checking us out.

So we knew it was gonna be a good dive.

NARRATOR: Andrew and Kim get in the water next to the

whale, excited to shoot.

CHRIS: Tiger sharks are probably the apex predator

around the Hawaiian Islands.

And they'll eat everything.

But, when a dead whale shows up, it's like ringing the

dinner bell for tiger sharks.

So, by and large, sharks don't consider humans food.

We are simply not on their menu.

But occasionally, people do get bitten and

we don't really know why.

One possibility is defense.

So, getting in the water around these sharks is

obviously a really cool experience, and the chances

of being bitten are obviously low, but we never advise that

for the public because that's a good way to

become an accident.

NARRATOR: An ominous quiet surrounds Kim and Andrew.

And the tiger sharks vanish.

After only minutes in the water, they discover the

tiger sharks had a very good reason to leave quickly.

ANDREW: A big shadow started appearing,

headed right towards us.

And I was thinking, what in the world is this?

'Cause it was way bigger than any shark I'd expect.

KIMBERLY: She was by far the biggest white shark I've ever

seen and, honestly, her girth was approaching

pilot whale size in just sheer mass.

ANDREW: This white shark swims right by Kim and I,

and heads directly towards the whale and took a big bite.

DANNY: There it is.

(whistles).

She is massive.

ANDREW: This thing is so big.

I would estimate this shark at six meters,

that's about 20 feet long.

NARRATOR: This seemed like the opportunity of a lifetime and

Kim didn't want Mark to miss it.

In French Polynesia, another megashark sighting...

but this time...it's a tiger.

And it may be the largest tiger shark

ever caught on camera.

Marine biologist Kori Burkhardt recorded this

female in 2018...

And named her Kamakai.

KORI: We have seen some really, really big sharks.

But none quite like her.

NARRATOR: The south Pacific is known to grow some of the

biggest tiger sharks in the world...

Bigger than Hawaii.

Bigger than Tiger Beach, Bahamas.

And French Polynesia may be attracting the biggest of them all.

Male tiger sharks can grow to a whopping 13 feet.

Females?

Even bigger.

And Kamakai: she's off the charts.

KORI: When we first met Kamakai it was really unexpected.

I've been diving with tiger sharks in multiple countries

and she is by far the biggest I've ever seen.

The smaller sharks took a, took a back seat to her for sure.

NARRATOR: Kori is five foot eight without her fins.

Based on that, Kamakai could be 16 feet!

Larger tigers are extremely rare...

The largest ever documented tallied 18 feet.

Her massive girth also sets her apart.

KORI: It's not just her length, but her width as well.

She can be 5 meters long, but when she's like 3 meters wide,

including her fins, like, that's insane.

NARRATOR: Kamakai could've been pregnant...

And, if so, are big sharks like her coming here to give birth?

Finding her again may unlock those secrets.

KORI: The biggest priority and the biggest goal would be to

see her physiological changes since the last time we saw her.

If she's skinnier, if she looks like she's a bit

smaller, maybe she did pup.

ANDY: Okay, here we go.

NARRATOR: Kori enlists cameraman and shark conservationist

Andy Casagrande to help with the search.

ANDY: She's got to be one of the biggest tiger sharks that

I have ever seen.

NARRATOR: Andy knows big sharks and knows how to be

in the water with them.

But he's never dived with the tigers of Tahiti.

ANDY: There's only a handful of spots in the world where

you get this sort of density of tiger shark action.

Super pumped. This is day one.

NARRATOR: Since the government banned shark fishing in

2 million square miles of the South Pacific in 2006...

These waters have become a vibrant Sharkapolis...

More than 20 different species.

With tigers at the top of the pecking order.

Less than a mile from the main island of Tahiti is a hot spot

known for big sharks.

KORI: You can see we have sharks here already,

just as we pull up.

Some black tip sharks, grey sharks, and hopefully

we can see some tigers here.

ANDY: Let's suit up.

NARRATOR: Andy and Kori decide to free dive,

using only snorkels.

Scuba gear could spook the sharks.

Their plan: to take pictures of as many dorsal fins

as they can.

Like a finger print, each is unique.

They'll use the fin shots to look for a match with Kamakai.

ANDY: Kori, I am going to follow your lead, eh?

KORI: Yeah.

ANDY: Wow, there's a lot of sharks here.

I mean, I'm gonna follow you.

Anytime you dive down, I'll follow you.

KORI: Ka ka ka kay!

NARRATOR: Kori's underwater call lets Andy know there's a

tiger shark close by.

KORI: Ka ka ka kay.

NARRATOR: Andy goes after a dorsal I.D. shot.

The underbelly is smooth, no claspers.

The dorsal fin shows mating scars.

She's a female.

ANDY: Kori, on the next one, if she comes by, can you

dive down and try to get closer?

KORI: Yeah.

NARRATOR: To measure the shark Andy will use Kori as a comparison.

But first, she must get close.

KORI: Ka ka ka kay.

NARRATOR: Kori is a master free diver.

She dives 60 feet deep and holds her breath for up to four minutes.

She makes no noise at all.

Now the tiger comes right in.

It's bold.

Maybe too bold.

KORI: Ka ka ka ka kay!

Ah!

NARRATOR: A big Tahitian tiger shark goes eye-to-eye with

marine biologist Kori Burkhardt.

NARRATOR: Kori must swim close to get a size comparison.

She's big, 12 or 13 feet.

But Kamakai is around 16 feet,

and the dorsal fin isn't a match.

So this is not Kamakai.

ANDY: Wow, that was incredible.

NARRATOR: But it is another large female tiger shark.

And it supports findings that bigger sharks now thrive

in Polynesian waters.

Andy and Kori aren't ready to give up yet,

Kamakai could be out here too.

In Hawaii, divers Kim and Andrew are experiencing a

close encounter with a massive great white...

And their friend Mark races to meet them.

KIMBERLY: I've been to Guadalupe and I've seen quite

a few white sharks in person, and this was by far the

largest that I've ever seen.

It was really surreal.

Her pace was not what you would imagine.

She was really just very stately in her

movement and manner.

ANDREW: She stuck around for about half an hour,

circling the whale and feeding.

And then she dove straight down under the whale and

I thought, she's gone, this is it,

Mark's not gonna get to see her.

I know how rare white shark sightings are in Hawaii.

CHRIS: Typically, white sharks are not seen very frequently

in the Hawaiian Islands.

There was shark control programs that were done in

the '50s, '60s and '70s and I think they caught four total,

out of thousands and thousands of sharks that were caught.

So while we know white sharks come to the Hawaiian Islands,

they don't come in huge numbers like we see off the

coast of California or Mexico, South Africa or Australia.

ANDREW: Tiger sharks started moving in and feeding on the

whale, so I figured the white shark was definitely gone.

NARRATOR: Mark is finally in the water.

Suddenly, the tiger sharks disappear again.

And it's quiet.

Until, out of the depths, a giant emerges, and

it's heading straight for Mark's boat.

TIM: It's coming right here! Holy!

MARK: The shark came up to the prop and I thought it was

gonna bite my prop on my boat.

NARRATOR: But the great white shark decides rotting whale

meat is a better meal and returns to the carcass.

As the great white continues to chow down,

the divers capture amazing footage.

MARK: This was my first experience with white sharks.

Couldn't believe what I was seeing, it was

a really special experience.

NARRATOR: The shark makes the most of this lucky break,

filling her immense body with as much whale meat as possible.

With such a big belly and voracious appetite,

could she be eating for two?

Could she be pregnant?

CHRIS: It's possible that she's been out for a year and a half.

She could be carrying a womb full of close-to-term pups

and getting ready to make her migration back to

coastal California or Mexico to give birth.

Or the other possibility is she could just have

a belly full of whale.

It's thought that a white shark could take out over

400 pounds of whale meat in a sitting.

NARRATOR: Finally, the white shark has eaten her fill and

dives down deep, disappearing.

ANDREW: We stuck around for a while, hoping she'd come back.

The tiger sharks moved in and we decided to call it a day.

We were exhausted.

MARK: It was an incredible day on the water.

NARRATOR: But who is this giant from the deep?

Kim hopes her photos will solve the mystery.

KIMBERLY: There have always been stories about

white sharks in the Hawaiian Islands, but there haven't

been very many documented instances of them.

We had ID shots and video and it was more than enough

to present to at least the scientific community for identification.

NARRATOR: In Tahiti, Kori and Andy decide to search

for Kamakai where Kori first encountered the massive tiger shark.

A fisherman alerted Kori to the location.

KORI: He called us and said that he had this crazy crazy

spot where they've had this huge influx of tiger sharks.

NARRATOR: It was flush with tigers, but finding one like

Kamakai there was a huge surprise.

The spot is 220 miles north, inside an atoll, just a few

day's swim for a fast-cruising tiger.

It's the largest atoll in the Polynesian group.

A ring of coral reef makes a lagoon 50 miles long,

20 miles wide.

KORI: It's massive.

One of the biggest in the entire world and its

protected, so it's like getting a chance to be in the

open ocean but, with a little bit of barrier around you.

And there's only two ways to get in and out.

NARRATOR: Kori and Andy head in with Taurama Sun,

the fisherman who first called Kori.

He's been fishing inside the lagoon for his entire life.

And the tiger sharks are new.

TAURAMA: We was really surprised to see many many

sharks like this.

ANDY: So many tiger.

TAURAMA: So many tigers, yeah.

NARRATOR: Fishing in the lagoon has always attracted sharks...

But the increased sightings here suggest

the government's protection measures are paying off.

ANDY: Hey.

Wow, looks like we've got at least three tigers right at

the back of the boat.

There's another one at the front and another one over there.

Thank you.

Got it.

NARRATOR: Tiger sharks are normally solitary.

But here they're everywhere.

And something about them is distinct.

ANDY: Holy smokes, a lot of sharks here.

KORI: So many tigers, they are everywhere.

This is amazing!

NARRATOR: All of these tiger sharks are less than nine feet,

immature juveniles and sub adults.

But what is it about the lagoon that attracts younger tigers?

And what was a mature shark like Kamakai doing here?

ANDY: So this thing is just a super basic, non-invasive,

spring-loaded fin cam system.

NARRATOR: Andy hopes this tool can help provide answers.

ANDY: We are tracking with it and seeing what it sees.

And we're basically diving into the secret life of the shark.

NARRATOR: Two sharks with cameras can scout a much

bigger section of the giant lagoon than a couple of divers.

KORI: So if we can see what they are doing and

why they are doing it,

I think that's really helpful for the behavior.

NARRATOR: With other species like bull sharks and great whites,

the young segregate themselves so they

aren't attacked and eaten by the adults.

Maybe that's what's happening here.

PIERRICK: They come all at the same time...

NARRATOR: Pierrick Seybald is Kori's safety diver.

She'll need him for this dive.

PIERRICK: Like a little gang.

NARRATOR: She's going to try and attach the cameras to the

tiger sharks, by hand.

KORI: Andy, I am going to go ahead and jump in.

NARRATOR: These young tigers are more unpredictable than adults.

ANDY: One coming up behind you.

NARRATOR: Kori wants to start with a small juvenile.

She makes her move.

ANDY: Got it!

NARRATOR: They still need a second volunteer.

This one's a sub-adult.

KORI: That looks bigger than all of them.

Want me to go?

ANDY: Let's do it.

NARRATOR: Kori's two for two.

ANDY: Nice work!

NARRATOR: But this camera shark moves in for a close up.

(grunting).

The first thing it films is a bee line right for the safety diver.

Pierrick rubs receptors located in her snout.

He wants to calm her down.

But it's clear.

This young tiger doesn't want calm.

It wants a diver.

NARRATOR: In Hawaii, Kim Jeffries couldn't wait

to find out more about the massive great white

feasting on a sperm whale carcass.

KIMBERLY: When I got home, the first thing I did was download

the images and videos and I immediately reached out to

my friend, George, who I've worked with in the past

to identify white sharks in Guadalupe.

NARRATOR: Using images stored in a database, researchers

have a system to identify individual sharks that visit

Guadalupe Island in Mexico,

a great white hotspot in the Pacific.

Currently, 261 unique white sharks have been identified.

CHRIS: So it turns out white sharks have unique markings

that enable us to identify them, based on the white and

gray markings along the side of their body, along their

gills, along their tail and of course...

Over the years, they acquire unique scars.

During mating they quite often bite each other.

In addition, they'll compete with each other over food or

sometimes the things that they eat will fight back.

So those unique scars and unique markings have been used

by researchers to identify individuals.

NARRATOR: With the help of the Marine Conservation Science Institute,

shark photographer George Probst makes

a startling conclusion.

KIMBERLY: He responded that we had possibly seen Deep Blue,

to which I said, "You're off your rocker, George and

you've seen too many white sharks at this point."

NARRATOR: In 2013, off the coast of Guadalupe Island, Mexico,

photographer, Michael Maier, films possibly the

largest great white shark ever caught on camera.

Local shark researcher, Mauricio Hoyos, names her Deep Blue.

Experts at the time estimated her to be 20 feet long

and 50 years old.

MARK: I got goose bumps from hearing that news.

Deep Blue is probably the most famous shark in the

world besides Jaws.

KIMBERLY: When George told me that it was Deep Blue, I was

really shocked because I've been to Guadalupe and I went

in the season where you see the big females.

But nothing that I'd seen even compared to that legend of

Deep Blue.

NARRATOR: Using photos like Kim's, scientists can now

better calculate Deep Blue's size.

With Kim as a reference,

Deep Blue is at least 20 feet long.

But what was Deep Blue doing here in Hawaii in 2019,

six years after being spotted off of Guadalupe Island.

CHRIS: You know, 25 years ago, if you'd asked any shark

biologist what kind of shark we thought a white shark was,

we would have said a coastal shark.

And it wasn't until the advent of some of the technology that

we use, like satellite tags, that literally changed our

minds overnight of white sharks from being a coastal

species, at least in the Northeast Pacific, to being

an open ocean species.

Most of the sharks that have been tagged and tracked,

some have been tagged on the Farallons,

some have been tagged in Guadalupe.

We see very little movement of those sharks between

those two locations.

They tend to all go out to the same place, kind of in the

middle of the Pacific.

Researchers coin this area, kind of halfway between Hawaii

and Baja, the shared offshore foraging area.

NARRATOR: Footage of great whites in Hawaii is extremely rare.

But deep, submersible missions have captured something

surprising that could be a clue why few people see the

great whites that make the journey here.

MAN: Holy! WOMAN: Ooh!

MAN: Huge shark. Look at this guy.

CHRIS: ROV and submersible studies have sighted

white sharks as deep as 1000 feet around Hawaiian Islands.

MAN: It is a great white. That is a great white shark.

MAN 2: No way.

MAN: That is huge.

Look at that, a 12-15 foot great white.

CHRIS: So it's very likely that white sharks are present here,

they're just so deep we rarely see them.

NARRATOR: If Deep Blue swam from Guadalupe Island to Hawaii,

she would have covered over 2,400 miles,

a remarkable distance.

But, as Kim, Mark and Andrew were about to discover,

Deep Blue wasn't alone.

NARRATOR: The search for a mega tiger shark named Kamakai

has led to a vast Polynesian lagoon full of

juvenile tiger sharks.

One of them is after the dive team.

Young tigers can be very erratic.

The team members decide not to push their luck.

ANDY: Get on the boat.

NARRATOR: Kori and Andy successfully deployed two

fin cams to monitor behavior here.

Now they must wait.

KORI: Phew. ANDY: Wicked.

NARRATOR: The fin cam is designed to release

after a few hours.

A tiger shark can cover a lot of ground in that time;

they've been known to swim 60 miles a day.

The footage should give Kori and Andy an idea of what the

young tigers are doing in the lagoon.

And, possibly, what brought Kamakai here.

Three hours later.

They get a signal on their receiver.

ANDY: Kori, it sounds like the camera has popped up

way out there, like way outside the lagoon.

But in the deep water, yeah?

KORI: Yeah.

NARRATOR: The first camera they detect is from the

bigger tiger: the sub-adult.

Looks like the camera came off as she headed

out of the lagoon.

ANDY: Alright. Nice work!

NARRATOR: But the smaller female dropped hers

inside the lagoon.

ANDY: Nice.

Two fin cams deployed.

Two retrieved.

Let's check the footage.

NARRATOR: In Hawaii, Kim, Mark, and Andrew have just had an

encounter with possibly the world's largest great white.

And news of another has them itching for more.

KIMBERLY: After learning about the new sighting, it really

pushed us to go out the next day.

NARRATOR: But the next morning, Mark has to work.

So Kim and Andrew head out in Kim's boat, Rubber Ducky.

And they find the whale quickly.

ANDREW: There was already a boat out there with five divers.

KIMBERLY: And they said they hadn't seen anything except

for tiger sharks.

NARRATOR: Andrew gets in the water right away,

and Kim takes a moment to relieve herself.

ANDREW: Kim is hanging off the side of her boat,

taking a leak, and I see a massive white shark swimming in,

directly underneath her.

I poke my head above the water and say,

"Hey, guys, there's a shark under your boat."

KIMBERLY: And I said, "Yeah, yeah, whatever, no big deal."

'Cause they'd only seen tiger sharks in the area until then.

NARRATOR: But this isn't a tiger shark, it's a great white.

A very large great white.

KIMBERLY: I pushed myself back into the boat really quickly,

grabbed my mask and my camera, put my fins on and

rolled back into the water.

I wasn't sure whether or not it was Deep Blue or not.

She was incredibly huge and just incredibly majestic.

She was a little bit more inquisitive than Deep Blue

which was one of the first indicators to me that

something was slightly different.

NARRATOR: It was indeed a brand new 18-foot female that

had never been recorded before.

KIMBERLY: I got to name it, as a result of taking pictures

and presenting it to be identified, and so I named her

Haole Girl as a tribute to the Hawaiian culture and

a white visitor to our islands.

It's possible that this shark has never encountered humans before.

So I think she was just really curious and

wanted to check us out.

ANDREW: This shark was especially interested in our boat.

It's possible that she thought the boat was a

chunk of the whale.

KIMBERLY: So, the boat that we were in is Rubber Ducky.

It's my boat, it's about 17 feet long.

ANDREW: It has sponsons around the side of it that are filled

with air and a hard hull.

This shark would repeatedly come up and nose the sponsons.

KIMBERLY: She gave a little test nibble on the starboard

side and that's when she popped one of the tubes.

ANDREW: We hear air hissing out.

It must have been just a couple minutes before she came

back to the same area, took a nice bite and

made a big gash right into it.

KIMBERLY: My boat is sinking.

MARK: 10:00 on Tuesday morning, I get a text message

from Kim that says,

"Shark bit the boat. We're fine, come out now!!!"

KIMBERLY: Mark came out in about an hour.

He did bring some tie-downs to strap the tube in place.

MARK: So, not long after I had checked their boat out, we saw

that the shark was coming in behind the boat that I brought

out and that's when I got the really cool picture from the

surface of Kim in the water right in front of Haole Girl.

NARRATOR: Mark captured incredible photos of Kim and

the shark, really showcasing her size.

ANDREW: After swimming around us for hours,

she eventually took off.

CHRIS: Finding one white shark on a whale, sure.

Getting three large female white sharks on a whale,

that's different, right?

That means those sharks had to be close enough in the

vicinity to, number one, detect the odor of that whale

and then also it might mean that these sharks

are traveling together.

It's something we've never really been able to

study or understand.

NARRATOR: In French Polynesia, Kori and Andy hope fin cam

footage from two juvenile tiger sharks may finally lead

them to the mega tiger Kamakai.

ANDY: What is that?

KORI: That's a fish.

NARRATOR: The bigger shark headed out.

ANDY: Looks like she's heading deeper.

NARRATOR: At around eight feet long, and at least

four years old, she's approaching adulthood.

And heading outside the lagoon.

ANDY: Cool.

NARRATOR: It's more dangerous out here.

Hammerheads patrol these waters.

Adult hammerheads are cannibals,

known to eat smaller sharks.

Like young tigers.

Kori and Andy came to the lagoon in search of Kamakai.

So far there's no sign of her.

But these teen tigers may hold clues to

what brought Kamakai here.

ANDY: There's like one, two.

This little one is obviously encountering

other juveniles here.

That one right there, that one right there.

That is a rad shot of that tiger cruising

amongst its friends.

They're not being aggressive.

KORI: They don't seem to be really in competition.

NARRATOR: Tiger shark pups are much smaller when

they're born: 20 to 30 inches long and very vulnerable.

Maybe these young sharks were born here, or nearby...

And the lagoon serves as a sanctuary.

ANDY: If they swim out the pass, they are basically

subject to being predated on by big sharks.

KORI: I think this is where they kind of learn to be

sharks and once they're big enough to get past that

learning curve and it's not as dangerous for them to go out.

NARRATOR: The strong currents in and out of

the lagoon provide a constant supply of food.

And the shallower water keeps out the larger hammerheads.

ANDY: If I was a little tiger shark, I would hang out

in this lagoon too.

It's like the perfect safe zone,

where there is food, safety, friends.

It makes perfect sense.

NARRATOR: The pieces of the puzzle may be coming together.

Huge females gather off the island of Tahiti,

showing mating scars.

Maybe Kamakai was so big because she was pregnant.

KORI: That could be one reason that she was so wide.

It's very possible that she was coming in dropping those

babies off and heading back out.

NARRATOR: A lagoon full of young tiger sharks.

Which suggests a rare pupping ground may be nearby.

No Kamakai, but evidence of stages in the tiger shark life cycle.

14 years after protection, the waters off French Polynesia

have transformed into a big tiger paradise.

A safe haven where a shark like Kamakai can birth a

new generation of mega tiger sharks.

Like French Polynesia, environmental protections

in Hawaii seem to be making an impact.

Since Deep Blue and Haole Girl,

even more great white sightings have occurred.

