1
00:00:01,400 --> 00:00:04,433
{\an8}♪♪♪
2
00:00:09,233 --> 00:00:13,066
{\an1}NARRATOR: Alone, a single fish
may be insignificant.
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00:00:16,233 --> 00:00:20,800
{\an1}But together, they can hold
the fate of an entire coastline.
4
00:00:24,066 --> 00:00:26,742
In the deep,
billions of sardines
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00:00:26,766 --> 00:00:29,609
{\an1}begin a mass migration...
6
00:00:29,633 --> 00:00:33,676
Sparked by a whisper
of cool water.
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00:00:33,700 --> 00:00:38,876
{\an1}It's the largest movement
of living things on Earth.
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00:00:38,900 --> 00:00:43,042
{\an1}And it's about to become
nature's greatest ambush.
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00:00:43,066 --> 00:00:48,276
{\an8}♪♪♪
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00:00:48,300 --> 00:00:52,233
{\an1}Every predator along the coast
is counting on this event...
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00:00:54,300 --> 00:00:57,366
{\an1}...to feast on the abundance
the sardines bring...
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00:01:03,200 --> 00:01:06,042
{\an1}...before they slip away
into the deep.
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{\an8}♪♪♪
14
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[ Waves crashing, wind blowing ]
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NARRATOR:
Off the southern tip of Africa,
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00:01:56,400 --> 00:02:01,033
{\an1}the frigid South Atlantic mixes
with the milder Indian ocean.
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00:02:03,566 --> 00:02:07,209
{\an1}The waters are cold and rich
with plankton,
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00:02:07,233 --> 00:02:10,133
fed by upwellings
from the mighty Atlantic.
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00:02:13,033 --> 00:02:16,476
Perfect conditions
for a tiny fish to thrive.
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00:02:16,500 --> 00:02:23,342
{\an8}♪♪♪
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00:02:23,366 --> 00:02:27,809
{\an1}Sardines by the billions
live here year-round,
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00:02:27,833 --> 00:02:30,776
{\an1}swimming and feeding together
in loose shoals
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00:02:30,800 --> 00:02:33,600
{\an1}of hundreds of thousands
of individuals.
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00:02:35,866 --> 00:02:40,809
{\an1}Then in late April, ocean
currents undergo a subtle shift.
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00:02:40,833 --> 00:02:47,242
{\an8}♪♪♪
26
00:02:47,266 --> 00:02:49,442
{\an7}As the southern winter
approaches,
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{\an7}upwellings and eddies force
a tendril of cold water
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00:02:53,033 --> 00:02:56,442
{\an8}toward the east.
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00:02:56,466 --> 00:03:00,142
{\an7}The warm Agulhas Current
moves further offshore,
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00:03:00,166 --> 00:03:03,433
{\an7}allowing the cold stream
to gain momentum.
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00:03:05,833 --> 00:03:08,976
{\an7}The cold-water sardines
instinctively cluster
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00:03:09,000 --> 00:03:10,842
{\an7}in the chillier current.
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00:03:10,866 --> 00:03:16,109
{\an8}♪♪♪
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00:03:16,133 --> 00:03:20,209
150 miles out to sea,
on the Agulhas Banks,
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00:03:20,233 --> 00:03:22,800
schools begin to mass
together...
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00:03:24,566 --> 00:03:29,166
{\an1}...until they form a mega shoal
20 miles long.
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00:03:32,466 --> 00:03:34,709
{\an1}Then the single superorganism
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00:03:34,733 --> 00:03:37,476
pours
into the cold-water highway
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00:03:37,500 --> 00:03:40,400
toward the coast
and shallower water.
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00:03:44,000 --> 00:03:47,676
{\an1}It's the biggest biomass
migration on the planet,
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00:03:47,700 --> 00:03:52,209
{\an1}exceeding the great herds
of the Serengeti.
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00:03:52,233 --> 00:03:57,976
{\an1}Yet, exactly why they do it
remains a mystery.
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00:03:58,000 --> 00:04:01,666
{\an1}The journey serves no apparent
benefit to the fish.
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00:04:04,233 --> 00:04:07,309
{\an1}It will inevitably dead-end
in a warm sea,
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00:04:07,333 --> 00:04:09,500
{\an1}unsuitable for sardines.
