All language subtitles for BBC.Natures.Great.Events.S01E06.The.Great.Feast.HDTV.x264.AC3.MVGroup.org.en

DAVID ATTENBOROUGH:
The power of the sun drives the seasons,

transforming our planet.

Vast movements of ocean and air currents

bring dramatic change
throughout the year.

And in a few special places,
these seasonal changes

create some of the greatest
wildlife spectacles on Earth.

The seas along the Pacific coast
of North America

can be some of the richest
on the planet.

These coastal waters
create the perfect conditions

for the greatest explosion
of life on Earth.

It's driven by some of
the tiniest creatures.

As their numbers multiply,
they feed vast shoals of fish,

which in turn provide food
for ever larger hunters.

Billions of lives will be shaped
by this immense bloom.

And the mightiest hunter of them all

has devised a remarkable way
to harvest this great feast.

It's January.

Both land and sea are locked
in the depths of winter.

(BIRDS CAWING)

The seas along the coast of
Alaska and British Columbia

can become the richest on Earth.

But for the moment, they lie dormant.

The time of great feasting
is many months away,

and a number of magical changes
must first take place.

The most crucial change
will be driven by the sun.

But now it is weak and offers little
to those trapped here for winter.

This coastline,
a maze of islands and inlets

carved by glaciers,
will also shape this great event.

For now, it remains shrouded in cold.

Only the toughest can survive.

(WIND BLOWING)

Steller's sea lions huddle together
to share warmth.

It's 1 5 degrees below zero.

They have little choice
but to suffer this,

the coldest Alaskan winter on record.

The shoals of fish they depend on

spend winter in the deepest water.

(SEA LION GRUNTING)

For now the fishing is hard.

(SEA LION GRUNTING)

It's an unforgiving place
to raise a family.

Conditions are so severe

that mothers must suckle their young
for up to three years.

For this pregnant sea lion,
the risks are even greater.

The seas must come to life in good time

for the arrival of her pup,

and at this stage,
the odds don't look good.

(WIND HOWLING)

For now, all she can do is wait

for the sun to bring change.

These seas have the potential

to be so rich at the height
of the great feast,

that they will attract animals
from across the vast Pacific.

And 3,000 miles away
in the waters of Hawaii,

another mother is about to embark
on an epic journey.

(HUMPBACK WHALE SINGING)

This humpback whale
has already given birth.

Her calf is just a few weeks old.

He stays close to his mum.

(HUMPBACK WHALES SINGING)

The difference between Hawaii
and Alaska could hardly be greater.

These are calm, warm waters
with few predators,

an ideal nursery for the youngster.

The calf is now drinking

400 litres of milk every day,

building up strength

for the long voyage
he'll soon have to undertake.

More than 5,000 humpbacks
come to Hawaii each year.

The males,
lured here in the hope of mating,

compete among themselves
with great shows of strength.

But none of these whales
can actually feed here,

for these tropical waters
are comparatively lifeless.

(WHALE ROARING)

The ocean's greatest riches

are only to be found in colder seas.

So all these whales must return
to the North Pacific to feed.

The playful calf suckles
from his mother every day.

But she hasn't had anything to eat

since she left Alaska
over four months ago,

and she won't feed again
until she returns.

Like the pregnant sea lion,

this mother has to get her timing right.

She must arrive in Alaska
for the moment when the seas

are at their richest, full of fish.

Their journey north
will take three months.

Back in Alaska,
the seas are starting to awaken.

It's March,
and as the sun gathers strength,

winter loosens its grip.

For the sea lions,
things are beginning to look up.

The sun is drawing life from the depths.

(SEA LIONS BLOWING AIR)

With each passing day,
the sun warms the water for longer,

penetrating deep into
the mineral-rich waters.

Fertilising nutrients of
phosphorous and nitrogen

fuel a miraculous change
that is just beginning.

Empty seas start to come to life.

As we enter an enhanced view
of this microscopic world,

we see the beginnings
of a magical transformation.

Phytoplankton,
tiny floating plants, emerge.

Each is scarcely bigger
that a speck of dust.

But together, these plankton will bloom
in such immense numbers

that they transform lifeless seas.

And whether that will happen this year
is yet to be determined.

All creatures here, from the sea lions
to the migrating whales,

ultimately depend on
these miniature plants.

For one creature that relies
directly on the plankton,

this is the moment to emerge.

Pacific herring have spent the winter
in the depths of the fjords,

but they now rise up and
head for the shallow coast.

Stimulated by the sun
and the warming water,

they gather
in their hundreds of millions.

But they're not drawn here to feed.

They're following
an irresistible urge to breed.

Groups of males
sweep through the shallows

and release their sperm
in vast, milky clouds.

The females follow,
covering the seabed with eggs.

Such a concentration of fish

is just what the sea lions
have been waiting for.

The herring won't be here for long.

The sea lions must make the most
of the fishing while it lasts.

Other predators gather,
also hungry after the lean winter.

This short-lived bounty

is a magnet
for millions of migrating birds.

