>> NARRATOR:
At up to 40 feet long

and weighing several tons,

they are one of the most
spectacular sights in the sea.

>> There are 28,000
species of fish.

About 400 of them
we call sharks,

and the largest of those
is the whale shark.

It's the largest of all fish.

An average whale shark
is twice the size

of the largest
great white shark.

So you're really talking
about an animal

that is a leap and bound bigger
than its next biggest relative.

Whale sharks are
found everywhere

in the tropical oceans.

So you'll find them
in the Pacific Ocean,

the Indian Ocean,
and the Atlantic Ocean,

anywhere where it's warm enough,
which pretty much means anywhere

where it's over
about 72 degrees Fahrenheit.

>> NARRATOR: While they may
be the largest fish in the sea,

the animals are gentle giants.

>> These are sharks that feed

by filtering tiny food items
out of the ocean

rather than having huge teeth
and biting things.

They're a very large animal
that's feeding very low

on the food web.

It's pretty much the same way
the great whales feed.

They're fairly indifferent
to the presence of people

and they really present
no harm to us at all.

>> It's amazing to be
in the water

with an animal three
or four times your size,

watching the majestic movement,
the power.

At the same time,
they are so tame,

so gentle, so fearless.

It's a fantastic thing.

>> NARRATOR: Named for their
size and feeding habits,

the animals are capable
of making vast migrations.

Yet despite their enormous size,
little is known

about whale sharks.

>> We don't really know
what role they're filling

in the ecosystem.

So we're asking
simple questions like,

how many whale sharks are there
and where do they come from,

and where do they go?

>> NARRATOR:
Whale sharks are thought

to be solitary animals
most of the year,

but during certain seasons
they gather in large numbers

in different places
around the globe,

including off the Yucatan
Peninsula in Mexico.

>> This is the
largest aggregation

of whale sharks in the world,

and it's happening
a stone's throw

from one of the biggest
tourist destinations

in the Caribbean.

It really is one
of nature's wonders.

>> Major funding for this
program was provided

by the Batchelor Foundation,

encouraging people
to preserve and protect

America's underwater resources.

And by Divers Direct,
Emocean Club,

inspiring the pursuit
of tropical adventures

and scuba diving.

>> NARRATOR:
Cancun, Mexico,

is one of the most popular
tourist destinations

in the Caribbean,

attracting millions
of visitors each year.

But just offshore from the miles
of hotels and hustle and bustle

lies a fragile yet highly
productive ocean ecosystem.

Each summer, the region is home
to the largest known aggregation

of whale sharks in the world.

>> About 20 years ago,
we thought

that whale sharks were
solitary off-shore animals.

And then they started
to discover

that in certain places
in the world

there are places quite close
to the shore

where whale sharks actually
gather in large numbers.

And we discovered that one of
those places is Yucatan, Mexico.

And in two places at least
here in Yucatan, Mexico--

near Isla Holbox,
and here near Isla Contoy--

there are places where dozens,
sometimes hundreds

of whale sharks gather
in the same place.

The reason whale sharks come
here is to feed.

And when they come
to Isla Holbox

on the northern side
of the Yucatan,

they mostly come
to feed on zooplankton,

but when they come to the
Caribbean side of the Yucatan,

they're here to feed
on fish eggs.

And they feed on fish eggs
and nothing but fish eggs

all day, every day
for at least four months.

It's the most amazing biological
aggregation I've ever seen.

They tend to be sub-adults,

so these are not
fully grown whale sharks.

They're in the high 20s
to the low 30s of feet.

And they tend to be
overwhelmingly male,

which is interesting,
because if you go

to the offshore locations where
the really big animals are,

most of those animals
are female.

So there seems to be some sort
of segregation

in the ocean where juveniles
and males go to one place

and adults and females go
to a different place.

We don't really know
why this is.

>> NARRATOR:
While the animals can dive

to at least a mile deep,
they tend to feed

at or near the surface.

>> We're pretty sure
that whale sharks fall

into that feast
or famine feeding mode where,

when conditions are good
as they are here in Mexico,

they can eat nonstop
for four months.

But then when they leave,
they can go a really long time

before they have the need
to eat again.

And that's how their life goes.

They go from buffet
to buffet, but they've got

to run a marathon in between.