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00:04:11,333 --> 00:04:14,376
How far they travel
depends entirely on the vagaries
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00:04:14,400 --> 00:04:16,600
{\an1}of this year's cold current.
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00:04:18,666 --> 00:04:20,242
{\an1}But one thing is certain...
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00:04:20,266 --> 00:04:24,600
{\an1}an entire food web is counting
on the sardines to make the run.
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00:04:28,766 --> 00:04:32,076
[ Birds squawking ]
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00:04:32,100 --> 00:04:35,800
{\an1}Some predators will follow
the shoal for weeks.
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00:04:37,033 --> 00:04:40,966
{\an1}Others wait for the feast
to pass close to shore.
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00:04:41,966 --> 00:04:45,466
{\an1}Some even race hundreds of miles
to intercept it.
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00:04:54,600 --> 00:04:57,842
{\an1}To the multitude, this year's
sardine run can mean
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00:04:57,866 --> 00:05:01,866
{\an1}the difference between
abundance and deprivation.
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00:05:04,000 --> 00:05:06,800
All are at the mercy
of the current.
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00:05:12,000 --> 00:05:15,276
{\an1}If the water temperature
stays below 70 degrees,
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00:05:15,300 --> 00:05:18,209
{\an1}the sardines could travel
1,000 miles
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00:05:18,233 --> 00:05:20,933
up the Eastern coast
of South Africa.
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00:05:22,333 --> 00:05:24,876
But if the tendril
of cold water fades,
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00:05:24,900 --> 00:05:29,576
{\an1}the shoals will turn, disperse,
or disappear into the deep.
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{\an8}♪♪♪
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00:05:38,633 --> 00:05:40,676
The coastline waits.
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00:05:40,700 --> 00:05:45,209
{\an8}♪♪♪
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00:05:45,233 --> 00:05:48,409
{\an1}The first hazard for the fish
lies just 100 miles
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00:05:48,433 --> 00:05:50,342
{\an1}from the sardine's home turf...
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00:05:50,366 --> 00:05:55,842
{\an8}♪♪♪
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00:05:55,866 --> 00:05:59,833
{\an1}...a colony of some 4,000
Cape fur seals.
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00:06:01,900 --> 00:06:03,509
{\an1}They're local predators,
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00:06:03,533 --> 00:06:06,233
{\an1}patrolling the shallows
close to shore.
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00:06:11,600 --> 00:06:14,766
The pups need milk
every four hours...
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00:06:17,100 --> 00:06:19,600
{\an1}...so moms can't go far to hunt.
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00:06:27,400 --> 00:06:29,576
{\an1}And they're reluctant to leave
the safety
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00:06:29,600 --> 00:06:31,633
{\an1}of coastal kelp forests.
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00:06:34,100 --> 00:06:36,276
The towering plants
offer protection
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00:06:36,300 --> 00:06:38,400
{\an1}from great white sharks.
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00:06:40,533 --> 00:06:43,309
{\an1}If the seals are to feast
on sardines,
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00:06:43,333 --> 00:06:47,142
they need the shoals
to come to them.
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00:06:47,166 --> 00:06:52,776
{\an1}Mothers depend on the oily fish
to fuel their milk supply.
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00:06:52,800 --> 00:06:55,666
{\an1}And they're already pregnant
with next year's baby...
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00:07:03,100 --> 00:07:06,366
{\an1}...a precarious position
when your food source is fickle.
82
00:07:10,666 --> 00:07:14,176
{\an1}The colony is crowded.
83
00:07:14,200 --> 00:07:16,366
{\an1}Pups cling to mothers.
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00:07:18,233 --> 00:07:19,242
[ Seals barking ]
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00:07:19,266 --> 00:07:20,900
Tempers fray.
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00:07:28,100 --> 00:07:31,300
{\an1}But this year, the sea delivers.
87
00:07:35,233 --> 00:07:38,176
{\an1}The cold current pushes clouds
of zooplankton
88
00:07:38,200 --> 00:07:41,433
toward the coast
and the seal colony.
89
00:07:44,200 --> 00:07:46,500
The little fish
follow their food...
