Sea of Cortez Oceans

They cover two-thirds of our planet.

They hold clues to the mysteries of our past.

And they're vital for our future survival.

But the secrets of our oceans have remained largely undiscovered.

I'm with a shark.

Yes! Yes!

Explorer Paul Rose is leading a team of ocean experts

on a series of underwater science expeditions.

For a year, the team has voyaged across the world to build up a global picture of our seas.

We are doing some pretty uncharted research here.

This is psychedelically colourful!

We're here to try and understand the Earth's oceans and put them in a human scale.

Our oceans are changing faster than ever.

I've never seen ice like this before.

There's never been a better time to explore the last true wilderness on Earth.

It's that way. Something quite big.

Yes, look! Woo-hoo!

It's a whale, here.

The team is exploring a unique corner of the Pacific Ocean, the Sea of Cortez.

-Oh, my goodness.

-This is SO beautiful, isn't it?

Those are whales.

-And this is the first day!

-I know!

-It feels good, doesn't it?

-It certainly does.

The Sea of Cortez is a rich, fertile gulf,

separating the peninsula of Baja California from mainland Mexico.

This sea is an exceptional marine environment,

home to the greatest variety of whales and dolphins found anywhere in the world.

Look at them go!

But today, this ocean paradise is under threat.

In the last 50 to 100 years,

humans have had a growing impact

on the systems that make the sea so interesting -

the health of sea lions, sharks and sperm whales,

you know, all these big animals that are found here in this young sea.

Fishing, tourism and industry have triggered complex changes here,

and it's these that the team has come to investigate.

This is definitely on the edge.

Environmentalist Philippe Cousteau will examine the shifting balance of this delicate ecosystem.

Woah, look at that!

If you're seeing an explosion of squid, that is at the cost to some other species.

Maritime archaeologist Dr Lucy Blue discovers how local people have found a way to protect our seas.

They are very aware that the seas only have a limited resource.

They have to be farmed in a way that is sustainable.

There's five sperm whales down there.

Marine biologist and oceanographer Tooni Mahto

explores how life is responding

in a rare encounter with one of the largest carnivores on Earth.

I got sonar boomed. I felt that boom going right through my body.

The Sea of Cortez is a sea under change,

and we're going to witness those changes.

That's a fantastic mission for a diving expedition.

This will be a voyage of discovery into a sea of change.

Expedition leader Paul Rose will head up their first mission -

the search for an ocean predator that once dominated this sea.

Hammerhead sharks - as soon as we put together the Sea of Cortez diving expedition,

hammerhead sharks was the only image that came to mind.

Is this the hammerhead video?

Yeah, this is filmed right here, right underneath us.

These pictures were taken 16 years ago, in a spot directly beneath the expedition boat.

-That was here?!

-Yeah, right here.

Right here, that's spectacular.

-And the research...

-Across the world, sharks are in decline.

Tens of millions are caught each year.

The team has come here to see how that's effecting this once-thriving hammerhead population.

-That's a fantastic shot.

-That's a great shot, good lord.

There's no real evaluation of how many there are left and what their habits are and how they're changing,

and the scientists need more information, and the way we can do that

is get sightings, study their behaviour and that all contributes.

It's all gold dust.

Hammerhead sharks are easily spooked,

so Paul is using special kit that doesn't produce bubbles.

Rebreathers allow you to stay underwater much longer,

but you need to be an experienced diver to use them safely.

There's a few different ways to kill yourself with these, and they're all instant.

You don't seem... There don't seem to be near-misses with them.

If you haven't set something up right, it's going to kill you.

Serious business!

This is the El Bajo Seamount, an extinct volcano.

It was once one of the best places in the world to see hammerhead sharks.

Now, this looks like hammerhead territory.

These are Cortez stingrays, which hammerheads eat,

and these are barberfish, that clean parasites off their skin.

So, we're definitely in the right place.

Hammerheads are vital to the health of the ocean.

They weed out the sick and injured and help keep marine life in balance.

But they've been heavily fished, so Paul doesn't know how many he'll find.

