Blue Planet Revisited

Sharks - nature's perfect solution to an underwater life.

They've been swimming in the oceans for over 400 million years...

...and, as top predators,

play a vital role in keeping our seas healthy

and productive.

But they're coming under increasing pressure,

millions are hunted and killed every year.

Never have sharks needed friends

more than they do today.

For three weeks, I've been in the Bahamas for Blue Planet Live.

Watching,

monitoring,

and diving with one of the richest shark populations on the planet.

I want to reveal why sharks are thriving here

and find out if there are lessons to be learned

from these crystal clear waters

that could help secure their future elsewhere around the world.

Our blue planet is home to more than a thousand species of shark...

...and their cousins, the rays.

They come in a myriad of shapes...

...and sizes...

...and are found across all of our oceans...

...from the tropics...

...to the Arctic...

...and into the deep abyss.

There are a few places where the number and diversity of sharks

is unparalleled.

The Bahamas is one of them,

earning it the title of shark diving capital of the world.

700 islands are scattered over 84,000 square miles of ocean.

This location is unique -

perched on the edge of deep water,

where the seabed plunges to a depth of 4,000 metres.

The meeting of shallow water and deep, open ocean

leads to a profusion of life.

In winter, the resident Caribbean reef sharks

and bull sharks

are joined by visitors,

bolstering the shark and ray population to 78 species.

In 2011, the Bahamas were declared a shark sanctuary,

making it illegal to fish for or kill any species of shark.

These protected waters offer me a unique chance

to get close to these amazing top predators...

...and to see first-hand what it takes

to have a healthy, thriving population of sharks.

Within seconds of coming down here,

I'm greeted with one of the most dazzling displays

you'll ever see underwater.

There's probably two or three different sort of shark

at this location, but the dominant kind

is going to be the Caribbean reef shark.

And I can already see at least 20 of them here in the water around us.

I guess the first question that people would ask would be,

isn't it dangerous, isn't it risky to be surrounded

by this many apex predators?

And I have to say,

I feel just as comfortable being in here,

surrounded by all these extraordinary animals,

as I would do going for a walk with a pack of poodles.

These animals are so good at sensing their environment,

they know what's prey in the water around them,

and it's not us.

They may well swim in close but at the last second,

they just bank away.

They could not be less interested,

and the statistics about sharks prove that's true.

Around the world, you're more likely to be killed taking a selfie

than you are to be killed by a shark.

In fact, statistically speaking,

the chance of being killed by a cow, a deer or even a vending machine

is higher than the risk posed by one of these.

Sadly, this abundance of sharks is not typical

across all of our oceans.

This is not a sight that you get to see just anywhere.

So, around the world, we human beings are taking

at least 100 million sharks from the world's oceans

every single year.

In some places, sharks have declined by over 90%.

And in the time it'll take for you to watch this programme,

over 11,500 will be killed.

It's a number that simply cannot be sustained.

If it carries on like this,

then our children will not have the opportunity

to dive in seas like this,

surrounded by these stunning predators.

The Bahamas isn't the only place to offer protection to sharks.

Today, a total of 17 sanctuaries have been created around the world,

covering over 7.5 million square miles.

But this still amounts to only 5% of our oceans.

Sharks need more help,

and if we don't give it to them,

much of the life in our oceans will suffer.

As apex predators,

they remove any sick or injured animals,

keeping fish stocks healthy.

Animals below them in the food chain

are kept in check.

And removing sharks would unbalance whole ecosystems.

Over 3 billion people depend on the ocean for their livelihoods.

It's essential we protect sharks for our sake

as well as theirs.

And a vital step towards this is combatting the reputation of fear

that many sharks still hold.

I always had a passion for the ocean.

I fell in love with scuba diving.

I fell in love with everything.

It was a calling, I think.

Cristina Zenato left her homeland of Italy over 20 years ago,

heading for the Bahamas.

Ever since, she's become an advocate for sharks.

And two decades of diving at one site,

off the island of Grand Bahama,

has convinced her that these animals are a long way from being

mindless killers.

Cristina is known locally as the Shark Dancer...

...and this is her stage.

I love that there is a busy silence.

It is the most peaceful and calming moment of my day.

My babies are Caribbean reef sharks.

I love watching their behaviours

and their interactions.

They appear to me as different

as any other human being that I encounter.

Some of them are more dominant.

Some of them are shy.

And some seemingly seek out a closer encounter with Cristina.

The first time that shark settled in my lap...

...and every time, she settles in my lap,

and I feel her weight over my legs,

that is the most amazing feeling...

...and there's nothing, to this day, that beats that.

You can feel everything about the shark.

You can feel that it is a living, breathing creature

that is aware of her surroundings,

that is aware of what I am doing to her,

that is aware of my touch.

And the suit might actually have a nice feeling to their skin.

These sharks are 8ft long.

I could never force an animal of that size

to do anything or to sit anywhere.

It's their decision to come in,

it's their decision to stay,

it's their decision to go.

There is a total disconnect from humans to sharks.

We can swim in the ocean with sharks in a way that you could never

walk around on the snow with a polar bear following you.

We have to make that connection with the sharks,

understanding they are way, way less dangerous

than many creatures out there.

Cristina's unique relationship with sharks

allows her to do something quite extraordinary.

She can take out fishing hooks that are caught in their mouths.

Over the years, she's removed more than 300 hooks.

We must change our ways,

because we need to protect the oceans

and we need to protect the sharks.

And when you reach that message,

then you have a victory.

A greater understanding of these misunderstood creatures

can undoubtedly help sharks.

And with such a diverse and healthy population on its doorstep...

...the Bahamas has long been at the forefront of global shark research.

The Bimini Biological Field Station,

or Shark Lab,

has been increasing our knowledge of sharks and rays

for the last 29 years.

Heading this institute is Matt Smukall,

who's had a passion for the marine world

for as long as he can remember.

My first memories were snorkelling in the Florida Keys.

Growing up, I always had an affinity and a connection with, you know,

spending pretty much every weekend and all summer in the ocean.

My favourite group of animals are the sharks.

That's what originally brought me to the Shark Lab,

that's what makes me enjoy waking up every day and doing this job.

The Bimini Shark Lab started in 1990.

Right now at the Shark Lab, we're studying everything from

southern stingrays to bull sharks, tiger sharks,

lemon sharks, hammerheads,

but we take it from a very ecosystem-driven model,

where we want to understand

everything that's going on around Bimini

and how that's impacting these big sharks.

One of the biggest and most impressive species,

and the focus for a number of Shark Lab studies,

can be found a stone's throw from the heart of a busy marina.

These are bull sharks...

...drawn in by the scraps discarded from fishing boats.

They spend much of their lives in murky estuaries...

...so this clear water gives me a unique opportunity

to see them up close, and Matt a chance to learn more

about this little understood species of shark.

I'm here on the bottom of the harbour

and, as you can probably see,

I'm absolutely surrounded by bull sharks.

This is an opportunist that has a very wide array

of different kinds of prey,

so they'll feed on fish, on rays, on birds at the surface,

on dolphins, they'll even bite through the shells of turtles.

Now, all the sharks that I'm seeing around me at the moment