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00:07:50,266 --> 00:07:52,942
{\an1}...directly into the kelp beds.
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00:07:52,966 --> 00:08:00,966
{\an8}♪♪♪
92
00:08:01,233 --> 00:08:04,076
For the seals,
it's the moment of the year.
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00:08:04,100 --> 00:08:12,100
{\an8}♪♪♪
94
00:08:12,933 --> 00:08:16,876
{\an1}Their front flippers are large
and incredibly powerful.
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00:08:16,900 --> 00:08:20,942
{\an8}♪♪♪
96
00:08:20,966 --> 00:08:25,409
{\an1}Like paddles, they propel
the seals at 15 miles per hour.
97
00:08:25,433 --> 00:08:31,742
{\an8}♪♪♪
98
00:08:31,766 --> 00:08:35,876
{\an1}And they provide control when
maneuverability matters most.
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00:08:35,900 --> 00:08:43,900
{\an8}♪♪♪
100
00:09:09,566 --> 00:09:12,076
{\an1}Every seal cooperates.
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00:09:12,100 --> 00:09:19,909
{\an8}♪♪♪
102
00:09:19,933 --> 00:09:22,366
{\an1}The seals swallow fish whole...
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00:09:24,766 --> 00:09:27,209
{\an1}...even when they're underwater.
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00:09:27,233 --> 00:09:35,233
{\an8}♪♪♪
105
00:09:49,933 --> 00:09:55,142
{\an1}In the onslaught, the sardines
school in an ever tighter mass.
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00:09:55,166 --> 00:09:58,509
{\an1}It's a proven defense.
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00:09:58,533 --> 00:10:01,309
{\an1}Every fish is equipped
with a lateral line...
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00:10:01,333 --> 00:10:05,033
{\an1}sensory cells in its head,
trunk, and tail.
109
00:10:06,466 --> 00:10:09,442
{\an1}It's sensitive enough to pick up
the slightest change
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00:10:09,466 --> 00:10:11,100
in water pressure.
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00:10:14,133 --> 00:10:17,009
When a fish feels
its neighbor move,
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00:10:17,033 --> 00:10:19,866
{\an1}it instantly responds in kind.
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00:10:21,300 --> 00:10:26,209
{\an1}Millions of tiny, synchronized
movements combine into one,
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00:10:26,233 --> 00:10:29,142
{\an1}forming a superorganism
that shape-shifts
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00:10:29,166 --> 00:10:31,533
{\an1}and slips just out of reach.
116
00:10:35,600 --> 00:10:38,576
{\an1}The assault by thousands
of hungry seals
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00:10:38,600 --> 00:10:41,266
barely makes a dent
in the giant shoal.
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00:10:43,733 --> 00:10:46,342
{\an1}The sardines make their getaway
up the coast,
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00:10:46,366 --> 00:10:48,200
{\an1}and the seals don't follow.
120
00:10:50,566 --> 00:10:53,133
They need to get back
to their hungry pups.
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00:10:56,166 --> 00:11:00,009
{\an1}The shoal always stays
in the cold current,
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00:11:00,033 --> 00:11:02,666
{\an1}covering up to 40 miles a day.
123
00:11:05,800 --> 00:11:09,733
{\an1}Now the females drop eggs
as they move up the coast...
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00:11:11,466 --> 00:11:12,942
{\an1}...prompting some to suggest
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00:11:12,966 --> 00:11:16,942
that this is
an annual spawning run.
126
00:11:16,966 --> 00:11:20,933
{\an1}Others say it's simply
driven by wind and cold water.
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00:11:22,966 --> 00:11:27,200
{\an1}With each mile, the water grows
imperceptibly warmer.
128
00:11:29,966 --> 00:11:33,109
There's no telling
where or when,
129
00:11:33,133 --> 00:11:36,676
but the cold current
will eventually dissipate.
130
00:11:36,700 --> 00:11:41,742
{\an8}♪♪♪
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00:11:41,766 --> 00:11:45,909
{\an1}For now, it remains strong,
impelling the fish onward.
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00:11:45,933 --> 00:11:53,933
{\an8}♪♪♪
133
00:12:07,600 --> 00:12:11,633
{\an1}By early May, the sardines
approach another landmark...