Our plan is to sit here, still and quiet, and hopefully the hammerheads will come by.

Paul, surface. Paul, surface.

Unknown to Paul, he's gone silent for another reason.

-The boat has just lost radio contact.

-Paul, surface. Paul, surface.

With Paul 40 metres underwater, this could be a serious situation.

Obviously,

We've seen the kind of equipment he's working with.

If there is a problem, we've got no way of knowing.

Paul, surface. Paul, surface.

For the time being, we don't know where he is or what he's doing, which is not great.

Richard Bull is in charge of dive safety.

It makes me very, very nervous, it really does.

If I can relax at all during the dive,

it's when I can hear them talking and they're calm,

and I haven't got any of that now.

Paul, surface. Try PTT. PTT.

Paul, surface.

Yeah, yeah!

A sea lion. Woo-hoo!

RADIO STATIC

-BROKEN SPEECH OVER RADIO:

-'It's beautiful.'

HE LAUGHS

That's a nice surprise!

Oh, oh! Laughter!

LAUGHTER OVER RADIO

Well, something's very good.

I thought it was a shark.

The Rose chuckle!

We like that.

Paul's now been diving for hours, but still no sign of sharks.

This nutrient-rich current should help bring in the hammerheads,

but where the heck are they?

-And?

-It was an exciting dive, but no hammerheads.

-Not a single one?

-Sadly, no.

I really felt that we would find them.

It felt like hammerhead territory, it was all there.

But no hammerheads.

Paul dives the Seamount again and again, but still no sightings.

Just 20 years ago, this was a hammerhead hot spot.

It's becoming clear this shark population is in severe decline.

'Three days of expedition time and, you know, didn't get a sniff of one.'

No hammerheads.

There used to be hundreds of them on the Seamount like this,

and now we'll be very lucky to find one or two.

There is a sense in me that says, well, maybe there's none here.

In the Sea of Cortez,

thousands of hammerhead sharks are caught each year,

mostly to satisfy the demand for shark fin soup in the Far East,

and there's further evidence of how destructive this trade can be,

as Dr Lucy Blue has discovered.

One of the boat crew found this skull on a beach on one of the islands here, and, as you can see,

this is the hammerhead of the shark, and it's actually quite a small one.

It just shows that they're not fussy about what size,

they'll take them small or big, juvenile or adult.

Once they've chopped off all the fins,

which is what they're after, they discard the rest.

The fins can reach something in the region of like 100 for one kilo,

so you're talking big business, really.

And this is happening on a large scale, so, yeah...

In this sea, hammerhead numbers have been dramatically reduced.

Some estimates suggest only 10% are left.

It's the demand for shark fin soup.

You know, it's barely credible.

For someone from England, you think, well, shark fin soup?

But that's what's happened.

Shark fin soup's supposed to have some fantastic properties,

but it's not worth decimating a whole species for, is it?

The decline in the number of sharks is shifting the balance of life in the sea.

Later in the expedition, the team will explore

the surprising consequences which that's having here.

Did you see that?!

Next morning, this corner of the Pacific Ocean offers the expedition a welcome lift.

There's a whole pod of them.

Look at them go!

-We're seeing a pod of common dolphins, but there's quite a lot of them.

-There are.

They seem very small, so I don't know if they're young teenagers who are out for a laugh!

Showing off.

More than 30 species of whales and dolphins are found here.

The loss of sharks has reduced competition for food, so dolphins are actually doing well.

It shows how the balance of life is more complex and surprising than it first appears.

Man, they're so lovely!

For the next dive, environmentalist Philippe Cousteau,

grandson of explorer Jacques Cousteau, hopes to investigate another part of the puzzle.

We're headed off to Los Islotes to go diving with sea lions,

which I have to say is one of my favourite things to do in the world.

Large breeding colonies of California sea lions are found here.

But as commercial fishing increases in this sea, it's starting to affect them.

Now, there's been a lot of overfishing of their traditional food, like sardines,

in the Sea of Cortez, so a lot of the sea lions are suffering because of that.

The animals of Los Islotes are a mysterious exception.

Somehow, these animals are thriving.

