[ Whale vocalizing ] ♪ Buchan: I remember as a child being around these huge animals.

That sense of mystery and might.

-[ Whale hoots ] -I think I can hear it.

♪ [ Whale hoots ] It's just amazing that these animals are filling the ocean with their sounds and their song.

They are very simple sounds but for me they're super beautiful.

Narrator: It's summer.

Whales are gathering along Patagonia's Pacific coast.

Home to the fjordlands -- long, deep, flooded valleys that were carved out by glaciers over millions of years.

These remote, rich waters are a magnet for wildlife, and increasingly for people.

At the ends of the Earth is a land of extremes... home to spectacular wildlife.

For centuries, people and animals have battled for supremacy.

But now, enemies are becoming allies.

Together they face new challenges... ...in our rapidly changing world.

Madriz: You are at the mercy of the elements.

Narrator: This is the story of what it takes to survive... ...on the edge of the world.

♪ It's the start of another all too brief summer.

Patagonia's 600 glaciers are rapidly melting.

Freshwater cascades off the mountains.

As it pours into the fjords, it mixes with saltwater, stirring up the water column, and drawing up nutrients from the depths, feeding more and more plankton, which in turn supports an entire food web.

Patagonia's fjords are now bursting with life.

Running for 1,000 miles up the west coast, this is one of the most extensive fjordland regions on Earth.

Fed by dozens of these fjords is an incredibly rich feeding ground -- the Corcovado Gulf.

And heading straight for it is the largest animal that has ever lived... A blue whale.

Weighing nearly 200 tons, he's twice as heavy as the largest dinosaur.

♪ It's been a long swim from warm equatorial waters more than 3,000 miles away.

But it's all worth it... ...for the krill.

During the summer, billions of these tiny crustaceans swarm these waters to feast on the plankton.

For the next few months, he'll gorge himself on around four tons a day before returning north.

While whales are here for the krill, oceanographer Susannah Buchan is here for the whales.

With 700 migrating to the Corcovado Gulf every summer, there's nowhere else she'd rather be.

As a child I developed this kind of obsession, this passion for these large animals, and as I grew up and understood how whale populations had been decimated through centuries of commercial whaling, it just became unbearable not to do something to help.

Narrator: Susannah has been visiting Patagonia since 2007, studying whale acoustics using underwater microphones.

She's recorded tens of thousands of hours of blue-whale song and has made an extraordinary discovery.

We found out that the blue whales here produce a unique song dialect.

[ Whale hoots ] Narrator: In fact, these are a distinct subspecies of blue whale, one of just five on the planet.

But they're not the only leviathans in these waters.

[ Ship horns blare ] Susannah's data has revealed a shocking and unfortunate coincidence.

Buchan: The noise made by large ships is in the same frequency band as the songs made by blue whales.

Their songs are drowned out.

Narrator: It's a big problem.

Blue whales rely on their calls for communication and courtship.

But ships aren't just noisy -- they're deadly.

[ Ship horns blare ] Summer is peak season for whales...and boats.

Over 1,000 vessels pass through these waters every day, and more and more whales are being hit.

Buchan: [ Speaking Spanish ] Ohhhh!

We've got some whales.

Narrator: Susannah is determined to protect these magnificent creatures, and she's hatched an ingenious plan.

Buchan: Beautiful.

What I would like to achieve here is to implement an acoustic alert system that will alert ships to the presence of whales to reduce the risk of ship strikes.

Narrator: A prototype has already been made by the University of Concepción, and with the cooperation of shipping companies, by 2030, the hope is to extend these systems all along Patagonia's Pacific coast.

[ Whale hoots ] Buchan: An ocean without whales would be devastating for all of us.

If we want healthy oceans, then we want whales to be part of those ecosystems.

Narrator: Susannah's plan will be a game changer, but human activities affect whales in many different ways.

And this one has paid the ultimate price.

A team of vets is launching an investigation to track down its killer.

♪ Narrator: In Patagonia, summer is all too short.

