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00:00The power of the Sun drives the seasons, transforming our planet.
00:10Vast movements of ocean and air currents bring dramatic change throughout the year.
00:22And in a few special places, these seasonal changes
00:26create some of the greatest wildlife spectacles on Earth.
00:35The seas along the Pacific coast of North America
00:38can be some of the richest on the planet.
00:45These coastal waters create the perfect conditions
00:49for the greatest explosion of life on Earth.
00:54It's driven by some of the tiniest creatures.
00:59As their numbers multiply, they feed vast shoals of fish,
01:03which in turn provide food for ever larger hunters.
01:11Billions of lives will be shaped by this immense bloom.
01:15And the mightiest hunter of them all has devised a remarkable way
01:24to harvest this great feast.
01:26CHILDREN
01:36It's January.
02:06Both land and sea are locked in the depths of winter.
02:15The seas along the coast of Alaska and British Columbia
02:19can become the richest on Earth.
02:23But for the moment, they lie dormant.
02:29The time of great feasting is many months away.
02:32And a number of magical changes must first take place.
02:41The most crucial change will be driven by the sun.
02:47But now it is weak and offers little to those trapped here for winter.
02:51This coastline, a maze of islands and inlets carved by glaciers,
03:04will also shape this great event.
03:09For now, it remains shrouded in cold.
03:13Only the toughest can survive.
03:19Stellar's sea lions huddle together to share warmth.
03:25It's 15 degrees below zero.
03:28They have little choice but to suffer this.
03:39The coldest Alaskan winter on record.
03:42The shoals of fish they depend on spend winter in the deepest water.
04:02For now, the fishing is hard.
04:04It's an unforgiving place to raise a family.
04:15Conditions are so severe that mothers must suckle their young for up to three years.
04:21For this pregnant sea lion, the risks are even greater.
04:38The seas must come to life in good time for the arrival of her pup.
04:42And at this stage, the odds don't look good.
04:51For now, all she can do is wait for the sun to bring change.
05:08These seas have the potential to be so rich at the height of the great feast
05:12that they will attract animals from across the vast Pacific.
05:16And 3,000 miles away, in the waters of Hawaii,
05:23another mother is about to embark on an epic journey.
05:37This humpback whale has already given birth.
05:46Her calf is just a few weeks old.
05:53He stays close to his mum.
06:08The difference between Hawaii and Alaska could hardly be greater.
06:16These are calm, warm waters with few predators.
06:26An ideal nursery for the youngster.
06:30The calf is now drinking 400 liters of milk every day,
06:36building up strength for the long voyage he'll soon have to undertake.
06:46More than 5,000 humpbacks come to Hawaii each year.
07:00The males, lured here in the hope of mating,
07:03compete among themselves with great shows of strength.
07:16But none of these whales can actually feed here.
07:33For these tropical waters are comparatively lifeless.
07:37The ocean's greatest riches are only to be found in colder seas.
07:47So all these whales must return to the North Pacific to feed.
07:58The playful calf suckles from his mother every day.
08:01But she hasn't had anything to eat since she left Alaska over four months ago.
08:10And she won't feed again until she returns.
08:22Like the pregnant sea lion,
08:24this mother has to get her timing right.
08:29She must arrive in Alaska for the moment when the seas are at their richest,
08:33full of fish.
08:39Their journey north will take three months.
08:54Back in Alaska, the seas are starting to awaken.
09:16It's March, and as the sun gathers strength, winter loosens its grip.
09:24For the sea lions, things are beginning to look up.
09:29For the sea lions, things are beginning to look up.
09:36The sun is drawing life from the depths.
09:39With each passing day, the sun warms the water for longer,
09:54penetrating deep into the mineral-rich waters.
10:00Fertilizing nutrients of phosphorus and nitrogen fuel a miraculous change
10:06that is just beginning.
10:09Fertilizing nutrients of phosphorus and nitrogen fuel.
10:13Empty seas start to come to life.
10:22As we enter an enhanced view of this microscopic world,
10:26we see the beginnings of a magical transformation.