>> NARRATOR: Watching dozens
of whale sharks

vacuuming up plankton
is a spectacular sight.

>> You sail
into this ocean of fins.

It's quite extraordinary
to see the size,

and it never gets old.

It's like being a kid.

You're just very excited about
seeing these animals.

>> NARRATOR: This aggregation
first caught the attention

of scientists in 2003, when
locals started taking tourists

to see the animals.

>> The tourist operations
started when fisheries deplete.

And we figured out that there
was so few knowledge

about the whale sharks.

Our research was
developed in order

to gather enough information
to manage the tour operation.

>> NARRATOR: The Mexican
National Commission

for Protected Areas
formed Project Domino

with U.S. collaborators

to better understand
the animals' movements

and devise
conservation measures.

To ensure responsible
whale shark interactions,

local authorities
also worked closely

with researchers
and other stakeholders

to develop guidelines
for tour operators.

>> There are about 19 different
guidelines.

It is mostly to be respectful
with the sea life.

>> Based on the
research findings,

the government created
a whale shark biosphere reserve

in 2009 to protect the animals.

But experts quickly discovered

that the whale sharks
also aggregated outside

of the boundaries
of the reserve.

>> That demonstrates
that animals do not care

about borders.

>> NARRATOR: In the meantime,

popularity of the tourist whale
shark encounters took off.

>> In 2003, there were
about ten boats only.

By 2004, there
were 50 boats allowed.

Nowadays we have more than 250.

>> Ecotourism is definitely
a two-edged sword.

It's a tremendous
opportunity for people

to connect with nature.

And we absolutely want
to encourage that.

But we've got to do it in a way
that is going to be safe

for the people and safe
for the animals.

>> This is no longer ecotourism.

It's massive tourism.

If you can imagine
over 100 boats

at the same time
on this small area.

All the fumes, the possibility
of leaking oils

and things like that,
could be a disaster.

>> When you have that many boats
and that many animals

all in the same place,
it's pretty much inevitable

that at some point, propeller
is going to meet flesh.

And we see a significant portion
of the animals show signs

of recent interactions
with boats.

>> We lack a lot of enforcement.

It's supposed to be
surveillance every single day,

but to be honest,
in the last three years,

we've been having the visit
of the surveillance people

for no longer than three days
in the whole season.

>> It really falls back on the
eco-tour operators themselves

to be self-regulating,
and as we know from banking

and other sectors of society,
if you rely on people

to regulate themselves,
it doesn't always go

as well as it could.

>> NARRATOR: Rafael says that
while most tour operators

are trying to be conscientious,

they are facing
a tremendous amount

of pressure
from ticket agencies,

which guarantee guests
animal encounters

or they get their money back.

>> That, in my opinion,
is something

that should never
have existed at all

because that is putting
a lot of pressure

on the animals.

The ideal thing should be
to establish a max number

of boats to interact per day
in the area.

>> It really does need a
disinterested third party

to come in and say, okay,
too many boats.

We need to limit entry,
we need to limit the number

of people, we need
to increase the costs

of doing this
because the market forces

have made it so cheap that
margins are so razor thin

that the whole system is
really running on a knife edge.

>> NARRATOR: To better
understand the animals

and make conservation
recommendations,

the Georgia Aquarium
has teamed up

with Rafael de la Parra
and others

to form a non-governmental
organization.

>> We call that blue realm
orCh'ooj ajauil

which means "blue realm"
in Mayan.

<font color = #FFFFFF><i>Reino azulin Spanish.</i></font>

What we're trying to do is
take a broader approach

than just whale sharks and look

at protecting
the whole marine region

because we recognize that the
whale sharks are a reflection

of a much bigger picture,

which is this extraordinarily
productive ecosystem

that they have here.

>> NARRATOR: Despite the fact
that tourists are coming

to see the animals in droves,
still relatively little is known

about these charismatic giants
nicknamed "dominos"

by the locals because of their
polka-dotted skin pattern.

One way to get a good estimate
of how many animals

are in the area is
to count them from the air.

>> Okey dokey, here we are.

Look, a bunch
of them right here.

Lots of them.

Woo-hoo!

Many, many, many, wow!

On the aerial survey
that we are conducting

hopefully once a week
for the whole five months

that the season lasts,
trying to locate them

and to count them.

