Original subtitles

NARRATOR: It's one million square miles of mystery,

filled with myths and legends

and astonishing deep-sea creatures.

MAN: There seems to be all these unique anomalies

within this part of the Caribbean.

NARRATOR: From magnetic fields to strange geography

and bizarre weather,

it's the site of countless disasters.

But something is driving some of the world's deadliest sharks

to the Caribbean's mysterious depths.

And one man wants to know why.

What he finds may change what we know...

MAN: This type of footage has never been documented before.

This is just insane.

NARRATOR: ...about Sharks of the Bermuda Triangle.

The Bermuda Triangle.

An enigma wrapped in tales of lost planes and sunken ships.

MAN: Mayday, mayday, mayday.

NARRATOR: But the Bermuda Triangle's biggest mystery

may be its sharks.

What's attracting them here,

and why are they diving to the Triangle's deepest regions?

♪ ♪

AUSTIN GALLAGHER: We do have some acoustic tags.

NARRATOR: Marine biologist and shark expert

Dr. Austin Gallagher has devoted his career

to unraveling the relationship between ocean predators

and ecosystems like the Bermuda Triangle.

As chief scientist and founder

of the non-profit Beneath the Waves,

he believes there is something unusual happening right here.

GALLAGHER: Throughout my studies, I've learned

that tiger sharks spend a lot of time on the surface,

and using these waters to hunt air-breathing animals

like turtles and birds.

But here, tiger sharks don't seem to be doing that at all.

In fact, they don't seem to be

spending any time at the surface.

Tiger shark behavior here is really weird.

I've never seen anything like it.

NARRATOR: The Bermuda Triangle

is often linked with stories

of unique magnetic forces,

confusing compass readings,

and mysterious disappearances.

JOE ROMEIRO: There's always some kind of lore about ships

that couldn't find themselves, or planes that have been lost,

and with these magnetic anomalies,

you can see that, if sharks are truly using magnetic sources

to find one place to the other,

then this place is unique to that.

GALLAGHER: For scientists, it's kind of fun

to go into these places and try to understand what's going on.

The animals look healthier and stronger

than anywhere I've ever seen.

ROMEIRO: That triangle is basically

right smack in the middle

of a huge migratory route

for almost every shark species in the Atlantic.

So within the Triangle, there's always been a lot of thought

of being this mysterious magnetic pole.

♪ ♪

NARRATOR: Rumors of magnetic anomalies

have long plagued the Bermuda Triangle.

The most famous of these incidents

is the disappearance of Flight 19.

In 1945, five Navy bombers took off on a training mission

from Fort Lauderdale, Florida.

The squadron leader reported that both of his compasses

stopped working and their position was unknown.

When they didn't return,

a search and rescue plane took off,

but it, too, vanished.

From magnetic vortexes to alien interference,

there have been many theories

to explain the disappearances within the Bermuda Triangle.

Today, scientists believe it's not supernatural forces

at work, only natural ones.

But when it comes to sharks,

something unusual is happening here.

GALLAGHER: Let's be honest,

the Bermuda Triangle is just kind of weird,

and a little freaky.

Interestingly enough,

some of the wildest and strongest animals on our planet

really do prefer to be found in some of these spots.

NARRATOR: The target of Dr. Gallagher's research

is Rose Island,

an 11-mile spit of land

surrounded by underwater trenches.

These waters offer limited food sources for sharks,

and yet still attract them here,

including one of the ocean's great apex predators,

the tiger shark.

GALLAGHER: Tiger sharks really do rule Rose Island.

They are the true knights of this area.

There's a good chance that the Bermuda Triangle is emitting

electromagnetic cues that could be aggregating

these large tiger sharks in the water.

NARRATOR: Tiger sharks are one of the largest, most aggressive

species in these waters and the world,

growing up to 24 feet,

weighing up to a whopping 3,100 pounds.

Unlike great white sharks, known to be notoriously picky,

tiger sharks have been known to eat nearly anything

they encounter; even other sharks.

YANNIS PAPASTAMATIOU: What kind of makes them unique

from other sharks is a very, very broad diet.

Probably the broadest diet of any species of shark.

And part of the reason that they have such a broad diet

is A) because of their size,

but also because they have some pretty unique-shaped teeth,

and those teeth are really good

at sawing through things that are hard.

So that really sort of extends the number of prey items

that they can try to consume.