10:32Phytoplankton, tiny floating plants, emerge.
10:39Each is scarcely bigger than a speck of dust.
10:48But together, these plankton will bloom in such immense numbers
10:53that they transform lifeless seas.
10:59And whether that will happen this year is yet to be determined.
11:02All creatures here, from the sea lions to the migrating whales,
11:17ultimately depend on these miniature plants.
11:21For one creature that relies directly on the plankton,
11:29this is the moment to emerge.
11:36Pacific herring has spent the winter in the depths of the fjords,
11:39but they now rise up and head for the shallow coast.
11:45Stimulated by the sun and the warming water,
11:48they gather in their hundreds of millions.
11:51But they're not drawn here to feed.
12:00They're following an irresistible urge to breed.
12:09Groups of males sweep through the shallows
12:12and release their sperm in vast milky clouds.
12:16The females follow, covering the seabed with eggs.
12:32Such a concentration of fish
12:34is just what the sea lions have been waiting for.
12:37For it is close to the sea lions.
12:40Tatooie is an end
13:07The herring won't be here for long.
13:09The sea lions must make the most of the fishing while it lasts.
13:18Other predators gather, also hungry after the lean winter.
13:29This short-lived bounty is a magnet for millions of migrating birds.
13:37This is just the first brief course in the Great Feast.
13:54The herring spawning will be over in a matter of days,
13:58and the shoals will be finished on the first time.
14:01The herring spawning will be over in a matter of days,
14:05of days, and the shoals of fish will then scatter along the coast.
14:14The herring have spawned on an astonishing scale.
14:22They turn hundreds of miles of coastline white with spawn.
14:29In this bay alone, they have laid 800 billion eggs.
14:35The herring's spawning is so timed that when the next generation hatch in a few weeks,
14:49they'll be able to feed on the growing plankton.
14:52And this year, the herring appear to have timed it just right.
15:05The minute plant plankton, the driving force behind the sea's transformation,
15:14are starting to bloom.
15:18Great swathes of sea grow green with life.
15:21The humpbacks are still out in the middle of the Pacific.
15:35They've missed the first taste of the great feast.
15:38At just eight weeks old, the young calf must cross the biggest ocean in the world.
15:48His mother will only swim as fast as her young calf.
16:05As he tires, she supports him from beneath.
16:08She's been living off her fat reserves for the last six months,
16:26and has lost a third of her body weight.
16:44She's close to starving.
16:46It will be a further two months before mother and son reach their feeding grounds in the North Pacific.
17:02It's May, early summer in Alaska, and the days are getting ever longer.
17:18The sun continues to fuel the growth of microscopic plants that make up the plankton bloom.
17:24They're joined by a growing community of tiny animals, zooplankton.
17:43These are the first creatures to feed on the bloom.
17:54Over the coming months, they will multiply, crowding the surface waters in their trillions.
18:03The next stage of the great feast is underway.
18:06All life here depends on this plankton bloom.
18:31The herring feed on it directly.
18:34The greater the bloom, the more abundant the shoals.
18:44And the fish themselves become food for the larger hunters.
18:54But the shoals of herring are now spread far and wide.
18:57And once again, for the sea lions, the fishing is tough.
19:04They must venture further to find food.
19:09But open water is a risky place to fish.
19:18This male sea lion hunts alone.
19:22He's three meters long and a ton in weight.
19:26The smaller females travel as a group, keeping a watchful eye in all directions.
19:52They know that killers lurk in the depths.
20:04The surface is a dangerous place to linger, especially if you're alone.
20:10Orca.
20:15The sea lion is wounded, but the king is dead.
20:45Killers keep their distance.
20:50His powerful jaws are still a threat to the hungry orca.
20:58He struggles towards the safety of land.
21:11But his injuries are slowing him down.
21:15Blow by blow, they wear him down.
21:41It's a carefully coordinated attack.
21:47One killer distracts his attention while another hits his soft underside.
21:57One killer distracts his attention while another hits his soft underside.
22:09The richest seas on Earth can be treacherous.