So far in 2009 was the
largest aggregation ever.

And we counted up
to 420 whale sharks

in a single spot.

Today, we count up to 170.

>> Little one.

>> NARRATOR: Another way
to study the animals

and track their movements is
to satellite-tag them.

>> A lot of what
we're doing here

involves deploying
different types of tags

that will tell us about
what whale sharks are doing

when nobody's watching.

We have what we call
archival tags.

Those are tags that record data

about what the whale
shark is doing.

They save it inside
the tag and then

at some predetermined time
the tag is programmed

to release itself
from the whale shark,

float to the surface, and begin
to report its treasure trove

of data via satellite back
to the researcher.

We also have real-time tags.

Those focus on telling you
where the animal is right now.

And those are tags
that are towed along

behind the animal,
floating at the surface.

And they report to us
via the same GPS system

that your car uses.

And so those are able to tell us
at any given moment

where the whale sharks
are going.

One of the things I'm
really excited about this year

is that I'm connecting those
real-time tags to social media.

So this year our
whale sharks are going

to be tweeting their locations
in real time by Twitter.

And that's a really
fun piece of science

that's going to allow kids
and the public

to follow along
with science as it happens.

>> NARRATOR: In addition to
recording the animal's location,

the tags also collect
temperature data

and depth profiles.

>> Attaching tags of any kind
to whale sharks

is the biggest challenge.

We struggle with getting
them to stay on.

Whale sharks are very fast
and very large.

They have the thickest skin
in the animal kingdom.

So getting a tag into
their skin and getting it

to stay there
for months turns out

to be much harder
than you think.

>> NARRATOR: Through the use
of satellite tags,

experts have been able to figure
out a general migration pattern

for the animals.

>> There are other places
in the Caribbean

where you can see
whale sharks all year--

in Honduras, for example,
around Utila.

Other places like Belize
you see them mostly

in the springtime, and then
in the Gulf of Mexico,

mostly in the summertime
and into the fall.

And this reflects a rough
migration pattern

where they migrate
up the coast of Mesoamerica

and then into the Gulf of Mexico
where they do a big loop

over the course
of the summertime.

>> NARRATOR:
But as with anything,

there are always exceptions
to the rule.

>> There's a famous whale shark
called Rio Lady

who was tagged by Bob Hueter
from Mote Marine Laboratory.

And Rio Lady was tagged here
at the offshore location

and she went off
to the South Atlantic.

She didn't go into the Gulf
of Mexico at all.

In fact, she went the exact
opposite direction.

She went right across
the Caribbean

and out into the islands
in the South Atlantic.

Her tag came off not far
from a place

called St. Peter
and St. Paul Rocks,

which is right on the equator

about 800 miles
off the coast of Brazil.

And so her total migration path
was over 4,000 miles.

>> NARRATOR: Since then,
Rio Lady has returned

to the aggregation site
in Mexico

where scientists were able
to put a new tag on her.

>> So we'll see if she goes back
to that offshore location.

Why does she go there?

Why does she do something
different from all the others?

We think she's
a big pregnant female

and we suspect that
she probably was going

to that offshore location

for pupping or some other part
of the reproductive cycle.

Reproduction is probably
the biggest black hole

in our knowledge
about whale sharks.

Nobody's ever seen them mating,

nobody's ever seen
them giving birth.

People have found, occasionally,
newborn whale sharks

in the size of sort of one
to two feet in length.

And we do know that they give
birth to live offspring

and that females can have
as many as 300 babies

in their uterus at once.

>> NARRATOR:
During whale shark season,

Rafael and his wife spend
three or four days a week

studying the whale sharks
from the air or in the water.

In addition
to tagging the animals,

scientists also take photos
to identify

and track the whale sharks.

>> You have to jump
and chase the animal

and be perfectly perpendicular,
and take the photograph

right behind the fifth gill,
on top of the pectoral,

and catching as much
as possible the dorsal part

of the animal.

>> And if you can get that photo

and mark some spots on it,
and upload it to this website,

there is a
computerized algorithm

that then compares that photo
with every other photograph

in the database.

And there are whale sharks
from all over the world

in this data set.

And it returns a list
of potential matches,

and then you can look
at them visually

to confirm whether
in fact you're looking

at the same animal or not.