CHRIS: The white shark population has probably been

reduced for over 100 years, due to loss of their favorite

food and over-hunting.

So now that white sharks are coming back, we don't know

whether the patterns we're seeing now are the patterns

that were always there or whether they're new patterns

as the population grows.

NARRATOR: Did the team film the world's biggest known

great white shark?

Quite possibly.

But they definitely encountered two of the largest

white sharks ever recorded in Hawaii, giving hope that an

even larger shark might be hiding somewhere in the deep.

ANDREW: I know how rare white shark sightings are in Hawaii

and this experience was absolutely incredible.

By far the best I've ever had in the water.

KIMBERLY: This was one of the most amazing experiences I've

ever had in my life.

There have always been legends of white sharks in Hawaii but

to actually have gotten the chance to see one

and then ultimately getting to name one,

was just absolutely incredible.

NARRATOR: Locals are still talking about

what happened here last spring.

It was a perfect day for fishing.

MAN (off screen): Whoo! That's a big one.

NARRATOR: But below the surface,

two heavyweights of the shark world

were on a collision course.

MAN (off screen): That's insane!

NARRATOR: It's a rare face-off

between a bull shark and a great hammerhead

prompting a team of experts

to dig deeper into the encounter...

MAN: One, two, three.

NARRATOR: ...in the hope to uncover surprising behaviors...

VALERIE HAGAN: We might have a predation.

DR. YANNIS PAPASTAMATIOU: I have no idea what is going on here.

NARRATOR: ...and come face-to-face

with two of the biggest...

MAN:

NARRATOR: ...baddest...

DR. MIKE HEITHAUS: Look out! Look out!

NARRATOR: ...super predators on the planet.

But which one takes the crown?

Several people captured the event

in the spring of 2021.

MAN (off screen): That's insane!

NARRATOR: The video quickly went viral.

A bull shark chases a monster great hammerhead

and pins it to the beach.

There's no escape.

The bull shark circles...

followed by a second.

Then the hammerhead is ripped to pieces.

Marine biologist Dr. Mike Heithaus was floored.

DR. HEITHAUS: I've never seen anything like this.

A lot of times, we've got these big, top predators

but they don't usually

pay much attention to one another.

In this case, it was a head-to-head battle.

We had a winner and a loser.

NARRATOR: An encounter of this magnitude is rare.

It provides the perfect opportunity

to understand how these apex predators

stack up in a one-on-one battle.

Fishing Charter Captain Mike Myers saw the whole thing.

CAPT. MIKE MYERS (off screen): Oh, my gosh.

DR. HEITHAUS: Can you walk me through what happened that day?

CAPT. MYERS: I had clients onboard.

I just saw it.

"Oh, my gosh, a huge hammerhead."

DR. HEITHAUS: How big do you think that hammerhead was?

CAPT. MYERS: I'm estimating somewhere around 12 to 13 foot.

They kinda swam up towards the beach

and people were over there screaming and hollering

because he kept beaching himself.

Every once in a while, one of the bull sharks

would come up and grab 'em by the tail

and jerk it and then swim up real fast.

And all of a sudden, you look down...

and then...

the sand just exploded.

We looked as hard as we could

after that whole mess happened.

There wasn't a fin on the ground.

There wasn't anything in the water.

He was gone.

DR. HEITHAUS: You've been out here a long time.

CAPT. MYERS: I've seen a lot of bizarre things

with these sharks over the years.

Oh, my gosh.

I've never seen anything close to that.

NARRATOR: Big sharks are known to attack

and eat smaller sharks.

But these two apex predators are powerful equals.

The hammerhead, sleek, massive,

and can turn on a dime.

In a one-on-one fight, they are fearsome opponents.

Great hammerheads can grow to be nearly 20 feet long,

almost twice as big as the bull shark.

Bull sharks may be in a different weight class,

but they pack a lot of punch for their size.

Stocky with a superior jaw strength.

Bull sharks have a bad reputation

for a good reason.

DR. HEITHAUS: Lots of questions come out of this video.

CAPT. MYERS (off screen): Oh, my gosh.

DR. HEITHAUS: They're both top predators.

You don't really think about one going after the other.

So to see them battling it out

is incredibly unique.

If these sharks are going head-to-head,

who's gonna come out on top?

When top predators battle it out with one another

or have interactions

that can cascade through the rest of the ecosystem.

So learning about the interactions

among top predators is really important.

NARRATOR: To investigate this surprising new dynamic,

Mike has assembled a team of experts.

DR. HEITHAUS: We're gonna try to get to the bottom of this

by first studying bull sharks and great hammerheads separately

and then going to a place where they might come together

to see if it's a collision or if they go their separate ways.

NARRATOR: First up, the great hammerhead.

Team member Erin Spencer

leads this part of the investigation.

ERIN SPENCER: They're one of the most recognizable sharks in the ocean.

When you see that cephalofoil

and just see the eyes and how big that head can get,

it really kinda takes your breath away.

NARRATOR: Famous for its elongated head extensions

called cephalofoils,

the great hammerhead has an advantage

over the bull shark

in its uniquely positioned eyes.

With a nearly 360-degree field of vision,

it has the best depth perception of any shark,

giving it pinpoint accuracy on attack.

Its wide head also contains more electrosensory receptors

than other sharks.

SPENCER: All of these pieces come together to make them

as good a predators as they are.

But because they're so big and wide ranging,

they're really difficult to study.

We use something called biologgers

which are essentially

animal mounted data collecting devices.

And the biologgers are like Fitbits for sharks.

DR. HEITHAUS: So by putting that on the back of the shark,

it can give you a three-dimensional path

of how it's moving through its environment,

how it's speeding up, slowing down,

pitching, rolling.

We just gotta get out there, catch a hammerhead

and get one of our accelerometer tags on its dorsal fin.

NARRATOR: While Erin readies a hammerhead 3D biologger,

Mike heads back out to the scene of the crime...

to look for more clues with Captain Myers.

For a few months a year,

this relatively deep channel west of Fort Myers

is a fisherman's paradise.

MAN: I told you it's a big one.

DR. HEITHAUS: It is packed full of these giant fish called tarpon.

They could be more than 200 pounds

and they're one of the world's most coveted game fish.

NARRATOR: As the water warms each spring,

thousands upon thousands of tarpon

migrate north to Boca Grande to spawn.

Anglers come from all over the world to try their luck.

As they fight these mammoth fish,

bull sharks and hammerheads cross paths

in their quest for easy prey.

Over the years, Captain Myers

who captured the video of the attack

has observed both predators on a daily basis.

DR. HEITHAUS: Have you ever seen the bull sharks or hammerheads

go after tarpon that aren't hooked up?

-So-- -CAPT. MYERS: Oh, God, yeah.

The bull sharks will get around these schools.

That's 10,000 fish running up and down this beach.

I have seen numerous, numerous times

the hammerheads come in.

People don't realize how agile that fish actually is.

NARRATOR: What Captain Myers recalls next intrigues Mike.

CAPT. MYERS: And what's really cool,

when a hammerhead comes, bulls aren't around.

They don't want nothing to do with it.

NARRATOR: It contradicts the behavior

Captain Myers captured on video a year earlier.

CAPT. MYERS: The hammerheads come in

and there's no more bull sharks.

What I saw floored me.

NARRATOR: The team decides to deploy

the hammerhead tag right here in Boca Grande Pass.

But the next morning, Mike gets some bad news.

(sighs)

DR. HEITHAUS: Unfortunately, we just heard

from Erin and she's been exposed to COVID,

so she can't make it out today.

But she's programmed the tag for us and we've got a crew.

So we're gonna go out and try to catch a great hammerhead.

Anything we need to be thinking of to get this on for you?

Not having her on the boat is gonna be a big challenge

'cause that's one less experienced person

to handle a shark.

But hopefully we can get it done and get some great data for.

NARRATOR: Mike will work with

Mote Marine Laboratory biologists

Valerie Hagan and Jack Morris

to see if they can get the tag on a hammerhead by themselves.

HAGAN: Jack and I work with one another

for most of our field work.

JACK MORRIS: That's fishing, right?

So you always come up with the expectation

that you hope you're gonna get what you want.

And when you do, it's amazing.

NARRATOR: They set ten fishing lines

along the mouth of Boca Grande Pass,

its prime hammerhead territory.

DR. HEITHAUS: That is a piece of stingray.

And a hammerhead loves stingrays.

They'll actually use their head

to pin 'em to the bottom

to hold them down so they can get a bite.

NARRATOR: While they wait for a catch,

Mike preps Erin's 3D biologger.

DR. HEITHAUS: What it can do is help us

recreate a three-dimensional track of the hammerhead.

And it samples at such a fast rate.

We can see if they're doing burst swims

to try to catch something.

And you're out here in Boca Grande,

we know that bull sharks and hammerheads

can be on a collision course.

So learning more about each

is really important to understand

how they're going after a prey

or are they maybe eating one another?

NARRATOR: By the time the last line is in the water,

it's time to circle back and check the first

where something is already on.

DR. HEITHAUS: So, this is a blacktip shark

and they're one of the more common species

along the coast of Florida.

And these are snacks for great hammerheads.

NARRATOR: Catching the hammerhead's prey is a good sign for the mission.

MORRIS: Here goes. Okay. Oh, there it goes.

DR. HEITHAUS (off screen): And away.

NARRATOR: The next hook looks more promising.

DR. HEITHAUS (off screen): Yeah, it's dragging it.

HAGAN: I saw the buoy actually made a splash.

DR. HEITHAUS: Yeah. This is not nurse shark,

not blacktip.

-Yes! Hammerhead! -HAGAN (off screen): Whoo!

-DR. HEITHAUS: Whoo! -HAGAN: That's a biggun.

DR. HEITHAUS: Two of 'em. There's another one right here.

-HAGAN: What? -DR. HEITHAUS (off screen): We got two hammerheads.

NARRATOR: The second hammer is free swimming,

analyzing the situation.

Hammerheads are known to eat their own

when the opportunity arises.

HAGAN (off screen): We might have a predation

about to happen.

NARRATOR: They need to secure the hooked shark

as quickly as possible.

But there's another problem.

HAGAN: I tried to pull on that, but there's no give.

DR. HEITHAUS: We've got a hammerhead here

wrapped up in a crab pot.

NARRATOR: Until they untangle it,

the hammerhead is a sitting duck.

And the second hammerhead circles

closer and closer.

DR. HEITHAUS: Okay. You gotta go to the right.

-You gotta get reverse. -HAGAN (off screen): Port side?

MORRIS (off screen): We gotta get him away from that other shark.

DR. HEITHAUS: I know.

Ahh! Look out! Look out! Look out! Look out!

MORRIS (off screen): How about we swing it out?

NARRATOR: The team struggles to untangle the line

before the great hammerhead becomes shark bait.

DR. HEITHAUS: (grunts) Forward.

Let go. Let go. Let go.

-Yes, free! -HAGAN (off screen): Oh.

-DR. HEITHAUS: Nice job. -HAGAN: Yeah. (laughs)

DR. HEITHAUS: Okay, we just have the shark now.

-HAGAN: Holy cow. -DR. HEITHAUS: That is a big animal.

Well, we got a really nice 10-foot-plus great hammerhead.

We have another slightly smaller one around.

This is the exact size we want for this tag.

Oh, beautiful.

I don't see the other one now.

HAGAN (off screen): We probably spooked the other one off.

NARRATOR: But the battle to subdue the shark is only beginning.

MORRIS: You know, the hairs on your skin

start to stand up a little bit.

Once you get what you want, you wanna keep it.

DR. HEITHAUS (off screen): Look out. Look out. Look out.

-Don't try this at home, kids. -MORRIS: Nicely done.

HAGAN (off screen): Definitely female.

Hello, gorgeous.

NARRATOR: Val attempts to secure the shark's powerful tail.

-DR. HEITHAUS: Get it? -HAGAN (off screen): No.

I couldn't get that lower lobe.

It was close.

NARRATOR: Handling a shark this big is proving difficult

without the help of their teammate Erin.

-(Hagan grunts) -DR. HEITHAUS: We're gonna move the top lobe.

(grunts)

We're gonna lose this shark.

-HAGAN (off screen): Okay. -(grunts sharply)

NARRATOR: The urgency is compounded by the fact

that great hammerheads are fragile.

MORRIS: There's theories that they fight an awful lot

when they're on a hook and they overexert themselves

and they run out of energy very quickly.

HAGAN: It's wearing us out. It's wearing her out.

And we want this animal to survive.

DR. HEITHAUS: Hey, slow it, slow it.

NARRATOR: The shark zooms around

to the other side of the boat, trying to throw the hook.

DR. HEITHAUS: Jack, can you come back?

MORRIS: Yeah. Okay, what do you want me to do?

DR. HEITHAUS: I want you to get the dorsal.

Let's clamp this thing on and get it.

Otherwise we are gonna lose this animal. -MORRIS: Alright.

NARRATOR: Finally, the tail rope is secured.

HAGAN: Come on.

DR. HEITHAUS: Put the tag on.

Get it as far as you can.

Excellent.

HAGAN: I was very focused on the tail

and then I looked up and I saw that the tag was on.

DR. HEITHAUS: Good. Let's get a quick measurement and go.

Fast, fast, fast, fast.

HAGAN (off screen): 345.

DR. HEITHAUS: The hook is bent and out.

You gotta get that tail rope up fast.

-Good swim. -HAGAN: Whoo!

NARRATOR: The biologging tag will capture 3D data,

providing valuable insight

into how great hammerheads move through the water.

And help the team see how these giants

stack up against bull sharks.

With the tag finally recovered and a clean bill of health,

Erin's back on board to walk Mike

through the hammerhead data.

DR. HEITHAUS (off screen): She can build a computer model

so we can see not just how it navigates and where it went,

but maybe how it's attacking its prey.

SPENCER: This is when the hammerhead is released.

We start at the surface and then just go straight down.

And then we can actually see

how the animal starts to move around.

NARRATOR: The shark heads down to a depth of about 40 feet.

It swims away from the boat in sweeping lateral movements.

SPENCER: Here, we see that the shark

is kind of meandering down a little bit slower

and is kinda midrange,

and then there's a really quick turnaround.

NARRATOR: It cuts through the water with its hydrodynamic head,

making several tight, very rapid turns.

SPENCER: And then there's a really quick

bolt up to the surface,

almost a vertical line.

DR. HEITHAUS: There's probably a reason for that

because why else would you burn that energy

-if you didn't have to? -SPENCER: Yeah.

We can say, okay, using the mathematical models,

actually how many calories would a shark need

to consume to sustain that sort of movement pattern?

DR. HEITHAUS: If you need a lot of energy,

you gotta eat that bigger prey

to get you more energy like other sharks.

NARRATOR: Erin's tags were only beginning

to reveal the secret abilities of the great hammerhead.

When it tilts its head, the hydrodynamic potential

of the great hammerhead cephalofoil is unleashed,

allowing the shark to move and turn with rapid precision.

And this makes hammerheads more nimble and agile

than other sharks,

including bulls.

DR. HEITHAUS: If you combine the speed,

the size, and maneuverability,

I mean, that's an impressive predator.

Bull shark versus hammerhead, who wins?

SPENCER: I vote hammerhead.

DR. HEITHAUS: One for team hammerhead.

NARRATOR: The awesome power

of the great hammerhead is coming into focus.

But Mike and the team are no closer to understanding

why the hammerhead was attacked

by bull sharks at Boca Grande.

NARRATOR: The team has proven that great hammerheads

are formidable opponents,

but what about the other contender in the battle?

DR. HEITHAUS: Now it's time to investigate

the other species in this matchup.

Bull sharks.

NARRATOR: Maxing out at around ten feet,

the bull shark is smaller than the great hammerhead.

But what it lacks in size, it makes up for it elsewhere.

It's thick with a broad head and big mouth,

built for taking out large prey.

The bull shark is super adaptable.

It has a reputation for being aggressive.

DR. HEITHAUS: Seeing that video

really shows us that bull sharks

might attack great hammerheads and kill 'em.

But the question is, is this a common event

that's happening more often

when they're out there coming into contact?

NARRATOR: To dig deeper into the bull shark component of this matchup,

Mike enlists Dr. Yannis Papastamatiou.

DR. HEITHAUS: Yannis is one of the top shark scientists in the world,

and has helped developed new technologies

to get more insights into their behavior.

For this project, we're gonna try something

that's never been done before.

We wanna put a camera on the back of a bull shark.

And until now, that's only been done with sharks

that have been caught,

and that might really change the behavior of the shark,

so we're gonna go out there and try to put a camera

on a bull shark without catching it.

NARRATOR: Along the southeast coast of Florida,

there's a thin band of warm, shallow water.

It creates a shark super highway,

bringing all sorts of species in contact with one another,

including lots of bull sharks.

DR. PAPASTAMATIOU: I'm really hopeful

we'll get this tag on,

but I, you know, I'm also a little bit nervous

because it's going to be somewhat challenging

to get a tag on a free-swimming bull shark

in blue water, in a current.

I'm hopeful.

But it's going to require a well-behaved shark.

And I also hope she won't bite me.

DR. HEITHAUS: We're heading about four miles offshore,

and that's where we should be able to find bull sharks.

DR. PAPASTAMATIOU: We should get about ten hours of video footage.

DR. HEITHAUS: Then that dissolves in a couple days,

-there's nothing left on it. -DR. PAPASTAMATIOU: Yep, yep.

So within a week, there'll be nothing

on the shark's fin at all.

NARRATOR: To keep the shark at arm's length,

they'll use a spring-loaded pole

to snap the tag on the shark's fin.

-DR. PAPASTAMATIOU: Okay, so that's now primed. -DR. HEITHAUS: Right.

DR. PAPASTAMATIOU: If you now click the small trigger...

-DR. HEITHAUS (off screen): Watch your fingers. -DR. PAPASTAMATIOU: Yep.

DR. HEITHAUS: One, two, three.

-DR. PAPASTAMATIOU: And that'll pop. -DR. HEITHAUS: Yeah.

DR. PAPASTAMATIOU: We just need one to behave the right way

and we'll get it on.

DR. HEITHAUS: If we pull this off,

it'll be a world first.

DR. PAPASTAMATIOU: No pressure. (laughs)

DR. HEITHAUS (off screen): No one's ever done it.

There's no pressure. Just go do it.

NARRATOR: If bull sharks are hunting hammerheads

more commonly than thought,

this camera could pick up hard evidence.

To bring a bull shark in and keep it close enough

for a tag deployment, bait is needed.

It injects a constant scent trail into the current,

drawing a roadmap directly to the divers.

DR. PAPASTAMATIOU:

NARRATOR: It's a silky shark.

She makes tight circles, sniffing out the food

and sizing up the human competition.

Silky sharks are a bold species

that spend a lot of time in the open ocean,

where food is scarce.

The bait is working...

but it's not the species they're after.

DR. HEITHAUS: Silky sharks don't really have

a sense of personal space,

especially if you have a camera in your hand.

NARRATOR: Then as quickly as they came,

the silkies disappear.

DR. PAPASTAMATIOU:

NARRATOR: The bull shark zeroes in on the bait.

It's a big female.

In order to tag a free-swimming bull,

they'll need the most bold and inquisitive shark they can find.

Experts generally agree

that bulls are one of the most dangerous shark species.

Most bull shark-human interactions

take place in murky water,

where biting is the only way to identify possible prey.

In clear open water, the team and the bull shark

can see one another

and maintain healthy boundaries.

She's a good candidate for the camera tag.

DR. HEITHAUS: We got the bull sharks we wanted.

If this goes well, the shark's gonna swim away

with the camera on it, and we will be done.

NARRATOR: With daylight fading,

the team has limited time to pull this off.

It's a deployment that's never been done before.

The big female comes in closer.

She's curious.

Confident.

The perfect shark.

Yannis readies the trigger.

He needs to slip the opening of the clamp

over the dorsal fin of the shark.

It's a game of inches.

One miss and the shark will be spooked.

NARRATOR: Clamping the tag on a free-swimming bull shark

is a cat-and-mouse game.

Every time he gets close, the bull changes direction.

DR. PAPASTAMATIOU:

NARRATOR: Success.

DR. HEITHAUS:

NARRATOR: In a first for science,

the bull shark swims off, unfazed by its new bling.

DR. PAPASTAMATIOU: So the tag is on an animal.

First part is done.

She's the perfect size,

she came in close and took my shot, and, uh, it worked.

In the end, she responded perfectly,

didn't seem to bother her much at all,

she just slowly swam off.

DR. HEITHAUS: Camera on. Everybody's okay.

-DR. PAPASTAMATIOU: Yeah. -DR. HEITHAUS: Now, one more step.

-Get the camera back. -DR. PAPASTAMATIOU: Getting the camera back.

NARRATOR: The tag will remain on the shark

for two days.

Tracking one bull will allow the team

to see everything from the shark's point of view.

But camera tags only tell one part of the story.

To see if hammerheads are on the bull shark menu

like in the video,

the team has to take a cloacal swab,

otherwise known as a fecal sample.

DR. HEITHAUS: One of the most important things

we need to know about predators is what they eat.

Usually, that's been figured out

by looking at the stomachs of dead sharks.

DR. HEITHAUS: It turns out, if you just get a little swab

and collect shark poop,

you can run that through a DNA test

and see what had been in its stomach.

This cloacal swabs are gonna help us figure out

if these bull sharks are eating a lot of other sharks

and may even go after great hammerheads.

NARRATOR: The next morning,

Mike and PhD student Davon Strickland

head off shore to swab bull sharks.

Davon is part of the next generation of marine biologists

trying to unravel the mystery

of how sharks interact with one another.

DR. HEITHAUS: He also happens to be a co-captain

of FIU's football team.

DAVON STRICKLAND: With football being a game of inches,

how that's translated in the shark work

is you gotta make sure you know your role,

because there's so many things that could go wrong,

you gotta be able to work as a team.

