They call it America's last frontier.
500,000 square miles of wilderness.
This is Alaska.
Home to some of the hardiest animals on the planet.
Alaskan seasons run fast and furious.
Opportunities are fleeting.
For people as well as animals.
Survival means making the most of nature's gold rush.
Play it right, and you will hit the jackpot.
Get it wrong, and you could lose it all.
It's not about your size, it's about your attitude.
This land belongs to the bold.
This is Alaska.
It's March and Alaska's far north is frozen solid.
For 65 days, this place was in permanent darkness.
But things round here are about to change.
Polar bears have spent the winter hunting across thousands
of miles of sea ice.
But the ice is beginning to melt.
In a few short months, 24-hour darkness
will become 24-hour daylight.
The great seasonal transformation has begun.
The polar bears will have to scratch a living on land.
But for everyone else, the good times are just around the corner.
Of all the states in America, Alaska is by far the biggest
and the most northerly.
A third of it lies above the Arctic Circle.
Temperatures can drop to 80 below.
The pale rays of early spring
hardly seem up to the task of warming anything.
Across Alaska, thousands of rivers lie frozen.
There are three million iced-up lakes.
25,000 glaciers.
Even the waterfalls have stopped mid-fall.
Nothing moves.
When the sun does finally unlock the land,
every opportunist will be waiting.
The North Slope -
the coldest, wildest part of all Alaska.
This is the tundra.
Even trees struggle to take root in the icy soil.
But life is possible even here.
An arctic ground squirrel.
He spends his entire winter asleep.
Out like a light for eight months straight -
the longest, deepest hibernation of any animal on earth.
This is one extreme lifestyle can only be seen
using a special filming burrow.
He's pretty much stopped breathing.
His heart is barely beating.
The sun is getting higher every day.
In the darkness of his burrow, the squirrel's body clock
drags him out of bed.
There's no time to waste.
Last time he saw it, back in the autumn,
this was his territory.
Now he's got to fight for it all over again.
For the next two weeks, he'll barely have time even to eat.
It's a constant battle to keep rival males of his turf.
There's a sense of anticipation in the air.
Females emerge a few days later.
He won't want to miss his first date.
And there she is.
But what is he doing?
SQUIRREL CHIRPS
She'll only be fertile for 12 hours in the entire year.
- SQUIRREL CHIRPS - There's no time for hesitation.
He cautiously makes his move.
She might be in a hurry, but she can still be choosy.
He knows that while there are other males around,
she could easily go off with someone else.
He won't leave her side for 24 hours.
An Alaskan spring moves fast
and if you don't seize the moment,
it will pass you by.
The exact arrival of spring is hard to predict.
But for some, working out when it might arrive
has become a total obsession.
CHAIN SAW ROARS
Deep in central Alaska,
the Tanana River freezes to over one metre down.
And every Spring the townsfolk look forward to the day
when it will break up and flow again.
It's such a big deal
they've held a festival for nearly 100 years to celebrate.
It begins on 1st March with the digging out
of the heart of the frozen river...
..setting the stage for a truly Alaskan event.
The whole town joins in.
On the count of three.
One...
Two...
Three.
The day the river breaks up, this wooden tripod will fall,
marking the first day of spring - a day everyone is waiting for.
OK, that's it. We're done. Good job, everyone. Thank you.
THEY CHEER
As part of the celebrations,
everyone has a bet or two on when the tripod will actually drop.
Whoever gets it right, to the nearest second,
will hit the jackpot.
And then the wait...
begins.
The tripod is tethered to a watchtower
where the official clock will stop as soon as the tripod collapses.
They take it so seriously, there is even a watchman on 24-hour duty.
The nights become shorter.
Still, the tripod stands.
Each day bulks up with seven minutes more daylight.
Four weeks later, the tripod is starting to shift.
At long last, on 25th April,
at 3.48 in the afternoon,
spring arrives.
SIREN BLARES
Round here, though, they don't call it spring.
This season is what they call 'break-up.'
The thawing of the rivers is a season all of its own.
That's how much it means to an Alaskan soul.
The sun's power has started to revive Alaska's heart.
365,000 miles of rivers will break up within a matter of weeks.
Life is getting going again.
Stoneflies have been waiting under the ice all winter.