Using this process, we've now
got over 1,000 animals

in the whale shark aggregation
from our site in Mexico.

>> We have some animals here

that now have ten-year
visitation histories or more.

And these animals stop
becoming numbers

and start becoming
old friends for us.

>> NARRATOR: One big concern
the scientists have

is boat collisions
with the animals.

>> When they are feeding
on surface,

they are vulnerable
to boat collisions

or propeller damage.

And in this area,
besides the tourist operation,

we have a lot of traffic.

We have at least three
to four times a week,

a couple times per day,

big cargo ships passing right
where the whale sharks

are aggregating.

>> NARRATOR: To avoid
potential disaster,

the scientists want
to collect data

on the ship traffic
occurring in the area.

Vessels over 300 gross
tons are required to use

what is called "the Automatic
Identification System."

>> And what the Automatic
Identification System is,

or AIS, is a method
for tracking vessels at sea.

So we're able to see
where they go,

what they carry,
how large they are,

and learn about the
various characteristics

of vessel traffic by collecting
and archiving AIS data.

If you look at this map,
you'll see there really isn't

a whole lot of ship coverage.

There's a little bit right
here between Cozumel,

Playa del Carmen for monitoring
ferry traffic,

but there really isn't any
coverage further north.

And so what we're
going to do is

install an AIS receiver
just north here

and we're going
to be able to cover

where the whale shark
aggregation is

and start to characterize
where whale sharks

and ship traffic
happen together.

>> NARRATOR:
To install the receiver,

the experts head
to Isla Contoy...

a small island located
where the Gulf of Mexico

and Caribbean meet.

>> We're looking
for the highest point

for miles around so
that we can cover

as much of the ocean
with the AIS as we can,

and this tower behind me is it.

All righty.

>> After a lot of hard work,
the lights are blinking.

We've got power, the solar
panels are charging the battery,

the antennas are up.

Everything's working,
which is great.

We're going to want to
at least archive vessel traffic

for a year, look at seasonal
changes and things like that.

We'll look at the sightings
of whale sharks

that people have
collected over years

and we'll combine those
sightings and look

at where ship traffic intersects
with those sightings.

And then what
we'll be able to do is,

do some statistics
to look at the risk

of collisions between feeding
whale sharks and ships.

When we see what the risk
of collisions is like,

we can make recommendations

to slightly tweak
the shipping lanes

around aggregations
of whale sharks.

And that's really going
to help us work

with the maritime industry
to say,

"Hey, of course you guys have
rights to these waters as well,

"but if you could just move
your shipping lane a mile

"to the east, you're going
to reduce the chances

of hitting whale sharks
by so many percent."

That kind of informed
decision making, I think,

is the best way
to work together.

It's been done with whales,
particularly in the U.S.

with the North Atlantic
right whale,

where they've shifted traffic
lanes just ever so slightly

to reduce the risk of collision
with these right whales.

And what that's done is,
just a few degrees shift

in the shipping lane
has resulted

in more than 50% reduction
in risk

to collision with right whales

and a more than 80% reduction
in risk

from collision with other
large baleen whales.

>> We really get
great satisfaction

from taking the science
and turning it

into effective
conservation outcomes.

>> NARRATOR:
In addition to using

traditional satellite tags,
Jake is also experimenting

with a new tag design that he's
putting together himself.

He assembles the tag
in his hotel room

before the team heads
out on the water.

>> What this is doing
is recording pitch,

roll and heading,
as well as depth.

So every time the animal
changes direction,

changes depth
and changes orientation

in the water, we're able
to measure that.

And this is recording
100 times a second.

It's sort of like we are able
to ride along

with the animal and see
what it's doing underwater.

We need to recover these tags to
get the information off them.

Because these tags
are recording data

at such a fine scale,
and because it's all that data,

it's not possible to transmit
over satellite.

>> NARRATOR: The scientists put
one of these behavioral tags

on a shark they nicknamed
Señora Elastica.

For the next three days,
they hope to see her again

at the aggregation site
to recover the tag.

>> We thought she had gone,
we thought we had lost her.

And then Jake went out
to take some photos one day,

just really for recreation,
and from the deep,

underneath him, Señora Elastica
rose from the blue

and he was able to reach down
and pluck the tag off,

and now we have a hundred hours
in the life of a whale shark,

which is really an
extraordinary data set

that nobody's had before.