DR. HEITHAUS: He also is a pretty good person

to have on the boat when we're handling big sharks.

We need those long arms.

(indistinct chatter)

Oh, my gosh. The visibility here is insane.

NARRATOR: They set their lines just at the edge of deep water.

DR. HEITHAUS: So we are right where we'd expect

to find bull sharks,

the perfect depth range,

so that's why we're just gonna drift along here with the bait.

I thought I saw a shadow there.

Oh, there's a shark right there.

NARRATOR: It's an eight- to nine-foot bull shark.

STRICKLAND: Let me take it, let me take it.

-DR. HEITHAUS: Yeah. -STRICKLAND: Oh, there's two of 'em.

DR. HEITHAUS (off screen): Okay, that should help.

NARRATOR: The larger shark makes the first move.

DR. HEITHAUS: There, it's right, it's right next to the bait,

it's taking a look at it.

Take it, take it, take it.

Oh, oh, oh. Yup. It took it. Okay, get ready.

Watch your feet.

Okay, I think we're in business.

Careful, careful.

Yup, slow, slow.

Heads up, heads up. Clear, clear, clear.

Move, move, move, move, move.

That is a big bull shark.

Neutral.

Heads up now. Oh!

DR. PAPASTAMATIOU: He go?

DR. HEITHAUS: Bit the line.

STRICKLAND: So close, but yet so far.

DR. HEITHAUS: Bummer.

DR. PAPASTAMATIOU: The shark actually bit through the mono.

She was fresh, so she was really strong.

So we got out to the surface,

but she had the mono in her mouth.

That tooth just sliced through it.

It's the way it goes.

NARRATOR: It's not long before they have another curious shark.

DR. PAPASTAMATIOU (off screen): Shark.

NARRATOR: A big female.

DR. HEITHAUS: Back up, back up, back up!

Oh, damn!

DR. PAPASTAMATIOU (off screen): Okay. Pull the line.

DR. HEITHAUS: Nice. Yes.

Okay. Whoo!

Good job.

NARRATOR: The team makes sure she is calm

and getting water through her gills.

DR. HEITHAUS: This is perfect.

NARRATOR: Then they take a measurement.

-DR. PAPASTAMATIOU: 187. -DR. HEITHAUS: Yup.

It probably outweighs you by a hundred pounds.

STRICKLAND (off screen): Oh.

And this fish is longer than I am tall.

-DR. HEITHAUS: Okay. -DR. PAPASTAMATIOU: Alright.

DR. HEITHAUS: So what we need to do is get her upside down,

we're gonna do this cloacal swab,

we need to try to keep it out of the water.

NARRATOR: Flipping the shark on its back

puts it into tonic immobility,

a relaxed, trance-like state.

It helps keep everyone safe during workups.

They'll send the swab off to be analyzed

for hammerhead DNA.

While they have the shark, they will also implant

a permanent tracking transmitter in her belly.

DR. HEITHAUS: Right there?

DR. PAPASTAMATIOU: Yeah, that's fine.

NARRATOR: The shark will now alert the team

any time it passes a receiver

in a network along the coast of Florida and beyond.

DR. HEITHAUS: We can follow them for years,

so using the transmitters, video cameras,

and the DNA techniques, we can start to piece together

a much better picture of bull shark life in general.

NARRATOR: The acoustic tags can help

the team see where and when bull sharks may overlap

with great hammerhead habitat.

It could also reveal whether bull sharks

are gathering in groups.

DR. HEITHAUS: Okay, it's in.

NARRATOR: All that's left is to suture the wound

and release the shark.

Everything's in place.

STRICKLAND: Let me know when you're ready.

DR. PAPASTAMATIOU: Okay.

STRICKLAND: It's out. Nice!

NARRATOR: The team is confident.

If these bulls are hunting hammerheads,

evidence will be with them soon.

Two days later, the bull shark's fin cam surfaces.

DR. PAPASTAMATIOU: It did pop off about six miles offshore.

but then we had a pretty strong current,

so it was very rapidly moving offshore.

NARRATOR: When they finally catch up to it,

it's in deep water,

way out in the Gulf Stream.

DR. PAPASTAMATIOU: I was really, really happy

when that tag was in my hands.

NARRATOR: Back at the lab,

the team discovers the tag captured hours of video.

DR. PAPASTAMATIOU: This is the first time that one of these camera tags

is being put on a free-swimming bull shark,

and so I'm really excited to see

what the tag is going to show.

NARRATOR: The shark swims away as if nothing happened.

It's proof their tagging technique

is minimally stressful to the animal.

It cruises alone for hours.

-Then... -DR. HEITHAUS (off screen): Whoa.

DR. PAPASTAMATIOU (off screen): So, there's another shark came right over it.

-DR. HEITHAUS: Yeah. -DR. PAPASTAMATIOU: There's another one.

That's one, two, three, four,

five, six, seven.

NARRATOR: It's a gang of bull sharks.

DR. HEITHAUS: Yeah, look at that.

DR. PAPASTAMATIOU: I mean, that's right on top of each other.

There's a lot of sharks here.

DR. HEITHAUS (off screen): One there.

-DR. PAPASTAMATIOU: There's another one there. -DR. HEITHAUS: Look at that.

DR. PAPASTAMATIOU (off screen): It's just bull sharks all over the place.

And we're seeing at least

six, seven, eight individuals in frame.

-Camera's only pointing forward. -DR. HEITHAUS: Yeah.

DR. PAPASTAMATIOU: It tells nothing about

on the sides or behind.

DR. PAPASTAMATIOU (off screen): So whatever number we calculate,

the group size will be larger.

DR. HEITHAUS: And these are big animals.

DR. PAPASTAMATIOU: I have no idea what is going on here.

I mean, a lot of this is just not known.

You know, why are all these sharks

hanging out in these regions?

NARRATOR: The footage didn't show

any interactions with great hammerheads,

but it has confirmed a remarkable social life

between bull sharks.

DR. HEITHAUS: Are they feeding in groups?

Maybe these bull sharks are actually

maintaining relationships with other sharks

or working together when they're hunting.

NARRATOR: And the results from the cloacal swabs also arrived.

DR. HEITHAUS: It turns out that these bull sharks

were eating other sharks.

We didn't get any great hammerheads,

but it does show that these bull sharks

are eating big prey

and it's plausible

that they could go after other larger sharks.

NARRATOR: Scientists already know that sharks are hesitant

to take on the risk of a one-on-one fight with an equal.

It's possible the video evidence points

towards something scientists haven't considered before,

multiple sharks using their collective strength

to take down another apex predator.

In order to see whether this dynamic exists

between multiple bulls and hammerheads,

Mike jumps into the ring himself.

The Bahamian islands of Bimini

are only 50 miles east of Florida.

But worlds away in terms of shark activity.

Bulls regularly patrol these waters

and great hammerheads visit in the winter.

It's a prime location to observe them up close.

DR. HEITHAUS: That water is crystal clear

and so you can actually get in the water

with the great hammerheads in a way

that you couldn't in Boca Grande.

It's also an area where both of them are coming into

at least some semblance of proximity,

but are they actually battling it out?

Or do they give each other space?

NARRATOR: It's the ideal spot to witness

these two predators coming head-to-head.

Local scientist Candace Fields

will lead this leg of the expedition.

CANDACE FIELDS: I'm from Nassau, Bahamas,

so Bimini is an absolutely amazing place

for great hammerhead sharks,

mainly because of the fact that there's so much prey available for these guys.

NARRATOR: Candace brings Mike to a dive site

known for hammerhead aggregations.

But the occasional bull shows up here, too.

When they arrive,

a swarm of nurse sharks is already on patrol.

DR. HEITHAUS: We're really interested to see

if, like, one bull shark comes in

or if maybe a group shows up

because it sure is seeming like

-bull sharks may not be as solitary as we used to think. -FIELDS: Mm-hmm.

Hopefully we'll see both hammerheads

and maybe bull sharks.

And so I'm just super pumped to get in the water

and just see what we got.

NARRATOR: They don't have to wait long.

-DR. HEITHAUS: Got one? -FIELDS (off screen): Yeah.

DR. HEITHAUS: Oh. Oh, yup. Hammer.

Time to get geared up.

NARRATOR: The team drops to the bottom

and camps out next to the chum crate.

It's not long before the great hammerhead

comes in to investigate.

It's a nine-foot male.

His body posture is relaxed as he circles closer.

They watch the great hammerhead

make sharp, agile turns.

Just like what Erin is seeing in her data.

Then a second hammerhead enters,

a female, about the same size as the male.

She's no threat to the other shark.

They're solitary individuals here investigating the bait.

DR. HEITHAUS: Candace and I could see

that maneuverability they have,

you know, how they're able to move up and down,

and also how they interact with one another.

NARRATOR: Both hammerheads look strong and healthy.

DR. HEITHAUS: It's really awe-inspiring to be

so close to such big animals.

NARRATOR: Then shadows appear from the surface.

Bull sharks.

They glide in to survey the scene below.

Three of them.

A potential gang.

DR. HEITHAUS: Here's our opportunity to see

how these sharks interact when they get together.

NARRATOR: The bulls descend,

swimming a wide, careful arc around the two hammerheads.

They size each other up,

pushing in closer.

The bulls are smaller

but they have numbers.

A challenge over bait could happen at any second.

Then they move in to investigate the humans.

DR. HEITHAUS: They seem to be a little less focused

on what's going on,

kind of out front of us and more,

"How do I get close when you don't see me?"

NARRATOR: The hammerheads are dominant,

showing no sign of fear.

The body language of the bulls is relaxed and confident.

It's a bull versus hammerhead standoff.

Suddenly, a game-changer appears on the horizon.

DR. HEITHAUS:

NARRATOR: The new hammerhead on the scene

dwarfs the other sharks.

It's a 13-foot female.

Now, it's a three-on-three showdown

between bull sharks and hammerheads.

The imposing shark works her way

to the center of the group.

DR. HEITHAUS:

NARRATOR: She's about the same size

as the hammerhead attacked in Boca Grande Pass.

MAN (off screen): That's insane.

NARRATOR: But this super predator

brings a completely different power dynamic to the face-off.

FIELDS: It felt as though she was running the show.

She was making much closer passes to us

than the other sharks were,

perhaps because she feels far less threatened by us

as potential predators.

NARRATOR: The bull sharks circle, sizing her up.

The hammerhead makes quick turns,

possibly bracing for a three-on-one fight.

DR. HEITHAUS:

NARRATOR: The bull sharks take turns coming in...

closer and closer.

The 13-foot great hammerhead stands her ground.

The bull flinches first.

As the hammerhead approaches,

the bull gets a sense of her true size...

and retreats.

FIELDS: Things underwater kind of changed.

The dynamic changed a bit.

So it was really cool to see that she kind of

made everybody else clear out a little bit.

NARRATOR: The team has now seen first-hand the power and dominance

a giant great hammerhead has over bull sharks.

DR. HEITHAUS: Bull shark kinda gave way first.

They both turned,

but it's like that bull shark was kinda,

"You can have the swim lane first."

FIELDS: Exactly. Unlike most people think

that all sharks are at the top of the food chain,

but that's obviously not the case, right?

DR. HEITHAUS: Yeah, you can really see

the difference in maneuverability.

Those bull sharks are, like,

a tank trying to get turned around

and the hammerheads just spin on a dime.

FIELDS: Absolutely.

I mean, maybe that's another reason

why the bulls aren't coming in as much.

You know, the hammerheads have so much body

and so much capacity to move around,

whereas the bulls don't.

DR. HEITHAUS: That's just what we were looking for,

an opportunity to see these two big predators together,

but it doesn't mean when they get together,

it's gonna be one eating the other.

It might actually take special situations

for bull sharks to go after hammerheads or vice versa.

NARRATOR: After bearing witness to the head-to-head showdown,

Mike believes there's an answer

to which shark would come out on top.

DR. HEITHAUS: Based on what we've seen,

I think if it actually came down to a battle

and you had a bull shark and a great hammerhead,

the great hammerhead's gonna come out on top.

They are bigger, they are fast, they are maneuverable.

NARRATOR: So how did the hammerhead

become a victim in Boca Grande?

Back in Florida, Mike sits down

with the video one more time.

Instead of focusing on the aggressive behavior

of the bull sharks,

he takes a closer look at the hammerhead.

DR. HEITHAUS: The thing that I noticed

is that the hammerhead's

not really swimming quite right.

Think about that 3D track from Erin,

those sharks are able to turn on a dime.

NARRATOR: Unlike the giant great hammerhead in Bimini,

when faced with a threat,

these sharks swim stiffly in a straight line.

DR. HEITHAUS: I would've expected it to be

accelerating rapidly, turning quickly,

or even turning the tables

'cause that hammerhead was bigger

than the biggest bull shark that's there.

That suggest to me that that was a hammerhead

that was in trouble.

NARRATOR: The great hammerhead

may have been injured before the attack.

It was the height of tarpon season.

It's possible the hammerhead was hit by a boat

or accidentally hooked on a fishing line

while pursuing a tarpon.

It's likely the bulls sensed that it was compromised

and went in for the attack.

DR. HEITHAUS: And the bull sharks were then able to just follow it

and wait for the hammerhead

to be too exhausted or injured to fight back.

And then they finished it off.

This video is amazing,

but probably the exception to the rule.

In the end, bull sharks and great hammerheads

are both amazing top predators in their own right,

but when it comes to

bull shark versus great hammerhead,

they probably don't go after one another

unless the scales are really unbalanced.

But if a great hammerhead or a bull shark's in trouble,

they can become dinner.

NARRATOR: Two apex predators dominate the ocean--

the great white shark,

a lone hunter,

and the orca, known as the killer whale.

Both sit atop the oceanic food chain,

so when orca begin to hunt

great white sharks in South Africa,

it's big news.

Experts want to know, will it happen again?

And if so, where?

It's happened before.

Orca have hunted and killed great white sharks,

one of the first reported cases

off the coast of California in 1997,

and again in 2017 off South Africa,

five dead white sharks washed ashore.

Shark scientists wondered why orca would hunt

dangerous prey like a white shark.

With attacks happening in oceans around the world,

experts are looking for similarities and patterns

and what the effect would be on the marine ecosystem,

particularly in New Zealand.

KINA SCOLLAY: When the orca started to kill

the great white sharks in South Africa,

the rest of the sharks actually disappeared

and haven't come back for years.

If that happened in New Zealand,

not only would we lose this population of great whites

that we've learned so much about,

but it would also be disastrous for this ecosystem

to lose an apex predator like that.

NARRATOR: There are several theories

about exactly why the sharks vanished,

but the coincidence of the orca attacks

and the disappearance of the sharks is hard to ignore.

And there's a lot at stake,

including the health of the marine ecosystem.

(calling)

New Zealand has a local orca population

of between 150 and 200,

while the white shark aggregation

is one of the largest in the world,

estimated to be over 5,000.

If the orca begin to go after white sharks here,

they have plenty to choose from.

New Zealanders Kina Scollay

and Dr. Ingrid Visser are investigating.

Orca could be hunting great white sharks already,

but no white sharks have washed up on New Zealand beaches...

...so they're searching for other signs of orca predation--

any strange behavior,

wounds from an encounter,

anything that points to orca hunting white sharks.

NARRATOR: Local great whites are in New Zealand waters

from December to June,

when many will leave on their annual 2,000-mile migration

to the coast of Australia and the Tropical Pacific.

Local orca, on the other hand,

remain in New Zealand waters all year round,

roaming the coastline in search of prey.

(bang)

Ingrid is New Zealand's top orca specialist,

but today is her first dive with great white sharks.

NARRATOR: Great white sharks in this area

are curious and aggressive, which makes them dangerous.

Orca and white sharks have shared

the top of the ocean food chain for millions of years,

so why would orca attack great whites like these now?

INGRID: Even though orca are the largest

of the dolphin family and they can be friendly,

we still have to consider that they are

one of the top predators of the ocean.

NARRATOR: Ingrid's research tracks the 200 or so orca

living in New Zealand's waters.

INGRID: Yeah, I know, big guy! Hang in there.

The exciting thing about this adventure for me

is that we've got two top predators,

and we don't really know what's happening between them.

NARRATOR: Orca and white sharks

are the top two ocean predators,

yet they're fundamentally different.

Orca are air-breathing mammals.

(blows air)

White sharks are water-breathing fish.

Orcas live in pods of up to 40,

made up of individual family units

that remain together for life and hunt cooperatively.

Some new research suggests

white sharks may occasionally hunt in groups,

but they tend to hunt alone.

The largest great white ever recorded measured over 20 feet

and weighed 5,000 pounds--

small for an orca.

Killer whales can grow to 30 feet or more

and weigh as much as 20,000 pounds.

But as different as they are,

orca and great whites are both sophisticated,

tough, and hungry predators.

NARRATOR: Kina and Ingrid dive again and again,

searching for evidence.

NARRATOR: In 2017,

a predator-on-predator interaction of another kind

took place along the coast of South Africa.

Five dead great white sharks washed up on local beaches.

The news is shocking.

Scientists conducted an investigation.

Of all the evidence collected,

it was the bite marks on the shark bodies

that revealed the killers.

The teeth marks belonged to orca.

Stranger still,

the killer whales had taken only the shark livers

and left the rest of the bodies untouched.

This was the first recorded case

of orcas killing white sharks in South Africa.

Shark and orca scientists

wondered when and where it might happen again.

INGRID: We can't rule out that the orca here in New Zealand

could hunt great white sharks in exactly the same way.

(bird squawking)

NARRATOR: The Foveaux Strait

sits at the southern end of New Zealand,

over 6,000 miles to the east of South Africa.

Both regions have large populations of great whites

and roaming pods of orca,

a combination that resulted in a fatal confrontation

in South Africa.

And if white sharks and orca

ever cross paths in New Zealand,

this is where it could happen, in the Foveaux Strait.

NARRATOR: Large, boisterous,

and aggressive great white sharks.

What possible motive could an orca have

for attacking a great white?

There isn't a clear answer,

but to Ingrid, it makes some sense.

INGRID: Typically, in New Zealand,

the orca are not just targeting prey to take the whole thing.

They're focused on particular parts of them,

and that's the liver.

NARRATOR: When the South African orcas

killed the great whites, this is what they did--

hunting for liver with great precision.

Liver is a prize for any predator.

To hunt, mate,

and migrate thousands of miles

takes energy.

Liver is pure fuel,

so when they hunt, they're filling the tank.

New Zealand orca feed on the 25 species of rays and skates

that swim in local waters.

The preference for rays is unique to orca in New Zealand.

But recently, local orca have acquired a taste

for shark liver

from a smaller cousin of the great white, the sevengill.

And evidence suggests South African orca

started on sevengill sharks...

(calling)

...and graduated to great whites.

NARRATOR: Ingrid Visser and Kina Scollay are looking

for evidence that orca are hunting great white sharks

in New Zealand waters.

Ingrid has evidence that there's a disturbing pattern

in orca hunting.

New Zealand orca are hunting sevengill sharks,

just like the South African orca.

Sevengill sharks grow to 9 feet long and 200 pounds,

a much larger meal for an orca than a small ray.

But the sevengill shark is no easy prey.

INGRID: Sevengills are relatively new on the orca menu,

but I've seen it a few times now.

You see the orca, and they're very, very precise

in how they do it.

And I've got footage of orca with the sevengills

where they've ripped the pectoral fin

right under the pectoral girdle there,

and they've extracted the liver.

WOMAN: Whoopee! Oh, there's a shark.

Oh, shark! Shark!

INGRID: One of the things I find fascinating

is how the sevengills will actually turn

and defend themselves against the orca.

The way the orca hunt the sevengills is pretty impressive.

First of all, they'll come in,

and they'll karate chop the shark,

so they'll just come and lift their tail up

and whack them on the back.

Then they grab the sharks by the pectoral fin

and rip them open and pull the livers out.

NARRATOR: Ingrid captured rare footage

of orcas hunting sevengills in northern New Zealand.

Their precision in hunting for shark liver is clear.

KINA: What's really fascinating is that in South Africa,

the orca started by hunting sevengills,

and then they moved on to the great white sharks.

So, knowing what's gone on in South Africa,

what concerns me is exactly the same thing could happen here.

NARRATOR: A concentration of sevengill sharks

lives up along the western coast of New Zealand.

Kina has dived with them for years,

knows just where they live and how they behave.

KINA: Beautiful.

NARRATOR: They decide to drop in and see if the sevengills

can give them any clues.

Fiordland National Park is a vast, remote wilderness

on the western shore of New Zealand's South Island.

Most areas are accessible only by helicopter or boat.

KINA: You know, really, you fly over these mountains,

and you're in a completely different world,

and then under the water, it's completely different again,

different to just about anywhere else you'll dive.

Amazing.

NARRATOR: These deep fiords are murky,

stained with tannins from the ancient forest.

It makes the water dark, even in the middle of the day.

If orcas came here to hunt sevengills,

it's possible no one would ever know.

KINA: I actually haven't been in here for about two years.

So, that's after diving here

month in, month out for many years,

and I really felt like I knew these sevengills so well.

All this talk about orca eating them,

I just kind of want to come and have a look.

INGRID: Yeah. Absolutely, Kina, and I mean, look,

that ties in with the sightings that we've had recently

of the orca coming down this bit of coastline,

so I'd be fascinated to know if they're coming up here

to your sevengills.

NARRATOR: The only place for Kina and Ingrid to land

is on a small fishing trawler in the middle of nowhere.

KINA: My little secret spot

is only just literally one minute's flying time from here,

so I think it's easiest if I gear up here.

INGRID: Yeah.

KINA: And then I'm gonna hop in the helicopter

and just buzz around there and bomb in!

NARRATOR: Diving without a cage,

Kina will have to be careful of the sevengills

and keep an eye out for orca.