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00:12:13,666 --> 00:12:16,566
400 miles east
of the seal colony.
135
00:12:20,333 --> 00:12:21,942
Bird Island.
136
00:12:21,966 --> 00:12:24,133
[ Birds squawking ]
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00:12:28,000 --> 00:12:31,733
{\an1}It's the world's biggest colony
of Cape gannets.
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00:12:34,533 --> 00:12:36,342
For three months,
the birds have been
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00:12:36,366 --> 00:12:38,576
{\an1}feeding their growing chicks.
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00:12:38,600 --> 00:12:43,476
{\an8}♪♪♪
141
00:12:43,500 --> 00:12:46,009
They may be fierce
ocean predators,
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00:12:46,033 --> 00:12:48,409
but they're also
devoted parents.
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00:12:48,433 --> 00:12:54,176
{\an8}♪♪♪
144
00:12:54,200 --> 00:12:55,476
They're monogamous,
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00:12:55,500 --> 00:12:58,609
always returning
to the same nest.
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00:12:58,633 --> 00:13:00,733
[ Birds squawking ]
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00:13:03,100 --> 00:13:04,509
It's crowded.
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00:13:04,533 --> 00:13:07,542
{\an1}That means competition
for real estate...
149
00:13:07,566 --> 00:13:09,200
and food.
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00:13:16,766 --> 00:13:20,442
{\an1}With over 200,000 birds
in the colony,
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00:13:20,466 --> 00:13:25,100
{\an1}they need 9,000 tons of fish
in one breeding season.
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00:13:36,033 --> 00:13:39,042
{\an1}The gannets have pinned
their entire breeding cycle
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00:13:39,066 --> 00:13:42,366
on the unpredictable
arrival of sardines.
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00:13:44,100 --> 00:13:50,376
{\an8}♪♪♪
155
00:13:50,400 --> 00:13:54,233
{\an1}Scouts return with full bellies
and good news.
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00:13:56,600 --> 00:13:58,576
The fish are coming.
157
00:13:58,600 --> 00:14:03,842
{\an8}♪♪♪
158
00:14:03,866 --> 00:14:07,966
{\an1}The sardine superorganism
is 20 miles offshore...
159
00:14:10,666 --> 00:14:13,576
{\an1}...within striking distance
of the colony.
160
00:14:13,600 --> 00:14:21,600
{\an8}♪♪♪
161
00:14:26,300 --> 00:14:30,542
{\an1}The birds appear awkward
on the ground, even comical.
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00:14:30,566 --> 00:14:35,476
{\an1}But once they achieve air speed,
they are all grace and danger.
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00:14:35,500 --> 00:14:43,500
{\an8}♪♪♪
164
00:15:02,500 --> 00:15:05,200
{\an1}They soar 100 feet in the air.
165
00:15:07,433 --> 00:15:10,542
They scan the shoal
with binocular vision...
166
00:15:10,566 --> 00:15:18,566
{\an8}♪♪♪
167
00:15:26,000 --> 00:15:27,633
{\an1}...lock on to a target...
168
00:15:29,700 --> 00:15:32,642
then dive.
169
00:15:32,666 --> 00:15:36,742
{\an8}♪♪♪
170
00:15:36,766 --> 00:15:40,676
Gannets hit the water
at 60 miles per hour.
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00:15:40,700 --> 00:15:48,700
{\an8}♪♪♪
172
00:15:49,333 --> 00:15:52,542
Muscles lock their
neck vertebrae into place.
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00:15:52,566 --> 00:16:00,566
{\an8}♪♪♪
174
00:16:01,200 --> 00:16:04,709
{\an1}Airbags in the face and chest
absorb impact.
175
00:16:04,733 --> 00:16:12,733
{\an8}♪♪♪
176
00:16:16,133 --> 00:16:20,309
{\an1}The sardines swim deeper
to escape,
177
00:16:20,333 --> 00:16:23,100
{\an1}but the birds' momentum
carries them down...
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00:16:26,800 --> 00:16:30,576
{\an1}...30 feet underwater.
179
00:16:30,600 --> 00:16:33,442
{\an1}If a gannet misses the target,
it holds its breath
180
00:16:33,466 --> 00:16:37,209
{\an1}and paddles, penguin-like,
for a second grab.