This is just the first brief course
in the great feast.

The herring spawning
will be over in a matter of days,

and the shoals of fish
will then scatter along the coast.

The herring have spawned
on an astonishing scale.

They turn hundreds of miles
of coastline white with spawn.

In this bay alone,

they have laid 800 billion eggs.

The herrings' spawning is so timed

that when the next generation hatch
in a few weeks

they'll be able to feed
on the growing plankton.

And this year, the herring
appear to have timed it just right.

The minute plant plankton,

the driving force behind
the seas' transformation,

are starting to bloom.

Great swathes of sea
grow green with life.

The humpbacks are still
out in the middle of the Pacific.

They've missed the first taste
of the great feast.

At just eight weeks old,

the young calf must cross
the biggest ocean in the world.

His mother will only swim
as fast as her young calf.

As he tires,
she supports him from beneath.

She's been living off her fat reserves

for the last six months,

and has lost a third of her body weight.

She's close to starving.

(WHALES SPOUTING WATER)

It will be a further two months
before mother and son

reach their feeding grounds
in the North Pacific.

It's May, early summer in Alaska,

and the days are getting ever longer.

The sun continues to fuel
the growth of microscopic plants

that make up the plankton bloom.

They're joined by a growing community
of tiny animals...

zooplankton.

These are the first creatures
to feed on the bloom.

Over the coming months
they will multiply,

crowding the surface waters
in their trillions.

The next stage of
the great feast is underway.

All life here depends
on this plankton bloom.

The herring feed on it directly.

The greater the bloom,
the more abundant the shoals.

And the fish themselves
become food for the larger hunters.

But the shoals of herring
are now spread far and wide,

and once again, for the sea lions

the fishing is tough.

They must venture further to find food.

But open water is a risky place to fish.

This male sea lion hunts alone.

He is three metres long
and a ton in weight.

Few would dare tackle him.

(SEA LION BLOWS AIR)

The smaller females travel as a group,

keeping a watchful eye
in all directions.

They know that killers lurk
in the depths.

The surface is
a dangerous place to linger,

especially if you're alone.

Orca. Killer whales.

The sea lion is wounded,
but the killers keep their distance.

His powerful jaws are
still a threat to the hungry orca.

He struggles towards the safety of land.

But his injuries are slowing him down.

(ORCA CRASHING)

Blow by blow, they wear him down.

It's a carefully coordinated attack.

One killer distracts his attention,

while another hits his soft underside.

(ORCA CRASHING)

The richest seas on Earth
can be treacherous.

Orca attacks, although savage,

have little impact on the fate
of most sea lions.

Their survival depends
more on the tiny plankton

that sustains the great shoals of fish
on which they feed.

It's now late May.

The sunlight lasts for 1 7 hours a day.

But the bloom will need
more than just sun

if it's to reach its full extent.

Nutrients held in these waters
are continuously used up

as the bloom increases.

If they're exhausted too early,

the plankton will die
and the food chain will collapse.

The effects will be felt by all.

Meanwhile, on the sea lion colony,

new life is now arriving.

After a year carrying her pup,

this mother can at last give birth.

(SEA LIONS GRUNTING)

The pup is utterly dependant on his mum.

As he makes sense of his new world,

she encourages him
to take his first feed of milk.

The mother has waited
until early summer to have her baby -

such a small pup
would never survive the winter.

Along this coast,

thousands of pups are born
within a matter of weeks,

timed to coincide with the better
conditions that may lie ahead.

(SEA LIONS GRUNTING SOFTLY)

The migrating humpbacks
are still weeks away from Alaska

and their first meal.

(WHALE BLOWING AIR)

In these turbulent seas,

mother and calf must stay close.

A huge Pacific storm is brewing

and heading straight for
the coast of British Columbia.

(WAVES CRASHING)

Directly in its path
lies the sea lion nursery.

The pups are now
at the mercy of the elements.

The mothers must get their young
to the safety of higher ground,

if they can find it.

(WAVES CRASHING)

In desperation,
a mother tries to drag her pup away

from the gathering tempest.

A pup swept into the water

is unlikely to be seen again.

As the seas begin to subside,
many have survived.

But others have not.

There's nothing this mother
could have done to save her pup.

These mighty storms,
though devastating for some,

bring fresh life to the great feast.

(WATER RUSHING)

When these storms hit the coast,

they stir up vital nutrients

into the surface waters,
nutrients that feed the plankton.

Replenished seas combine
with the lengthening days

to create a plankton explosion.

And this has come just in time

for those at the end
of an incredible journey.

The humpbacks have arrived.

After 3,000 miles, mother and calf

have finally made it
to the coast of Alaska.

They join other whales
that have also made the long voyage.

But their journey isn't over,
for they have yet to feed.

They're heading for
a particular stretch of coast

deep in the network of channels,

where they know they can find
the great shoals of herring.

It's to these ancestral feeding grounds

that the mother now guides her new calf.

The unique geography of this coastline

holds the final secret
to this great event.