Wildlife and people have only a few months to make the most of the ocean's riches before the weather turns, making the waters less hospitable for both.

Right now, it's a gold rush.

With so much activity concentrated in such a small area... [ Ship horn blares ] ...there's bound to be trouble.

♪ On the eastern side of the Corcovado Gulf, a team of vets has been called to investigate a suspicious death.

♪ ♪ The corpse of a blue whale.

A stark reminder that in these busy waters even the largest animal on the planet is vulnerable.

Dr. Frederick Toro and his team are determined to identify the killer.

Dr. Toro: [ Speaking Spanish ] Narrator: It may have died of natural causes, but there's no shortage of other likely suspects.

Fishing nets... A ship strike... Pollution.

The team confirms that the victim is male, tragically only four years old.

Blue whales can live to be 100.

Had he survived, he might have fathered more than 20 calves.

There's no apparent external injury, so they go in.

♪ ♪ After six exhausting hours, Frederick's worst fears are confirmed.

There are signs of internal bleeding and a bruise on its heart.

He died of blunt-force trauma to the chest.

And there's only one thing out there that could inflict such damage.

A ship.

In the past week alone, three whales have been reported dead.

And that doesn't include the bodies that have never been found.

♪ But until the shipping traffic is controlled, summers in the Corcovado will remain deadly for these magnificent creatures.

♪ While the world's largest marine mammal is running a lethal gauntlet, up the coast, the world's smallest marine mammal is fighting its own battles.

This marine otter mom has a busy day ahead.

She has two very hungry, very demanding pups.

In Patagonia, these furry, playful creatures are known as chungungo.

This rocky coastline provides mom with plenty of nooks and crannies to set up a den and keep these mischievous pups out of harm's way.

♪ Mom spends the long days catching crabs, fish, and anything else she can find to fill their growing bellies.

♪ Even in summer, the waters here are cold.

Lucky for her, in terms of hairs per square inch, otters have the thickest fur of any animal.

But she's not the only predator here.

Something else is lurking in the kelp.

♪ Narrator: Off Chile's Pacific coast, a hardworking marine otter mom, a chungungo, is making the most of the calm, midsummer seas.

And she's not alone.

But our mom has nothing to fear.

Melinka Gomboa is collecting as many sea urchins as he can, to feed his family and sell at the local market.

Gomboa: [ Speaking Spanish ] Narrator: Fishermen like Melinka used to feel very differently about their fellow hunters.

Until just a few decades ago, the chungungo were seen as pests, their fur a valuable prize.

They were hunted almost to extinction.

But 15 years ago, realizing they were about to lose these remarkable creatures forever, Melinka's fishing community had a change of heart.

Today, the locals and the chungungo happily share this shoreline.

Sometimes the fishermen even toss them an extra snack... ...making our hardworking mom's life a little bit easier.

But these docks aren't just the perfect place for the otters to feast.

For the pups, they're an underwater playground.

♪ ♪ Exploring is all part of growing up.

In a couple of months, they'll have to fend for themselves.

Now, the chungungo and the fishermen are bonding over a new threat to their way of life.

Huge commercial fishing boats.

♪ ♪ With plenty of food on their doorstep, these chungungo rarely venture far from these docks.

They're lucky.

Some have to travel quite a bit further to get their fill.

This is Chiloé, an idyllic island popular with tourists.

But during the summer, its beaches are overcrowded for a different reason.

[ Birds calling ] Each year, tens of thousands of migratory birds come here to take in what, for many, would be its most unappealing feature -- the mud.

The swampy shallows are loaded with worms, clams, crabs, and all sorts of wiggly, nutritious goodies.

At low tide, it's an all-you-can-eat buffet.

Among the diners is a little bird with huge ambitions.

Soon these Hudsonian godwits will undergo a stunning transformation.

Their digestive organs will shrink and their wing muscles will grow, ready for an epic annual migration -- a 5,000-mile flight nonstop to Texas.

No sleeping, no eating, no drinking.

They are the ultimate long-haul fliers.