They could be anywhere.

NARRATOR: Kina Scollay is paying a visit

to an aggregation of sevengill sharks

in Fiordland National Park, New Zealand...

...and knows just where to find them.

He's looking for any signs

that orca are hunting these sevengill sharks.

NARRATOR: The sevengills are here,

drifting in and out of sight...

...checking out the intruder.

Ooh!

NARRATOR: Sevengills may be prey for orca,

but these sharks are no pushovers.

Oh!

That was awesome to go and visit those guys.

INGRID: Yeah, great jump!

KINA: Yeah, cheers, mate.

That splash and the noise of the helicopter

really has to attract them,

and they were straight on top of me when I got in,

but not as many as I would have expected to see.

INGRID: Really? Okay, well, that's really interesting

because given that we know historically

that orca are coming in here,

and we've had the reports recently,

and now you're seeing less sharks in here, too,

so, you know, it's indicative

that something's been going on, right?

NARRATOR: Lower sevengill numbers

could mean a few things are going on,

including predation by larger predators,

like orcas.

That would mark a change in their usual diet.

Traditionally, New Zealand orca hunt the many species

of rays and skates that live in these waters.

Like all dolphins, they have a special ability to find them.

INGRID: Orca hunt using echolocation,

which is a series of clicks that they send out...

(clicking)

...that bounce back and give them incredible information.

(calling)

They can tell even if a shark has a full tummy.

NARRATOR: It works like sonar.

The orca can detect their prey

even when it's buried in the sand.

(calling)

But filling up on rays and skates can be hard work

and burn a lot of precious energy.

(calling)

INGRID: Do you see them?

Look, they're in a really tight group over here, right there.

NARRATOR: Many rays are bottom feeders

and spend much of their time on or buried

in the sandy ocean floor.

Orca jaws are not designed to grab them off the bottom,

so the orca work together,

chasing the rays upward and catching them in the open.

But ray hunts don't always go smoothly.

Rays often flee to shallower water...

...making it dangerous for the orca.

There is the risk of a fatal stranding as the tide goes out.

And the ray may still escape.

NARRATOR: When orca hunt rays in New Zealand,

their size is not always an advantage.

After a lot of work

and coordinated effort among several orca...

...they catch the ray,

but it's a tiny payoff for all that effort.

And compared with white sharks, rays are a snack.

One 700-pound great white shark liver could be equivalent

to nearly 175 ray livers,

and it's a lot more work to hunt multiple rays.

While it is more dangerous to hunt a single great white,

it might be worth the risk.

KINA: It's really hard not to think

when you see animals that big

that their liver must be gold to a liver-eating orca.

NARRATOR: A great white liver can grow to 25 percent

of the shark's total weight.

If a 12-foot great white weighs 1,000 pounds,

it may have a liver weighing 250 pounds,

a big payoff for the orca.

Kina and Ingrid are off one of the Foveaux Strait's

large colonies of seals.

Over the summer, the white sharks consume many.

(barking)

Their livers are swollen with seal blubber and oil.

Ingrid and Kina are looking at the length of the sharks

to estimate their liver weight.

NARRATOR: Great white sharks as prey for anything,

even orca, is hard to fathom.

But the orca may see them that way.

INGRID: All our evidence points to the fact

that the New Zealand orca have a very strong culture

of hunting sharks.

If the rays were removed from the food web

here in New Zealand,

chances are the orca would shift their food preferences,

and they could start targeting great white sharks in earnest.

NARRATOR: So far, the supply of rays and skates

has been ample, but add warming oceans

to natural fluctuations in all animal populations,

and it's hard to predict what will happen.

NARRATOR: The half dozen white sharks swimming by

are more than impressive.

To an orca, they may represent

the food value of 1,000 rays.

NARRATOR: At 16 feet, this one great white shark alone

is the equivalent of 200 rays to a hungry orca.

It might be a motive for predation.

KINA: It's hard not to think

an animal as intelligent as the orca,

that they're coming through here at the perfect time of year,

when the livers are fat,

they've gotta see this as a food source.

And even though it's high risk,

we've seen in South Africa that they can decide it's worth it.

There's such a food source there.

INGRID: Oh, absolutely.

KINA: You've gotta wonder

whether they're not already onto this.

It may have been going on for a long time in New Zealand,

but we've just never heard about it.

INGRID: Yeah, exactly.

NARRATOR: Ingrid and Kina have found many similarities

between New Zealand and South Africa.

(calling)

In both places, the orca already have a taste

for sevengill sharks.

But after the orca killed five great whites in South Africa,

all the other white sharks disappeared.

In New Zealand, all of these sharks

are still here and hunting.

Then, like a bolt from the blue,

Kina and Ingrid finally see what they've been looking for.

NARRATOR: Kina and Ingrid are observing

local white shark behavior

when a male with a wound catches their eye.

NARRATOR: An unusual mark on a white shark's dorsal fin

looks like a bite.

KINA: What were those rake marks on the fin?

That was fascinating.

They were quite wide apart and very straight,

which was interesting.

And those were uniform. That was something new to me.

INGRID: Yeah, and it looks very similar

to what I see in the stingrays

when the orca have been biting them.

You know, you get these sort of like someone's raked the garden,

but it's teeth rake marks,

and that's what it looked like to me.

Yeah, so let me show you these.

This is a picture of a orca's teeth.

See how the teeth curve backwards?

And so here, this is a close-up of these teeth marks,

and this is what I think we saw on that great white shark.

KINA: Yeah, amazing.

INGRID: And when you look at the scale on here.

KINA: Same thing, that was what we saw on that shark!

INGRID: Yeah, so if I had to put money on it,

I'd say that it was orca.

KINA: Well, I certainly can't think of anything else,

and that is pretty phenomenal.

This could well be the evidence we're looking for.

NARRATOR: The bite marks could be a breakthrough,

the first visible sign

of orca-on-white-shark predation they've seen.

Ingrid and Kina devise an experiment

that will use sound instead of sight.

INGRID: Orca use a range of different sounds.

They use clicks for echolocation.

(clicking)

They use whistles and pulsed calls

when they're communicating.

(calling)

It's really impressive.

NARRATOR: So they'll use recorded whale sounds

and observe how the sharks react.

KINA: It's a little-known fact about great white sharks

that they actually have amazing hearing.

So, I think if the great white sharks react to orca sounds,

that might mean that they've met them before.

How they react could possibly even tell us

whether that experience was hunting or otherwise,

so this experiment is going to be very interesting.

NARRATOR: They mount an underwater speaker

on the dive cage.

The plan--play sounds from several other kinds

of whales first to try and draw the sharks in.

INGRID: Oh, that's perfect.

NARRATOR: Once white sharks are around the cage,

Ingrid will play the sounds of New Zealand orcas hunting.

KINA: Done.

It will be interesting to see if they are actually scared of orca

or if they, you know, if they know what it's like

to be scared of something.

INGRID: Do you copy me, Kina?

INGRID: Well, look, I'm gonna start playing

the first set of sounds now.

This is the humpback whale calls that you recorded.

(humpback whale singing)

NARRATOR: This is humpback whale song...

(singing)

...and possibly a great white dinner bell.

White sharks are known to hunt whale calves

in the Tropical Pacific.

(humpback whale singing)

NARRATOR: The circling great whites

begin to rush the speaker and the cage.

(humpback whale singing)

NARRATOR: The sharks are clearly responding

to the humpback whale sounds.

The question is, how will they react

to the sound of New Zealand killer whales?

NARRATOR: Ingrid Visser and Kina Scollay

want to see how great whites react

to the sounds of hunting orca.

(humpback whale singing)

First, as a test, they play humpback whale song.

(humpback whale singing)

The sharks come straight to the sound...

NARRATOR: ...including the shark

with the bite marks on its dorsal fin.

They have to wait a few minutes

for the sharks to settle down after the humpback reaction.

INGRID: Now I'm just gonna play you the sounds

from the orca that eat the salmon.

I recorded these guys off North America.

Stand by.

(orca whistling)

Can you hear that?

(orca squeaking)

(orca whistling)

INGRID: Yeah. Well, I guess that doesn't really surprise me,

given that these are the fish-eating orca.

NARRATOR: The sharks appear unresponsive

to the North American orca calls,

but these sounds have never been heard before

in New Zealand.

INGRID: Yeah. Kina, so now I'm gonna play you

the New Zealand orca.

These are probably the ones

that the great whites have heard before.

Stand by.

(orca calling)

NARRATOR: The sharks' response

was clearly to move away from the sound.

(orca calling)

NARRATOR: Ingrid and Kina observe that the sharks

keep the source of the orca sounds in sight

but stay well out of the way.

INGRID: How was that, mate?

KINA: Yeah. Well, another awesome dive down here,

but interesting.

We've only really had a glimpse, eh?

NARRATOR: The orca sounds changed the behavior

of the white sharks,

from fearlessly coming into the sounds of the humpbacks

to moving off and keeping their distance

when they heard hunting orca.

But was this a typical animal reaction to danger?

INGRID: You know, when you think about the bite marks

that we saw that could have been the orca,

and you saw the way that the great white sharks,

you know, there was a bit of reaction there, but not full-on.

KINA: Obviously, we'd have to do this a lot of times

to be able to say for sure,

but maybe actually the sharks aren't so scared of orca.

INGRID: Well, maybe New Zealand sharks are more exposed to it,

like even from when they're little sharks,

and so they just become habituated to it.

NARRATOR: When orca killed five white sharks

in South Africa in 2017,

many scientists believed it was a first for the region.

But is it possible that white sharks

have been fending off orca attacks

for thousands of years

and what we see are only the most recent incidents

in an ancient and ongoing battle?

INGRID: I guess the big thing for me is, you know,

how far are these orca going?

And we've got some evidence that suggests that they're

at least trying to have a nibble on them, but, uh, you know,

I'm curious to know just how far they've taken it.

NARRATOR: So far, there have been

no reported serial shark attacks in New Zealand.

But here on the far side of the world,

the unseen struggle between orca and white shark goes on,

in secret, for now.

NARRATOR: Sharks, dolphins,

an epic war waged beneath the waves.

MAN: He's got a dolphin in his mouth!

NARRATOR: Brain against brawn.

MAN: Oi, they're fighting, they're fighting. Oh, (bleep)!

WOMAN: Dolphins are very capable predators

in their own right.

MAN: People forget that killer whales

are actually dolphins.

MAN: I've never ever seen anything like this before.

NARRATOR: Now for the first time,

a chance to see how these gangs of the deep go to war.

Can there be a truce?

Or are these top predators locked in a blood battle?

Off Australia, predators stalk their prey.

These are called false killer whales,

but they're actually dolphins,

just super-sized.

They grow up to 20 feet long

and travel in pods of 10 or more.

Today they're on the hunt for shark.

The pod gives chase.

The shark can't outswim them.

The dolphins work as a team,

box in the shark,

and move in for the kill.

FRANCES FARABAUGH: Dolphins are very capable predators

in their own right.

NARRATOR: Frances Farabaugh is a shark biologist

at Florida International University.

FRANCES: I feel like there's this conception

in the general public that dolphins are the heroes

and sharks are the antagonists or the villains.

NARRATOR: When it comes to the fierce relationship

between dolphins and sharks, there's a lot we get wrong

and a lot more that we don't even know.

FRANCES: Both of these organisms are predators

that are making smart, intelligent decisions

about how to survive and how to feed.

NARRATOR: Primal decisions that often bring

these two top predators into conflict.

In some areas, 30% of the dolphin population

bear the marks of shark encounters.

And that's on the dolphins that survived.

But even smaller dolphins aren't defenseless.

They wield a powerful arsenal of weapons to combat sharks.

FRANCES: It's a mistake to think of dolphins versus sharks

as some kind of mismatched pairing.

There are advantages and disadvantages,

but they're quite evenly matched.

NARRATOR: Frances is on an expedition to gain insight

into the battle between sharks and dolphins.

She teams up with research specialist Kirk Gastrich

on the far side of the world

in what might be the bloodiest front

in the shark-dolphin war:

a place called Shark Bay.

KIRK GASTRICH: In Shark Bay, we know that

there are these interactions between sharks and dolphins.

The amount of dolphins with shark-inflicted wounds

on them is really, really high here.

FRANCES: We know that around 75% of dolphins here

show scars from interactions with sharks.

NARRATOR: On the western tip of Australia,

Shark Bay is a sprawling natural preserve.

3.2 million acres of pristine marine habitat,

overflowing with fish and squid.

A dolphin paradise.

Only one problem.

KIRK: They call it Shark Bay

because this place is just loaded with sharks.

NARRATOR: Frances and Kirk have a lot of ground to cover.

Their floating laboratory for the next week

is the 120-foot ship Infamis.

ASH: Straight in here, guys. Welcome aboard.

FRANCES: Thank you.

NARRATOR: Rounding out the expedition team

are Ash Sutton, the ship's captain...

ASH SUTTON: If you've come looking for sharks,

this is the hot spot around here.

NARRATOR: ...and Duncan Brake, an underwater cinematographer

who's been filming both sharks and dolphins for 20 years.

DUNCAN BRAKE: Dolphins seem to have

a bit of this love/hate relationship with sharks.

I don't know, but there definitely seems to be

this dichotomous relationship between the two species.

NARRATOR: The mission on the expedition:

capture video evidence of shark/dolphin combat.

They hope to detail how sharks outsmart

one of the most intelligent animals on Earth,

and find out how dolphins evade

one of nature's most efficient killers.

To get the footage, the team has custom-built cameras

to attach to shark fins.

KIRK: We know that there are interactions,

but we haven't really seen them with our own eyes.

NARRATOR: Do the sharks hunt during the day or night?

Do they target the sick or injured?

All questions the fin cam can help answer.

About 5,000 dolphins call these waters home despite the sharks.

They've figured out not just how to survive

but how to thrive.

FRANCES: There are lots of strategies and advantages

that dolphins have when they're trying to defend themselves.

One of them is that they're very social animals.

We know that, through research, they tend to hang out

in larger groups when they feel they're more vulnerable,

like at night and when they're resting.

NARRATOR: They also live and work together in pods,

a cooperative that not only provides protection

but is an effective means to hunt prey.

FRANCES: They're very fast, they're very strong,

and they easily outmaneuver a shark.

So, it's important not to think of them

as some kind of David versus Goliath.

Dolphins are powerful, incredible predators.

NARRATOR: Sharks don't play well with others.

There are no shark pods.

They're solitary hunters.

And in this part of the world,

the number one threat to dolphins is the tiger shark.

FRANCES: From a dolphin's perspective,

a tiger shark is always a danger,

because it only takes one slip-up

for you to be consumed by a shark.

NARRATOR: Tiger sharks have earned themselves

a nasty reputation.

DUNCAN: As an underwater cameraman,

you can be literally be covered in other shark species,

but then that big, old tiger shark will roll into town,

and you are looking at that one big tiger.

NARRATOR: Named for their distinctive stripes,

these apex predators can top 14 feet.

And they have an outsized appetite to match.

Unlike white sharks, which use their immense power and speed

to take down seals and dolphins,

tigers are all about a casual kill.

DUNCAN: I think tiger sharks

are gonna sneak up on something and grab it

instead of actually having to chase it around

all over the ocean.

NARRATOR: Video footage of tiger sharks fighting dolphins

is extremely rare and extremely hard to capture.

But if the team can get it,

the footage could unlock the secrets of this unseen war.

The first step is to find the sharks.

The team uses a baited remote underwater video, or BRUV.

FRANCES: With BRUVs, I drop a frame with a camera

and some bait down to the bottom of the ocean.

I pull that back up, and then I watch the video through

to see what showed up.

Make sure that that bait arm is pointing down current,

and just make sure it's...

NARRATOR: Strong currents can easily topple the BRUV,

so Duncan will check it out on the bottom.

NARRATOR: Sharks can easily detect prey

through clouds of muck.

FRANCES: Sharks sort of have a sixth sense.

They can sort of electrorecept.

So they have these little organs towards the front of their noses

that are called ampullae of Lorenzini.

They kind of detect little electrical currents.

And so they're not relying

necessarily exclusively on sight to hunt.

NARRATOR: Remoras are fish that cling to sharks.

They swim alongside and feed on the host's scraps.

FRANCES: Large remora, maybe a large shark nearby.

NARRATOR: A large remora could mean

that a very large shark is closing in.

FRANCES: I didn't read that. Can you say again?

Duncan, Duncan, test, test, can you hear me?

FRANCES: Excellent.

NARRATOR: The BRUV is rolling.

They'll leave it for a day

and then find out if they're in the right spot for sharks.

DUNCAN: With this visibility,

it's probably time to get out of the water

and let the BRUV do its work, I think.

NARRATOR: Stories abound of sharks sneaking up on swimmers,

and dolphins zooming to the rescue.

In 2018, off the coast of Australia,

a snorkeler diving with a pod of dolphins

suddenly spots a Galapagos shark.

These large predators are known

to take down seals and sea lions.

Before long, more sharks appear,

and they're getting closer.

But he hardly believes what happens next.

(dolphins squeaking)

A pair of dolphins charge

and scatter the threatening sharks.

(squeaking)

A dolphin pod has safety in numbers.

When the matchup is one-on-one, it's usually a different story.

MAN: He's got a dolphin in his mouth!

NARRATOR: Recently, two Australian oystermen

capture this savage struggle up close.

JASON DARKE: I've never, ever seen anything like this before.

Only on TV, and even then, it's rare.

We were going about eight kilometers out.

We were probably halfway there

when off in the distance we noticed a fin

which we assumed straightaway would be a dolphin.

A dolphin. It's a dolphin.

Jai, here, hold my phone.

JAI DARKE: And once we realized the size of it,

there's no curve in the back of it,

we realized that it was not a dolphin.

JASON: This was much bigger than a dolphin fin,

much, much bigger.

JASON: The shark we knew straightaway

was a great white shark.

It would've been approximately 10 to 12 foot.

Rather large.

He's coming this way, he's coming this way.

He's coming right to us.

He's got a dolphin in his mouth!

He just swam straight past us with a dolphin in his mouth.

JAI: This is (bleep) you see on Nat Geo Wild.

NARRATOR: But then things get wilder.

JASON: So, we'd been watching the shark for a while,

and I was carefully following the shark

as it was swimming away with the dolphin,

when, all of a sudden, out of nowhere...

Oh, my god, another one, another one!

JAI: Oi, oi, oi! Oh, (bleep)! Oh, (bleep)!

JASON: Oh, my god, another one, another one!

JAI: Oi, oi! Oh, (bleep)! Oh, (bleep)!

JASON: He's got a dolphin in his mouth!

NARRATOR: Sharks and dolphins.

This vicious rivalry has been raging for millions of years.

Two Australian oystermen get a firsthand look

at the aftermath of a battle.

JASON: Oh, my god, another one, another one!

JAI: Oi, oi, massive one, massive one!

Oh, (bleep)! Oh, (bleep)!

Look at it!

Oh, that just come out from underneath the boat.

The moment I saw the second shark,

adrenaline started pumping through my veins.

I didn't know what just happened.

Oh!

That scared the (bleep) out of me!

JASON: The second shark was bigger than the first.

It would've been 12 to 14 foot, probably,

but it was definitely bigger.

JAI: It was huge.

Oi, they're fighting, they're fighting,

they're fighting, they're fighting!

Oh! Oh, (bleep)!

He just stole that dolphin!

He just stole the dolphin!

Oh, he's massive!

Oh!

JASON: Look at the size of the thing!

NARRATOR: A dolphin is worth fighting over.

FRANCES: We do know that if a shark gets the opportunity

to eat a dolphin, they absolutely will.

And in fact, it's a really prized food source.

Like many marine mammals, dolphins have all this blubber,

so that's a good nutritious meal.

NARRATOR: From the injuries, it's clear the dolphin

was initially attacked from behind and below.

JASON: He swam straight past us

with a dolphin in his mouth.

NARRATOR: How did the shark get past this dolphin's defenses?

FRANCES: Dolphins are really quite zippy.

They can outmaneuver a shark fairly easily,

especially if they're in deeper or open water spaces.

NARRATOR: To understand how sharks catch

these slippery creatures, the team heads to a beach

that offers a unique look at Shark Bay's dolphins.

FRANCES: So, we're right now at Monkey Mia in Shark Bay.

There has been 20 years

of really incredible ecological and biological research

on the interactions between sharks and dolphins.

NARRATOR: Dolphins were first drawn here in the 1960s

by fishermen sharing their catch.

Today the site is regulated by the Parks and Wildlife Service.

FRANCES: We have some friendly dolphins that come here

very regularly, and we get to see them up close and personal,

which is really special.

NARRATOR: No need for a baited underwater camera.

Here, dolphins come to you.

And they're covered in scars.

FRANCES: So this individual that's just approaching us

just now is called Piccolo.

And you can see on her dorsal and on her back,

she's got scars from encounters with sharks.

Dolphins make this trade-off.

A lot of the food that they want most

and the easy fishing grounds, the yummy fish,

occur around shallow seagrass beds.

Unfortunately, that's also where tiger sharks

preferentially like to hunt.

NARRATOR: To protect themselves,

dolphins have a secret weapon: echolocation.

They can send out a beam of sound

from a fatty part of their head, called the melon.

The sound beam bounces back and forms a mental image

in the dolphin's brain of the world around them.

FRANCES: Echolocation is the way that dolphins have to see

in dark and low-lit environments.

Basically, it's like radar or sonar.

NARRATOR: But there are limits to this superpower.

FRANCES: So, it works kind of like wide beams on a flashlight.

They can only see kind of directly ahead of them

or to the sides.

So, if they get attacked from the back or from underneath,

they probably won't see the predator coming.

NARRATOR: Dolphins have a blind spot,

and sharks know it.

NARRATOR: Great whites use their massive power

to charge from beneath in a breach attack.