Marine biologist Tooni Mahto will be helping to unearth their secret.

The first aim is to check out how healthy this colony is.

He came close!

Woo! It's like speeding bullets.

Their manoeuvrability underwater kind of puts us to shame, I feel.

That one over there is a bit of a big boy.

I think he's one of the males.

Oh, and he's certainly coming round to check me out.

Yeah, that is a big male, that's for sure! He's awesome.

You can see that huge, bony crust on their head.

They use that to reverberate sound so that everybody can hear them

and let them know that they're in the territory and they're in charge.

Blowing bubbles is a way of saying, "keep your distance".

Hello!

This looks like the nursery area to me, with all the juveniles.

So, apparently, the pups here, in is this particular population,

spend an awful lot longer with their mothers than pups of the same species in different areas.

So they go and fish with their mothers so they learn that behaviour.

The number of pups in the water is a sign this colony is doing well,

as it means the females are healthy enough to breed regularly.

There were about 30 pups a year in the early '90s, and now there are more than 100 a year.

It's a real success story, which is good news.

But with many fish stocks declining, the mystery is why this colony's doing so well.

Something else must be going on.

Oh!

They look so incongruous on land, don't they?

And then as soon as he's in the water, he's absolutely perfectly streamlined.

Amazing. Master of his environment.

Gathering sea lions' droppings, or scats, might give Tooni clues about their diet.

Sea-lion poo number two.

Essentially, I'm doing the scientific equivalent of panning for gold.

I'm looking at the sea-lion poo,

and what we're looking for are the fish otoliths,

which are the ear bones of fish,

and from the otoliths, we can identify what the sea lions have actually been eating.

Oh, there's one.

Gold! I've found gold!

These ear bones could reveal the answer.

And it seems Tooni really has struck gold.

What we've found here is the fish otolith from a deep-water sea bass

that lives pretty much between 75 and 265 metres,

so that instantly shows that this population has, at some stage,

adapted to fishing at much deeper depths.

California sea lions normally hunt at depths of around 70 metres, catching fish such as sardines.

But the ear bones Tooni's found prove the animals at Los Islotes

have been able to change their hunting patterns.

And that is the reason why that population seems to be doing so well.

Because of this crucial adaptation, the Los Islotes sea lions

no longer have to compete with fishermen, and they're flourishing.

The fact that this particular colony has been able to adapt to the threats

and challenges that are facing it, and thrive, is a great story.

Hopefully, if this colony can exhibit this kind of behaviour,

then others can follow suit and there may be a bright future for the California sea lion.

Although life is changing fast here, change itself is nothing new to our seas and oceans.

In fact, their size and shape are constantly shifting.

Oceanographer Tooni has brought the team west, to the Bay of Conception,

because here, you can actually see that process in action.

Beneath these calm waters is a giant fracture in the Earth's crust.

It's part of the infamous San Andreas fault line,

and it created this sea.

The Sea of Cortez is quite young in geological terms.

The peninsula split away from the main coast line of Mexico about five million years ago,

so it basically started tearing apart,

and the great thing I like so much is the fact that it's still moving.

The whole of the Baja peninsula is moving pretty much west at a rate of five centimetres a year.

This bay offers Tooni the chance to look for evidence that this sea is getting bigger.

And Paul's hoping she'll cook a snack in the process.

Could we have six eggs - huevos? Would that be OK?

Good man. Thanks very much, thank you!

There we go. Don't forget these!

-Mind your head! Good luck, happy cooking.

-Thank you.

Tooni and Lucy are swimming over part of the San Andreas fault line.

As the Earth's crust is being ripped apart beneath them,

heat and gas from the centre of the planet are escaping through crack called hydrothermal vents.

Oh, look! Look at all these bubbles coming though.

Oh, God, yeah.

It's rare to see a hydrothermal vent in five metres of water.

They're normally found deep beneath the surface.

Oh, look, you can see the heat shimmer.

This is the shimmering water,

where the hot water is coming out of the ground and mixing with the colder seawater around it,

and that's the evidence of all the hydrothermal activity, accompanied by all the bubbles.