In just a few weeks, these godwits will be on their way.

♪ But first, they must fatten up by almost 40%.

They are so focused on finding food... ...they don't see it coming.

[ Birds crying ] ♪ Narrator: It's summer on Chiloé Island, and for Hudsonian godwits, the pressure is on.

They're gorging themselves before a 5,000-mile, nonstop flight to Texas.

They don't realize they're being watched.

An ingenious trap has been set.

And the birds are settling right in front of it.

♪ ♪ -Perfecto.

-[ Speaks Spanish ] Narrator: The people springing this trap aren't hunting for food.

They're hungry for knowledge.

The team is from the Universidad Austral de Chile.

Led by Juan Navedo, they come here every summer to study this astonishing bird.

Man: [ Speaking Spanish ] Navedo: [ Speaking Spanish ] [ Reading measurement in Spanish ] Narrator: The team measures and records the bird's weight and size.

The godwits are released unharmed and go right back to packing on the pounds.

It's only been a minor interruption to their preparations.

These days, the godwits have far more serious problems.

There are some on the island who have found a way to live in balance with nature.

For centuries, people here have made a living from the shoreline.

With almost 40 years of experience, Cristina Ovalle is an expert at what she does -- harvesting seaweed and shellfish.

Just like the birds, her work day is governed by the rhythm of the tides.

Ovalle: [ Speaking Spanish ] Narrator: It's easy work for the birds, but for Cristina, it's backbreaking.

Cristina's seaweed is sent all over the world, used to make medicines and cosmetics.

She has to work hard now to make the most of the warm weather and the long days.

♪ All summer long, the shores of Chiloé Island are filled with birds and people taking advantage of its bounty.

But 100 miles to the south, it couldn't be more different.

This is the Guaitecas, a group of inaccessible islands and a natural sanctuary barely touched by humans, home to one of Patagonia's most elusive animals... the Chilean dolphin.

Found only along this coastline, very little is known about this species.

This is one of the few times they've ever been filmed.

♪ ♪ Their distinctive round fins and white bellies make them easy to recognize.

At just five feet long, they're one of the smallest dolphin species in the world.

A calf, around two months old.

For the first year of her life, she'll follow mom everywhere, learning by example.

Like all dolphins, they are very social -- they hunt, play, and rest together.

But two have separated from the pod.

Late summer is the height of the breeding season, and these two want a little privacy.

♪ ♪ While these rare native creatures hide away, they have no idea that further to the north is a hoard of foreign invaders... ...millions of them.

♪ Narrator: Summertime in the fjords of Patagonia is drawing to a close.

But for some, the living is still easy.

[ Sea lions growling ] Gangs of young male southern sea lions are making the most of the last warm days.

They may look lazy on land, but under the waves, there's a party going on.

♪ These sea lions can hold their breath for up to 20 minutes and swim at 20 miles per hour, helpful talents for catching fish and impressing your buddies.

♪ ♪ For now, this gang is happy hanging out, but in about a year, the males will be ready to breed and they will fight each other for females.

Size is everything.

Fully grown, they can weigh over 1,000 pounds.

All this playing is an excellent way to bulk up and size up the competition.

This group has left the rocks for a man-made resting spot... with good reason.

The buoys mark the edge of a fish farm.

As fall draws near, these underwater pens are packed with hundreds of thousands of fully grown salmon.

And there are often escapees.

Salmon farming arrived in Chile in the 1980s.

These sheltered fjordlands are the perfect temperature for raising the valuable fish.

Today, there are more than 1,500 farms like this one, providing over 70,000 jobs and $5 billion worth of exports.

It's a huge boost to Chile's economy.

But this rapid growth comes at a price.

The farms are taking over traditional fishing territories.

Sergio Mayorga Miranda fears his way of life will disappear.

Miranda: [ Speaking Spanish ] Narrator: Sergio has been fishing these waters all his adult life.

And it isn't just the fishermen that are taking a hit.

It's the environment too.

To control disease among the captive fish, hundreds of tons of antibiotics are poured into the pens.