181
00:16:37,233 --> 00:16:45,233
{\an8}♪♪♪
182
00:17:02,866 --> 00:17:05,842
{\an1}This first hunt is all
for the youngsters.
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00:17:05,866 --> 00:17:08,076
{\an1}Gannet parents load up
their gizzards
184
00:17:08,100 --> 00:17:11,166
{\an1}and return at high speed
to Bird Island.
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00:17:27,833 --> 00:17:31,900
Every parent knows
exactly where to find its chick.
186
00:17:45,600 --> 00:17:52,576
{\an8}♪♪♪
187
00:17:52,600 --> 00:17:55,200
{\an1}The food cargo is precious.
188
00:17:58,066 --> 00:18:01,309
A healthy sardine run
means more young gannets
189
00:18:01,333 --> 00:18:03,442
{\an1}are given a chance to survive.
190
00:18:03,466 --> 00:18:07,542
{\an8}♪♪♪
191
00:18:07,566 --> 00:18:09,177
{\an1}But
192
00:18:07,566 --> 00:18:10,833
is the fledglings'
last free meal.
193
00:18:09,201 --> 00:18:13,666
this
194
00:18:13,666 --> 00:18:17,766
{\an1}The parent birds will leave them
forever and follow the shoals.
195
00:18:21,033 --> 00:18:22,709
{\an1}Any gannet that wants to eat
196
00:18:22,733 --> 00:18:25,776
must get on the wing
and follow the fish.
197
00:18:25,800 --> 00:18:29,842
{\an8}♪♪♪
198
00:18:29,866 --> 00:18:33,009
This is motivation
for the chicks to fly.
199
00:18:33,033 --> 00:18:39,809
{\an8}♪♪♪
200
00:18:39,833 --> 00:18:43,109
{\an1}The hungrier they get,
the harder they try.
201
00:18:43,133 --> 00:18:51,133
{\an8}♪♪♪
202
00:18:52,633 --> 00:18:54,542
{\an1}The learning curve is steep,
203
00:18:54,566 --> 00:18:57,576
against howling wind
and rough seas.
204
00:18:57,600 --> 00:19:05,600
{\an8}♪♪♪
205
00:19:11,166 --> 00:19:14,466
{\an1}Crash-landing in the waves
is their first pitfall...
206
00:19:22,466 --> 00:19:25,900
but the wild surf
is not the real danger.
207
00:19:28,300 --> 00:19:31,376
Fur seals hunt
these shores, too.
208
00:19:31,400 --> 00:19:39,400
{\an8}♪♪♪
209
00:20:22,300 --> 00:20:25,176
Fledglings don't have
the strength or experience
210
00:20:25,200 --> 00:20:26,776
for a water take-off.
211
00:20:26,800 --> 00:20:31,509
{\an8}♪♪♪
212
00:20:31,533 --> 00:20:33,976
{\an1}Soaked feathers weigh them down.
213
00:20:34,000 --> 00:20:42,000
{\an8}♪♪♪
214
00:21:09,000 --> 00:21:13,142
{\an1}Just as the gannets exacted
their toll on the sardines,
215
00:21:13,166 --> 00:21:17,376
the bird colony
now suffers its own losses.
216
00:21:17,400 --> 00:21:25,400
{\an8}♪♪♪
217
00:21:59,100 --> 00:22:03,600
{\an1}The lucky ones must dry
their feathers and try again.
218
00:22:06,100 --> 00:22:10,142
{\an1}They can't miss out on the first
sardine hunt of their lives.
219
00:22:10,166 --> 00:22:18,166
{\an8}♪♪♪
220
00:22:45,700 --> 00:22:49,600
{\an1}The sardines move east
at 6 miles per hour.
221
00:22:52,200 --> 00:22:55,900
{\an1}They're approaching the first
real crux of their journey.
222
00:22:59,300 --> 00:23:04,009
{\an7}600 miles into the run,
the coastline bends north,
223
00:23:04,033 --> 00:23:06,800
{\an7}and the continental shelf
starts to narrow.