KIRK: White sharks you would consider

more of an ambush predator.

FRANCES: It's probably the shark that you don't see

that you worry about,

because a lot of white sharks rely on surprise.

They're stealth predators.

NARRATOR: It's easy to sneak up on a lone dolphin,

but the safety of the pod can stop an ambush,

even from a great white.

A white shark swims with a group of dolphins.

The ocean-going mammals show no concern

for the killer in their midst.

Their ability to communicate and spot their stalker

gives the shark no chance at an attack.

The team heads out to search for more scarring,

and more signs of shark/dolphin battles.

FRANCES: To our port now just a little bit.

10, 11 o'clock.

Maybe 100 meters out.

KIRK: So, we've got one dolphin up here.

Appears just to be logging or just resting at the surface.

FRANCES: It definitely has scars.

KIRK: That's the thing about dolphins, though,

if they don't wanna stick around, they don't.

NARRATOR: It's a perfect display

of another dolphin defensive weapon: speed.

They can reach up to 22 miles per hour.

A simple flick of the tail and they leave a trail of bubbles,

able to outswim most predators, including sharks.

But there's a shark that's even faster.

The mako.

DUNCAN: Mako sharks are one of the fastest fish in the sea.

And compared to other sharks,

their speed and agility cannot compare.

NARRATOR: Mako sharks are torpedoes with teeth.

Blasting up to 45 miles per hour;

twice as fast as dolphins.

(woman screams)

WOMAN: Shark right here!

NARRATOR: Near Maui, Hawaii, Captain Steve Lawless

captures a mako and dolphin encounter off his snorkel boat.

(scream)

MAN: He's got the dolphin in his mouth.

NARRATOR: The mako has the dolphin by the tail;

a sure sign that the shark outswam its panicked prey.

MAN: Has he swallowed the dolphin

or is the dolphin hanging out of his mouth?

DUNCAN: I think a dolphin could quite easily

outmaneuver a tiger shark.

However, if we brought a mako shark to the table,

not a chance.

WOMAN: This is crazy!

NARRATOR: Luckily for the dolphins of Shark Bay,

there aren't many makos here.

But there are tigers, and the team wants to know

if they're in the right place to capture one.

Step one: retrieve the BRUV.

DUNCAN: How'd you guys do?

Everything back in one piece?

FRANCES: Everything's back in one piece.

DUNCAN: I can't wait to see what was down there with that remora.

NARRATOR: Is the footage binge-worthy?

Success: tigers on camera.

The team is in the right spot.

FRANCES: We know from BRUVs that this is an area

that has a lot of tiger sharks and many different habitats.

What we don't have evidence of on these BRUVs

is exactly what the sharks are eating.

NARRATOR: To really understand the shark/dolphin relationship,

Frances wants to capture a shark's-eye view of Shark Bay.

FRANCES: So, basically, what this is, is it's our fin camera.

What happens is we'll slot this over the fin of the tiger shark,

and we'll send it on its merry way.

KIRK: Alright, good to go? FRANCES: Good to go.

KIRK: Okay, got that?

NARRATOR: They set up a series of baited hooks

called a drumline.

FRANCES: Ready to go.

KIRK: Alright, going over.

Alright, we're on bottom.

FRANCES: One down.

KIRK: One down, four to go.

FRANCES: Alright, let's get the next one set.

NARRATOR: They check the lines every 30 minutes

to ensure no shark is harmed.

FRANCES: Got a shark on the line.

KIRK: Just want to see what we got.

Coming up!

Hooked good.

Coming under, coming under.

FRANCES: Alright, ready to go on that.

KIRK: Okay, on zero.

FRANCES: Zeroed.

Hold on.

KIRK: Watch it, Frances, watch it.

I'm losing the head here.

FRANCES: Oh!

NARRATOR: There's a primal conflict down in the deep:

dolphins and sharks.

MAN: Shark. WOMAN: Shark.

JAI: Oh, he's massive!

(scream)

JAI: They're fighting, they're fighting! Oh!

KIRK: Okay, on zero.

FRANCES: Zeroed.

KIRK: Watch it, Frances, watch it.

I'm losing the head here.

FRANCES: Oh!

NARRATOR: Shark researchers Frances Farabaugh,

Kirk Gastrich and cameraman Duncan Brake

are at one of the fiercest battlegrounds

in this ferocious struggle: Shark Bay, Australia.

FRANCES: Many of the dolphins that we've seen

have shown lots of evidence of encounters with sharks,

very specific scarring and bite marks.

So we know that these interactions are occurring.

NARRATOR: Their mission:

capture direct evidence of these battles

and observe offense and defense in action.

Which strategies work?

Which don't?

JASON: He's got a dolphin in his mouth!

NARRATOR: To do it, they want to catch

the region's supreme predator, the tiger shark,

and stick a camera on its fin.

KIRK: Pretty shark. Hooked good.

NARRATOR: They have their shark, but...

ASH: It's a bronzie.

DUNCAN: That moment when you're waiting for those stripes

to appear on the back of the shark,

and then you see a flash of bronze instead.

Yeah, it's almost heartbreaking.

You've got a shark; it's just not the right one.

NARRATOR: Bronze whalers are relatives of tiger sharks.

But they're not known for attacking dolphins.

KIRK: We'll get the bolt cutters ready, Frances.

FRANCES: Yep.

NARRATOR: The team decides to hang onto their fin cam

and keep searching for a tiger.

KIRK: Nice.

FRANCES: Okay, it's gone.

We just released it straightaway

and it was a really beautiful release.

DUNCAN: Right back to square one.

NARRATOR: Of nearly 500 species of sharks,

only about 10 target dolphins as prey.

The usual suspects top the list:

the tiger, great white...

JAI: Oh, he's massive! Oh!

NARRATOR: And hammerhead.

They mostly eat stingrays.

But a hammerhead will hunt down a dolphin given the chance.

MAN: Look at that shark, dude.

MAN: I got it, man. I got it all right here.

Holy (bleep).

NARRATOR: The notorious bull shark,

a known man-eater, makes the list.

DUNCAN: Bull sharks are very bold and brash.

Kind of bulldoze other sharks out of the way sometimes,

just to find out where the food is.

FRANCES: Every species of shark

is going to have different hunting modes,

different strategies, different sort of niches that they fill.

NARRATOR: But when it comes to hunting dolphins,

each of these different species share a common trait:

size matters.

JAI: Oi, oi, massive one!

JASON: Look at the size of the thing!

NARRATOR: To get past a dolphin's defenses,

the rule seems to be a shark needs to be as big or bigger.

But there are exceptions to every rule.

Off the Florida coast, a young blacktip shark is in pursuit

of a bottlenose dolphin more than twice his size.

DUNCAN: Yeah, blacktip sharks,

every time I've been in the water with them,

they always behave erratically.

They're like little kids on a sugar rush,

kind of bouncing around.

They don't really care about where you are.

They just want the cheeky free snack.

NARRATOR: The shark's running a risk.

His snack could attack.

The shark comes to his senses and backs off.

The team hopes to film their own dolphin and shark faceoff

with a fin cam.

FRANCES: Alright, one more.

KIRK: So we just finished checking the lines.

We re-baited everything.

We've got some fresh meat on there for the shark.

FRANCES: Ah, I think we actually got a shark on the line.

DUNCAN: As we were going around,

we noticed that both of the buoys were underwater.

KIRK: Watch your feet, watch your feet, watch your feet.

DUNCAN: So, like, for it to pull both those buoys down,

it was gonna be a huge animal.

KIRK: Alright, you can go neutral. Coming up!

DUNCAN: Yep, here he is coming up.

KIRK: Alright, hold on.

FRANCES: It's a tiger.

KIRK: Alright! Got a bruiser of a tiger.

DUNCAN: I jumped in the water.

The water around here is a little bit murky,

so we couldn't really tell how big she was

until we jumped in there.

KIRK: Ah, it's a big one. Big female.

FRANCES: Oh, it's huge.

DUNCAN: I've filmed tiger sharks all around the world.

However, jumping in the water here in Shark Bay

with these just huge, just off-the-chart,

ginormous, mama bus tiger sharks just blew my mind.

And it almost made some of the other sharks

that had been in the water look like tadpoles.

NARRATOR: Such a massive animal demands extreme caution.

FRANCES: Our first priority is the safety of everyone involved,

the safety of the animal, and then getting good science.

NARRATOR: Shark secured.

But there's a problem.

KIRK: Alright, this hook's straightening out,

so just be careful.

NARRATOR: A steel hook is the only thing keeping

this powerful shark safely in place.

And she's bending it.

KIRK: (bleep) It's straightening.

NARRATOR: If she straightens it much more,

this massive beast will break loose.

KIRK: Yeah, you are big, I know.

NARRATOR: Frances and Kirk have a decision to make.

KIRK: We can let her go, or we can try to do a workup,

hope this hook doesn't straighten fully

and we lose her before we get the camera on.

FRANCES: Alright, ready to go on that.

KIRK: Alright, Ash, you can come on over here.

NARRATOR: They decide to go for it.

KIRK: Come on up, Ash, we can probably get a tail on her now.

ASH: Got it.

We got a line on the tail, anyway.

KIRK: Yeah.

Once we lose control of the head though, we're (bleep).

NARRATOR: Keeping control of the shark's head is critical,

especially with her size.

A snap of the jaw could mean tragedy.

KIRK: Hands!

DUNCAN: This huge tiger shark, swinging around with its teeth.

Every time that shark shook its head,

the hook straightened a little bit more.

FRANCES: Okay, Kirk, incoming with the tape.

NARRATOR: The closest hospital is a six-hour boat ride away...

KIRK: Okay, hand me the tape again.

NARRATOR: ...more than enough time for someone to bleed out

if shark teeth meet human flesh.

KIRK: Okay, I'm zero, Frances, zero, zero, zero, zero.

FRANCES: Zero, I'm zeroed.

ASH: Okay, 3.8.

KIRK: 3.8.

NARRATOR: 3.8 meters.

This monster shark is 12 and a half feet long.

KIRK: She's so big.

NARRATOR: And the hook is straightening.

KIRK: Ah, it's probably gonna come out.

NARRATOR: If the shark breaks free,

it could swamp the boat...

KIRK: Yeah, she's pissed.

NARRATOR: ...or charge straight at Duncan.

KIRK: Maybe a little tighter on the tail, Ash.

ASH: It's gonna get lost!

KIRK: Watch out, watch out, watch out!

KIRK: Maybe a little tighter on the tail, Ash.

ASH: Yeah, it's gonna get lost.

KIRK: Watch out, watch out, watch out!

FRANCES: I got it, I got it.

NARRATOR: An almost 15-foot tiger shark

in Shark Bay, Australia, might be just perfect.

FRANCES: It's huge.

NARRATOR: The research team hopes to stick a fin camera

on the tiger's dorsal,

providing crucial insight into the epic clash

between sharks and dolphins.

But there's a problem.

KIRK: This hook's straightening out.

Watch your hands.

NARRATOR: The shark is bending the steel hook,

the only thing keeping her massive head still

and her bone-crushing jaws

away from underwater cameraman Duncan Brake.

DUNCAN: This tiger shark was on steroids, it was massive.

NARRATOR: Will the hook hold?

KIRK: If we're quick, we might be able to do this.

FRANCES: Got it.

NARRATOR: It's now or never.

KIRK: Alright, Frances, you ready?

FRANCES: Yep.

DUNCAN: That's pretty good,

that's going flush down the body.

FRANCES: Okay.

NARRATOR: The fin cam is on.

FRANCES: Clear.

KIRK: Okay. Awesome.

NARRATOR: They send her on her way.

KIRK: Dunc, I'm gonna do release, alright?

(snip)

DUNCAN: I really didn't comprehend

how big the animal was until it started swimming towards me.

Then she went right between my legs, and she was huge.

Then it swam off into the distance.

The fin cam looked like it was perfectly placed,

perfectly angled.

It's kinda creepy because within seconds,

in this water clarity, they just disappear.

KIRK: Cool.

FRANCES: Woo!

KIRK: We got it. Camera's out.

Now we're gonna check out, see what these guys

really do with their time.

FRANCES: That is a beautiful animal.

KIRK: Good work, Frances.

FRANCES: That was a truly massive individual

and just a beautiful, beautiful animal.

So I'm very excited to see what happens next.

KIRK: Any information we get back is gonna be novel.

So we're just really, really excited

to see what we get on this camera.

NARRATOR: Recently, another camera captured

a shark/dolphin clash, but this one flips the script.

DUNCAN: People forget that killer whales

are actually dolphins.

They're all part of the same family.

But they're bigger than tiger sharks,

and they're more cunning and more intelligent

than great whites.

If there's something that I am more cautious

of being in the water with than a shark,

it's definitely an orca, a killer whale.

NARRATOR: Off Costa Rica, a pod of orcas,

the world's largest dolphin, target a tiger shark.

DUNCAN: Orcas are so intelligent

that they will collaboratively hunt together

in order to take down their prey.

NARRATOR: The pod surrounds the tiger...

...trapping it at the surface.

(orca sings)

One orca moves in,

locking the shark in its jaws.

Now the rest of the pod gets a piece.

DUNCAN: And what's more twisted

is that they won't even eat the whole shark.

They'll dissect it and take out a special little bit

that they like the taste of.

When you pitch an orca against a shark

or several orcas against one shark,

it's almost game over every time for the shark.

NARRATOR: This battle goes to the dolphins.

FRANCES: And just because bottlenose dolphins,

the ones that are here, are smaller

does not make them any less shrinking violets.

They're still very vicious predators.

NARRATOR: Back in Shark Bay...

KIRK: Is it getting stronger?

FRANCES: Nope.

NARRATOR: The team hopes for their own amazing footage.

After a day hitchhiking on the tiger shark,

the camera automatically detaches and floats free.

Now the team needs to track it down

in 3.2 million acres of open water.

FRANCES: I think we might've passed it,

'cause we're starting to get weaker

and the signal's coming from that way.

NARRATOR: They're fighting the elements

and the setting sun to find it.

KIRK: As long as we're going the right direction,

I'll keep looking.

FRANCES: Okay.

I don't know if you can see behind us,

we're getting out of Shark Bay and sort of into the ocean.

It's a race against the clock.

KIRK: Keep this heading for a little bit.

(beeping)

FRANCES: If we don't find it before sunset,

it's gonna be nigh on impossible to collect at night

just because then we're looking for a black thing

in a black ocean.

KIRK: I think we're getting really close.

It's getting pretty loud.

FRANCES: Yeah?

(beeping)

KIRK: Watch out, watch out, watch out!

If we're quick, we might be able to do this.

NARRATOR: After attaching a specialized fin cam

on a tiger shark...

KIRK: Alright, Frances, are you ready?

FRANCES: Yep.

Woo!

KIRK: Camera's out!

NARRATOR: A team of shark biologists needs to find it.

FRANCES: I think we might have passed it,

'cause we're starting to get weaker

and the signal's coming from that way.

NARRATOR: The camera floated free a few hours ago.

The hope is that it captured something never seen before:

a shark's-eye view of that shark

going fin-to-fin with a dolphin.

FRANCES: What we hope to find when we get that camera back

is we're really looking for how these organisms may interact

with their prey species, including dolphins.

NARRATOR: Documenting a dolphin encounter as a shark sees it

would be groundbreaking.

It could answer long-burning questions

about these two top predators.

It could also capture a whole lot of nothing.

FRANCES: The signal's definitely coming from this direction.

KIRK: Let me have a quick listen.

(beeping)

Got it right there! Right there.

FRANCES: For real? KIRK: Yup.

FRANCES: Oh, I see it! Yup! Ha ha!

Yes, Kirk. Well done.

That moment where we plucked the fin cam...

KIRK: Got it! Woo hoo!

FRANCES: ...from the sort of setting sun

and the seething ocean was incredible.

KIRK: Ha ha ha! There we go, guys.

Love it.

FRANCES: Now you have to make sure that it all worked.

Well, we have footage.

KIRK: That's a good start.

FRANCES: Let's find the release.

And boom.

KIRK: There she goes.

Kicking strong.

NARRATOR: Shark Bay, from the point of view

of a giant apex predator.

FRANCES: We did find it way out in that offshore there,

so maybe she gets deeper.

Although we might lose the light later on in the day.

NARRATOR: They've got hours of footage

of this tiger on the move.

It's valuable data;

just not the eye-popping action they hoped for.

FRANCES: This happens in fieldwork all the time.

But when you only have a limited window

and a couple shots or maybe one shot at it,

when that happens, it's rough.

Yeah, it doesn't, it doesn't feel great.

NARRATOR: Sometimes it's a matter of being

at the right place at the right time.

Captain Ash had recent luck of his own.

ASH: So we're just filming out here one day

and we saw this object.

See, that's a tiger at the back of the boat.

So we just followed it, four dolphins just appeared

out of nowhere with a juvenile dolphin, you'll see them here.

See? See, that's the tiger.

Little juvenile right in front of the shark.

We thought, "Gee, this tiger is just going to eat

this juvenile dolphin."

And watch what happens when the adults get involved.

They end up flicking this bit of seaweed

in front of the tiger shark

and distracting it from the little dolphin.

As if they're, like, teaching the little dolphin,

"Don't be scared of this tiger shark.

And just in case you get into trouble, there's that seaweed."

NARRATOR: The pod of dolphins work together

to keep the little calf safe from the tiger.

FRANCES: I mean, given the water clarity

and just also the sort of maneuverable space,

they probably felt this was a pretty low risk situation.

NARRATOR: Ash's footage points out a potential flaw

in the team's fin cam deployment.

The camera doesn't see any dolphins,

because in daylight, dolphins see the shark first.

Nighttime might be when all the action happens.

The team has a solution: a special night vision camera.

FRANCES: We know that tiger sharks are active at night.

The real question is,

how are they interacting with their prey at night?

NARRATOR: This camera can answer that question.

It uses infrared technology to peer into darkness.

KIRK: To my knowledge, there has never been

a nighttime deployment of a fin camera in Shark Bay.

NARRATOR: Night is when these two top predators

bring all their weapons to bear.

Their super-senses, echolocation in dolphins,

electroreceptivity in sharks,

allow both to keep battling after the sun goes down.

They head north where Captain Ash feels they have

the best shot at catching a big tiger at night.

FRANCES: So, we're just loading up the boat now

to go set some lines to catch our sharks at night

so we can put on our night camera.

So, we gotta go.

DUNCAN: A lot more swell this evening.

There's a big storm front coming in.

So, we've got a limited amount of time to get this tag on.

ASH: Go get a tiger, mate.

NARRATOR: If there's no shark,

they'll have to pull the lines before the storm rolls in.

FRANCES: So, right now, we're just looking for the buoys.

It's a little after 4:00 AM.

The wind has picked up.

So, fingers crossed, we get a big tiger really quickly.

NARRATOR: They're in luck.

FRANCES: You see it?

ASH: There it is, dead ahead.

FRANCES: We have a big old tiger shark on the line.

We're gonna work her up as fast as we can

and go from there.

ASH: Alright. Ready?

KIRK: Yeah. I'm on it.

FRANCES: It's big.

KIRK: It's a big female.

ASH: You want a hand or are you alright?

KIRK: Yup, coming down.

NARRATOR: Working a tiger shark is hard during daytime,

but downright dangerous at night.

Teeth and whipping tail...

all in darkness.

FRANCES: Stakes are high.

You know, we got one shot left at this.

So we gotta try to make it work.

KIRK: Watch out, coming up, coming up.

NARRATOR: Once again Duncan dives in,

this time in ink-black waters.

DUNCAN: Whenever you enter the water at night,

you've always gotta be concerned of not what you can see,

but what you can't see,

and when the lights go out, no one knows what could happen.

KIRK: Hold on.

FRANCES: Oh, (bleep).

KIRK: Watch it, Frances, watch it!

KIRK: Hold on. FRANCES: Oh, (bleep).

KIRK: Watch it, Frances, watch it!

NARRATOR: Shark researchers Frances Farabaugh

and Kirk Gastrich are wrestling a tiger shark.

KIRK: Coming down, breathing.

Okay, you good?

ASH: Yeah, I've got it.

NARRATOR: They hope to attach a special nighttime fin cam,

but an incoming storm and a thrashing shark

might make that impossible.

KIRK: Although there have been daytime camera deployments

in Shark Bay,

there haven't been any nighttime camera deployments.

Whatever we get back from this camera is gonna be novel stuff.

So now that we've got the shark alongside the boat,

we're going to finish our workup,

attach this nighttime camera,

and let her go, see what she sees.

FRANCES: Try to just get it down a little bit more.

KIRK: Watch out, guys.

NARRATOR: The whipping shark and the crashing swells

are not making it easy.

FRANCES: Come on.

KIRK: How we going with that, Frances?

FRANCES: Almost done.

NARRATOR: Their underwater cinematographer Duncan Brake

is capturing the action up close.

Sometimes too close.

KIRK: Dunc!

Watch it.

You got it?

DUNCAN: Every couple of moments, there'd be a massive surge

which would be pushing us right in towards

the jaws of that massive tiger shark.

KIRK: Far as you got it? Okay. Cool.

Frances got the tag on her, and she's getting restless,

so we'd better get her back in the ocean.

NARRATOR: The shark is ready to release.

They have to time it just right.

KIRK: Okay, ready? FRANCES: Ready.

KIRK: Ready?

ASH: Hang on, hang on.

Yeah, I'm ready.

FRANCES: He's ready. KIRK: Good?

ASH: Yeah. KIRK: Go.

ASH: You're off? KIRK: Off!

ASH: Right-io.

NARRATOR: A first:

a nighttime fin cam deployment in Shark Bay.

KIRK: Woo! ASH: Awesome.

FRANCES: Yeah, that's a pretty incredible experience.

So now it's just a race against time

to make sure that we get the tag as soon as it pops up,

and that we gather that data and get it back.