With the melt, they are released into the daylight.
American dippers follow the rivers as they thaw.
For everyone that's braved the cold, it's payback time.
BIRD CHIRPS
A porcupine has spent the winter up trees, eating nothing but bark.
Now he's off to look for the first tender shoots of spring.
This willow ptarmigan has been sleeping in snowdrifts
to fend off the cold.
But he's starting to shed his white winter feathers,
looking forward to better times.
It's still too cold for most plants to get going.
In the Chugach Mountain Range though,
there's one that's staked an early claim.
It's a woolly lousewort.
The fur wrapping acts like a greenhouse.
Even on frosty mornings, the woolly lousewort is several degrees
warmer than the air around it.
This bold little pioneer now has enough of a head start
to produce the some of the first flowers of an Alaskan spring.
And it's ready with nectar for an early bee.
All across Alaska, spring's roll call has started.
As the sun penetrates even the deepest woods,
100,000 black bears will emerge from hibernation.
Most will have made their winter dens on the ground,
but this bear made hers higher up.
She's spent the last seven months in a hole inside a cottonwood tree,
five metres above the forest floor.
She's out, and she's not on her own.
Perched several metres above her are her two small cubs,
born inside the tree, and venturing out for the first time.
Their tree den was the safest start for them,
away from attack by other bears.
Somehow, she's going to have to get them down.
They're only around 12 weeks old,
and they already have strong claws and a natural instinct to climb.
But when you're this new to tree-climbing,
it's a little bit daunting.
The first cub seems to be a natural.
But his brother is still way up the tree.
BEAR CUB WHINES
He's still not sure what to do next.
A fall from this height would probably kill him.
BEAR CUB WHINES
A little gentle encouragement is all he really needs.
For an animal weighing 100kg,
balancing on a branch looks precarious.
But for black bears, climbing is a way of life.
Trees will be their refuge for their entire lives.
Their mother's devotion is total.
She won't leave their side for another year or more.
They have energy to burn
and they'll spend hours a day play-fighting.
But mum has lost a third of her body weight over the winter.
She has to keep eating for all three of them.
And there's not much around.
This is what Alaskan old-timers call the starving time.
This close to the Arctic Circle, winter is never far away.
All it needs is a change in the wind direction.
Raging winds from the North Pacific scream across the ocean,
picking up moisture, creating a blizzard.
WINDS GUST
For these sea otters, life couldn't get much worse.
It's 20 below.
Mothers are trying to protect their newborn babies
in the teeth of a sudden freeze.
This tiny pup was only a few days old.
Spring can be deadly when your luck runs out.
Some sea otters find ways to avoid the worst of the storms.
This is Valdez, the snowiest coastal town in Alaska.
Like many harbours, it's abandoned for the winter.
No-one likes to fish in these conditions.
Well, almost no-one.
In the calm waters, a lone male otter fishes for mussels.
He eats a quarter of his body weight every day.
It's snowing a little, but he's OK.
He has the densest fur of any animal.
Nearby, another sea otter has discovered her own little sanctuary.
She has a baby just days old,
- OTTER SQUEAKS - and he's taking all her attention.
She needs to keep him warm and dry,
so she preens him for hours at a time.
She even blows air into his fur - the fluffier she can make it,
the warmer he will be.
With a baby to nurse, she needs to eat twice as much as normal.
Sooner or later, she will have to leave him in the water
while she finds food for herself.
The problem is - he can't swim yet.
MACHINE RUMBLES
Everyone is impatient,
trying to get rid of the snow.
Just as it seems it will never get warm again...
..the sun returns, the sea calms, and the fishermen get their boats
ready for the start of the Alaskan fishing season.
Smells like money, eh, boys?
HORN WHISTLES
As the harbour gets busier, the otters move on.
But the days of shelter have been life-savers.
Mum takes her growing pup out into the open water,
and she has a surprise for him.
Suddenly, he's all on his own.
- But he can't go anywhere. - OTTER WHINES
His mother has fluffed him up so much he's unsinkable.
OTTER WHINES
He can't do much but go round in circles.
Once she's fed herself, she can scoop him back up and feed him too.
She'll be looking after him like this for the next six months.
The cold seas off southern Alaska are some of the richest on earth.