>> NARRATOR:
Once the team returned

to the Georgia Aquarium
in Atlanta,

they began to look
at the data in the lab.

>> And it is so much fun,
I have to tell you.

The way that you can
reconstruct her movements

in three dimensions,
you can see every tail beat,

you can see every dive
and every feeding behavior.

And that's really,
really exciting.

We've covered several night
times, several daytimes,

some surface behavior,
some bottom behavior.

It really is
extraordinary detail

that we've never had before
about what whale sharks do.

One of the things that it
really revealed to us is

how much time they spend
going up and down.

We thought a lot of the time,
they were either

at the surface or at the bottom,
but as we look

at the data in more detail,

we see that they're pretty much
constantly going up and down.

We really were surprised

exactly how much of their time
they spend in transit.

We're probably underestimating
how many whale sharks

there are out there
because we base that

on a surface assessment.

You look around, you say, "Oh,
there's about 150 animals here."

But if there's an additional
30% to 40%

that are on the bottom
at that moment,

and they're going
to swap with other animals

that are currently
at the surface,

then you're probably
underestimating

exactly how many whale sharks
there are in your aggregation.

That's probably a good thing.

We'd like to know there are
more animals out there,

but it's the sort of information
that we wouldn't have had

before this kind
of tagging technology.

So it's very exciting for us
for the first time

to be able to see
what whale sharks do

in their spare time.

>> NARRATOR: The Georgia
Aquarium is the only facility

outside of Asia that has
whale sharks on display.

>> We have four animals
in the aquarium,

two males and two females.

They came from Taiwan.

So those are Pacific animals,
not Atlantic animals.

>> NARRATOR: The aquarium's
research staff

not only conducts research
in the field,

but has also teamed up
with Emory University

to sequence the genome
of whale sharks

using tissue
samples collected

from captive animals.

>> We take the DNA
and we work in the lab

to create what's
called a sequencing library,

which is a sort
of form of the DNA

that can be sequenced
by the instrument.

Then what the instrument
effectively does is,

it converts the chemical
information to data.

And then, really, the bulk
of the work involves

putting the data together.

>> Whale sharks have so many,
like, unique features.

And the genome side is so big.

So if we decipher the genome
of this whale shark,

then definitely
we will be able to know

why the whale shark is so big

and why whale shark has some
very unique feeding mechanisms,

and how the whale shark species

is related to other
shark species.

>> The other reason the
genome is interesting

is that sharks were the first
group of vertebrates

to evolve an adaptive
immune system.

So they're the first vertebrates

to have specific antibodies
in their blood

to particular diseases.

And so if we want to know

about where our own immune
systems came from,

looking in the tissue
and DNA of sharks

is a great place to start.

>> We can also use
the DNA as a way

to develop tests
so that we can understand

how diverse whale shark
populations are.

>> So far, we think that whale
sharks are all one species,

but to be kind of frank, I
don't really believe that.

I believe we probably haven't
looked hard enough

at their genes yet.

>> NARRATOR: The scientists hope
to compare tissue samples

collected from
the captive animals

to those of other areas,
to determine whether or not

there are
distinct sub-populations.

>> That's a big shark!

>> As we probe further into
their genetic sequence,

I expect that we'll
find differences

between Atlantic whale sharks
and Indo-Pacific whale sharks

because it's very unlikely
that whale sharks are going

around the bottom
of South America.

It's just too cold
for them down there.

>> NARRATOR: The oceans are
still full of mysteries.

Whale sharks may be the biggest
fish in the sea,

but so far we only
know very little

about these gentle giants.

>> I love being offshore
with the animals,

and those days when it's really
hot and really still,

and all you can hear
is the swishing

of tails and dorsal fins
through the water.

And I like to think
about the fact

that this species has been
on the planet

for 70 million years.

So back in the days
when it was dinosaurs

and not tourists that
were roaming the Yucatan,

whale sharks were already here.

They were already probably
doing exactly

what we're seeing
them do right now.

I always come back
from the field

with renewed energy for science
and renewed energy

for trying to understand the
biology that's all around us.

Anyone who tells you
that there isn't great stuff

yet to be discovered
in the oceans

hasn't stuck their head
underwater lately,

because there's still plenty
of cool stuff to see.