Oh, that's hot! That's really hot.

It's actually burning my fingers.

This hot water is over 90 degrees Centigrade.

It once trickled down though cracks in the Earth's crust, towards the furnace of the inner earth.

There, it was super-heated and forced out into the Sea of Cortez.

Right. We brought our eggs with us,

and we're going to bury them here, cos it's really, really warm here,

and then we're going to take them back on board for lunch.

We're cooking in the sea floor - it's not right!

Hot mineral-rich water like this is only found in places where fault lines are tearing the Earth apart.

It proves that directly below the team,

the Earth's crust is slowly moving and this sea is steadily growing.

Seas and oceans are thought of as immovable features of our planet.

This dive has shown they're anything but.

It's quite amazing to think

that this action of the tearing apart of these two land masses is a continuum.

It's been going on for five million years.

But although this process created the Sea of Cortez, it will also destroy it.

As Baja California continues to move north-west,

it will eventually break away from the mainland to become a giant island.

Then the Sea of Cortez will disappear for ever, engulfed by the rest of the Pacific Ocean.

Hey, hey! I know what you're holding behind you.

You can't fool me. Boiled eggs. Hard-boiled eggs, soft-boiled eggs?

I'm struggling with soldiers.

I don't know what Spanish is for "soldiers"!

-That looks perfect.

-It does look good.

-That's a hard-boiled egg.

That's a perfect, perfect, hydrothermal vent boiled egg.

Is it OK to eat? Of course it's all right to eat. It's blooming great.

-You could do it like an oyster, couldn't you?

-I could.

-What? In one?

Ohhhh.

That's absolutely brilliant.

Did you just down an egg in one?

It's brilliant. Well, I thought it was worth a go.

You're disgusting!

-Sea of Cortez, eating eggs cooked by Lucy and Tooni on a hydrothermal vent.

-Awesome!

Oh, cheers, mate.

At the start of the expedition, the team saw how hammerhead sharks were being decimated.

Now they plan to investigate a surprising knock-on effect.

The invasion of another fearsome predator.

They are ugly creatures.

A few decades ago, there were no Humboldt squid in the Sea of Cortez.

Now there could be over 20 million.

'They've taken over in a really short space of time,'

and that's to do with the amount of fishing that's gone on in this sea.

They've taken out the top predators,

'and now the Humboldt squid have basically filled in the giant empty space.'

Growing to over two metres long, these are ferocious cannibalistic hunters.

Look at the beak. They're so strong.

-You see it overlaps?

-Yeah.

That is kind of hooked over, so, you know, if your finger's in there, it's gone.

-Yeah, and look at the eye.

-Ooh, that's too eerie!

Humboldt squid are thought to have excellent vision

and are armed with over 30,000 barbed hooks inside their suckers.

I mean, you can feel them. They are properly sharp, these hooks.

The team wants to find out what impact the squid invasion is having.

-Honestly, that is nasty.

-And that means seeing them hunt.

Humboldts live in the depths of the ocean.

Local fishermen say catching one tempts others up from the deep.

-I've caught a squid!

-We've got a squid here!

-Oh, my God!

-Well done.

We've got squid in the area!

'We've been fishing about two hours, and we've run into a huge pile of squid,

'and what's really interesting is that every single time'

we put a hook down, it brings up a squid that's got marks and rips and bites all over it.

A number of the ones we pulled up have actually been eaten,

so this is demonstrating the sort of cannibalistic habits of the squid,

which is really quite unnerving.

Watch your mate get caught on a line and then eat him on the way up.

To see how they hunt, there's only one option - to dive in.

I don't particularly want to get in there with a whole load of arms and suckers and teeth.

Dive safety supervisor Richard Bull is also worried.

There are some very serious reports of people getting grabbed by them, divers getting grabbed by them.

One grabs them, another one grabs them,

and then another one grabs them, and if you don't react quickly,

then you are on your way down to the deep.

This is to keep us safe.

In case something goes wrong, the rest of the crew can grab...

There'll be a line tied to this and they can grab us and bring us up.

It's now past midnight and the weather has started to deteriorate.