The longline fishing season has just opened,
and the crew of the Magia are out early.
Round here, the prizes are big...
..but so is the competition.
These fishermen could make 60,000 in just a few days.
They need to be ready. If they get it wrong, they lose everything.
The biggest prizes are in the deepest water.
But not many fishermen have the gear to work here.
You need five miles of lines and hooks
and the latest technology to even stand a chance.
They're after black cod, one of the most prized fish in Alaska.
Hundreds of dollars worth of bait gets cut to size
and loaded onto the hooks.
Then the lines are sent half a mile to the bottom of the ocean.
This is longlining.
And the waiting begins.
By dawn, the scene has been set
for one of nature's most audacious heists.
The boat is surrounded.
Sperm whales, 50 tonnes apiece.
There are six of them, maybe more.
For the crew, this spells disaster.
- With this many whales, it's pretty much game over. - Yeah.
'You see a spout and you know we are in trouble.
'They're prowling, waiting to come upon us.
'They're premeditated.'
These whales are nearly 20 metres long.
They're as big as the boat.
And they're smart.
They can recognise an individual fishing boat
just by the noise of its engine.
The lines are now full of fish, it's time to haul in the catch.
The captain kicks the engine into gear.
But he just can't pull them in quick enough.
ENGINE RUMBLES
This noise is like a dinner bell for whales.
Down she goes!
One by one, they dive.
And the crew can do nothing about it.
The whales carefully follow the lines down into the darkness.
They zone in with their sonar.
Then, with their long jaws,
they delicately work the fish off the line.
It's the perfect sting and the easiest meal in the sea.
The crew haul their lines to the surface,
but it's pretty much a waste of time.
All that's left are some red rockfish
that the whales didn't want...
..a few bent hooks...
and the chewed remains of the precious black cod.
That's all the whales leave us!
The crew think they've lost 90% of today's catch to the whales.
No market for those.
The four-day fishing trip should have paid up well.
But now they'll go home empty handed.
Sperm whales all across the Gulf of Alaska are now learning
the trick from each other.
There are at least 120 of them targeting the black cod boats
and raiding their lines.
And more are coming in every year.
In Alaska, nature's riches are abundant,
but sometimes you have to fight for them.
The weeks are slipping by and the sun is getting stronger.
In the southern forest, the black bear cubs are growing fast.
But mum's reserves are running low.
It seems like a lot of effort for not much reward,
but she'll eat whatever she can get.
Up in the tundra, there's been a baby boom
of arctic ground squirrels.
Each baby has grown ten times bigger in just over a month.
A family of Lapland longspur chicks is eating anything
the parents can rustle up.
CHICK SQUEAKS
They'll be fledging when they're only eight days old.
Everything here is in a race to grow.
CHICKS CHIRP
A caribou baby is on its feet the day it's born,
ready to join the vast herds up to a million strong.
Spring might have arrived late, but now it's in rush.
The sun punches higher and higher as the days lengthen
and the ground warms.
But not even the sun at its strongest
can take away every speck of ice.
Great icy glaciers.
They scrape across the land,
picking up thousands of tonnes of shattered rocks and boulders.
Debris that is vital to the next stage of spring.
These flecks of ancient rock - rich in minerals -
lie deep inside the glacier.
For now, they are trapped.
But under the glare of the sun, the dense blue ice begins to melt.
Little trickles of water slide under the glacier.
Trickles become streams,
and streams become rivers,
cutting their way through the heart of the ice.
When they finally reach the glacier's edge,
they cascade to the ground.
300 billion tonnes of meltwater.
The water that has carried the minerals from far inland
now delivers them directly to the sea.
A giant plume of silt slides from the land,
spreading the richness all along the southern coast.
With the sea full of sunlight and flushed with nutrients...
..the Alaskan spring is about to deliver its greatest bounty.
Nature's gold rush.
First to arrive are herring in their billions.
The richness of the water is what's brought them here.
But they soon attract attention by their sheer numbers.
Sea lions.
Pacific white-sided dolphins join the chase.
The herring on the edges of the shoal don't have a chance.
They're attacked from all sides.
Diving birds snatch them from below.
Herring gulls reach down from above.
The fish are now trapped against the surface with nowhere to go.
Plenty of herring manage to escape.