NARRATOR: But there's a problem.

ASH: Dead ahead, Frances.

KIRK: You got it?

FRANCES: Yep, got it.

So we were just headed on our way back into the boat

and the tag popped off.

NARRATOR: Instead of hours,

the camera releases after only a few minutes.

FRANCES: All of the, what you had hoped

and you did all this work for,

it's just defeat snatched from the jaws of victory.

You're so high and then you just drop so low.

So here you can see the animal and the boat.

And then floats back up towards the surface here.

Bummer.

NARRATOR: But there is a silver lining.

FRANCES: What this does is the night vision camera works.

We can see the animal's head.

And it's encouraging to see these, these images come back.

So it's something, an area for further exploration, for sure.

KIRK: Off!

It came back with our first glimpse

of some underwater nighttime footage from these tiger sharks.

You get confirmation that this technology could work.

NARRATOR: The battle beneath the waves of Shark Bay

remains hidden for now.

But Shark Bay does reveal something to the research team.

This war might not have winners and losers.

FRANCES: I think it's a mistake to think of this conflict

between dolphins and sharks as a zero-sum game.

When it's in balance,

you end up with a healthy, functioning ecosystem,

which is what we're looking to better understand and protect

and preserve as we move forward with a changing planet.

NARRATOR: This balance between the ocean's supreme predators

is revealed off the Florida coast.

A diver is in the middle of a bait ball.

This swirling mass forms as a defensive maneuver,

a way to confuse predators.

Predators like sharks and dolphins.

But here, they put their differences aside.

DUNCAN: So, when there's a big bait school in the water,

all these sharks and dolphins

are collectively working together,

collaboratively preying on all these little fish.

When the ocean provides, it's almost like the sharks

and the dolphins have called a ceasefire

so that they can meet in the middle and take down their prey.

NARRATOR: It's another glimpse

into the world of sharks and dolphins.

(man yells)

One more chance to gain insight

into their complicated relationship,

one that is changing how we view each animal.

FRANCES: It's a mistake to think of dolphins versus sharks

as some kind of mismatched pairing.

It's not one that's like a heavyweight champion

and one that's a lightweight, by any means.

DUNCAN: With sharks versus dolphins,

there's not ever a clear-cut winner or loser.

It's just nature.

NARRATOR: The waters off The Bahamas are a battleground.

In the war between sharks

and dolphins.

Using photographic evidence.

MIKE: One species that might cause that kind of bite

would be a bull shark.

NARRATOR: Specialized bite pads.

MIKE: It went through this simulated dolphin blubber

like butter.

NARRATOR: And, for the first time ever,

a decoy dolphin as their secret weapon.

These biologists will attempt to uncover

which sharks are the culprits.

MIKE: That dolphin is in big trouble.

They're coming right for it!

Yes!

NARRATOR: Shedding new light on these two apex predators,

locked in deadly underwater combat.

BOATER: Hey, they're fighting they're fighting.

Oh!

He's got a dolphin in its mouth!

It's right under us.

Look at the size of the thing.

NARRATOR: A bloody battle, as old as time,

is being waged beneath the waves.

Shark versus dolphin.

One of the front lines for this oceanic clash

is located 55 miles off of Florida.

Bimini is part of 700 islands that make up The Bahamas.

Nearly one third of dolphins here show signs

of shark attack.

A team of shark and dolphin researchers is here

to discover what sharks are targeting these dolphins,

the Atlantic Spotted Dolphin and the sleek grey Bottlenose.

KEL: We've got dolphins on the bow.

VALERIA: Wow, look at them ride.

NARRATOR: Dr. Mike Heithaus is a shark specialist

and a Dean at Florida International University.

He's joined by Dr. Valeria Paz, a dolphin expert,

and local Bahama dolphin researcher

Kel Melillo Sweeting.

First part of the mission:

photograph the scars to match them to the predators.

VALERIA: Hey, Mike. Did you see that notch

on that dorsal fin? MIKE: Yeah. You know

that couple notches there,

yeah, that's the kind of injury that could be caused

by a shark.

KEL: Two mother-calf pairs.

One of them had a distinct shark bite scar.

She actually got that injury as an older calf,

younger juvenile.

So what we're seeing now is a few years old,

really well-healed scar.

VALERIA: She came really close, so I was able

to get some really good footage.

NARRATOR: While foraging,

some dolphins occasionally break away

from the pod to crater feed.

Turning upright, using their nose,

or rostrum to dig and find prey.

This is when the dolphins are most vulnerable.

KEL: They have to remain vigilant because a shark

could be around at any moment.

We're also seeing signs of previous shark attacks.

One bottlenose dolphin had both pectoral fins injured.

MIKE: Here in the Bahamas, you can find more

than a dozen species of sharks.

But it's most likely the ones attacking dolphins

are the bigger bull sharks, tiger sharks,

and maybe great hammerheads.

These are the top predators here.

What a great snorkel. A couple mom-calf pairs.

There was one that it looked like had a bite

on the peduncle there.

KEL: Yes. Maybe a shark sneaking up from behind?

MIKE: Hopefully the pictures will help.

KEL: Yes.

NARRATOR: With so many large sharks in this area,

the dolphins have a lot of possible predators.

VALERIA: This bite is definitely on the side

of the flank so maybe it was trying to escape

or evade when it turned and then it got bit.

MIKE: Yeah, you see it's a pretty broad bite.

One other species that might be able to do that

something like the tiger shark,

they just have that big wide head compared to other sharks.

And then their teeth are really different.

You've got similar sized teeth in the top and bottom jaws.

Instead of being for puncturing

they're really meant for cutting.

And you've got really fairly long distances between the

teeth, so that should give us some clues.

KEL: This is a bottlenose dolphin,

took this photograph right around Bimini and you can see

it has a pretty fresh injury to its back here.

VALERIA: That's fairly sizeable.

MIKE: Yeah and it's super clean too,

so not a lot of diagnostics there and one animal

that could do that around here is the bull shark.

This is a replica jaw, you can see that's a big mouth

but with a clean bite a really big great hammerhead

might be able to leave a mark like that.

Now we just need to get impressions of shark bites

so we can get a sense of how they're holding

and gripping and releasing the prey and what that

would look like on a dolphin.

NARRATOR: There are 10 types of hammerheads,

but here in Bimini, the team sets out in search

of the great hammerhead to see

how it might be biting these undersea mammals.

Up to 20 feet Long, as large as a fully grown great white,

these giants congregate in the shallows off Bimini.

MIKE: These great hammerheads are huge sharks.

They have speed, maneuverability

and the teeth in the upper and lower jaw are different.

You get kind of cutting teeth on the top and gripping

teeth on the bottom.

So it's possible that great hammerheads are taking out

dolphin calves and if they get one of those in their mouth,

it's going to be really hard for that dolphin to get away.

NARRATOR: Mike and Valeria want to see

what great hammerhead bites look like on prey to compare

with the scars they've photographed on the dolphins.

Local shark diver Neal Watson has been working

with hammerheads here for more than a decade.

He's going to help the team get a bite impression.

NEAL: Today we're going to try and feed a whole bonito

to one of the hammerheads and the key difference

is we're going to try and actually get it back.

It's something unique that we don't do usually

but I think we'll be able to give it a shot.

MIKE: When we're gearing up to dive with sharks,

I'm really always running through worst possible cases

in my head, because you got to be prepared.

I'm always thinking about, okay,

if a shark is aggressive, what are we going to do?

Where am I going to be relative to Valeria?

What am I going to do if a shark comes around

from behind? You have to be really, really vigilant

whenever you're dealing with large, potentially

dangerous animals.

Great hammerheads don't attack humans,

but we're going to see how they feel about visitors.

NARRATOR: The smell of fish may entice the hammerhead,

but also bring in other species of sharks.

VALERIA: Tiger shark and I think I see some bull sharks

coming in.

NARRATOR: Tiger sharks and bull sharks are ambush

predators, known to sneak up on their prey,

so the team stays on high alert waiting

for the great hammerheads.

VALERIA: Those nurse sharks are definitely coming

to check us out.

And although their jaws might seem small,

once they bite onto something, they really hold on.

MIKE: We have to keep this fish away from them

or we might not get it back.

NARRATOR: Finally, the great hammerhead approaches,

and her size lives up to the name.

VALERIA: Wow, that is a beautiful shark.

Probably about 12 feet or more.

MIKE: Yeah, that's a large female.

Definitely big enough to eat a dolphin.

This hammerhead seems interested.

VALERIA: Hey Mike, tiger shark behind you.

MIKE: Here she comes!

Oh man she's trying to swallow it whole.

Well, there goes one bonito.

VALERIA: We've got another hammerhead.

MIKE: We've got to get the hammerhead to let go of

that fish.

Looks like the hammerhead is coming back around

for another go.

Okay, let it go, let it go! VALERIA: Yes, you got it!

MIKE: Let's get this up to the boat.

What an incredible dive.

VALERIA: That was unbelievable, those hammerheads.

The size of that one.

Must have been 12 to 14 feet maybe?

MIKE: Definitely capable of taking out a spotted dolphin,

maybe a bottlenose dolphin juvenile.

VALERIA: I'm excited to see that fish.

MIKE: Well, after all that we got one bonito head back.

VALERIA: Definitely scraped all the skin out.

MIKE: Yeah. It's not a clean cut

by any means and bonito is not a dolphin

but I guess if that was a hammerhead biting a dolphin

you wouldn't expect something clean.

It would probably be more scrapes through the tissue.

NARRATOR: The tearing bite of the hammerhead matches

the ragged scars seen on the dolphins.

VALERIA: That's definitely what we saw

when the hammerhead was approaching the fish

and it grabbed it and kind of teared.

It was not a clean cut. MIKE: No. So. We didn't

get tooth impressions like you might hope for

but it's some first clues.

For the sharks and dolphins here off Bimini,

they're pretty well-matched adversaries.

The sharks, body size, strength, cutting teeth.

And the dolphins live in groups, they're smart,

and they're super-fast and maneuverable.

NARRATOR: To observe just how intelligent dolphins

are Mike and Valeria head to the Clearwater

Marine Aquarium in Florida.

All of the dolphins here are injured or unable

to survive in the wild and cannot be released.

Animal care specialist Katie Wojdyla provides

daily enrichment.

KATIE: Right now I'm doing what we call face time

and all it is is a little playtime,

it's offering them any interaction

if they would like it.

We have right here in front of you is Hope.

She's currently 11 years old.

She really seems to enjoy water play.

NARRATOR: Animal care specialist Brooke Bowersox

has seen the damage sharks can do first hand.

BROOKE: This is PJ, you can see that she has a nice scar

back there on her peduncle.

MIKE: Yeah, and that just looks like a fresh bite

that we see on dolphins like the ones in Bimini.

You see that's not the only scar,

there's also places where it looks like the jaws come over.

VALERIA: Since the scar healed so well,

it's really difficult to tell what species

could've made that.

MIKE: Yes, a bull, tiger even great hammerhead,

you just can't tell from that healed wound.

NARRATOR: To avoid attacks, dolphins have an arsenal

of defenses, including intelligence.

With brain mass larger than any shark's,

dolphins are second only to humans in brain

to body weight ratio.

Making it easy for them to outsmart sharks.

But they also have a secret weapon to evade predators:

echolocation.

MIKE: Echolocation is really kind of a dolphin's

superpower.

VALERIA: Dolphins emit sound and they have a part of

their head that is called the melon.

This area receives the sound waves,

and it translates to what's going on

in their surroundings.

It allows them to navigate without using sight.

NARRATOR: Echolocation helps dolphins find prey

or detect predators.

MIKE: We're going to do an experiment to figure out

how we can use echolocation or how effective it is,

but first we've got to let him use all his senses.

What are we going to do? BROOKE: Yeah.

So this is a cognitive concept called the match to sample.

What we're going to do is we're going to show Nicholas

this buoy and then we're going to ask him to go across

to the other side of the pool where there's three

different sample items and ask him to select

which one matches what he's seeing here.

And you can see that he got it right.

MIKE: He did pretty well at that last one,

but now it's time to turn out the lights

and just do echolocation. How does this trial work?

BROOKE: So what we're going to do now

is we're going to place eye cups over Nicholas' eyes

and Bree is going to send him over to our right

with Katie is, where he's going to echolocate

on that red boat.

Once he echolocates on it, he's going to travel over

to where our samples are and they have those samples

under water. So using his echolocation,

he can make the correct selection.

MIKE: You see just no hesitation.

No worry about having his eyes, just echolocation

straight there.

BROOKE: Correct. VALERIA: And he did.

MIKE: It's incredible.

So, this really just shows how impressive

that echolocation is.

Also shows how smart they are and that smarts

and echolocation help them survive out in the wild,

including avoiding sharks. BROOKE: Absolutely.

NARRATOR: Back in The Bahamas, Mike and Valeria believe

hammerheads could be responsible for some

of the ragged bite scars they've photographed

on dolphins.

But they want to investigate another shark

that may be a predator.

And this one is second only to the great white

in the number of attacks on humans.

Tiger sharks.

Growing up to 18 feet, weighing nearly a ton

they'll eat just about anything

from tires to turtles. BOATER: No way.

NARRATOR: To dolphins.

New South Wales, Australia.

Off the coast of Newcastle, a tiger shark goes in

for the kill.

A lone dolphin is no match for the 11-foot tiger shark.

It disables its tail and the dolphin is dead in the water.

MIKE: Tiger sharks are incredible predators.

They also have teeth that are curved and have serrations,

so they cut in both directions.

So once they grab onto something,

they can shake their heads back and forth

and cut straight through it.

NARRATOR: And there's no place better to find tigers

than Tiger Beach, in The Bahamas.

The team will try to get bite impressions

from the tiger sharks and study the tiger's feeding

style to compare that with their photos of dolphins

with shark attack scars.

Underwater cinematographer Duncan Brake has been diving

these waters for more than a decade.

Neal Watson will be using whole bonito again

to get a bite impression.

Immediately, the team is met with an eager

group of tiger sharks.

MIKE: We want to get a tiger shark to bite the bonito

to examine how it uses those serrated teeth.

We've got one heading in.

VALERIA: There's a lot of lemon sharks coming in, too.

MIKE: Lemon sharks don't have much sense of personal space

and they can be aggressive eaters, so let's keep

the bait away from them.

NARRATOR: The lingering smell of the bonito fish starts

to catch the sharks' attention.

Two tigers approach.

MIKE: We usually think of tiger sharks as solitary

animals, but this fish has caught the interest

of more than a couple.

VALERIA: This one's definitely interested.

MIKE: Come on! Hold on! Yes!

NARRATOR: Neal manages to hold on to part of the fish.

MIKE: Let's get up to the surface.

VALERIA: That was incredible. Such large animals.

MIKE: No shortage of sharks. NEAL: None.

MIKE: And I think we're going to need bigger bonito

next time. NEAL: Yeah.

These are big three-foot bonitas but they're kind

of a one-bite meal for these tiger sharks.

I was able to wrestle this piece away.

I think it was indicative how they were feeding.

They would grab the bait and if they only got a little bit

of it they would let go momentarily to try

and get a little bit closer and I was able to pull it out.

MIKE: And that's what you see on the dolphins sometimes.

It's not just always a clean bite in but it looks like

there's bite and slash release bite again.

And that's kind of what you see here on that bonito.

VALERIA: Yeah. That's definitely similar

to the scars that Kelly showed us.

NARRATOR: The tiger sharks' slashing bite matches

what the scientists saw on the dolphins.

KEL: For a shark, a dolphin is no easy meal,

but is a really rich meal.

Lots of meat, lots of blubber.

But the dolphins have evolved to fight back.

MIKE: Once dolphins have seen a shark,

it's kind of the game's up for the shark,

it's not going be successful and the dolphins will

actually kind of chase and herd sharks away.

There's one video where a juvenile great white shark

approaches a group of dolphins and one dolphin

peels off and just chases that shark away

and the sharks just kind of, "Forget it.

It's not worth it," and it heads out.

These dolphins are not just swimming snacks for sharks,

they can detect sharks and kind of hold their own.

NARRATOR: Dolphins have one more advantage:

the ability to communicate with one another.

VALERIA: Dolphins are definitely chatty

and they use sound to communicate,

and it's really important to their everyday life.

KEL: We're observing some Atlantic spotted dolphins

and we're going to use this hydrophone,

an underwater microphone, to hear the sounds

through the headphones and hear their whistles, squeaks,

squawks, chirps.

Vocalizations are super important to dolphins,

to help keep track of the group, find food,

possibly even alert each other to predators like sharks.

NARRATOR: Even with echolocation and the ability

to communicate, dolphins in The Bahamas are still

under siege.

The team concludes that the ragged scars

they've seen on the dolphins could be from tiger sharks

and hammerheads.

But many of the scars they photographed were cleaner

and more defined.

Could there be a third species of shark attacking dolphins?

Bull sharks have the greatest bite force of any shark

relative to their body size.

Could they be responsible for preying on dolphins?

They prowl the shallow seas, using the sandy bottom

and murky water to conceal their attack.

Both dolphins and humans never see them coming,

until, it's too late.

MIKE: Here in Bimini, the bull sharks

and the dolphins are often hunting in the same areas,

and that can include murky waters.

The bull sharks are probably mainly hunting for smaller

things, but if they get a chance to grab a dolphin,

they're going to take it because that dolphin

represents an incredible meal with all the fat

and energy in the blubber.

NARRATOR: The team needs a bite impression

from the bull shark to compare to the dolphin scars.

But this time they'll attempt something

that's never been done before.

They're creating a life-sized dolphin decoy,

but first they need to test out the material

they'll be using to make the dolphin,

while also collecting more bite data.

MIKE: This is basically a gelatin block

that is the density of dolphin blubber

and we've turned it into a giant underwater lollipop.

So what we'll do is put a little bit of fish on this

to entice a shark to bite.

And when they bite it, it's going to give us

a jaw impression.

NARRATOR: They head to the waters between Florida

and Bimini.

MIKE: This is the perfect place to come

to find bull sharks. There's lots of food here,

the water temperatures are right

and it's a known spot where groups of bull sharks

get together.

NARRATOR: While Mike gets the bite,

Valeria will be on shark measuring duty.

A laser device can pinpoint the exact length

of the shark.

MIKE: Bull sharks have a reputation as a more

aggressive species, but they usually don't bother divers.

But we do have bait on the pad here,

so we've got to stay alert. VALERIA: Copy that.

A couple of bull sharks are coming in.

I'm going to get some measurements.

They look definitely the size that would attack a dolphin.

MIKE: They're interested in the fish,

but they're being cautious.

VALERIA: They're definitely curious, just not biting.

MIKE: Wait. This one's coming back around.

VALERIA: Watch out, your hands!

MIKE: Didn't even see it. (bleep)

I count three bull sharks.

They're all more than 6 feet long.

I'd say they're big enough to attack a dolphin.

We just need to get one to bite this pad.

Oh, that was close!

VALERIA: We need a good bite and the size of the shark,

to compare it to the bite marks on the dolphins

in Bimini.

MIKE: Wait a minute.

I think we have another taker!

I can't hold it!

VALERIA: That bull's coming right back around Mike.

MIKE: Get the lasers ready.

VALERIA: Yes, we got it!

MIKE: Look at that. Oh, this is incredible.

You just see the width of that bite,

it just bit on and went through this simulated

dolphin blubber like butter.

You can see why dolphins just lose big chunks

if a big shark gets a hold of them, and that one,

we got a really nice laser hit on.

So we'll know exactly how big the bull shark

was that did that.

And we got a bonus. This shark left a tooth behind.

They lose so many teeth in their lives.

They're constantly shedding. So

a loose tooth, even in dolphin blubber can get stuck.

Usually, we're not so lucky to have them left behind.

A nice bite width there on a real-world situation.

So this is exactly what we wanted, I am psyched.

NARRATOR: The bite pad reveals that the ragged bite

marks from the photos were probably not caused

by the bull shark.

The precise incision on the pad could mean bull sharks

are the ones leaving the cleaner scars.

But there's another way to find out whether

these bull sharks have attacked

the underwater mammals.

MIKE: Right now we're trying to catch a bull shark.

We got a piece of bonito on a small circle hook

so we can throw it to the bull shark that we want,

catch it, get it up, and see if it's eaten a dolphin.

NARRATOR: In sharks, the reproductive and digestive

systems come together at a common area called

the cloaca, so the team will take a sample from this area.

VALERIA: So here's the swab kit.

We're going to be using the cotton swabs to get fecal

matter from the bull shark and that will tell us

a little bit about what they have been eating.

That is going to be really useful to see if we see

any dolphin DNA in this fecal matter.

MIKE: First, we have to catch one.

Handling sharks can be really dangerous

if you're not careful and that's especially true

for bull sharks.

They got that big mouth, sharp teeth,

but the tail is incredibly powerful.

So you've got to always be aware of your surroundings

and work together as a team.

There we go.

Okay there's a bull shark right below us.

VALERIA: See it.

MIKE: They're right next to it.

Yes, it's on, it's on it, it's on it.

VALERIA: Oh. Nice.

MIKE: Okay now I need everybody to be beyond

careful right now. -Yeah.

Right down there. It's a good sized one for sure.

Watch your feet, watch your feet.

That is a big bull shark.

VALERIA: Oh. It's a big one.

MIKE: Fresh shark, the trick now is to hold on

as much as you can.

Ah!

That is definitely big enough to attack a dolphin.

No question.

Okay. Get ready.

I'll start back further, try to bring it around.

Well, we're trying to get a tail rope on it so we get.

VALERIA: I got you. I got you. I got you.

MIKE: Slow, slow, slow, you're good, you're good,

you're good. Nice and easy.

Oh close.

Okay. Excellent.

Okay. Good job. Okay.

Now, we've got control of the animal, so now, cleat that off.