ROMEIRO: It's the largest predatory fish

in tropical waters.

Its basic job is cleanup crew for the ocean.

Anything that's dead, dying, diseased, or dumb

falls under a tiger shark's category for prey.

NARRATOR: And why all the activity here at Rose Island?

Dr. Gallagher believes this is part of a major highway

along the tiger sharks' annual migration.

ROMEIRO: A lot of what we know about sharks and their migration

is based on magnetic fields.

We believe that sharks follow along these corridors,

up and down these areas, trying to find their way around things,

but usually use these islands, and certain magnetic barriers,

as sort of a map to get from one place to the other.

GALLAGHER: Our hypothesis is that these animals are using

habitats just north of Rose Island

for some type of important purpose.

There's a big drop-off, so it goes from really shallow,

20, 30 feet, to over 1,000 feet,

and really what our objective is on this trip

is to find these tiger sharks

and tag them with some cutting-edge technologies

to help us understand if they are using these deep areas

and why they might be doing that.

NARRATOR: For Dr. Gallagher,

unraveling this mystery of the Bermuda Triangle,

the link between tiger sharks and Rose Island,

may all depend on one particular shark named Mabel.

GALLAGHER: Mabel is a 12-foot tiger shark

that I first met in February 2008.

WOMAN: Okay, which way do you want to go?

GALLAGHER: And oftentimes when you tag a shark,

you pretty much expect to never see it again.

With Mabel it was a different story.

WOMAN: No, no, get someone to measure down on the tail!

MAN: Got it.

GALLAGHER: We actually caught her again

six months later at the same spot.

At that point, we put in an acoustic tag

so we could track her movements.

And what we've learned is that she really loves Rose Island,

but she's only at the surface for short periods of time.

♪ ♪

NARRATOR: Dr. Gallagher has been watching

Mabel's acoustic pings closely.

He knows her patterns.

GALLAGHER: We don't know exactly where Mabel has been

in between her transmissions,

but based on connecting the dots,

we can infer that she might have been in the deep trench

right off of Rose Island.

These animals are always trying to conserve their energy

and go to areas where they know that something important

is happening, whether it's a food source,

maybe it's where they want to give birth to their babies,

or maybe it's where they want to go mate

to sustain their populations.

The first thing we really need to do

is just do a little check-in with the sharks.

We gotta get eyes on them.

If we can make some preliminary observations

on these tiger sharks, it might help inform

what the next step of our research might be.

NARRATOR: Joining Dr. Gallagher on this expedition

is marine biologist Oliver Shipley,

an expert in shark feeding dynamics.

OLIVER SHIPLEY: The reason that we wanna make the chunks

nice and small is 'cause sometimes

you can actually overfeed the sharks

and then they swim off.

MAN: Tiger! Woo!

NARRATOR: It doesn't take long

before the first tiger shark arrives.

GALLAGHER: Pretty exciting moment here.

We got a tiger shark circling the boat, which is awesome.

We're gonna keep it interested here,

so that'll be great if we can keep the shark around.

We're gonna get in the water now,

try to take a look at what's really going on

with these tigers.

-MAN: You on? -GALLAGHER: Yep.

SHIPLEY: It's always a little bit apprehensive.

There's a few nerves before you get in the water

with a big shark like a tiger shark.

GALLAGHER: Alright, boys, remember what I said?

Eye contact with the shark at all times.

You know, be respectful.

♪ ♪

NARRATOR: They use plastic sticks

to keep the sharks at a safe distance.

And they soon spot an intriguing clue.

♪ ♪

This female tiger shark has fresh bite marks on her body;

a possible lead

on what's driving tiger sharks to Rose Island.

GALLAGHER: Cluing in on these little observations,

like mating scars, is really the first step

in trying to uncover this puzzle.

PAPASTAMATIOU: We can get a lot of information

from the presence of fresh mating scars.

ROMEIRO: If it's something usually fresh,

we know that the mating process took place

somewhat around the area.

So we start to get an idea of where these areas are.

NARRATOR: Now, in their search for Mabel,

Dr. Gallagher and his team set drum lines,

a series of baited hooks.

GALLAGHER: So you can actually see, looking out here,

that we have all of our drum lines in this nice, long line.

Basically serves as a nice net,

so if there's any tiger sharks in the area,

they can sort of smell our bait

and then we start reeling the shark in during a tagging.

So we're really setting up this awesome fence almost,

for tiger sharks to come find us.