But even those that do get away have a much bigger hurdle ahead of them.
'This is the Alaska Department of Fish and Game, the fishery will
'occur in approximately two minutes, two minutes.'
This annual herring run brings out every boat in the bay.
But the law says you can only fish for a very short time.
'25 seconds, stand by for countdown.'
Spotter planes line up the fishermen
and the boats jostle for the best positions.
- Here in Sitka... - 'Ten...' - ..it's game on.
'..nine...
'eight...
'seven, six, five,
'four, three,
'two, one...
'Open!'
They might only get 15 minutes to catch what they can.
But if they play it right, they'll catch 1,000 tonne of fish.
You can make your year's salary in a day.
It's that big a deal.
Every year, 20 million-worth of herring are pulled out of the sea.
But this is only a fraction of the total numbers.
As the fishermen draw in their nets, the escapees rush to the shallows,
but there's a final barrier in their path...
A wall of bubbles.
These bubbles may seem more fragile than a fishing net,
but they are just as deadly.
Humpback whales.
Only half a mile from where the fishermen are working,
a pod of humpbacks are also working the herring bonanza.
But their secret is teamwork.
The lead dives first.
Then the rest of the pod follow one by one.
As they descend, they blow out a curtain of bubbles.
WHALE VOCALISES
The herring are spooked
and they bunch into a desperate little circle.
The trap is set.
WHALE VOCALISES
Their timing is perfect.
'Ten, nine, eight, seven...'
For the fishermen of Sitka, their time's up.
'..five, four, three, two, one, closed!'
But the humpbacks can carry on round the clock,
each catching a tonne of fish a day.
For two frantic weeks of spring, the herring run draws in fishermen
and wildlife to these rich bays.
People have been harvesting the seas here for 14,000 years...
..ever since the first settlers arrived.
Spring in the south is especially significant for Harvey,
a member of the Kaagwaantaan clan.
Right now, when it gets to this point and the weather starts warming,
you tend to watch what is happening with the weather and the land
and the things around us.
This specific area has been very special to a lot of Alaskan natives.
The ocean and the lands around it provided for our people.
For thousands and thousands of years, the herring have been coming here.
All he needs are hemlock branches for his harvest
because Harvey knows the secret of the herring's arrival.
They're not feeding in these nutrient-rich waters.
The herring are here to spawn.
But first, he and his family have to find them.
It's all about looking for the signs.
I know my father said the seagulls were the ones that named the herring.
They started calling.
They'd say, "Yah, yah, yah!"
And that's usually when they saw herring.
They'd said the herring are coming.
The whales seem to agree.
That's another sign that they're in the right place at the right time.
WHALE SHOOTS OUT AIR
Ah!
Ha-ha!
Time to set the trap.
Throw it in, Dale.
The hemlock leaves are strong and dense,
the perfect place for the herring to lay their eggs.
All they can do now is hope they have timed it right.
Early the next day, the herring arrive in the shallows.
Straight away, they begin to lay on every surface
including Harvey's hemlock branches.
Millions and millions of eggs
pounced on by hundreds of hungry mouths.
The spawn is so thick it changes the colour of the sea.
In three days, 800 billion eggs are laid along this coastline.
As the tide goes out,
a frosting of tiny eggs is left sparkling like jewels in the sun.
Harvey and his family have come back to their hemlock branches.
HE HEAVES
The branches are so thick with eggs,
they can barely lift them from the water.
Harvey's family will share the herring roe with native communities
right across Alaska.
But they'll start with their nearest and dearest.
Do you think Mom will like it?
I think Mom will really like it!
Finally, spring has paid dividends.
To those Alaskans that have timed it right,
the rewards have been generous.
The sun has transformed Alaska,
hustling out winter
and bringing back the good times.
Everywhere is full of life
and colour.
The starving time is finally over.
Those that struggled in the early days of spring are now cashing in.
But the sun's return has only just begun.
24 hours of daylight will bring a whole new set of challenges.
And a new cast of characters ready to face them.
BEARS GROWL
For better or worse, the Alaskan summer is on its way.
Of all the stories from wild Alaska,
the most intriguing came from the fishermen of Sitka.
They told us about a story of giant ocean predators -
50-tonne sperm whales - that were targeting their catch of black cod.