A little bit lower. A little bit lower,

so its tail's kind of in. Good.

NARRATOR: But just as they're about to tie the shark off.

MIKE: Oh no, look out, look out, clear clear, clear!

Look out. Careful. Careful.

No, do not grab this.

It popped the monofilament.

NARRRATOR: They've lost control of the most

dangerous part of the shark, its jaws!

MIKE: Back off! Back off!

MIKE: Agh!

No, do not grab this.

It popped.

We had the shark actually drop when there was a swell and it

popped that monofilament, so we're just going to do a quick

repair on the fly, so we have control of the animal here.

I need another roundy. I'm going to tie into this,

and get the crimping tool. VALERIA: I got it.

MIKE: We've got to write down the lengths.

Mark that, 216.5. VALERIA: 216.5.

MIKE: 252. That's about 8 and a half foot Bull Shark.

That's definitely big enough to go after a dolphin. Okay.

Get the cloacal swab kit. VALERIA: Yup.

We are going to be opening up the swab kit and making sure

that everything is set up for the cloacal swab.

Make sure this is up so that it's out of the water.

MIKE: Okay. VALERIA: All right.

MIKE: Great job. That's perfect.

VALERIA: Here we have the vial.

We're going to go ahead and place it in here

and make sure to label it and we'll send it out to

the lab to find out what sharks have been eating.

MIKE: Okay, we can release any time.

NARRATOR: Releasing an angry shark is even more dangerous

than catching it.

The crew has to be careful not to get caught

in the lines as it thrashes.

MIKE: Look out.

Okay. Hang on. Hang on, hang on.

Are we ready?

here we go. Three, two. One.

Great, great. Good job.

That was great.

We got that shark up, tag in, cloacal swab done,

and a great release.

The cloacal swab showed us these bull sharks hadn't

eaten a dolphin recently, but that doesn't mean

they're not dolphin predators.

It just means they're not eating them all the time.

NARRATOR: The cloacal swab was inconclusive

but the bite pad shows that bull sharks could be the ones

making the clean bites seen in the photos.

Mike and team are now ready to deploy their nearly

200-pound secret weapon.

They want to get an even more realistic view of what

a bull shark bite would look like on a real dolphin.

MIKE: This is Gooey, our dolphin model and Gooey

was made out of non-toxic gelatin.

We want to make sure if a shark gets a mouthful

of Gooey, it's completely harmless to the shark.

Gooey was made so that the consistency is exactly

like that of dolphin blubber.

And it's pretty much the same size as an Atlantic spotted

dolphin in Bimini or a juvenile bottlenose.

NARRATOR: This is the first time a dolphin decoy

made of non-toxic materials will be used

in shark research.

MIKE: The bite-pads were a great first step,

but they're just kind of a fairly narrow pad

and so a shark might bite that very differently

than something that's shaped like a dolphin.

It's rounded and in some places it's so big

that it's kind of like trying to palm a ball

that's too big for a shark trying to bite it.

So we have created something completely unique,

a gelatin dolphin.

NARRATOR: It's sink or swim time for Gooey.

The team takes her to an area known for bull sharks.

They're joined by underwater cameraman Sean Havas,

who will capture this "first" in shark research.

MIKE: As soon as Sean and I are in let's get Gooey

in right next to us. VALERIA: You got it.

I'll be looking at you guys for directions.

Once I put it in if you need me to give it some life.

MIKE: We'll let you know but hopefully Gooey

will do its job.

VALERIA: We're strapping a camera onto Gooey to get

a better angle.

We're positioning it so that it faces the peduncle area

where we think sharks may be more enticed to bite.

Mike, should we deploy Gooey?

MIKE: Ready for Gooey.

VALERIA: Copy. We'll deploy. You got it Mike.

NARRATOR: Deploying this enormous dolphin decoy

takes teamwork.

VALERIA: Kirk, look at the camera.

Make sure it's at the right angle when it gets deployed.

Lucas, make sure that the pectoral fins are not getting

stuck by the ladder, and let's do this.

All right. Please clear the deck.

One, two. Slide.

MIKE: All right.

Gooey's swimming.

VALERIA: Mike, what are you seeing down there?

MIKE: Well, right now, it's pretty lonely.

Just hanging out with Gooey. No sharks yet.

So hopefully, we get some interest soon.

VALERIA: Gooey right now doing a natural behavior.

This is called logging. Logging is when

they're resting and there may be more vulnerable

during this behavior.

MIKE: We got Gooey exactly where we need it to be.

It looks so real!

VALERIA: Gooey is of similar size of those dolphins

that we saw in Bimini.

Although her colorations are a lot different,

the silhouette from below mimics

that of a real dolphin.

NARRATOR: Sharks are attracted to contrast.

They may not see color,

but this silhouette should lure them in.

If one attacks, Mike will not only get a bite impression,

but the exact size of the shark.

They'll be able to record if smaller juvenile sharks

might attack a dolphin, or is it mostly

the larger mature sharks.

MIKE: The idea is, we want to get length on the shark

that attacks Gooey so we know not just what species

grabbed the model, but how big it was.

NARRATOR: The bull sharks arrive.

And it's time to put Gooey to the test.

Will she be a trick or treat for the bulls?

MIKE: These are big bull sharks.

They are definitely a threat to the dolphin.

We've got four sharks, they're circling

but we're not seeing a whole lot of interest right now.

Try giving Gooey some motion.

VALERIA: Copy Mike, will give it some movement.

Kirk, can you please give it some motion?

MIKE: No. Still not interested.

That's not terribly surprising since bull sharks

probably only very, very occasionally attack

dolphins that they see.

She looks like a dolphin and kind of moves like a dolphin.

Maybe we need to add some smell.

Sharks have an incredible sense of smell.

They can smell a couple of drops of blood in a swimming

pool worth of water.

That means that if there's a good scent trail,

they can follow it for miles.

Now one is starting to move toward it.

Come on! No. Okay.

We may have to do a bit more than this.

We're going to come up and think about what

our next steps are to try to get a bite here on this model.

VALERIA: Copy that. Let's pull her in.

VALERIA: So we're bringing Gooey in.

Her silhouette looked really good underwater,

but sharks used multiple senses to detect prey,

so we're going to add a little something to see if we can

entice them to bite Gooey. One two three, pull.

NARRATOR: The team has one more trick up their sleeves

to try and get a shark to bite Gooey.

MIKE: Gooey almost looks real when you're far enough below.

We had the sharks around,

but they didn't really show any interest in the dolphin.

VALERIA: We know sharks don't bite every single dolphin,

so we need to add something to entice them.

MIKE: What I think we should do is strap a bit of bait

down here. Then when the sharks come in at the bait,

they try to grab the bait, and they're going to grab

Gooey as well right in an area

where we see bites on a lot of wild dolphins.

NARRATOR: The team attaches bait to the area

where they've seen many bite scars, the peduncle,

to see if a bite here will match what they've seen

on the wild dolphins.

VALERIA: The peduncle is a really strong muscle

at the tail end of the dolphin, and it allows them

to move their tail really fast, it allows them

to maneuver, and get to great speeds.

KEL: The peduncle is where the dolphin's

power is for swimming. If it gets a serious

enough injury or if the spinal cord is severed

or damaged, then that dolphin might become

incapacitated, giving the shark a second chance

to come in for the kill.

MIKE: Echolocation and vision, most of that

for the dolphin is directed forward.

So coming from below and behind is the easiest way

to sneak up and make that ambush attack.

As the sharks come in to get a bit of food,

they're going to bite the dolphin model,

and we'll get those really nice tooth impressions

once they've bitten in. VALERIA: Definitely,

adding the bait, that extra scent will really entice

the sharks to bite Gooey.

Ready. Let's do this.

NARRATOR: Gooey not only looks good,

she smells good too.

MIKE: We've got one coming in!

A shark coming up from this angle from below and behind.

That dolphin is in big trouble.

There's definitely sharks more interested now

that there's some fish on Gooey.

VALERIA: It's coming in close.

We definitely have their attention.

MIKE: They're going right for it!

Look at that.

(Excited screams)

Yes! That is exactly what we wanted.

Let go now please.

Man that bull shark just nailed Gooey.

VALERIA: Whoa, look at that.

MIKE: It's incredible, isn't it?

You can see where each tooth just traces through,

even the serrations on the teeth.

VALERIA: This could have definitely been fatal.

MIKE: Oh yeah, it almost nicked the spine.

There's too much vital there. This dolphin would have

bled out, and the shark could have come back later

to finish it off.

VALERIA: Good job, Gooey. Let's pull it up.

MIKE: It's pretty incredible just how much that shark

got out of Gooey. I mean. That was probably 20 pounds

of gelatin. That was a stunning success.

It actually simulated real life more than we would've

thought because Gooey was kind of listing to the side.

And if a dolphin sees a shark coming,

it's going to turn its back to it to try

to maneuver away. And so the shark came

straight from the bottom up and bit here.

It would've gone right next to the spine and you can see

a nice clean cut, and so an 8.5-foot bull shark,

no problem killing a dolphin.

Gooey really taught us a lot.

From just one bite we were able to see that even

with this big round object a bull shark leaves

a clean bite not a ragged one.

With the 3D-scan were we able to see how each tooth

moved through and that these bull sharks are leaving

clean bites even on big round dolphins and it really

showed us that it's going to take a big adult bull shark

to take down a dolphin.

Evolution tends to hone behaviors that make

predators super-efficient, and prey good at getting away.

For dolphins, if they aren't paying attention

and good at avoiding predators, they're not going

to leave many calves in the next generation.

And so that arms race between predator and prey is going

to continue for sharks and dolphins.

NARRATOR: The evidence collected with the bite pads

and dolphin decoy suggests that hammerheads,

tiger sharks and bull sharks could all be responsible

for the bites seen on dolphins here.

And still, the battle of The Bahamas between

some of the best designed and most intelligent species

in the ocean rages on.

KEL: The fact that there are so many sharks

and so many dolphins in the Bahamas might be a really

good sign for the health of the oceans here.

You have food all year round, mates all year round

and even when a dolphin gets bit by a shark,

if it's lucky enough to get away,

it's healthy enough to survive that attack.

VALERIA: This clash between the predators,

there's no winners or losers.

It's just the opportunity to catch a prey.

MIKE: We have great hammerheads, we have

tiger sharks, we have bull sharks, all in this one spot

and there're dolphins there too.

This battle between sharks and dolphins in the Bahamas

isn't going to end.

SARA: Mike, you got a couple coming on your stern right now.

MIKE: There's one right here.

SARA: It might get more interested.

NARRATOR: Shark scientists, Dr. Mike Heithaus and Sara Casareto,

are about to reveal why sharks seem to attack boats,

from fishing trawlers to tiny kayaks.

SARA: Once Mike casts that line, I'm expecting the moment

that fish hits the water for the sharks to be all over it,

and as he's reeling that in,

we're gonna see a lot faster behavior.

MIKE: Okay. Ready?

SARA: You're good.

MIKE: Bait's out.

That one just bumped me.

Okay. This one's coming fast.

SARA: That shark is coming in hot.

Pull in that fish, Mike.

MIKE: Ah!

NARRATOR: It was understood, if you stayed on a boat,

you'd avoid a terrifying confrontation with a shark.

That's not true anymore.

STEVE: Holy! JEFF: Oh, my God!

STEVE: Watch out! JEFF: That thing is huge!

ERIKA: He chomped on the boat!

NARRATOR: Erika Almond was fishing off the Gulf Coast of Florida

on a 34-foot boat when a great white shark took interest.

MAN: No way.

ERIKA: Holy moly.

That's huge.

Great white.

Wow.

When we first saw the shark as it came closer, we were able

to estimate it to probably about 14 to 16 feet.

Now, we've all seen Jaws and we know the outcome of that.

NARRATOR: Great white sharks are rare in the Gulf of Mexico,

which made the encounter even more terrifying.

ERIKA: As the shark was coming at the motors, if it hit

underneath with the prop or on the back itself, you could

almost hear the teeth scrape against the metal of the

actual motor itself.

MAN: Biting the engine.

ERIKA: I thought, "Oh, my gosh.

We're gonna need new motors or a paddle to get us out of here

because they're going to be gone."

Oh, God.

Watch your hand.

We could not believe what we had just encountered and

been a part of.

I didn't know that that was something that sharks would do.

Wow. Great white.

NARRATOR: Erika's encounter is not unique.

Many boaters have the same showdown with sharks.

Dr. Mike Heithaus and shark biologist Sara Casareto are

off the Florida Coast to investigate why these

frightening interactions take place.

MIKE: You go online these days and you see more and more

videos of sharks biting boats or just getting uncomfortably close.

And the question is is that just more people with cameras

or is there something going on with the sharks?

And that's something we're out here to investigate.

SARA: A lot of boating activities involve sensory

stimulation that can actually pique sharks' interests.

It involves splashing, a lot of times you're out on a boat

and you're fishing or there's chum in the water.

Holy (bleep).

SARA: And all of those things could attract a shark.

So we're heading about three miles off the coast of

Palm Beach where the water depth is about 100 feet.

This is an area with a lot of boat activity and there's been

reports of shark interactions.

MIKE: Florida is an incredible place for sharks.

One reason is we have so many habitats in such a small area.

You've got mangrove forests along the coast, seagrass beds,

coral reefs, and deep water that comes close to shore.

That means all the different species that are in these

areas can kind of mix.

So you've got nurse sharks, lemon sharks, bull sharks,

tiger sharks.

Even great whites come through here.

NARRATOR: They set up shop three and a half miles off the

coast to explore why sharks are attracted to boats.

In addition to the two biologists,

cinematographer Duncan Brake will document the shark's

behavior from below the surface.

He's filmed sharks all over the world and has had

his share of boat-shark encounters.

DUNCAN: One of the craziest interactions I've seen with a

shark and a boat was when we were following a bull shark

that we'd seen cruising along the coast.

As soon as we approached it, it decided it didn't want us

in its space, and it turned around and just went straight

for the engine and did three or four bites before it turned

around and, and swam away.

At which point, we decided we were gonna back off

and leave it be.

SARA: All good, Duncan?

DUNCAN: All good.

SARA: All right.

MIKE: You're clear.

NARRATOR: The team's first mission is to reveal why

sharks suddenly circle boats.

MIKE: We're here on the spot but no sharks yet.

SARA: Any sharks down there?

NARRATOR: Duncan is in the water with an underwater comms

to relay anything he observes.

SARA: Copy that, Duncan.

So, Mike, Duncan wants us to start revving that boat

engine, see if we can draw some of those lemon sharks

in with the sound.

MIKE: Okay. Sounds good.

Sound travels an incredibly long distance underwater and

sharks have amazing hearing.

So, you know, if they're not doing something else,

that might attract them in.

Okay.

Ready to rev. He's clear.

Engine's in neutral.

Revving.

SARA: Duncan, I'm looking and I don't see anything.

Do you see anything from your end?

SARA: Copy that.

Crystal clear water, Duncan.

MIKE: Sharks don't have ears like us but they can still

hear incredibly well.

They even have special cells on their body that can feel

vibrations, whether it's sound or the movement of

animals through the water.

SARA: That boat engine has really equated to, for a lot

of the sharks in the area, the ringing of a dinner bell.

They hear that and they think, "Free meal."

MIKE: Okay I think we got one coming in right here.

DUNCAN: I spent a lot of hours in the water with lemon sharks.

There's one thing for certain, no matter the size,

you've got to be on guard.

They can spin on a dime.

They have amazing maneuverability, being able

to turn right around and almost bite their own tail.

MIKE: Lemon sharks are a pretty cool species.

You know, it gets to be nine or ten feet long.

They're pretty intimidating in size when you're underwater.

They're also pretty intelligent sharks.

You know, they've been trained to run mazes.

And you can see, when they're underwater and you're swimming

with them, they're really figuring things out.

But the other thing about lemon sharks when you're

diving at least with them, no sense of personal space.

They just kind of bump straight past you.

They're not attacking.

They're just going where they go.

NARRATOR: Within minutes, two lemon sharks become a dozen.

The only bait in the water, a rumbling engine and

Duncan's scuba bubbles.

SARA: The lemon sharks in this area are majority

female hanging out.

MIKE: And you never expect to see the little ones out here.

NARRATOR: While the sharks circle, Dr. Heithaus and Sara

reveal why they believe sharks are biting boats.

MAN: Watch out!

MAN: It's a huge one!

NARRATOR: Videos of sharks gnawing on hulls abound.

JEFF: Ah!

STEVE: Oh, my God!

Oh! (bleep)!

SCOTT: Jeff, let it go.

NARRATOR: Steve Minkema and his buddies, Jeff Crilly and

Scott Crilly, were fishing off the New Jersey shore

when a great white decided to show them how its jaws work.

JEFF: Oh, my God!

This thing is huge!

This thing, holy (bleep)!

STEVE: Oh, my God!

SCOTT: We were all set up.

STEVE: All excited to catch a big fish.

I forgot who saw it first.

JEFF: Ah!

This thing is huge!

STEVE: I remember you saying, "Holy crap.

This thing is big."

JEFF: Massive.

Half the size of the boat.

SCOTT: He comes up on this side.

JEFF: Right for the chum bag here.

Just opens his jaw and grabs it.

STEVE: He's going for the chum bag.

JEFF: Ah! (bleep)

SCOTT: Let it go!

JEFF: Ate our chum bag like.

SCOTT: Yeah.

JEFF: You said like a Tic Tac. SCOTT: Like a Tic Tac.

JEFF: (bleep)! Holy! Oh, my God!

Holy (bleep)!

STEVE: He came right up.

He's scraping on the back of the boat.

His teeth are grinding into the back.

JEFF: It was chomping like this.

He's going for the chum bag.

Ah!

I don't think he could have bit through the hull,

but like the size of him and the weight of him,

I think if he really wanted to,

he could have pushed in and swamped the boat.

SCOTT: Jeff, let it go. JEFF: Holy (bleep)!

STEVE: Once he got what he wanted, he, he just swam away

like nothing happened.

JEFF: Dude, that was the coolest (bleep) thing

I've ever seen.

Monster majestic shark.

STEVE: Yeah.

Something you'll never forget, right?

JEFF: No. Once in a lifetime.

Ah!

Oh, my God, dude!

MIKE: One thing you see in just about every viral video

of sharks attacking boats is one of these.

It's a chum bag.

Basically a mesh bag with bait in it.

Fishermen use it to attract fish in so they can catch them.

We're gonna do the same thing but for sharks so

we can study them.

So we're gonna put this in here, off the back.

Sara, you can throw yours in now.

SARA (over radio): Hey, Duncan, we're about to put the chum bags

SARA: In the water, so keep an eye out for the shark behavior

to possibly change.

SARA: We've just put essentially a meal in the

water for them and they're just trying to get that.

So we should see lemon sharks coming up, biting the chum bag,

and appearing to bite the boat but, in reality,

they're just trying to get the fish in the bag.

NARRATOR: The sound of the boat engine draws in a shark,

but it's the scent of the bait that revs them up.

MIKE: Whoa!

It pulled it out of my hand.

Luckily, it didn't get any bag but it almost did.

So you can see how quick this happens.

If you're not expecting sharks around, it could be pretty

surprising to have one appear at your chum bag.

SARA: When we just have the sound of the engine,

the sharks were just cruising.

They were hanging out, checking to see if anything

was coming up.

But once we put chum in the water and we put fish in the

water, they start going to more of a hunting mode,

and that's when their movement gets quick.

It gets erratic, and sometimes it can be very unpredictable.

NARRATOR: This aggressive behavior could mean trouble

for Duncan down below.

DUNCAN: If you see them swarming all around us,

it definitely gets the adrenaline going.

What you have to do is try to make sure you don't get

between them and the food.

NARRATOR: A chum bag might explain why sharks swarm boats

and also why they sink their jaws into them as well.

MIKE: You can see the way it pulled the bag out of the water,

the shark missed it, bumped into the boat.

That could look like an attack in the right viral video.

But what's going on is that the shark's just missing.

And they have what's called a nictitating membrane.

SARA: Sharks have this defense to protect their eyes, which

is kind of like an eyelid that closes up.

Some sharks roll their eyes to the back of their head 'cause

the back of their eye is actually a lot thicker and denser.

And in that moment, they're blind.

MIKE: So at the last second before it hits the boat,

it's kind of losing that sense of vision, and that may be

one of the reasons that we see these sharks attacking boats.

SARA: If what they were going for, let's say a chum bag,

moves 'cause of a wave or the fisherman pulls it out, they

still have that propulsion forward.

They're gonna maybe bite the boat and they might just miss.

Oh!

NARRATOR: With so much chum in the water, the researchers

question whether sharks are too dependent on bait for food.

The team will catch a shark and take a blood sample.

SARA: With the blood, we're breaking it down into plasma

and red blood cells.

We're then gonna do what's called an isotope analysis,

where we look at the chemical composition of these

components, to get a sense of what these sharks are feeding

on and how much of it might be chum and bait.

NARRATOR: The team sets up a catch-and-release.

MIKE: One, two, three.

NARRATOR: The time the shark is immobilized is kept to a minimum.

MIKE: The way we're trying to catch these sharks is designed

to minimize stress to the animal.

We're using a relatively small circle hook.

That let's us catch the shark right in the side of the jaw,

and these sharks heal incredibly quickly.

This really shouldn't hurt the shark at all so they're back

to their normal behavior right away.

Nice.

The shark has it.

SARA: Right now, one of the sharks have got our hook.

We're gonna let it run with it so it tires itself out and

it'll become easier to.

MIKE: There we go. SARA: Pull in.

MIKE: Okay.

We're gonna pick up the buoys here, gently bring the shark

up next to the boat, get it swimming along side.

DUNCAN: While the scientists are catching the sharks to tag

them and take samples, we've gotta be really careful when

we're trying to capture this on film, because the shark's

attached with a hook to the boat effectively.

