Galapagos: Realm of Giant Sharks

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Narrator:
A remote island

in the Pacific Ocean.

A place forgotten by time.

Here, in one of the last great

ocean sanctuaries,

a mysterious parade

of giant sharks passes.

Most are pregnant females

about to give birth.

What has drawn them here?

And where are they going?

Researchers have come

to the Galapagos Island

chain to track these

Dinosaurs of the sea.

To follow them wherever

they travel across the globe.

On a journey of discovery

to the Galapagos.

REALM OF GIANT SHARKS

Jutting out from the sea,

at the far northern end of

the Galapagos archipelago,

is an ancient, crumbling volcano called

Darwin Island.

And just to its south,

a magnificent natural arch.

A group of scientists, working under the

auspices of the Galapagos National Park,

has just arrived.

In the swirling currents below,

something else is slowly approaching.

It's a whale shark, the largest fish

ever to have lived.

It's part of a steady stream of giant

sharks that passes by Darwin Island.

This team is hoping to find out

what draws them

to this tiny stretch of ocean,

and where are they going.

They wait on a rocky reef.

Finally,

a massive silhouette appears.

At about twelve meters in length,

this female is almost fully grown.

The team rises up to meet her.

They'll attach satellite

tracking devices

anchoring them in the

thick skin on her back.

In his log, team leader, Jonathan Green,

describes the encounter.

Jonathan Green:
The shark had

barely flinched.

So at this point, I swim

down towards her head.

Once in front, I turn and

let the current carry me

the full length of her

body, past the tail.

Her colossal size is apparent

as her body slides by.

The whale shark continues

placidly on her way,

seemingly unaware of the

procedures going on around her.

Narrator:
Whenever she

breaks the surface,

her tags will relay her location

via satellite to the scientists.

Ranger, as this whale shark is called,

is now part of one of the most

ambitious studies of marine

animal migration ever undertaken.

For several weeks, she stayed just

north of the Galapagos Islands.

Then she headed south and

east to the coast of Peru.

Over one thousand kilometers away.

Ranger's is not the only incredible

journey documented by this team.

Take the case of Jaws,

another mature female.

With tag in place,

Jaws headed north and west

out into the rugged undersea terrain

of the Galapagos Rift Zone.

She appeared to be going out to sea.

Instead, she turned around and made her

way back to the Galapagos Islands.

Like Ranger, she too went south to

the coast of Peru.

Then there's Kimberly, a mere teenager

at 5 meters in length.

She arrived at Darwin Island with

Jaws and followed her to the west.

Kimberley split off, veering

to the south.

Her route took her to another rugged

zone known as the East Pacific Rise.

Along the way,

Kimberly zig-zagged through the ocean

in a pattern probably

associated with feeding.

At a point 3500 kilometers

away from Darwin Island

the transmissions showed

that her tag had detached

and was floating on the surface.

Another creature could

have bitten it off.

She may have removed it herself

by rubbing up against rocks.

Or she might have caught

by fishermen who discarded it.

Where were these sharks headed?

Were they following familiar routes?

Or possibly shifts in

water temperatures,

or the availability of food?

These are questions that captured

the imagination of Jonathan Green,

a naturalist and photographer

who has worked in the Galapagos

for over two decades.

Jonathan Green:

For me, one of the main

interests that held

me here is as a child,

I was very, very interested

in dinosaurs, and

this is a real life

Jurassic Park situation,

because we've got a 60, 70 million year

old animal, in terms of the species.

Sharks have been around for

perhaps 300 million years.

So they're definitely members

of the dinosaur era.

They roam around our

earth today, around the

planet, and we know absolutely

nothing about them.

How can it be that we know more

about mice or about the ant

than we do about a whale shark?

Narrator:
Whale sharks belong to

an ancient class of fish whose

bones are made of cartilage,

and to a subclass that includes

sharks and rays, the Elasmobranchs.

Of at least 500 species alive today,

the ground sharks are most common,

including hammerheads and

the classic reef sharks.

Whale sharks belong to a relatively

small group, called the carpet sharks.

They are known for the particular

arrangement of their fins,

and for a distinctive

fold of skin near their

nostrils and just above their mouths.

These may be sensors, handed down by

ancestors that dwelled

on murky sea bottoms.

At full size, a whale shark can reach

18 meters in length and 30 tons.

Over a lifetime that can last 70 years,

these giants roam the oceans,

scooping up a diet of plankton,

krill, and small fish.

Struck by how little was known about

how whale sharks live,

Jonathan helped spearhead an effort

to get basic data.

He and other dive guides photographed

their unique identifying markings,

the pattern of spots

that line their bodies.

They submitted these 'fingerprints'

to an international database.

In time, Jonathan enlisted scientists

from the Galapagos National Park,

the Charles Darwin Foundation,

and the marine animal

tracking program at the

University of California at Davis,

in an ambitious project to study

the movements of whale sharks

that pass by Darwin Island.

Most attempts to track them

have begun in places

where they come together

in large numbers

like the Sea of Cortez, off

the Pacific Coast of Mexico.

Here, billions of tiny crustaceans

called Copepods hatch at once,

turning the sea a milky grey.

That draws dozens of whale

sharks to feed on them.

You can often see them

feeding vertically

to get at the dense food concentrations.

Their arrival is a welcome

sight for schools of small

fish, which use them as shields.

With a band of skip-jack

tuna nearby, a school

gets as close as it can

to the giant shark.

The predators keep their distance.

This is only one of many gathering

spots for whale sharks.

You can find them off

the coast of Belize,

where they feed on the eggs of snapper

fish that spawn here in spring.

Or, you can find them off

the coast of Western Australia,

where coral spawn in massive numbers

just after the full moons

of March and April.

Alex Hearn:
Most of the studies that

have been done to date

have been focused on aggregation sites

where they come together to feed,

and those are mainly smaller

individuals, they're mainly males.

We have almost a unique

situation here, where we have

a large number of very

large, pregnant females.

Nothing is really known about

where they go to give birth,

how they mate, where they mate.

So there are a lot of questions that

still need to be answered out there.

Narrator:
The answers could

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