The waves are coming in strong.

It's really rough. The wind is picking up.

This is definitely on the edge.

If you're not in in five minutes, it's off.

Watch the line.

Cor, look at that current.

OK...

-Flipping heck!

-That was a very rough entry in the water.

Woah! Look at that.

I can see squid.

They're right here.

There are loads of them.

Look, there's one.

Oh!

Oh, my goodness!

We can see the squid, which are kind of racing and pulsing out of the darkness.

As they come closer, the squid seem to be doing something peculiar.

There are several of them flashing their colours,

and we can see these ghostly white shadows that are flashing red.

You see the colour of him? That red flash.

These flashes may be a form of language

that could possibly help groups of squid to communicate as they hunt.

They are definitely attracted to the lures.

Yeah, there it is.

God, they move quick.

The squid have started to attack the team's bait in a pack.

There's, like, 10 or 20 out here.

Invertebrates don't normally hunt together like this.

But Humboldt squid are intelligent.

By flashing, they might be organising themselves into a hunting pack.

And that's helping them to devastate local fish stocks, eating an estimated 10,000 tons a night.

Underwater, Tooni and Philippe are unaware of how windy it's become on the surface.

It's kicking up, it's getting very rough.

It's deteriorating more.

I'm thinking we're on the edge.

-It's my job to say no.

-Agreed.

We've put our men at the edge of our capability and the seas have picked up

and the weather is obviously getting worse, so time to bring them back.

The rough seas will now make for a dangerous exit from the water.

Get him over that ladder quickly.

Well done, mate.

Too rough, really, wasn't it?

It was one heck of a dive, that's for sure.

Are you all right, mate?

I'm pooped.

What time is it?

-Ten past three.

-So we've been squid jigging since eight o'clock, eight o'clock this evening?

The success of the Humboldt squid

is having a radical effect on this ecosystem.

If you're seeing an explosion of squid,

that is at the cost to some other species.

They'll eat their way down the food chain

till there's nothing left down there.

And this problem isn't just affecting the Sea of Cortez.

Many invertebrates, like squid, are booming throughout our oceans.

The expedition has witnessed one of the great changes

affecting life in our oceans today.

After the late night, Paul gives the team some time off.

It's a very good part of the expedition,

right in the middle of it, and in the thick of it.

I'm loving this sea.

Just looks like it holds those hidden jewels

that, essentially, we are all here to try and find.

Now I have this real sense of ownership and it saddens me to think

that anything at all is being done to harm this special, beautiful place.

The team has already seen some of the surprising effects

of man's impact here,

but there's more to explore in this remarkable sea.

There's still a lot of challenges ahead.

We've got sperm whales coming up here, all these great things

we've still got to do in the northern part of the Sea of Cortez.

For maritime archaeologist Dr Lucy Blue,

oceans aren't just about the creatures living within them.

For me, it's the connection between the people in the past,

their relationship with the sea and what

that can tell us about people living today.

Lucy's been researching a shipwreck that tells a tragic story

of man's relationship with the ocean.

It's a boat that was smuggling migrant workers with the aim

of trying to get into the Unites States of America.

'It is a bit like an investigation into, you know,'

the lives of these people

as they took this treacherous journey across the sea.

-It was a transport ship or what?

-Exactly, of people.

'And there will be clues left within the shell of that boat'

to give us an indication of what life on board was like.

You can just see it emerging out of the bottom of the sea.

This is the wreck of the Fang Ming.

Sort of eerie as you swim around

these abandoned pieces of decking and rotting ropes.

The Fang Ming was formerly a working vessel in China,

possibly a fishing vessel,

and then she subsequently crossed the Pacific,

carrying this cargo of Chinese migrant workers.

Lucy wants to find out

where the Chinese workers were kept during the crossing.

Wow!

You first!

It's like walking into a deserted building.

It feels a little bit like a slavery ship or a prison.

This was meant to carry boxes of fish.

Instead, in this tiny dark space,

88 men and seven women were kept for weeks at sea.

Imagine what it would have been like, all crammed in here.

It must have been quite horrific.