It can take as little as five minutes,

or as many as five hours.

We really don't know until we bring it up,

which makes that moment really exciting for us,

'cause you never know.

It's like, you know, the lottery every time.

You don't know if you're gonna win or not.

There's something on this, I think.

It's a tiger. Woo!

MAN: This one looks good.

GALLAGHER: Oh, boy.

NARRATOR: Then, after nearly an hour...

MAN: It's swimming like a tiger. It's a tiger.

NARRATOR: There's a bite.

GALLAGHER: Got a beautiful tiger shark.

Oh, my god!

NARRATOR: But is it Mabel?

MAN: Woo!

Oh! Oh, tail.

♪ ♪

MAN: It's a tiger.

Oh!

NARRATOR: Dr. Austin Gallagher caught a tiger shark

in the Bermuda Triangle, but it's not Mabel.

It's a 12-foot-long, sexually mature male.

GALLAGHER: Hold it. Don't let it run, don't let it run.

Do not let it run.

Guys, this is a really strong shark. Okay.

NARRATOR: Finding a male tiger shark may mean one thing:

it's mating season.

GALLAGHER: It's rare that you see a large male shark

of any species in an area where there's a lot of females.

When we saw him, it only supported our theory

that they might be mating here.

No, that's good, that's good.

NARRATOR: In the Bahamas, female tiger sharks

seem to prefer the company of their own gender.

Some scientists speculate that as a group,

it's easier for female tiger sharks

to fend off unwanted sexual advances from males.

MAN: Hang on, hang on, hang on.

MAN: Is this good?

MAN: Yeah, that's fine, tie it off.

And then come in, Mo, and like hold.

PAPASTAMATIOU: When you look at the distribution of sharks,

we have what's called sexual segregation,

which means that you find males and females in different areas.

One popular explanation is that females are avoiding males

outside of these mating periods.

So it makes sense that if she doesn't want to reproduce

at that point, that she avoids

that sort of mating behavior altogether.

And that may explain why you see females in separate areas

from where you find the males.

NARRATOR: With pregnancies that last up to 16 months,

the female tiger sharks only mate once every three years.

When females are ready to mate, it's believed that they let

the male tiger sharks know by releasing pheromones.

If so, this male has likely caught a scent

and is on the search for a receptive female.

GALLAGHER: That shark is definitely

one of the breeding males.

There's few of them.

Here we go, boys.

-MAN: Watch the head. -MAN: Yeah.

GALLAGHER: Alright, I'll take the tag.

NARRATOR: Dr. Gallagher attaches a satellite tag

to the shark's dorsal fin.

MAN: Yep, it's coming, it's coming.

Keep going, keep going. Nice, nice.

GALLAGHER: Satellite tags are awesome.

One of my favorite tools.

These offer scientists like us the chance to collect

high-resolution data on the sharks

without us having to follow them.

NARRATOR: The tag remains attached to the shark,

recording vital information,

including location, depth and water temperatures.

After several weeks, the tag will pop off,

float to the surface

and transmit all the data to a satellite.

GALLAGHER: Being able to get a male with the tag on it

that will actually reveal its depth preferences and locations,

could actually help us pinpoint

exactly where these animals are going to.

So that's really valuable for our larger questions here,

about mating, vertical habitat use

and interactions between males and females.

So, getting a male is actually huge for us.

Tag's in, fin clip.

See, I'm taking a little fin clip here.

Fin clip. Pass it to Jill.

NARRATOR: To study the genetic diversity of these tiger sharks

in the Bermuda Triangle,

Dr. Gallagher clips the dorsal fin

for blood and tissue samples.

GALLAGHER: These are gonna provide invaluable insights

into the genetics and the hormones

and stress levels of these animals.

Oh, he's ready to go.

These are pieces of the puzzle that we're gonna put together

to understand how valuable the Bermuda Triangle is for sharks.

Okay, good?

MAN: Yeah.

MAN: You ready, guys?

GALLAGHER: Push him right that way.

Beautiful!

Nicely done, guys.

Wow, that's a huge shark.

Woo! Whoa! Yes!

That was amazing!

Woo!

NARRATOR: But there's still no sign of Mabel

around Rose Island.

Mabel's acoustic tag should be constantly sending pings,

but so far, there's no signal.

GALLAGHER: The great thing is that tag lasts

for up to seven years, sending a uniquely coded ping

with that shark's identification number out.