22:31Orca attacks, although savage, have little impact on the fate of most sea lions.
22:45Their survival depends more on the tiny plankton that sustains the great shells of fish on which they feed.
23:03It's now late May.
23:14The sunlight lasts for 17 hours a day.
23:18But the bloom will need more than just sun if it's to reach its full extent.
23:37Nutrients held in these waters are continuously used up as the bloom increases.
23:46If they're exhausted too early, the plankton will die and the food chain will collapse.
23:52The effects will be felt by all.
24:02Meanwhile, on the sea lion colony, new life is now arriving.
24:09After a year carrying her pup, this mother can at last give birth.
24:14The pup is utterly dependent on his mum.
24:36As he makes sense of his new world, she encourages him to take his first feed.
24:43of milk.
24:50The mother has waited until early summer to have her baby.
24:54Such a small pup would never survive the winter.
25:01Along this coast, thousands of pups are born within a matter of weeks,
25:06timed to coincide with the better conditions that may lie ahead.
25:13The migrating humpbacks are still weeks away from Alaska and their first meal.
25:18The migrating humpbacks are still weeks away from Alaska and their first meal.
25:22The migrating humpbacks are still weeks away from Alaska and their first meal.
25:31The migrating humpbacks are still weeks away from Alaska and their first meal.
25:35The migrating humpbacks are still weeks away from Alaska and their first meal.
25:42In these turbulent seas, mother and calf must stay close.
25:46A huge Pacific storm is brewing and heading straight for the coast of British Columbia.
26:05Directly in its path lies the sea lion nursery.
26:28The pups are now at the mercy of the elements.
26:35The mothers must get their young to the safety of higher ground, if they can find it.
26:49In desperation, a mother tries to drag her pup away from the gathering tempest.
27:07The pup swept him by the deepest.
27:35A pup swept into the water is unlikely to be seen again.
28:05As the seas begin to subside, many have survived, but others have not.
28:35There's nothing this mother could have done to save her pup.
29:05These mighty storms, though devastating for some, bring fresh life to the Great Feast.
29:21When these storms hit the coast, they stir up vital nutrients into the surface waters, nutrients that feed the plankton.
29:31Replenished seas combined with the lengthening days to create a plankton explosion.
29:44And this has come just in time for those at the end of an incredible journey.
30:01The humpbacks have arrived.
30:08After 3,000 miles, mother and calf have finally made it to the coast of Alaska.
30:25They join other whales that have also made the long voyage.
30:37But their journey isn't over, for they have yet to feed.
30:42They'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.
31:00It's to these ancestral feeding grounds that the mother now guides her new calf.
31:05The unique geography of this coastline holds the final secret to this great event.
31:23Glasses have carved a landscape of deep fjords and islands over tens of thousands of years.
31:35This patchwork creates a labyrinth through which powerful ocean and tidal currents flow,
31:45bringing up the vital raw ingredients needed for the bloom.
31:50It's as if an endless supply of fertilizer is being added to the water.
31:59In other seas, the plankton would be subsiding by now.
32:02But here, the seas are repeatedly invigorated,
32:07which fuels the plankton bloom time and again throughout the summer.
32:17And with the sun at its most powerful,
32:20all these elements combine to create a plankton bloom of great intensity.
32:26In July, the ocean is alive.
32:37This floating community of plants and animals is the basis for all life here.
32:44And a bloom of this intensity signals the start of a truly great feast.
32:49Where this rich soup hits the seabed, life carpets every available surface.
33:00The feasting begins with millions of tiny mouths.
33:23Barnacles sift morsels of plankton brought in on the currents.
33:30Many of these creatures started their lives as part of the plankton
33:34before reaching adulthood and settling on the sea floor.
33:45These animals are giants.
33:47They filter the plankton-rich water,
33:50growing larger here than anywhere else in the world.
33:53jellyfish gather, forming great swarms.
34:15They too eat the plankton, rising to the surface where it is at its most abundant.
34:23The plankton bloom is so vast it radiates across the North Pacific.
34:43Blooms like these provide Earth with over half of its oxygen.