Apparently, there were actually people employed on the boat

to control them, to keep them crammed in these confined quarters.

The Chinese workers were just hours from their destination

when the Fang Ming was seized by the authorities.

Everyone on board was sent back to China.

In 1999, the Fang Ming was sunk

to become the first artificial reef in Latin America.

All these old pipes and walls have just been colonised by marine life.

It's just completely taken it over.

But for Lucy, the Fang Ming

will always be a reminder of a deeper human story.

You start to think about, you know,

they had reasons to put their lives at risk in that way,

to endure that experience and it's sort of representative

of migrant workers, illegal immigrants, you know?

The sea is providing an access for people to move around the globe

for reasons that we wouldn't have necessarily seen in the past.

For anyone navigating these waters,

the weather can be dangerously unpredictable.

The expedition arrived just after a hurricane

and now the weather's threatening again.

Wahey!

That's a bit of bolt!

-Yes, first time we've seen this weather, isn't it?

-Absolutely.

Is the hurricane coming back?

I checked with the captain

and he said the weather would be all right.

"The wind's going to pick up but no hurricane," he said.

What about the thunder and lightning, where does that fit?

He didn't mention it, he just talked about wind!

So there's going to be no wind,

but we're going to be struck down by lightning?

Yeah, I don't know, I'd better check again.

I didn't think it rained here... Oh, my goodness!

It's funny. I was just thinking about a passage-making brief,

you know, get ourselves organised for the big crossing.

I'd better incorporate some severe weather briefing, I think.

Paul was hoping to move north,

but because of the weather, the team is stuck here.

We really are, you know,

squeaking every possible thing into this expedition.

We don't really need too much bad weather, that's for sure.

So we're gonna anchor for, probably, at least five hours

and then set out at three or four in the morning, make way again.

Once the storm has blown through, they set sail again.

The team is heading north

to meet one of the most isolated tribes in Mexico.

They're known as guardians of this sea,

and Lucy's keen to find out why.

This is the area where the Seri Indians live,

so they're basically indigenous people who live here

and fish the seas, so it's that sort of symbiotic relationship

between what's happening around the edges of the ocean

and the people that live there

and how they sort of work with the oceans and fish the seas, etc.

Just over 450 Seris exist today.

Lucy's been invited to see their approach to managing this sea.

That must be Chapo then, yeah?

Chapo? Hello, Chapo.

-My name is Paul.

-Lucy.

Chapo, thank you so much for your help.

83 year-old Chapo Burnett is the village shaman, or holy man.

He still fishes with his son Raimundo.

OK, thank you.

They work in a notorious area called Hell's Channel,

so Chapo asks the sea gods for a safe passage.

PERCUSSIVE CHANTING

Chapo and Raimundo are going to collect scallops.

Lucy wants to see how they go about it.

He's actually walking along the seabed with the bag between his legs

and he's gathering them in the way that you might harvest crops.

Quite a nice comparison.

Harvesting of the land and harvesting of the sea.

In just a few minutes, Raimondo has almost filled his bag,

but the Seris are careful to manage the stocks.

When I talked to Raimondo,

he implied that they basically do crop rotation.

If they feel that they're over-harvesting one area,

they move to another area and maybe fish octopus,

so the principles are sustainable.

This approach clearly works.

In Hell's Channel, the scallop beds

are productive and healthy year after year -

a stark contrast to the rest of the Sea of Cortez,

where shellfish production is collapsing.

-For you.

-Oh, thank you, Sir.

Eat!

Mmm, that is delicious!

I'm never going to cook a scallop again, that was absolutely gorgeous.

-Oh, yeah, no kidding. Muy bien, thank you.

-Thank you.

The Seri Indians demonstrate a technique

that balances the needs of people with the health of the sea.

OK, anchor?

They are living in a modern world.

They have to compete with large commercial fishing operations,

and yet they're also very aware

that the seas only have a limited resource,

they have to be farmed in a way that is sustainable.

For the last target of the expedition,

the team aims to carry out pioneering research

on one of the planet's largest carnivores.

I've asked a couple of sperm whale scientists who work around here

to come and join us for a few days on board.