We download the data and then we can construct a map

of how the shark uses the waters of the Bahamas.

So she's kind of gone AWOL.

She's probably down in the deep trench,

right to the north side of the island.

This is corroborated by our acoustic data.

NARRATOR: The Bermuda Triangle contains

some of the deepest trenches in the world.

The Puerto Rico Trench, at the Triangle's southern point,

reaches depths of over 27,000 feet.

But Dr. Gallagher suspects that Mabel may frequent

the Tongue of the Ocean, a steep, underwater trench,

less than a mile away from Rose Island.

The deepest branch of the Great Bahama Canyon,

it's named for its shape that's like a tongue.

GALLAGHER: The Tongue of the Ocean drops off steeply,

just half a mile or so offshore.

It goes from about 30 feet to 300 to thousands really quickly.

We really have no idea what's going on

down in the deep trenches here.

Anything could be happening in the deep sea.

It's one of the final frontiers for human exploration,

even more interesting, in my opinion, than exploring space.

ROMEIRO: So, animals of all sorts

can live within this trench,

and it seems like there's reports of all kinds

of different creatures living within the Tongue of the Ocean.

It's sort of become this legendary spot.

NARRATOR: If Mabel is in the Bermuda trenches,

she may not be alone.

Once thought to be a barren zone with few life-forms

able to sustain themselves without the sun's light,

marine biologists have discovered that the deep waters

of the Bermuda Triangle are home to other sharks,

from the megamouth to the sharpnose sevengill.

Among the diverse shark population

in the depths of the Bermuda Triangle,

one small shark stands out for its audacious attacks.

The cookie cutter shark.

A terrifying shark with a deceptively sweet name.

PAPASTAMATIOU: Cookie cutters have very distinctive teeth.

The teeth are actually fused together.

Each individual tooth is fused together,

unlike what you see with other sharks.

NARRATOR: This rarely photographed shark

makes dramatic vertical migrations.

During the day, it dwells in depths of over 3,000 feet,

but at night, it rises up over 2,000 feet to hunt.

PAPASTAMATIOU: If you look on the underside

of a cookie cutter shark,

it actually has cells that produce light,

what's called bioluminescence.

ROMEIRO: When a predator sees the bioluminescence

in the water, it goes over there

to see if anything's been disturbed.

A cookie cutter shark uses this opportunity to latch on

to the side of these predators and take a bite from it.

NARRATOR: The cookie cutter only grows to 20 inches,

yet has the audacity to attack whales, tuna,

even great white sharks.

The proof is in the telltale injury

the cookie cutter leaves on its victim:

a hole in the skin about the size and shape of a cookie.

ROMEIRO: If you ever looked at how they get cookie dough

out of something, it's with a scoop,

and that's basically what these sharks do.

They have this jaw structure that can latch on to the side

of an animal and, like, scoop out a piece of flesh.

NARRATOR: The cookie cutter shark spends its days

deep in the ocean, but even at shallower depths,

these sharks can be extremely difficult to locate.

Tiger sharks are no strangers to these depths.

They routinely swim over 1,000 feet below the surface.

If Mabel is diving into the trenches,

it's impossible to know how deep she's going or why.

To find her, it's a game of cat and mouse.

Her acoustic tag emits a noise that can be picked up

with a hydrophone; a device like an underwater mic,

embedded in the ocean floor.

But the transmitter cuts out at 1,000 feet,

so they must wait for her to swim closer to the surface.

GALLAGHER: We have about 100 sharks tagged

around Nassau and New Providence here,

with these internal transmitters that send out acoustic signals

every minute and a half or so.

So they're being picked up by receivers,

but while we're actually on the boat,

I'm gonna put this transducing hydrophone in the water here.

We can listen for the sharks in the area,

just to check to see if anyone's around, like Mabel.

(static)

Well, we know she's here,

so we're increasing our odds of finding her.

I mean, we could be searching anywhere here.

We picked Rose Island because we know this is her hot spot.

This is where Mabel lives.

I think we have a good chance of finding her now.

(static)

(pinging)

We got something.

Oh, my god.

♪ ♪

(pinging)

GALLAGHER: You hear that?

(pinging)

Guys, it's Mabel, 22689, she's right around the boat right now.

This is amazing!

NARRATOR: Dr. Austin Gallagher continues his search for Mabel,

a tiger shark in the Bermuda Triangle.