This may keep the salmon healthy, but it contaminates the surrounding waters.

Also the cages sometimes break.

And while that provides sea lions with an easy meal, Atlantic salmon are an invasive species.

They prey on native wildlife, disrupting the food chain and threatening the balance of the ecosystem.

For Sergio, it is clear what needs to be done.

Though outbreaks of disease need to be prevented, the government has introduced incentives to reduce the use of antibiotics and the companies are showing interest.

Meanwhile, the fishermen work hard to keep their catch sustainable.

This time of year it's jaiba mora crabs.

But they only keep the adults, protecting future catches.

The surrounding environment benefits too.

As scavengers, crabs keep the waters clean, and they provide a tasty meal for any animal with the right tools.

Dexterous paws and sharp teeth are one such winning combination.

But sometimes... a big beak will do the job.

Patagonia's rich waters support a fantastic diversity of marine life, including a little-known creature that may help us understand one of the biggest threats to our oceans.

And this woman is determined to unlock its secrets.

♪ Narrator: It's early fall in the fjordlands of Patagonia.

The air is getting colder and the nights longer.

To the east of the Corcovado Gulf is the Comau Fjord.

25 miles long and more than 1,500 feet deep.

A wildlife-rich hotspot with hidden treasures just below the surface that very few know about and even fewer have seen.

♪ ♪ Haussermann: Patagonia is very special because there are secrets hidden there that, as a marine biologist, it's really the dream to unravel.

For me, it's the most beautiful place on Earth.

Narrator: In this remote fjord, Vreni Haussermann has made an extraordinary discovery.

Cold water corals.

Unlike tropical corals, which need sunlight, these depend solely on plankton for survival.

Ecosystems like this are usually found as deep as 8,000 feet, only accessible by deepwater submersibles.

This is one of the only places on Earth where these corals can be found in shallow waters, giving Vreni a rare opportunity to get a good, long look at them.

♪ They're worth the attention.

Greenhouse gasses are not just warming the world.

They're also increasing the acidity of our oceans.

Here in the fjord, the waters are naturally acidic.

They are a great case study for ocean acidification because the prognostics say that the oceans in the world in 2100 will be like the fjord here, and this gives us lots of opportunities of research.

Narrator: If we can figure out how these corals cope with the conditions here, it might help us to protect marine life in other parts of our rapidly changing world.

But these creatures are in danger from a familiar threat.

When I arrived, there were three small salmon farms and the fjord was near pristine.

Well, nowadays there are more than 20 farms and they are much, much bigger than before.

Narrator: Contamination from fish farms has led to bigger and more frequent algae blooms.

And after dying off, the decomposing blooms suck oxygen from the water, leaving less for marine life.

Boat traffic has also increased here.

There's more trash, more lost fishing lines and nets.

Vreni has seen half of the corals die along the fjord's shoreline.

Haussermann: They are species that we hardly see anymore, that disappeared.

The whole system could destabilize and collapse.

Narrator: Vreni is determined to fight for the corals.

She's going to use her research to convince the government that there's something worth saving here and that these areas deserve to be protected.

For Vreni, it's a lifetime of dedication and passion that she hopes to pass on.

Haussermann: I've discovered a couple of new sea anemones.

Two of them I've named after my kids.

For me it's really important that they feel responsible, that they feel that their generation should really take care of what's living there and preserve it for future generations.

Bring the beauty of the marine life to people because once they've seen it, they can start caring for it and help to protect it.

Narrator: In Patagonia's fjords, summer is over.

Migratory visitors are heading for their winter homes... ...while the locals hunker down for the tough months ahead.

This wild coastline has given animals a place to feed, breed, and take shelter... and people the chance to reap... -...study... -[ Whale hoots ] ...and enjoy the natural wonders... of Patagonia's fjords.

♪ ♪ Next on "Patagonia: Life on the Edge of the World"... ...in the mountains, condors own the skies.

While pumas reign below.

But their world is changing fast and they need to adapt to survive.

♪