How are you?

Dr Karina Acavido Whitehouse and Dr Diane Gendren are experts on whales.

Welcome. Thanks for joining our expedition.

With the scientists on board,

the team prepares for the challenge ahead.

I'll show you around. 'Sperm whales, that's all we care about.'

We can't even speak or think or do anything clearly

because we're full of sperm whales.

There are certain experiences

that could stay with you for the rest of your life,

and I think if we do manage to snorkel with the sperm whales,

I don't think I'd ever, ever forget that.

Ever.

Next morning the search begins.

Relatively little is known about sperm whales.

They live far off shore and are hard to find.

Locating them is the first task.

So our plan is to go about another hour north-east

and begin our search pattern, and see what we can find.

Sperm whales dive for up to 40 minutes at a time.

Diane and Philippe are using a directional microphone

to try to track them under water.

Anything within this spectrum of the cone, it's going to pick up.

Anything outside, like here, like my voice,

which is quite loud right next to it, it doesn't pick up.

It's pretty cool. Let's see what we can hear.

Sperm whales are amongst the loudest animals in the world.

Their clicks reach 220 decibels - louder than a shotgun blast -

so they can be heard for many miles under water.

So you can hear the sperm whales clicking.

As soon as I turn it off of where the sperm whales are,

the sounds - the clicks - go away.

So that way, we know which way to go, right?

Yeah, they are this way.

Roger, that's all copied.

So do you have an estimate on numbers in the group, over?

Got a pretty broad sweep all along the port side.

-It seems like there would be more than one group.

-That's great news.

Whales, we've actually come right onto a really large group,

so we're timing this pretty perfectly.

Very exciting times.

Lucy catches the first glimpse.

Oh, is it gonna turn? It's going, it's going, it's going!

Here we go, look.

Woo-hoo, did you see that?

I hope these guys saw it as well.

You couldn't book him, could you?

This is the team's chance to take a closer look.

Learning more about sperm whales is important

because they're a vital part of the ocean's food chain,

particularly here in the Sea of Cortez

where their main diet is Humboldt squid.

We've decided to pop in the Panga and kind of get a bit closer

and see how they respond to us being around them

and maybe getting in the water with them.

And we got some dolphin escorts here that are swimming next to us.

You could almost touch them.

Then the moment Tooni's been waiting for.

Oh, my goodness, look at these!

The whales rise up to breathe.

Part of the challenge in studying these animals

is that you really only get the briefest glimpse

of their life cycle by witnessing them only on the surface,

so the opportunity to try and get underwater and film them

is very important.

But that's not going to be easy.

-No, he's diving.

-No, he's diving.

Seeing as it's the deepest diving mammal on our planet,

we could be here for some time.

Sperm whales can dive to over 2,000 metres,

so until they re-surface,

studying them underwater will be out of the question.

Right, we do our absolute utmost to get to swim with sperm whales

and as soon as they see us they're just like,

"You know what? I'm not interested today,"

and that's it, one flick of the tail, gone.

Lucy and Karina want to find out how healthy these whales are.

Their sheer size makes taking blood virtually impossible,

so Karina's the first scientist to try to capture

a sample of the whale's breath in the wild.

So we take the lids off once we are really close?

Well, actually, we are very close.

Germs in the whales' breath

will tell Karina if they have any infections in their lungs.

But taking a sample is easier said than done

as the sample dishes have to be held right over the whale's blowhole.

Oh, no!

No!

Please, please, don't. Don't go. No, no, no, no, no!

Oh, how very disappointing!

Reel her back in. Yes, next time.

They fail to capture a single sample,

but Karina has an ingenious Plan B.

Oh, wow! What a superb looking thing.

It is a fabulous idea to link science collecting

with a small, miniature helicopter, wow!

With sample dishes attached,

the helicopter can fly straight through the whales' breath

without disturbing them.

But pilot Augustine Paen has strong winds to contend with.

Oh, the wind, the wind, the wind, the wind!

No problem.

It's a very tricky thing to fly, this.