224
00:23:09,200 --> 00:23:12,576
{\an7}Their cold-water ribbon
is pinched against the coast
225
00:23:12,600 --> 00:23:15,266
{\an7}by warm offshore currents.
226
00:23:16,933 --> 00:23:19,076
Billions of sardines
must squeeze
227
00:23:19,100 --> 00:23:21,766
into the cold
but narrowing channel.
228
00:23:25,533 --> 00:23:28,942
{\an1}The shoal is stretched longer
and thinner.
229
00:23:28,966 --> 00:23:31,209
{\an1}The fish pack tighter together.
230
00:23:31,233 --> 00:23:37,809
{\an8}♪♪♪
231
00:23:37,833 --> 00:23:42,266
{\an1}This current delivers them to
a place called the Wild Coast.
232
00:23:44,300 --> 00:23:49,342
{\an1}It's a 200-mile stretch...
A pristine, untouched transition
233
00:23:49,366 --> 00:23:52,442
between temperate
and tropical biomes.
234
00:23:52,466 --> 00:23:58,509
{\an8}♪♪♪
235
00:23:58,533 --> 00:24:01,509
It's not only a mix
of water temperatures,
236
00:24:01,533 --> 00:24:05,466
{\an1}it's also a crossroads
for myriad species.
237
00:24:06,766 --> 00:24:10,142
{\an1}It's June and humpback whales
pass from Antarctica
238
00:24:10,166 --> 00:24:12,309
to breeding grounds
farther north.
239
00:24:12,333 --> 00:24:19,842
{\an8}♪♪♪
240
00:24:19,866 --> 00:24:22,242
{\an1}Others live here all year round.
241
00:24:22,266 --> 00:24:30,266
{\an8}♪♪♪
242
00:24:37,266 --> 00:24:41,909
{\an1}50 miles ahead of the shoal,
resident bottlenose dolphins
243
00:24:41,933 --> 00:24:43,800
{\an1}relish winter's arrival.
244
00:24:49,933 --> 00:24:54,100
{\an1}Dolphins live in social groups
of about 25 members.
245
00:24:58,533 --> 00:25:02,766
{\an1}Their play reveals why
they're such formidable hunters.
246
00:25:06,933 --> 00:25:10,042
They're fast, they communicate,
247
00:25:10,066 --> 00:25:11,966
{\an1}and they move as a unit.
248
00:25:14,666 --> 00:25:17,733
{\an1}A real-life sardine nemesis.
249
00:25:19,466 --> 00:25:22,642
And this resident pod
is just the advance guard
250
00:25:22,666 --> 00:25:24,833
{\an1}for an even greater army.
251
00:25:30,500 --> 00:25:34,742
{\an8}♪♪♪
252
00:25:34,766 --> 00:25:36,676
Common dolphins.
253
00:25:36,700 --> 00:25:44,700
{\an8}♪♪♪
254
00:25:44,733 --> 00:25:47,609
{\an1}They spend most of their lives
in warmer waters
255
00:25:47,633 --> 00:25:50,942
along the coast.
256
00:25:50,966 --> 00:25:54,866
{\an1}This time of year, their calves
are just beginning to hunt.
257
00:25:57,333 --> 00:26:01,633
{\an1}Mothers need to wean them before
next spring's breeding season.
258
00:26:03,333 --> 00:26:06,509
{\an1}A glut of fish would be
a crucial windfall.
259
00:26:06,533 --> 00:26:11,109
{\an8}♪♪♪
260
00:26:11,133 --> 00:26:15,976
There's no guarantee
the sardine run will reach them.
261
00:26:16,000 --> 00:26:18,342
So they come to it.
262
00:26:18,366 --> 00:26:24,042
{\an8}♪♪♪
263
00:26:24,066 --> 00:26:28,976
{\an1}As they head south, hundreds
of small family pods converge.
264
00:26:29,000 --> 00:26:37,000
{\an8}♪♪♪
265
00:26:41,366 --> 00:26:44,309
A dolphin super pod
begins to form,
266
00:26:44,333 --> 00:26:47,076
{\an1}streaming to intercept
the shoal.
267
00:26:47,100 --> 00:26:55,100
{\an8}♪♪♪
268
00:26:57,066 --> 00:27:02,609
{\an1}100 miles to the south, the fish
pour along the Wild Coast...