So if at any point that hook pops, that shark can swing by

its tail in almost this 180-degree motion.

And if we're in the way, we could get caught in the

shark's jaws or also between the shark and the boat.

MIKE: Okay. Got it. 252.

SARA: Awesome.

MIKE: So that's eight feet.

SARA: What we got here is an eight-foot lemon shark.

Caudal vein's a little deep 'cause it is a bigger shark.

And so Mike right now is drawing blood.

And once he's drawn the blood, he's gonna give that vial over

to me so that way, I can break it down to the three

components we wanna analyze.

NARRATOR: The caudal vein is the largest in the tail of a shark.

MIKE: Heads up. Heads up. Let it go.

Always assume they're gonna do the most dangerous possible

thing and you will not be disappointed and you'll be safe.

SARA: Got it? MIKE: Yup.

All we're doing now is getting some blood from

that caudal vein here.

There we go.

Good job.

That'll do the trick.

Okay, Sara.

SARA: Are you gonna stay by the head?

MIKE: I'll come to the head. SARA: Yeah.

MIKE: There we go.

SARA: Trade. MIKE: Okay.

SARA: Got it? MIKE: Yup.

SARA: So what I got here is the blood that Mike just drew

from the lemon shark.

What I'm gonna do is, first, put it in this vial, which

will make it easier for me to access with a pipette.

When we're taking blood from these lemon sharks, we are

able to then do a chemical analysis that helps us

determine whether or not the food is coming from just the

natural fish in the area or if it's coming from

a fisherman's chum bag.

NARRATOR: With sample in hand, the shark's released.

MIKE: Okay.

Now, we're gonna get this hook out and we're gonna let her go.

SARA: Got it.

MIKE: Duncan, you ready for it?

DUNCAN: I've been in the water for lots of shark releases,

and you never quite know how the shark is gonna react.

MIKE: Okay. I'm on.

Don't get anywhere near that mouth.

SARA: Perfect.

NARRATOR: This one decided to leave its mark.

MIKE: Oh, no! Look out! Look out! Look out! No!

DUNCAN: On the release, the shark was a little bit grumpy.

You know, it had been measured.

You know, had, had its blood taken.

You know, it's just like humans going to the doctor's.

We don't really like it but it has to get done.

It turned around and went straight for the engine.

It just took a big bite out of the side of the boat.

MIKE: Oh, no!

We're good.

There we go.

A little spree.

Nice job. Nicely done.

DUNCAN: Wow.

Just look at the damage that shark caused on, on the side

of the boat here.

It just shows how strong the bite force of these

lemon sharks are.

It's actually ripped part of the gel coat off with a couple

of chunks out of the boat and actually shredded the rubber

of the rub rail.

Wow.

It really proves that, you know, if these sharks really

wanted to mess us up when we're in the water,

we wouldn't stand a chance.

NARRATOR: Sharks circling boats and biting hulls while

snatching chum bags makes perfect sense.

But what about sharks biting boat engines?

MAN: Oh, my God!

MAN: Ah! MAN: (bleep).

NARRATOR: In the sea battle between sharks and boats.

MAN: Ah! MAN: (bleep).

NARRATOR: The sharks appear to target one area.

ERIKA: Oh, God.

The shark was definitely most interested in the

motors more than anything.

It would come under the water and grab the bottom of the propellers.

MAN: No way.

ERIKA: You could hear a loud, a large thumping sound and

then a scrape as its teeth hit the, hit the

motors and props themselves.

I thought either we are going to lose an engine or

we're gonna have to paddle ourselves home.

Oh, God.

NARRATOR: This isn't a case of missing a chomp on a chum bag.

These sharks going out of their way to gnaw on the

metal engine and props.

MIKE: We saw that we could get these lemon sharks up to the

boat just from the sound of the engine, but there are

plenty of videos online of sharks biting engines, and

that's not about the sound.

There's a lot more going on,

especially the creation of electric fields.

And sharks have an incredible electroreception sense.

It's kind of their superpower.

NARRATOR: All living things create an electrical charge.

A human heart beat is regulated by electrical

charges that signal muscles to contract and release.

An EKG reads those charges.

Fish also create electrical signals, signals that sharks can detect.

SARA: These boat engines are sending out these electrical signals.

And sharks have what are called ampullae of Lorenzini,

which are these little tiny pores around their snout and

particularly around their mouth area.

These allow them to detect electrical signals in the water,

which is super helpful when you're trying to get

fish or any sort of animal that's moving in the water.

But it can also lead to confusion when you're around

man-made objects that also emit electrical signals.

NARRATOR: It's called electroreceptivity.

And some sharks, like the great white, are so adept at

it, they can perceive as little as one millionth of a volt

in the water.

That's a tiny fraction of what a common AA battery generates.

Sara has constructed a test to reveal how effectively sharks

can detect electrical charges,

like those created by a boat engine.

SARA: What we have here is we have two circuit boards.

Both of them are powered by batteries in the Pelican case

and they both emit a current of about 20 milliamps.

And once we close the Pelican cases, we actually have these

switches on the outside to help us easily turn it off or

on and do any alterations we need.

What we're gonna do is we're gonna place both of these

circuits in the water, but one's gonna be on and the

other one's gonna be off.

This will enable us to observe the sharks and see how they

react and how they respond to the circuit that's emitting an

electrical field compared to the one that's not

emitting an electrical field.

NARRATOR: Sara's test should capture a shark's interest.

One last check.

MIKE: The one with the arm up has its power is on, right?

SARA: Yeah.

So once they're both in the water, I'm just gonna swim

over and I'm gonna put that arm down, so that way

it's on and running.

MIKE: Okay.

But otherwise you got them exactly identical?

The only difference is this one's got current going through it?

SARA: Absolutely.

And the one that is on, I actually already covered the

light bulb up, so we know that light is not gonna play

a factor in the shark's behavior.

MIKE: Awesome.

So, yeah, this will be a good test to see if they're

cueing in on electric fields rather than something

floating in the water.

SARA: For sure.

And then we're just gonna tie them off the side of the boat,

20 feet of line each, and see what happens.

MIKE: My expectation is we're gonna have a good number

of lemon sharks.

This is where they hang out.

But we might see bull sharks, and it is Florida,

so you never know what might show up.

NARRATOR: The moment they splash in, they're vulnerable

to the sharks.

A diver's vision is limited by the mask.

Lugging a bulky air tank means fleeing to escape

is out of the question.

SARA: You have to always assume that there is the

potential for an aggressive encounter,

especially when you're diving with sharks.

And that's why it's really important to kind of keep your

head on a swivel, be aware of your surroundings.

It's better to assume the worst and be prepared for it

than to be taken off guard.

NARRATOR: Company arrives.

NARRATOR: The two testers are out.

They're about 10 feet apart.

NARRATOR: The waterproof battery sending out an

electrical field draws a lot of attention.

The charges from the battery appear to mimic what a shark's

prey creates or a boat engine emits.

It would explain why many viral videos show sharks

attacking boat propellers.

JEFF: Ah!

MIKE: It was pretty incredible to see that from underwater.

And you could see the sharks knew that both of those boards

were out there and they checked out both of them,

but they spent almost all their time by the electrified one.

SARA: That's when they would get close.

They would bump it.

Sometimes not so gently.

Yeah, I mean, we can even see it right now.

They're still swimming past it.

They're still checking it out.

And what was really neat was also seeing the different

type of behaviors.

MIKE: That was incredible.

And if you think about how that relates to boat engines,

yeah, it probably shows that it is that electric field that

they're zeroing in on when they bite the motor.

SARA: Yeah.

And then let alone if there's any other stimuli going on,

such as someone fishing off of the boat, that's further

attracting the shark and getting them into that

foraging mindset.

MIKE: Yeah, well, I would say that that was a successful test.

NARRATOR: Science reveals why sharks attack boat engines,

but what about plastic kayaks and canoes?

Many of the most frightening viral videos

show sharks attacking kayakers and canoeists.

BEN: Yeah, do that.

CHRIS: Holy God! BEN: Oh, my God!

CHRIS: Holy (bleep)!

Oh.

BEN: Watch out!

CHRIS: Whew!

NARRATOR: Matt Rosenquist, Ben Sasse, and Chris Ester

are avid fishermen.

They prefer to head out under their own power.

CHRIS: I prefer canoes 'cause of the serenity.

You know, it's peaceful.

It's not noisy with the boat motors.

NARRATOR: The three friends were about three miles off

shore, fishing in the Florida Keys.

There were no engines to attract a shark when...

BEN: Oh. Watch out!

CHRIS: Oh, my God!

MATT: He attacked us. He literally attacked us.

BEN: When it first started coming up towards the boat,

Matt would say, "Oh, I think it's a nurse shark."

And then all of a sudden, I see these massive jaws.

MATT: Do you see that?

It came straight at the boat.

Hit it with all its force. And it was not happy.

BEN: Watch out!

MATT: That was a moment that if we had not had Chris's

canoe there, it could have been really, really bad.

CHRIS: Holy (bleep)!

MATT: I think Ben even fell into Chris's canoe.

CHRIS: Oh.

MATT: That was the confirmation that we were in

for the fight of our life.

BEN: Wait! Bull! Oh, my gosh!

NARRATOR: A bull shark came in charging, just like its namesake.

CHRIS: I remember the feeling of being kind of tossed,

and we're just hanging on for dear life.

Oh!

NARRATOR: Bull sharks have very high testosterone,

more than a male African Elephant in heat.

And this one was proving it.

MIKE: When you're a bull shark with that stocky build, you're

one of the few sharks in the ocean that'll eat prey about

your own body size instead of much smaller than you,

you know, that's a recipe for boat versus shark run-ins.

CHRIS: It was intentional.

It wasn't a single like, "Get away from me."

It was over and over.

Oh!

It would attack and then it would turn back around and attack.

BEN: Watch out!

I didn't realize it but my butt went in the water for a second.

SARA: It's really easy to just sit back and enjoy a shark if

you're on a 20-foot vessel.

But if you're on a small canoe or a kayak, that can be a

little more concerning.

There's very little separating you from the water,

and it wouldn't take much to knock you over.

CHRIS: My God!

Oh!

BEN: It was like one part excitement and then this

other part, like surreal.

Is this really happening?

MIKE: There are a few things that could attract

a shark to a kayak.

You know, one would be the silhouette.

You know, for a big shark, like a white shark,

that silhouette may mimic what its prey is.

For other species, the silhouette may be something

worth checking out 'cause maybe there's other prey

around some floating object.

But then there are other sensory inputs too.

You know, the paddle dipping in, if a shark's nearby,

might be worth investigating.

Not necessarily, you know, flying in to attack but just,

"Hey, something novel in the environment.

I'll check that out."

NARRATOR: A kayak, lemon sharks, and a fishing pole

allow Mike to reveal why a shark might attack a kayak.

SARA: All right, Mike, you head on out with the kayak and

I'll keep an eye on you from the sky with the drone, okay?

MIKE: Sounds good.

SARA: All right.

All right. We're sending the drone up.

Right now, I'm just keeping an eye on Mike on the kayak

using the drone.

Getting a bird's eye view of things.

Seeing where the sharks are, where Mike is.

NARRATOR: Duncan is below for the underwater vantage point.

As if on cue, the sharks arrive.

A bit of a homebody in the shark world, lemons prefer

a home range rather than long migrations.

MIKE: So I'm out here kayaking.

We might see one or two lemon sharks, but I'm not putting a

lot of stimulus into the water.

Just a little bit of sound when I put the paddles in

and there's the silhouette.

But this silhouette doesn't match the prey of the sharks

we see around here.

Let me know if any sharks are coming.

SARA: There's one or two who keep swimming past Mike on the kayak.

You got one coming under your bow, just swimming past you

right now, Mike.

MIKE: Yup.

NARRATOR: Mike wants to avoid what happened to Ben Chancey

off Stuart, Florida.

Ben's an experienced paddler who's fished from kayaks for

18 years.

CHANCEY: He's right underneath of me.

Oh, my God.

Whenever a fish over 300 pounds decides to go crazy and

you're in a kayak, there's nothing you can do.

We're off the East Coast of Florida and we're trying to

catch the biggest fish that we've ever caught out of a kayak.

We get out there and we catch a bonito for bait and then we

drop that bonito down and something huge grabs it.

Lo and behold, I realized it's a giant bull shark

and I'm like, "Wow. We've got a bull shark on.

This is crazy."

It's spinning me around.

It's almost like being on a rollercoaster ride and

I'm getting pulled all around.

And I'm like, "I don't, I don't know what's going on."

It pulled so hard, it felt like it's gonna flip me right

over out of the kayak and I couldn't hold on to the rod anymore.

There was a moment where I was paused and I'm like,

"Oh, I got flipped over."

I didn't automatically go, "I better get for the boat

'cause I could get eaten."

Once I realized that fish was still tied off to my kayak,

I'm like, "I gotta get to the boat."

So I swam as fast as I could.

I did my best Michael Phelps impression.

It might not look like Michael Phelps but I felt like

I swam as fast as him to get back to the boat.

MAN: He's still on.

MIKE: You might think that these interactions are

unprovoked, but when you look at the kayaks and canoes,

there's one common thread most of the times, fishing.

BEN: Watch out!

CHANCEY: Oh!

MIKE: What we saw already is shark's not super interested

in the kayak, but we're gonna ramp it up a little and test

the conditions we see in a lot of those videos by adding some bait.

Now, we don't have a hook here.

We'll tie the fish on and I'm gonna throw it out there.

Let's see what happens.

SARA: Once Mike casts that line and the fish hits the water,

I'm expecting the sharks to immediately be

drawn to that sound.

And as he reels that in, follow it because there is

fish blood.

That's just a free meal on the end of the line for the sharks.

MIKE: Okay. Ready?

SARA: You're good.

MIKE: Bait's out.

SARA: We're gonna see a lot faster behavior.

They're gonna be really interested in the kayak and

what's the end of that line.

MIKE: Sara, the bait's out but I can't see anything.

Let me know if I need to reel.

SARA: Right now, one is passing right underneath you, Mike.

No. She's coming.

MIKE: Okay. This one's coming fast.

SARA: Pull in that fish, Mike.

MIKE: Ah!

Woo! Perfect.

So you can see how fast that shark is swimming toward the boat.

That's exactly the kind of situation where you could get

a shark running into a kayak, not 'cause it wants to bite

the kayak but 'cause it's interested in the fish

on the end of the line.

Yeah.

That one's nice and close.

NARRATOR: The science behind shark behavior reveals the

truth behind most viral videos.

But there are some videos where biology or chemistry

aren't the cause of boat/shark encounters.

MAN: No way.

NARRATOR: Sometimes it's personality.

JEFF: Ah!

NARRATOR: Not the boaters but the sharks.

Carl Torresson was fishing just off-shore of Jupiter, Florida

when he came in contact with one ornery bull shark.

CARL: We started the day offshore fishing.

We got the word that there was a, a good cobia bite

going on the beach.

We were about this far offshore.

We found, we came in here, my dad told me,

"The shark's attacking the boat. What's going on?"

Every time he grabbed the boat, the boat would stop.

Then he came back around and when he hit the side of the

boat, it was like a boom.

I thought we hit a reef.

SARA: Bull sharks have a reputation for being a bit

more aggressive, a bit bolder.

And that's not necessarily untrue.

CARL: This wasn't about the electricity in the water.

This shark was just an angry, angry shark and

we were interrupting his day.

He attacked the boat and he kept attacking the boat with,

with intent to kill the boat, kill whatever he was biting.

The power that he was grabbing the boat with is unbelievable.

MIKE: That video of the big bull shark attacking a fishing

boat is something I'm not used to seeing at all.

CARL: After he hit, ate the motor and was biting on the

motor, he actually came by and hit the side of the boat.

Boom.

You were literally moving.

It was like a Universal Studios' ride but it was so surreal

that it was a shark doing it and that a shark was that powerful.

MIKE: In our studies of bull sharks, we found that

different individuals have different personalities,

if you wanna call them that.

Some are bold. Some are shy.

You know, not every individual is gonna react the same in

every situation.

You know, maybe these guys came across a big shark

that was willing to attack and

just decided to go after the boat.

I mean, it's hard to tell what the motivation of that shark

was but it certainly was going after the boat.

NARRATOR: To observe how bull sharks react to anything new

entering their space,

Sara and Mike head to a known bull hangout.

SARA: I've seen that video.

That bull shark was behaving really aggressively.

But that sort of behavior is really rare,

especially when you're diving.

MIKE: Yeah.

You know, these are big predators and they can get aggressive.

But usually there's a reason for it.

So we're down there.

I'm not expecting to see anything like that, but still

we'll stay shoulder to shoulder, keep our eyes on things.

SARA: Uh-hmm.

DUNCAN: I think if there's anything the area, we're

drifting along the edge there, they'll come up and

investigate us.

NARRATOR: Duncan will film the encounter.

DUNCAN: Whenever you jump in the water with bull sharks,

you've gotta have your wits about you.

They're incredibly unpredictable shark that's

always testing you, coming from all different angles.

You pretty much have to have your head on a swivel.

NARRATOR: In addition to having very high testosterone,

bull sharks are thought to be more dangerous to humans

than great whites.

Sara and Mike need to be aware at all times of how many

sharks are around and where they are.

NARRATOR: They ease into the bull shark's space.

As observed, bull sharks will ram a boat and

are known to attack humans.

NARRATOR: Surrounded by bull sharks, shark researchers,

Dr. Mike Heithaus and Sara Casareto, gauge the

sharks' behavior to determine if they're in danger.

MIKE: That was incredible.

And the amazing thing to me is bull sharks have such a bad

reputation for being aggressive and, I mean, there

are videos of them bodyslamming boats,

but those sharks were just so calm.

SARA: They were just cruising.

I mean, I did not at any point feel worried.

MIKE: There is some personality in there too.

SARA: Yup.

MIKE: You could see some of the individuals would come in

really close, but give plenty of space.

And others were just hanging out really far in the distance.

SARA: Yeah.

They were enjoying the dive just as much as we were, it seemed.

MIKE: It really shows that, you know, these animals are

not, as a rule, super aggressive.

These are not animals that you'd expect to be coming in

and just attacking a boat for no reason at all.

NARRATOR: While the viral videos of shark/boat

encounters are intense.

BEN: Watch out!

NARRATOR: No one on a boat or a kayak was bitten.

That changed off the coast of Tasmania in Australia.

DARYL: It's a really unique little area.

Quiet area.

Not too much drama happens here in Stanley.

It's a historic town, and there's around 700 people that

live here in Stanley full-time.

It's always been a fishing village.

NARRATOR: Winter in Tasmania.

The water is cold and few venture in for a swim.

A shark attack seems like an impossibility.

TODD: The incident at Stanley was an extremely rare occurrence.

I've never seen a shark or heard of a shark doing that before.

DARYL: I know that sharks have been sighted off Stanley,

but I've never heard of sharks attacking a boat or people at all.

NARRATOR: Even so, a warning of a large shark in the area

was issued when John Arnott and his son, Lucas, age 10,

were fishing off the coast.

Without warning, a shark grabbed the boy off the boat

and dragged him into the water.

Within seconds, the father dove in to save his son from

the jaws of the attacker.

The shark, thought to be a great white,

let him go in moments.

Many claimed the boy's life jacket and heroic father

saved his life.

DARYL: We hear of surfers being taken by great whites,

but we've never heard of that happening anywhere in Australia.

NARRATOR: The child was released from the hospital

after being treated for wounds on his chest,

shoulder, and head.

DARYL: Probably, everybody was a bit numb for a start because

it was just something that you just never

hear about in Australia.

TODD: I've only had around sort of one great white

touch the boat.

It's more curiosity than anything.

And it's very, very unlikely that you'll get grabbed by

a shark off a boat.

Well, I mean, it can happen but it's very unlikely.

NARRATOR: It seemed a line was crossed between shark and human.

Being on a boat didn't mean you were safe.

MIKE: The reports of that encounter in Tasmania are like

nothing I have ever heard before.

A boy was dragged out of a boat while he was fishing.

But we just don't know enough about what happened.

SARA: It's really hard to know what was going on in the

shark's head at that time.

They were fishing.

There was that stimuli.

But it's just such a weird occurrence.

It's, I've never heard of something like that happening

before with any type of shark.

NARRATOR: Encounters between sharks and boats will only increase.

Fortunately, the truth is these aren't attacks.

JEFF: Ah!

MAN: No way.

NARRATOR: Just encounters with an animal in its domain.

DUNCAN: With shark populations all over the world declining,

I feel like if, you're lucky enough to have a

shark attack your boat.

You should just lay back and enjoy the moment and

look at the animal.

SARA: You are seeing one of the most well-designed

predators on the planet doing its thing.

And if you see anything super cool, let me know.

NARRATOR: The results from the blood sample from the

lemon shark are in.

It provides a rare insight into shark and boat encounters.

MIKE: When you look at the samples and you look at what

these sharks are doing,

they're not getting a lot of food.

You know, we're not really seeing indications that it's

probably completely changing their feeding behavior.

Most likely what's going on is that these sharks are in the

area and, hey, maybe get a little bit of free food here.

Why not take a few tail beats and go over there and

check it out?

Of course, there's more work to do, but the initial

indications are certainly that this is not having a major

negative effect on the sharks.

Whoa!

It pulled it out of my hands.

Our takeaway from looking at the behavior of these sharks

and all the videos is that these sharks are not really

trying to attack boats but they're responding to stimuli

like bait and electrical charges,

and you're not gonna need a bigger boat.

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YouTube Transcript:Sharks VS Orcas, Dolphins, & More! | 2025 Sharkfest MEGA Episode | National Geographic

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Sharks VS Orcas, Dolphins, & More! | 2025 Sharkfest MEGA Episode | National Geographic