She may be close,

but luring her to the boat is another challenge.

GALLAGHER: Really, what we need to do is bait up the area

with her likely favorite food,

which we like to think is barracuda.

Cross our fingers, hope for a little bit of luck,

and see what happens.

Yeah, that looks looking good.

MAN: There's something on it.

GALLAGHER: Okay, we got a shark.

Here we go, boys, here we go.

Yeah, Mo, I like that.

She's a pretty large individual.

NARRATOR: It's a large nurse shark.

GALLAGHER: Yeah, we got a good size nurse shark here.

This is a real diverse area,

so nurse sharks, tiger sharks, lemons, bulls.

We're doing a measurement right now.

We're doing the precaudal length, 155.

WOMAN: 155.

GALLAGHER: Fork length, 174.

Now I'm doing the spaghetti tag.

There, spaghetti tag's in.

Nice!

Woo! Nicely done.

That was great.

NARRATOR: Then, Dr. Gallagher and his team

continue their search for Mabel.

MAN: Grab the gaff, grab the gaff, grab the gaff.

NARRATOR: Soon, they hook another shark.

GALLAGHER: Can I have the gloves?

See how this line is trembling?

Oh, my god, it's big. Is that a hammerhead?

NARRATOR: It's a big one.

MAN: It's a hammer! It's a freakin' hammer!

GALLAGHER: Beautiful hammerhead.

Wow!

Oh!

Watch it, it's trying to run.

This is a huge hammerhead.

Alright, we need to cable it.

MAN: Cable it?

GALLAGHER: Yeah, we're gonna have to cable it.

NARRATOR: Despite the odd shape of their heads,

hammerhead sharks have an advantage

when it comes to tracking prey.

Their wide head is lined with the ampullae of Lorenzini,

electroreceptors that pick up movement of potential prey,

and their eyes have excellent binocular vision,

allowing them to detect stingrays

hiding in the sand below

and potential prey swimming above.

GALLAGHER: Watch it, watch your hands, it's gonna run.

MAN: It's just heavy.

Oh!

GALLAGHER: Not all of it, not all of it.

And we need to move fast

so we get the shark back, released quickly, okay?

NARRATOR: Hammerheads are susceptible to stress.

For the animal's health, they must be quick.

GALLAGHER: What it's gonna try to do

is ram its hammer into the boat.

That's bad.

Let's get a quick measurement and let's move fast, okay?

Quick measurement, let's go.

NARRATOR: There's no time to waste.

GALLAGHER: Let's go, measure, measure, measure!

Spaghetti tag.

Do the spaghetti.

It's gotta happen now, you can't wait, let's go.

MAN: Needle!

NARRATOR: For the animal's sake, and their own,

they must be very careful.

GALLAGHER: Good?

Okay, Mo, it's over.

Get everything off, get everything off.

MAN: Adrian, give me slack! Slack, slack, slack!

GALLAGHER: Move back, Andre, I'm gonna push him towards you.

Move everything back, let go.

Let go, let go!

Yes!

Nice healthy release.

Really good.

Really, really good.

It's this huge predator, it's insane.

It's actually the first one I've seen off New Providence.

It's just the Ferrari of the ocean, unreal.

I'm really tired.

It's the first hammerhead I've seen in a long time.

♪ ♪

NARRATOR: The diversity of sharks in the Bermuda Triangle

goes far beyond what Dr. Gallagher and his team

encounter close to the surface.

Deep within the ocean, amazing sharks we rarely encounter

are thriving in surprising ways.

One of the most ingenious is the deep-sea sawshark.

Under 3 feet long,

its saw-like nose is about one third of its length.

ROMEIRO: It rakes along the sand,

trying to find different crustaceans and shrimp

that live within the sand.

It can sit there and hit prey items out of the water,

press it against the sand,

and then it will roll those items right into its mouth.

It's a unique feeding behavior for an animal,

and especially for a shark.

NARRATOR: Despite its chainsaw-wielding appearance,

the Bahamas sawshark is harmless.

It lives at depths of nearly 3,000 feet.

ROMEIRO: Not much is known about the sawshark.

It buries itself in the sand, it's highly illusive,

and it's just one of those sharks you don't see a lot of.

NARRATOR: The Bahamas sawshark is still a mystery.

And it's not alone.

From rarely seen sharks in the Bermuda Triangle's depths,

to tiger sharks that dive deep for unknown reasons,

Dr. Gallagher is determined to uncover the truth.

