Next on Jonathan Bird's Blue World, Jonathan goes
into the ocean with the world's largest shark!
Hi, I'm Jonathan Bird and welcome to my world!
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I've journeyed to the warm and shallow waters of tiny Holbox Island
in the Gulf of Mexico to find and film the world's largest fish.
Holbox is barely more than a sandy spec on the map of Northern end of the Yucatan. It's
not your typical tourist destination. Until recently, this sleepy island wasn't much
more than a fishing village.
There are no paved roads, and everyone gets around in golf carts or other non-conventional
transportation.
The highway here is a stretch of beach where you can hit maybe 20 MPH if you have a fast
cart.
Downtown, this island has the charm of a place not yet discovered by throngs of tourists.
But everywhere there are signs. Something special has been discovered here.
Offshore in the cool waters of the Gulf of Mexico, a giant lurks!
I get up early to meet the boats to take me and the other intrepid snorkelers on the adventure
of a lifetime.
Right! Let's go find some whale sharks!
Instead of catching fish these former fishermen are now making their living taking tourist
to swim with the fish. A really big fish.
Using a GPS receiver to help him navigate, the captain takes us about an hour offshore.
Our guide Andreas watches the water with a carefully trained eye on the horizon.
Soon, we pass a pod of dolphins.
They circle the boat a few times to check us out, then vanish.
Then we come upon a group of Eagle Rays frolicking at the calm surface. I've never seen the
rays doing this before. I'm not even sure what they are up to, but after a few minutes
we have to move on.
We put boat back in gear and keep looking. A ripple up ahead catches Andreas's keen
eye. As we approach we find a giant Manta Ray feeding right at the surface mouth wide
open. Manta's can reach 20 feet across, but this is just a small one. Only about size
of car
Finally, Andres spots what we are looking for the huge head of a whale shark sticking
up out of water.
As we pull the boat up alongside the shark, I can see its massive mouth open and funneling
water in, like a gigantic storm drain. The shark is feeding. But what could it be eating?
It's more than 30 feet long. What could feed such an enormous animal?
To find out, I don my snorkel gear and hop over the side.
The whale shark passes right in front of me. The water is not very clear, and this is where
I get my first clue what is going on here.
The sharks have come to this section of the ocean because it is filled with plankton!
Whale sharks might be the biggest fish in the sea, but they eat only plankton and small
fish.
The word plankton comes from a Greek word meaning drifter, so plankton are drifting
organisms. Like these tiny Copepods
The water is filled with Copepods jellyfish and other drifting animals. They might be
small, but these planktonic animals are all food for the mighty whale shark.
Early in the morning, when the water is calm, the plankton forms a thick layer near the
surface.
Oooh! He's just surface feeding. What the whale sharks do here is they swim across the
surface of the water; with their mouth open wide; and all that plankton is sitting right
at the surface gets funneled right into their mouth.
The enormous mouth swallows up huge quantity of water
The water comes back out through the shark's gills, but cone like structure in the gills
capture the plankton like an enormous spaghetti strainer. So the whale shark swimming through
the water is like a big pool skimmer, filtering the plankton for breakfast. Each shark eats
hundreds of pounds of food every hour! It turns out that eating plankton is very efficient
for a large animal.
Conditions here around Holbox Island are perfect for plankton in the summer. The plankton makes
water really murky. But all that food attracts huge school of fish. It a bounty that feeds
many kinds of animals. Mantas Rays reed on the plankton, but the whale shark is by far
the most impressive animals that comes here. Reaching 50 ft long whale shark grow as large
as a school bus, but they completely harmless all they are plankton and tiny fish.
The fish attract other predators like dolphins, birds and bigger fish. That's why Holbox
has always been a great fishing area for the locals.
That's incredible. They are so huge and so much plankton that in the water we can
only see maybe 20 feet under water. So they are bigger than the visibility you can't
even see the tail from the head!
I can't believe how many sharks are feeding around the boat. There is so much plankton
here that it attracts whale sharks for hundreds of miles around. Some of the sharks have escort
schools of fish that swarms around them for protection. They too eat the plankton splashing
at the surfaces as they feed a long side the shark. But when I swim over to investigate
they hide under shark as if where huge swimming reef. Free diving and keeping up with these
sharks is hard work. They don't look like they are moving that fast. I mean their tale
just you know gently swishing back and fourth, but they are so big the tale so huge that
they are actually move faster than we can keep up with them. Swim as hard as you can
for about 30 seconds then your pooped and give up. Off they go
Later as the sun gets higher in the sky and the air gets warmer, the wind picks up and
waves start to form. The plankton layer dissipates, and the sharks get harder and harder to find.
They are diving deeper out of site.. Once they dive below we have no way to find them.
So we head back to shore
My trip to Holbox has been a tremendous success and lots of fun. The economy of this tiny
island has been transformed by this big, harmless, pockadoted shark. Here in Holbox the people
love whale sharks and they are protected by law. That's the best part of this story.
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