269
00:27:02,633 --> 00:27:04,900
{\an1}unaware of what lies ahead.
270
00:27:06,933 --> 00:27:10,409
{\an1}As the narrowing current
pushes them to the shallows,
271
00:27:10,433 --> 00:27:13,742
the shoal fragments.
272
00:27:13,766 --> 00:27:19,542
{\an1}Smaller, isolated bait balls
offer a new opportunity...
273
00:27:19,566 --> 00:27:21,142
for sharks.
274
00:27:21,166 --> 00:27:26,942
{\an8}♪♪♪
275
00:27:26,966 --> 00:27:30,209
{\an1}These migratory blacktips
and dusky sharks
276
00:27:30,233 --> 00:27:33,933
have moved down from
the warmer waters farther north.
277
00:27:36,066 --> 00:27:38,342
{\an1}Little is known of their lives,
278
00:27:38,366 --> 00:27:41,376
but shark nurseries
have been discovered nearby,
279
00:27:41,400 --> 00:27:42,842
{\an1}suggesting that the sharks...
280
00:27:42,866 --> 00:27:44,942
Like other creatures
along the coast...
281
00:27:44,966 --> 00:27:48,566
{\an1}may time their breeding cycle
to the sardine run.
282
00:27:52,300 --> 00:27:56,233
Tiny fish face off
with dozens of sharks.
283
00:27:59,700 --> 00:28:03,776
{\an1}It seems an unfair match...
284
00:28:03,800 --> 00:28:07,009
{\an1}but the sardines launch
their schooling defense.
285
00:28:07,033 --> 00:28:15,033
{\an8}♪♪♪
286
00:28:17,933 --> 00:28:22,233
{\an1}As the sharks move, they send a
pressure wave through the water.
287
00:28:23,766 --> 00:28:27,533
{\an1}The fish detect it through
their sensitive lateral lines.
288
00:28:30,966 --> 00:28:33,476
Just one moves out
of harm's way,
289
00:28:33,500 --> 00:28:36,409
and every fish
around it follows.
290
00:28:36,433 --> 00:28:42,576
{\an8}♪♪♪
291
00:28:42,600 --> 00:28:44,709
{\an1}It's incredibly effective.
292
00:28:44,733 --> 00:28:51,176
{\an8}♪♪♪
293
00:28:51,200 --> 00:28:54,242
{\an1}The sharks simply can't turn
and bite quick enough.
294
00:28:54,266 --> 00:29:02,266
{\an8}♪♪♪
295
00:29:13,200 --> 00:29:16,076
{\an1}The predators change tactics.
296
00:29:16,100 --> 00:29:24,100
{\an8}♪♪♪
297
00:29:24,233 --> 00:29:27,809
{\an1}With sudden bursts of speed,
they try and carve the shoal
298
00:29:27,833 --> 00:29:30,166
{\an1}into even smaller balls...
299
00:29:33,066 --> 00:29:35,809
{\an1}...but they just don't
coordinate enough.
300
00:29:35,833 --> 00:29:43,833
{\an8}♪♪♪
301
00:29:45,400 --> 00:29:49,109
{\an1}A school of 60-pound tuna
gets in on the action.
302
00:29:49,133 --> 00:29:53,176
{\an8}♪♪♪
303
00:29:53,200 --> 00:29:55,909
{\an1}Normally the sharks hunt tuna,
304
00:29:55,933 --> 00:29:59,100
{\an1}but they seem to know help
when they see it.
305
00:30:00,300 --> 00:30:04,376
The smaller tuna
are much more agile.
306
00:30:04,400 --> 00:30:08,709
{\an1}Within seconds, they slice
a bait ball from the shoal
307
00:30:08,733 --> 00:30:10,742
{\an1}and trap it against the surface,
308
00:30:10,766 --> 00:30:13,209
where it's easier
for everyone to feed.
309
00:30:13,233 --> 00:30:21,233
{\an8}♪♪♪
310
00:30:37,800 --> 00:30:41,876
Game fish and sharks
enjoy a temporary truce
311
00:30:41,900 --> 00:30:44,442
{\an1}as they feast on the same prey.