Glaciers have carved a landscape

of deep fjords and islands
over tens of thousands of years.

This patchwork creates a labyrinth

through which powerful ocean
and tidal currents flow,

bringing up the vital raw ingredients
needed for the bloom.

It's as if an endless supply
of fertiliser

is being added to the water.

In other seas, the plankton
would be subsiding by now.

But here the seas are
repeatedly invigorated,

which fuels the plankton bloom

time and again throughout the summer.

And with the sun at its most powerful,

all these elements combine

to create a plankton bloom
of great intensity.

In July, the ocean is alive.

This floating community
of plants and animals

is the basis for all life here,

and a bloom of this intensity

signals the start
of a truly great feast.

Where this rich soup hits the sea bed,

life carpets every available surface.

The feasting begins
with millions of tiny mouths.

Barnacles sift morsels of plankton
brought in on the currents.

Many of these creatures
started their lives

as part of the plankton
before reaching adulthood

and settling on the sea floor.

These animals are giants.

They filter the plankton-rich water,

growing larger here
than anywhere else in the world.

Jellyfish gather, forming great swarms.

They, too, eat the plankton,
rising to the surface

where it is at its most abundant.

By late summer,
the plankton bloom is so vast

it radiates across the North Pacific.

Blooms like these provide Earth
with over half of its oxygen.

This bloom eclipses even
the Amazon rainforest

in sheer abundance of plant life.

And it is most intense

where the ocean streams through
the maze of coastal waterways.

The shoals of herring are now
at their most plentiful.

After feeding through the summer months,

the fish themselves are a good catch,

the main target for predators
now gathering here.

After enduring the bitter winter,

the sea lions can enjoy the bounty
they've been waiting for.

Hunting together,
they drive the herring to the surface.

Then, with mesmerising grace,

they pick off fish one by one.

For a few short weeks,

they'll have their share
of the great feast.

Others arrive to feed
in the coastal waterways.

(DOLPHINS CLICKING)

Pacific white-sided dolphins.

They dart in and snatch fish as they go.

The tidal currents now
sweep herring up to the surface.

Here, they're within
diving range of sea birds.

Murres are the first to find the fish.

The shoal twists and turns,

trying to escape the surface dangers.

But murres are so fast
they can even out-swim the herring.

They head off the escape,

making the shoal turn in on itself,
creating a bait ball.

The birds corral the herring

into an ever-tighter ball.

But the commotion hasn't gone unnoticed.

Gulls, ever the opportunists,
are the next to turn up.

They can dive no more than a metre,

so the fish are still out of reach.

The murres only attack from beneath,

trapping the fish against the surface.

But they push the herring
within range of the gulls.

It's a feeding frenzy.

The table is set for
the mightiest predator of them all.

The humpbacks have reached
their feeding grounds.

After six months without a bite to eat,

the humpbacks can finally
break their fast.

The whales have learned to target
these ready-made balls of fish.

But they'll need more than
just a mouthful,

and with the feast now in full swing,

this is their chance.

To exploit the vast shoals of herring
that are in deeper water,

they rely on teamwork.

For these whales have developed
a truly remarkable way of hunting.

(WHALES SINGING)

The inlets echo to the sound
of a mysterious song.

(WHALES SINGING)

A curtain of bubbles

and a haunting call hold the secret

to an ingenious way of fishing.

(WHALES SINGING)

(HIGH-PITCHED SINGING)

This is ''bubble-net feeding''.

A dozen whales work together
to harvest the herring bonanza.

Such fishing requires
an extraordinary level

of intelligence and cooperation.

The lead whale dives first.

She is the bubble-blower.

It's her job to find the fish.

(WHALE SPOUTING AIR)

The rest follow in formation.

Each takes exactly
the same position in every lunge.

Once she's located the fish,

the leader blows a net of bubbles

that completely encircles the shoal.

(WHALE SINGING)

Another whale calls
to synchronise the group.

(WHALE SINGING CONTINUES)

Panicked by the eerie sound
and the blinding bubbles,

the fish won't cross
this fizzing curtain.

(HIGH-PITCHED SINGING)

As few as 1 00 humpbacks

have learnt how to feed
as a team like this.

And this is the only place on the planet
where whales fish in this way.

(LOUD MOANING)

At the height of the great feast,

these humpbacks fish around the clock,

each eating a ton of herring a day.

Only man has learnt to exploit the seas

on a greater scale.

As the summer ends,
the feast draws to a close.

The sun is weakening,

and with it,
the plankton bloom subsides.

The microscopic plants that brought life

to empty seas begin to die.

The herring descend
to spend the winter in the depths.

Life for the sea lions
will be harder once again.

But they've fed well enough
to face the dark days ahead.

(WHALES SPOUTING AIR)

The humpback whales
will soon leave these shores.

It's astonishing to think that

some of our world's mightiest creatures

ultimately rely on some of its tiniest.

Here, along the North Pacific coast,

the interplay between land, sea and sun

has produced a bloom of plankton
so immense

it has created
one of nature's great events.