The times that are really tough is when you get
eight to ten of them on you...
You don't stand a chance.
They'll rip every single fish off your hook.
The whale just comes up and puts its mouth on your ground line.
When the line is coming up like that, it just strips your black cod
right off the hooks.
There's been sets where I should've had 300-400 cod,
and, like, this last trip we had, I think, four.
It drives you absolutely mad.
I think the problem is getting worse,
definitely getting worse.
One fishermen, Stephen Rhoads, has been fishing here for 20 years
and he knows this story only too well.
I don't know how to quantify their intelligence,
but their effectiveness is almost perfect.
They're getting better at this every single year
and it's less work for them to hang out with us and take our fish
than it is to dive down and get them off the bottom.
There's no doubt that these creatures are very smart.
The camera team spent a week with Stephen and his crew
as they set out to fish.
And it doesn't take long before they see first hand
the extraordinary damage to his catch.
Coming in.
Broken ganion.
I feel like when the line jumps
you can feel the whales tugging fish off the hooks.
They're better predators than we are, man.
That's for sure. They're good at what they do.
The team's role was to film this extraordinary problem,
but they soon found themselves caught up
in Stephen's determined quest.
He wants to find a long-term solution to this problem.
We're not trying to get rid of the whales,
we're trying to find a way where they can have their natural prey
and we can fish.
And by hanging out with really smart people,
we can find a way to get back to where we can both make a living.
The smart people are a group of whale scientists.
Their investigation has been going on -
above and below the water - for ten years.
And they've already tried a few things to lure the whales away.
We've used some sound deterrents and it did work briefly,
but they're such an intelligent species that they figured it out
pretty quickly. It wasn't as effective as everyone hoped.
There clearly aren't any easy solutions.
The scientists now have to come up with another plan
to better understand the whales' movements.
Maybe satellite tags would help show where they were.
Then at least the fishermen could avoid them.
Oh, right there.
But after a week at sea, they've only tagged three.
There are 120 whales on this coastline...
..and the scientists simply don't have the resources to tag them all.
One of these is a new whale for us. It's not in our catalogue.
Yeah, they're becoming smarter and smarter.
It seems like their numbers are increasing.
The number of whales around is bad news for the fishermen
but good news for the film crew.
It's never easy working on boats at the best of times,
and the supersize camera gear is hard to handle.
- A little wobbly, right? - Yeah. Getting my sea legs.
They are starting to capture shots of the whales
as they sneak around the boat.
But the real action was happening beneath the waves.
The team decide to take the risk of sending down
some of their tiny underwater cameras.
Time-triggered, pressure-tested, and sealed in water-tight housing,
it's the only way they are going to see what's going on down there.
All set?
Each camera is attached to the fishermen's lines.
At 80m down, darkness takes over.
It's only the lights on the cameras
that allow them to see anything at all.
A further half-mile down,
they hit the seabed and start capturing this alien world.
The water's just above freezing.
The pressure is immense.
And the inhabitants seem less than friendly.
And then, amidst the darkness,
the distant clicking of sperm whales searching for prey.
Eight hours later, the cameras are hauled back up.
But the big question is -
did they capture anything that would shed any light on the behaviour?
Camera.
Barely made it.
The team have captured 50 hours of deep-sea footage.
But the cunning whales have completely avoided
being caught on camera.
- Nothing. - Nothing.
It's like fishing.
In spite of everyone's best efforts,
this extraordinary behaviour is still frustratingly hard to see.
After a week of filming and years of research,
to this day, there is only one single shot of a sperm whale
stealing fish off the longline,
filmed years ago by the scientists themselves.
The whales are outsmarting everyone.
It's not going our direction.
The whales are a bigger problem every year
and there isn't a solution yet.
Even though we sit right on top of the surface of the water
and try to look down in the deeps with our equipment,
and we bring a few fish up,
there is a lot more going on down there than we totally know about.
The team have witnessed the whales' extraordinary behaviour.
The collaboration between fishermen and scientists continues.
Perhaps one day they'll find a way to resolve
this riddle of the deep.
Next time...
Summer arrives in Alaska,
bringing with it the bounty that everyone has been waiting for.
But they'll need to cash in quick.
The days may be long but the season is short.
And the good times won't last forever.