We're moving up onto the whales right now,

nice and slowly, to parallel their course,

and then he can swing this in

and collect a sample of the blow, so it's all a matter of timing.

Go, Augustine, it's perfect, man!

Go, buddy!

Just a bit further out, Augustine.

He's gonna dive, yeah, can you believe it?

Tooni and Philippe aren't having much luck, either.

I think there's a whole load of sonar conversations

going on down there at the moment

which is basically the sperm whales telling each other

that there's a bunch of wannabes knocking around on the bay

and to get the heck out of here.

You can just see them. They're all, just diving all around us.

OK, Augustine. Get in there, buddy.

Despite the strong winds,

they're finally getting closer with the helicopter.

Good man, get in there!

Forward, mate. That's it - now, now!

Woo!

That's the sample, he's got it.

The germs caught in the dish will help reveal more information

about the health of the sperm whale population here.

Well done, that's perfect.

And with each sample so hard to collect,

this one will be important for Karina's research.

-Thank you.

-Perfect, thanks very much.

OK, that was a good sample.

And what is it that you're specifically looking for?

Microbacteria, for example, the agent that can cause tuberculosis.

There's a very common germ that causes infection in the lungs.

It can cause severe problems, even meningitis.

It's just a list of germs to start with.

Karina's early findings

suggest whales could have caught some of these bacteria from humans,

perhaps through activities like whale watching.

Her groundbreaking work

has highlighted this problem for the first time.

It might be an important development in protecting sperm whales.

Look, look! One two, three, four...

After almost five hours,

the whales finally seem to be staying at the surface.

Philippe and Tooni are desperate to observe them underwater.

I'm off!

There's five sperm whales down there!

The large females in this group are over nine metres long

and can weigh more than 12 tonnes each.

Now you can see how they just turn around and touch other

and they're so, so social.

The whales are socialising. This is a rare sight.

It suggests their food stocks are plentiful

as they can afford to take time out from hunting.

It shows the explosion of Humboldt squid

might actually be benefiting these animals.

Suddenly, Diane spots something astonishing at the surface.

Woo-hoo! That's a big male. This is amazing.

A large, mature male has joined the group.

This giant in the centre of the pack could weigh over 40 tonnes.

Male sperm whales have the largest brain

of any animal that's ever lived.

We don't see that every day.

No, seriously, this is...

you're lucky. It's a treat.

Adult males usually live in small groups

in the cold waters around the Poles,

so this one has probably come here to breed.

After a short time,

he grows sexually aroused and starts courting the females.

This behaviour is seldom seen and it shows

how important the Sea of Cortez is

as a breeding ground for sperm whales.

More than any other, this dive has illustrated

why the health of this sea is so vital to the life within it.

I'm blown away.

I'm one of the luckiest people on the planet.

There just aren't words to explain how incredible that feeling is.

I got sonar boomed.

I heard and felt that pulse just that boom going right through my body

as it was doing the kind of X-ray scan of what the heck I was.

I want a hug!

Oh, man! I felt like crying. It was a really strange reaction,

but you feel like crying when you're watching.

It's a spectacular end to the expedition...

How was it?

-Oh, my god, it was fantastic! Paul, Lucy...

A voyage that's offered a remarkable window

into the world of our changing oceans.

Well done, well done indeed.

The Sea of Cortez is a place in flux

and there's so many things we don't know

and so many things that we're doing carelessly,

and what is that doing to the natural balance?

This sea has revealed how destructive man's impact can be,

but it's also shown us we can live in harmony with the ocean,

and that in the face of great change,

life can adapt and even thrive.

The Sea of Cortez, at the moment,

still seems to be an incredibly rich place, so yes, it's changing,

but I personally feel like the sea finds its own equilibrium.

This shifting balance will create winners and losers

but as yet it's impossible to predict who they'll be.

Next time, the team braves the wild Southern Ocean...

..and explores its unique underwater world.

Very, very strange creatures, aren't they?

Parts are warming twice as fast as other oceans,

pushing marine life to the brink.

The expedition sees what can be done.

Oh, it's lobster everywhere!

Subtitles by Red Bee Media Ltd

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