MAN: Big tiger!

♪ ♪

NARRATOR: From vicious carnivores

to bizarre bottom feeders,

the Bermuda Triangle is home

to hundreds of shark species.

And one of the strangest lives in its deep seas:

the ghost shark.

Its appearance is otherworldly,

with a face that looks stitched together

like a fishy Frankenstein.

In reality, the stitches are sensory organs

that pick up the slightest movement of potential prey.

Its bizarre appearance includes a sex organ on its head.

ROMEIRO: Its sex organ actually has claspers on it

and it can lock into females, and then when finished,

it can retract back into its body.

NARRATOR: Female ghost sharks

don't immediately become pregnant.

They may even wait for years before making use of the sperm.

ROMEIRO: In the deep sea it's believed that it's very hard

for ghost sharks to find each other to mate.

So the female can actually store sperm in her body

till she's ready.

NARRATOR: Female tiger sharks can also store sperm

for months, waiting until they're ready to ovulate.

Dr. Gallagher hopes to catch Mabel before she mates.

GALLAGHER: Part of it is kind of a needle in a haystack.

Certainly luck plays a role.

She really loves Rose Island,

but she's only at the surface for short periods of time.

NARRATOR: While scanning the sea,

Dr. Gallagher and his crew must also watch the skies.

Hurricane season's only days away.

Tropical storms can sweep through the Triangle,

wreaking havoc on land and sea.

GALLAGHER: This time of the year, it can be really stormy,

thunderstorms can come in quickly,

and it can go from zero to 60 real fast.

(thunder)

NARRATOR: Severe storms and looming hurricanes

may be why so many ships and planes seem to vanish

in the Bermuda Triangle.

In 2015, the El Faro, a cargo ship, disappeared.

30 days later, the El Faro was discovered

at the bottom of the Bermuda Triangle.

Many believe Hurricane Joaquin was to blame.

Some experts believe tiger sharks may be seeking

deeper waters to take shelter

from the Bermuda Triangle's violent storms.

How do the sharks know bad weather's on its way?

ROMEIRO: The lateral line systems are these two lines

that follow along a shark's body,

that will actually detect pressure systems in the water.

It's this sixth sense that sharks have.

GALLAGHER: Weather plays a huge role in what sharks do.

We know that the weather can profoundly shape

the habitat use of sharks.

We know from other studies that big storms like hurricanes

can actually push sharks outside of the area

for temporary periods of time.

NARRATOR: A tropical hurricane can kill anything in its way.

To survive, sharks in this part of the Bermuda Triangle

must be ready to take refuge in deeper, undisturbed waters.

Each year, massive hurricanes brewing in the Atlantic

tear through the Triangle.

A hurricane's driving winds and towering waves churn the ocean,

mixing water temperatures and salinity into currents

that reach up to 300 feet below the surface.

GALLAGHER: It can be bright, sunny, clear skies one minute

and the next you could be caught in a squall

with torrential downpour and even lightning,

but you never know what you're gonna get,

and it kind of adds an element of sort of surprise

and a little bit of danger to the work as well,

because we're out here in the elements.

NARRATOR: For Dr. Gallagher and his team,

the skies remain clear.

They continue to monitor their drum line in search of Mabel.

GALLAGHER: We know she's in the area pretty close,

so now what we're doing is we're actually trying

to get some bait in the water now.

The boys are getting the stuff out there,

so we can maximize our chance of trying to recapture her,

start learning more about what she's doing.

MAN: That's a big one.

Big tiger!

GALLAGHER: Okay, guys, let's get into gear here.

NARRATOR: And soon, another shark takes the bait.

GALLAGHER: A little bit of slack, a little bit of slack.

MAN: A little bit of slack on that, okay?

GALLAGHER: That's it, that's it.

MAN: That's good, that's good, that's good, that's great.

This is amazing.

NARRATOR: This time it is Mabel.

GALLAGHER: Okay, wow, we got Mabel here.

NARRATOR: Dr. Austin Gallagher is exploring

one of the Bermuda Triangle's many mysteries.

The unknown shark behavior near its deep trenches.

GALLAGHER: Beautiful shark.

We're just gonna see how big she is,

it's been a while since we've seen her.

Okay.

Alright, guys, lean back a little bit.

MAN: Hold on, hold on.