34:48This bloom eclipses even the Amazon rainforest in sheer abundance of plant life.
35:02And it is most intense where the ocean streams through the maze of coastal waterways.
35:08The shoals of herring are now at their most plentiful.
35:26After feeding through the summer months, the fish themselves are a good catch.
35:31the main target for predators now gathering here.
35:50After enduring the bitter winter,
35:52the sea lions can enjoy the bounty they've been waiting for.
36:11Hunting together, they drive the herring to the surface.
36:15the shoreline to the surface.
36:28. . . .
36:31Then, with mesmerizing grace, they pick off fish one by one.
36:36. . .
36:37. .
36:40. .
36:42For a few short weeks, they'll have their share of the Great Feast.
37:12Others arrive to feed in the coastal waterways.
37:27Pacific white-sided dolphins.
37:35They dart in and snatch fish as they go.
37:43The tidal currents now sweep herring up to the surface.
37:56Here, they're within diving range of seabirds.
37:59Myrrhs are the first to find the fish.
38:15The shoal twists and turns, trying to escape the surface dangers.
38:20But myrrhs are so fast, they can even outswim the herring.
38:36They head off the escape, making the shoal turn in on itself,
38:41creating a bait ball.
38:49The birds corral the herring into an ever tighter ball.
38:53But the commotion hasn't gone unnoticed.
39:02Gulls, ever the opportunists, are the next to turn up.
39:10They can dive no more than a meter, so the fish are still out of reach.
39:22The myrrhs only attack from beneath, trapping the fish against the surface.
39:38But they push the herring within range of the gulls.
39:41It's a feeding frenzy.
39:58The table is set for the mightiest predator of them all.
40:15The humpbacks have reached their feeding grounds.
40:33After six months without a bite to eat, the humpbacks can finally break their fast.
40:38The whales have learned to target these ready-made balls of fish.
40:59But they'll need more than just a mouthful.
41:10And with the feast now in full swing, this is their chance.
41:21To exploit the vast shoals of herring that are in deeper water, they rely on teamwork.
41:26For these whales have developed a truly remarkable way of hunting.
41:50The inlets echo to the sound of a mysterious song.
41:56A curtain of bubbles and a haunting call hold the secret to an ingenious way of fishing.
42:26This is bubblenet feeding.
42:46A dozen whales work together to harvest the herring bonanza.
42:56Such fishing requires an extraordinary level of intelligence and cooperation.
43:11The lead whale dives first.
43:13It's the bubble blower.
43:18It's her job to find the fish.
43:24The rest follow in formation.
43:33Each takes exactly the same position in every lunge.
43:37Once she's located the fish, the leader blows a net of bubbles that completely encircles the shovel.
43:53Another whale calls to synchronize the group.
44:23It's her job to find the same position in every lunge.
44:26Panicked by the eerie sound and the blinding bubbles, the fish won't cross this fizzing kerb.
44:32The fish won't cross this fizzing kerb.
44:32All right.
44:33All right.
44:42Good morning.
44:43We'll do it.
44:43We'll do it.
44:50Good morning.
45:21As few as a hundred humpbacks have learned how to feed as a team like this.
45:40And this is the only place on the planet where whales fish in this way.
45:51At the height of the great feast, these humpbacks fish around the clock, each eating a tonne of herring a day.
46:10Only man has learned to exploit the seas on a greater scale.
46:15As the summer ends, the feast draws to a close.
46:35The sun is weakening, and with it, the plankton blooms subsides.
46:50The microscopic plants that brought life to empty seas begin to die.
46:56The herring descend to spend the winter in the depths.
47:14Life for the sea lions will be harder once again.
47:18But they fed well enough to face the dark days ahead.
47:26The humpback whales will soon leave these shores.
47:45It's astonishing to think that some of our world's mightiest creatures ultimately rely on some of its tiniest.
47:59Here, along the north Pacific coast, the interplay between land, sea, and sun has produced a bloom of plankton so immense
48:18it has created one of nature's great events.
48:22The wind has formed.
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