Galapagos: Realm of Giant Sharks Page #4

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Since then, Darwin and Wolf Islands

have become a Mecca for divers,

who come from all over the world

to take in the spectacle.

Hammerheads are among

the few sharks that must always

swim forward to force water

through their gills.

Facing into the current here during

the day offers them a period of rest.

The warm surface waters may

also aid their digestion.

While the sharks are here, they can

swing in close to the rocks,

where king angel fish come out

to clean them of parasites.

At times, larger ocean

creatures do return the favor.

A sea turtle draws the attention of

a school of pompano,

who prize its rough shell as a

kind of scraping stone.

After a day spent at the reef,

the hammerheads

peel off into the surrounding waters,

where they use their

acute senses to hunt.

How do they find

their way back to Darwin

through the featureless

and murky depths?

Sea turtles, along with some

migrating bird species and whales,

are thought to orient themselves

by reading the

alignment of Earth's magnetic field.

If sharks possess their own

navigational super-sense,

it's probably related

to sensory abilities

that have allowed them to thrive

all these millions of years.

The snouts of most sharks are

dotted with specialized organs

that pick up electrical

impulses given off

by the heartbeats or

muscle action of prey.

Research shows that hammerheads

may use this electrical mastery

to read magnetic signals given off by

volcanic formations

that lead like roads,

up the sides of Darwin and and other

landmarks strewn about

the world's oceans.

Whale sharks may be reading

these same signals,

but that doesn't mean they

always arrive on cue.

Day Five.

The team spreads out on

the rocks to increase

the chances of spotting a whale shark.

With none in sight, they move out

into the blue and drift.

Toward the end of the

scheduled 40-minute dive,

a whale shark finally appears.

But it's about 40 meters down.

It will take considerable

effort to reach it,

and their air is already running low.

With few other sharks around,

Jonathan decides to take the risk.

Jonathan Green:
I see her,

deeper than where I am,

a few more kicks is all it will take.

The next few seconds are a blur.

I see her dorsal fin is bent over,

but still go for a fin shot.

Narrator:
The shot bounces off the

dense tissue at the base of the fin.

Jonathan signals a team

member to try another tag.

But there's just not enough time.

As the shark swims off into the deep,

they must rise up slowly

to expel the excess nitrogen that

builds up in divers' bodies at depth,

and can lead to a life-threatening

condition known as the bends.

But several divers, including Jonathan,

do not have enough air to safely

reach the surface.

Fortunately, teammates

are there to assist.

Day six. No whale sharks in sight.

To widen their search, the team tries

snorkeling out into the blue.

Jonathan Green:
Three dives punctuated

by a snorkle in deep water.

But there was nothing.

Swam with dolphins though, so the day

has not been without its moments.

Narrator:
Even a series of time-lapse

shots, taken throughout the day,

fails to turn up any whale sharks.

The current has now picked up speed.

The team struggles to

hold on to the reef.

The end of this expedition

is just days away.

Finally, on Day 8, with only three

more days of diving left,

there is a subtle shift in conditions

below the arch.

The south-bound current has slowed.

Jonathan Green:
Dropping

in we feel the change.

Galapagos sharks are hugging the rocks,

silkies patrolling the blue,

and yes, swimming gently along the wall,

a small, approximately

3.5 meter whale shark.

Narrator:
This one is too small to tag.

But it could be a sign that

the whale sharks are back.

By afternoon, the north-bound

current is surging.

Cesar Penaherrera, from the

Charles Darwin Foundation,

spots a large whale shark approaching

and signals the others.

Eduardo Espinosa, a scientist with

the Galapagos National Park,

and a seasoned shark tagger, is on it.

But the shark is racing away.

He struggles to catch up.

His shot is off.

The tag breaks off and is lost.

Another setback.

The sharks may be back,

but the cables that

hold the satellite tags keep breaking.

Later, on the Queen Mabel,

Moab Villagomez, a crew

member, suggests a type of

knot used by fishermen,

to secure the tags to

their steel cables.

Because some of the shots have not been

penetrating the whale shark's skin

they give the air guns

fifty percent more power.

Day nine.

In his log,

Jonathan notes that the trip

now hangs in the balance.

But that it may not be in his power

to tip it in their direction.

Hanging at twenty-five meters, I see a

dark form above and out to the blue,

then clearly the outline of a shark.

I head out to swim under

and then rise up on the left flank.

The shot will be easier from the right.

So exchanging sides, I move forward.

And the shot goes in just for and

to the right of the dorsal fin.

The harpoon slides back out

and the tag, 108-103, glides

off to an unknown destination.

This time, its the

beginning of the dive.

And Jonathan has enough air

to stay and take in the scene.

I crawl south, across the balcony.

And just lie there for about ten minutes

as the hammerheads just stream by.

Their silver and bronze sheen,

almost aglow in the midday light.

Like celestial bodies

floating in aquatic space.

Far too beautiful to

capture in mere words.

I wish I could exchange

my gun for my camera.

But instead, capture

the image in my mind.

Mine,

forever.

Its the final day of the expedition.

Eduardo Espinosa sees a shark

theyll come to know as Margarita.

Based on her size, twelve meters long,

Margarita is thirty to forty years old.

And a survivor,

judging by the circular bites or

propeller marks on her lower abdomen.

Later on,

Jonathan finds Margarita

still at the reef.

Identifying her by tag number.

Heres an opportunity

to get a closer look.

With the current sweeping him away,

he descends to the rocks below.

Shes barely moving against the current.

I drop back then use the

rocks to get ahead.

I float up, then pass below her,

checking her huge belly

for signs of birthing.

Nothing I can detect,

but then, this is hardly

my area of expertise.

If a newborn shark does

come in to the world,

several jacks are there,

ready to grab a meal.

The cool season is now

drawing to a close.

On land,

the turbulence of

mating season is overtaking

the colonies of marine iguanas.

The big males keep a watchful

eye on their harems.

And on the other sires

that may challenge them.

Out at sea, the water is getting warmer,

as the Humboldt current slows and

Equatorial currents push south.

This is the time when

Humpbacks and other whales

head back south to summer

feeding grounds off Antarctica.

With less prey in the

waters off Darwin Island,

jacks, tuna, and other

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