GALLAGHER: We're gonna hook her up with some new jewelry,

and this means new cutting-edge tags.

We have camera tags and a new type of satellite tag

that we'd love to put on Mabel.

NARRATOR: Straining to keep Mabel still,

Dr. Gallagher removes the old tags,

replacing them with satellite transmitters

that will record her depths, temperatures and locations.

MAN: Let me work the leader and just hold the dorsal fin, okay?

NARRATOR: He's also attached a camera tag.

GALLAGHER: It's gonna go deep quick.

Mabel looked amazing.

Got a new tag on her.

What an amazing moment.

NARRATOR: The camera will film Mabel's journeys for 24 hours.

It will then pop off, float to the surface,

and send a location ping for retrieval.

GALLAGHER: Now that our technologies are allowing us

to go deeper and farther than ever before,

we're seeing new species, new behaviors and new things

that are wonderful and really inspiring.

Guys, that was awesome.

MAN: That was insane.

(laughs)

NARRATOR: Dr. Gallagher has no idea how deep Mabel may dive.

In the trenches, sunlight is only visible

in the euphotic zone,

up to 650 feet below the ocean's surface.

Beyond that, in the dysphotic zone,

only a small amount of sunlight reaches beyond 650 feet.

Any life-form this deep must be equipped to hunt or breed

with little visibility.

GALLAGHER: Some species of deep-sea sharks

do have really advanced vision.

Tiger sharks also have a specialized ocular structure

that allows them to detect shadows and silhouettes

a little bit better than other species.

The Tongue of the Ocean probably has

some of these deep-sea-dwelling animals,

such as other small sharks, squid, crustaceans,

and maybe even marine mammals.

These slow-moving animals in the deep sea

could provide an attractive and cheaper food source

for these sharks to exploit.

NARRATOR: In the trenches, not all sharks are apex predators.

Some are just as likely to be prey.

One shark, unique to the region,

is well protected by its own dental suit of armor.

The Caribbean roughshark is named for its course skin.

As with all sharks,

the rough shark is covered with dermal denticles;

small, tooth-like projections, coated in enamel.

These denticles protect

the nearly two-foot shark from predators.

It lives deep in the Bahamas' upper continental slopes

where, like most fish,

it is both predator and potentially prey.

♪ ♪

Back on the research ship, it's been 24 hours.

Dr. Gallagher and his crew get the signal.

Mabel's camera is ready to retrieve.

GALLAGHER: One of our team members actually went out

this morning and recollected the camera tag

that popped off Mabel.

And we actually have this information

on this hard drive right here.

We're gonna plug it in and see what this shark's been up to

for the last day or so.

These camera tags are just amazing.

They can tell us so much about how the shark is using

its environment, where it's swimming, how it's moving.

It is a little risky, though,

because you have to go out and recover this tag,

so when we get this data,

it's just so valuable, it's like Christmas morning.

So can't wait to open up this file

and see what Mabel's been up to.

NARRATOR: Dr. Gallagher wants to know

if Mabel is returning to the nearby trenches and why.

GALLAGHER: So it looks like the camera tag was turned on

just as we released her, which is great.

You can actually see her swimming down

right into the sea grass,

right off the south side of Rose Island.

Yep, she's swimming pretty slow.

Tiger sharks are actually known to be pretty lazy.

And here we have just a day in the life

of a mature female tiger shark in the Bahamas.

When I fast forward the clip to about two, three hours later,

I can see that she's in a completely different habitat.

Uh, she's in the blue now.

She's in the open ocean

and she's starting to swim a little faster.

You see that her gills are opening and closing

as the water comes through.

That's actually pretty cool

that we can see our handprint on her head there.

Tiger sharks actually have a small slime layer on their skin

that protects them from infection.

NARRATOR: As Mabel dives deeper,

the image looks otherworldly.

GALLAGHER: There are very few things that motivate

a 12-foot female tiger shark,

and it really just comes down to food and mating.

Last time we saw Mabel, she went completely AWOL.

We barely heard from her, and it looked like she was spending

a lot of her time in the open ocean areas,

just north of Rose Island, where it drops off really deep.

This video already suggests that this is what is truly happening.

Our depth sensor is telling us that she's at about 100 meters

right now, which is already at 300 feet.

She's starting to slow her tail beat frequency.

This is really cool.

When tiger sharks go down,

they stop swimming, so they can actually just sink.

