Galapagos: Realm of Giant Sharks Page #2

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bring crucial information

to the battle to preserve

these ancient creatures.

Whale sharks have long been hunted

on a small scale for their liver oil,

used as waterproofing for wooden boats.

Known as tofu sharks,

they are now targeted by

fishing fleets for their

characteristic white meat,

and for fins that can fetch

around $50,000 each.

Shark fin soup is a staple at weddings

and fancy dinners in China.

This custom is believed

to be responsible for

millions of sharks killed each year.

Whale shark fins are in demand,

not so much for soup,

as for bold displays

designed to lure shark fin

buyers into stores, or

customers into restaurants.

Whale sharks are now under

the protection of the

of the Convention on International Trade

of Endangered Species, or CITES,

and the Convention on Migratory Species.

There is a growing momentum

to safeguard them,

especially in countries where tourists

spend millions of dollars each year

to swim with these gentle giants.

The docile nature of

whale sharks is what

allows the Galapagos

team to approach them,

then to clip DNA samples from fins or

place satellite tracking tags

into their skin.

But if startled, a whale shark is

capable of moving swiftly out of reach.

At full size, a whale shark is powerful

and potentially dangerous.

If the approach is not just right,

or the tag inserted too deeply,

the response can be violent.

In the first of three expeditions to

Darwin Island, Jonathan

Green and his team

managed to tag 14 whale sharks.

To get reliable results, the team needs

at least twice that number.

So they are making the 30-hour

journey again on a small

but trusty expedition boat,

the Queen Mabel.

It's the heart of the cool season, and

the boat is carried along by north-bound

swells generated by a

current that flows from

Antarctica up the coast

of South America.

On his journey to the

Galapagos Islands, Charles

Darwin noted 'the

singularly low temperature

of the surrounding water, brought here

by the great southern Polar current.'

For thousands of humpback

and other whales,

it offers a free ride north from

summer feeding grounds off Antarctica.

The Humboldt current is thought to have

transported many of the unique creatures

that Darwin observed on these islands.

From the mainland, giant tortoises were

probably washed into the sea by storms.

The current carried them

across the thousand kilometers

of ocean to reach the Galapagos.

They gradually dispersed among the

islands, each one a world unto itself.

Down through the generations,

the tortoises adapted

to unique local conditions

and developed differences,

especially in their shells.

Iguanas most likely arrived

on rafts of vegetation.

Once here, they adapted to feeding

within intertidal zones.

It's in the sea that the Humboldt

current has had its greatest impact.

You can see its fertile wake in a

satellite image tracking chlorophyl,

a tracer for plankton blooms.

In combination with

west-bound trade winds,

it causes deep nutrient-rich water

to well up along the

South-American coast,

turning it into one of the world's

most productive fisheries.

Rising up onto the Galapagos plateau,

the Humboldt mixes with the cool

waters of the Cromwell Current,

surging in from the Pacific,

and with warmer currents moving

down from the equator.

That combination sets off an

explosion of sea life.

Manta rays arrive to

sift the upper levels

of the ocean for microscopic plankton.

When conditions are right,

sardines, anchovies,

mackerel and other bait

fish fill the seas.

That can attract

legions of striped marlin

from around the region and beyond.

Watching for a school to

be caught out in the open,

these swift predators

dart up from below.

The school closes ranks,

forming a bait ball.

Sea lions join the attack.

The school evades them by

twisting and turning as one.

But as fatigue finally sets in,

the predators move in to

pick off individuals.

Moving through these fertile waters,

riding the north-bound current,

a mysterious line of whale sharks is

headed for a tiny, remote outpost:

Darwin Island.

What draws them here?

That's the question this team

is hoping to answer

as they too arrive at Darwin island.

Jonathan Green:

The blue skies give way to low cloud

and the ocean reflects gunmetal grey.

The morning is spent

activating the satellite

tags, removing the old leaders,

and replacing them with shorter,

plastic-covered steel wire.

We then paint them with

an anti-fouling coat

and hang them to dry in the aft.

The guns are ready, lubricated

and cleaned.

Narrator:
Boarding a pair of

small boats, the team sets out

for the turbulent waters

of Darwin's arch.

Their strategy is simple:

Wait on the rocks.

If no whale sharks pass by,

they'll swim out into the current to

search for them in open water.

Jonathan Green:
After 30 minutes close

to the rocks, we head out to the blue

and almost immediately spot

a large female whale shark.

Clear markings, probably young, she is

pregnant and measures around 11 meters.

I am able to get alongside and shoot

the dart through the dorsal fin,

about 2/3 of the way,

close to the leading edge.

The dart goes all the way through about

15 centimeters of cartilage.

Narrator:
Then, the team witnesses

a scene that can only

deepen the mystery

of these giant sharks.

Another female suddenly appears.

It converges on the first,

then gives it a shove with its snout.

Was this a show of strength?

Or some other signal,

just between sharks?

Their two paths diverge into the deep.

The expedition is off to a great start,

at least, that's how it appeared

on its second day.

Jonathan Green:
The current remains

to the north, but is fluctuating.

Sea surface temperature still high,

25 degrees centigrade.

Big schools of hammerheads pass by,

out in the blue and down, deep below us.

We do a shallow dive before

lunch as skip-jack tuna

are feeding close to the anchorage.

Bright streams of quick silver weave

a complicated dance with sharks.

Late afternoon, we photograph

the sunset over Darwin,

and the light catches the spray

from the crashing breakers.

The Arch appears to capture

the last beams of sunlight,

like a magnifying glass,

concentrating them into a single

spotlight of white and gold.

Quite ethereal, but then, so is

the experience we are living.

Narrator:
Day three brings

an unexpected shift

in the currents that

swirl around Darwin.

The north-bound flow has

shifted to the south.

The hammerheads are now schooling

much closer to the reef.

The whale sharks seem to have

disappeared altogether.

Jonathan Green:
Conditions

are far from optimum,

as the current has swung

around 180 degrees.

Ending the dive with a drift,

we swim through a tornado of jacks,

and in less than three minutes,

are being sucked in behind the Arch.

Time to surface quickly,

before we get taken over

the platform and into

the maelstrom of crashing waves.

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