Galapagos: Realm of Giant Sharks Page #5

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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.

We find huge variations

in currents. Daily

you can have very low

current when you dive

first thing in the morning, 6:30 AM,

virtually no current.

By mid-day, you've got a howling

current going through.

What we've had here is not only

a complete change in direction,

but the strength seems to be

going up and down.

This morning when we jumped in,

we had something

probably around

a five-knot current, and that

simply becomes unworkable at that point.

Not only unworkable, but dangerous

because of the fact

that you've got divers

then that may be swept away from

the area that we're working in

and taken out into the

very rough ocean beyond.

Narrator:
The next day,

Jonathan is eager to know

whether the tags

they set are on securely.

Jonathan Green:
Do you have any data

on that, anything new?

Narrator:
He calls Alex Hearn, who

is monitoring the satellite signals

from the University of

California at Davis.

Jonathan Green:
Conditions that are not

too good. We've got a southerly current.

We put the two tags on, but we just

need to know if they're on the surface,

or if you have any data

that might show what

they're doing, if the

tags are still on, yeah.

Okay, you do. 1-0-7.

Okay, fantastic, fantastic.

Narrator:
One of the tagged sharks

has surfaced 40 kilometers North

and West of Darwin Island.

It's following the same route taken

by Jaws and Kimberley.

Are these sharks following the flow of

food driven by the Humboldt current,

or are they pursuing

some other imperative?

Consider their response to conditions

below Darwin's Arch.

As deep currents hit

the island, they carry

a flood of nutrients to the surface.

As a result, the rocky

reefs beneath the arch

are enveloped by

what one biologist called,

"a Great Wall of Mouths."

Everything from microscopic zoo-plankton

to schools of fish.

Moving through them are predators

such as sharks, and jacks,

along with those giant filter feeders,

the whale sharks.

And yet, even as they encounter

enormous schools

of small fish and dense plankton,

they keep their mouths shut tight.

There must be another reason

they are coming here.

Jonathan Green:
We know that they are

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