It's an energy conservation strategy,

and if Mabel's going to be going down to deep waters

to potentially interact with other sharks,

she needs to save up as much energy as possible.

It's definitely some of the coolest data I've ever got.

I have goose bumps right now, just looking at this.

Pfff, wow.

I can't believe what I'm seeing.

Mabel is opening and closing her mouth, and this is a social cue.

Mabel is calling for a mate right now at about 400 feet.

Our infrared camera is starting to kick in.

Okay, so now she's really going into complete darkness.

-(clunk) -Whoa!

NARRATOR: Then he sees it.

GALLAGHER: Wow, okay.

(clunk)

So, Mabel just got hit.

NARRATOR: Something no one has ever seen before.

GALLAGHER: I'm just gonna pause it and go back.

This is amazing.

So there's a lot of ideas kind of flowing through my head

right now, what this could be.

(clunk)

GALLAGHER: I think Mabel is calling for a mate right now,

at about 400 feet.

NARRATOR: After an intense search for Mabel,

a tiger shark living in the Bermuda Triangle,

Dr. Austin Gallagher has finally tagged her

and retrieved the video from her 24-hour camera.

As far as Dr. Gallagher knows, this is the first time

anyone has captured tiger shark behavior

in the trenches of the Bermuda Triangle.

GALLAGHER: This is the coolest data

that I have ever collected in my career.

People have been putting camera tags on sharks and animals

for many years now, but I don't think they have ever seen

anything as cool as this.

NARRATOR: For Dr. Gallagher,

the footage is nothing short of extraordinary.

GALLAGHER: Okay, wow. So Mabel is doing a deep dive now.

You can see that she's going just down along the edge.

And our depth sensor is now reading about 800 feet,

so this is crazy.

I can't believe this.

It looks like I am seeing the surface of a foreign planet.

These are deep water habitats that humans can't go to.

Our infrared camera is starting to kick in.

Okay, so now she's really going into complete darkness.

So I think she was signaling to a male previously,

and now she's at 1,000 feet.

This type of footage has never been documented before.

-(clunk) -Whoa!

So, Mabel just got hit.

NARRATOR: And then, something incredible happens.

GALLAGHER: I'm just gonna pause it and go back.

Something just moved Mabel

and pushed her over to the entire side.

I'm actually seeing the camera tag move as well,

slightly, kind of in response.

Okay, it just happened again, like a whiplash.

(clunk)

And again.

So Mabel just got hit three times from the left side, hard.

It looks like it moved her about 3 feet to the right.

This is amazing.

So there's a lot of ideas kind of flowing through my head

right now, what this could be.

I think that she just got hit by that male.

I think she is experiencing a mating attempt right now,

from a male.

Yeah, this is conclusive.

There's nothing else down in the deep trench here

that could be moving a large tiger shark like Mabel.

This is just insane.

I think we've discovered something

truly groundbreaking here.

We may have just made a quantum leap in our understanding

of shark biology, just from this video.

PAPASTAMATIOU: No one has ever seen tiger sharks

actually mating in the wild.

GALLAGHER: I think that Mabel's data

and that from her relatives, suggests that we have found

a conclusive mating area for sharks,

here in the Tongue of the Ocean in the Bahamas.

NARRATOR: If Mabel is any indication of her species,

the oceanic trenches of the Atlantic

may be the tiger sharks' preferred mating location.

PAPASTAMATIOU: The reason it's important is that

for wide-ranging animals like tiger sharks,

it's gonna be impossible to protect all the waters

that a tiger shark will move through.

Instead, what we can try to do is protect areas

that are really important

to the sort of life history of that species.

ROMEIRO: Finding the tiger sharks' mating grounds,

or the tiger sharks' birthing sites,

are like finding the holy grail within the science community.

If we know where these areas are,

we can better protect these areas

and thus protect these animals.

NARRATOR: Although Dr. Gallagher's research

will continue,

this footage appears to reveal something remarkable.

The Triangle's deep trenches

may be a hot spot for tiger shark mating.

GALLAGHER: Some of the wildest and strongest animals

on our planet really do prefer to be found

in some of these crazy spots.

So it's not really that surprising to me

that the largest predator in tropical waters

really loves its home in the Bermuda Triangle.

NARRATOR: With breakthrough footage like this,

scientists like Dr. Austin Gallagher

are shedding new light on the secretive lives of...

Sharks of the Bermuda Triangle.

Captioned by Side Door Media Services