312
00:30:44,466 --> 00:30:52,466
{\an8}♪♪♪
313
00:31:34,166 --> 00:31:36,742
{\an1}The main shoal flees north,
314
00:31:36,766 --> 00:31:40,533
{\an1}leaving this fragment behind
to be obliterated.
315
00:32:00,033 --> 00:32:02,776
{\an1}Even the gulls get their share.
316
00:32:02,800 --> 00:32:10,800
{\an8}♪♪♪
317
00:32:25,733 --> 00:32:30,376
{\an8}♪♪♪
318
00:32:30,400 --> 00:32:34,433
{\an1}The mega shoal is now way
out of its home habitat.
319
00:32:36,533 --> 00:32:40,676
As long as it's cold,
they swim blindly along.
320
00:32:40,700 --> 00:32:43,842
{\an1}They're heading toward a feature
of the South African coast
321
00:32:43,866 --> 00:32:46,676
{\an1}that will prove the most
consequential milestone
322
00:32:46,700 --> 00:32:50,176
of their journey...
323
00:32:50,200 --> 00:32:53,809
A sandstone buttress
called Waterfall Bluff.
324
00:32:53,833 --> 00:33:00,709
{\an8}♪♪♪
325
00:33:00,733 --> 00:33:04,776
{\an1}This rocky promontory shoves
the cold current eastward
326
00:33:04,800 --> 00:33:07,876
{\an1}to collide with the warm water
just offshore.
327
00:33:07,900 --> 00:33:15,900
{\an8}♪♪♪
328
00:33:17,233 --> 00:33:23,009
{\an1}Some years the cold water
can blast beyond this point...
329
00:33:23,033 --> 00:33:24,509
but not this year.
330
00:33:24,533 --> 00:33:27,500
{\an1}The vital current thins
to a trickle.
331
00:33:30,666 --> 00:33:35,033
{\an1}The sardines follow into
the bottleneck as if spellbound.
332
00:33:37,466 --> 00:33:40,909
{\an1}Every single fish follows
the same mission...
333
00:33:40,933 --> 00:33:43,842
Stick with the school
and stay in the middle.
334
00:33:43,866 --> 00:33:46,076
{\an1}But in the fading current,
335
00:33:46,100 --> 00:33:50,276
{\an1}the already fractured shoal
breaks up even further.
336
00:33:50,300 --> 00:33:54,309
{\an1}Small schools follow shifting
pockets of cool water
337
00:33:54,333 --> 00:33:55,966
into oblivion.
338
00:34:00,000 --> 00:34:02,976
{\an1}The great journey stalls
for the fish
339
00:34:03,000 --> 00:34:06,376
and conditions align
for every predator.
340
00:34:06,400 --> 00:34:10,409
{\an8}♪♪♪
341
00:34:10,433 --> 00:34:13,900
A familiar enemy has
trailed them all this way.
342
00:34:16,000 --> 00:34:18,809
Some gannets will fly
for 24 hours
343
00:34:18,833 --> 00:34:22,009
{\an1}to intercept the bottleneck...
344
00:34:22,033 --> 00:34:25,433
{\an1}and there are plenty more
roosting on the nearby coast.
345
00:34:28,033 --> 00:34:30,842
It's a true test
for the rookies.
346
00:34:30,866 --> 00:34:35,876
{\an8}♪♪♪
347
00:34:35,900 --> 00:34:38,366
The sharks are back
for more, too.
348
00:34:42,166 --> 00:34:45,442
{\an1}Until now, the sardines
have managed to slough off
349
00:34:45,466 --> 00:34:49,909
small bait balls
as sacrificial decoys.
350
00:34:49,933 --> 00:34:53,966
{\an1}But now they're more vulnerable
than they've ever been.
351
00:34:56,900 --> 00:34:59,409
{\an1}The high-flying gannets
are the first to spot
352
00:34:59,433 --> 00:35:01,076
a stalling shoal.
353
00:35:01,100 --> 00:35:05,676
{\an8}♪♪♪
354
00:35:05,700 --> 00:35:08,042
The birds stand out
against the sky
355
00:35:08,066 --> 00:35:11,742
like a homing beacon,
guiding in an army.
356
00:35:11,766 --> 00:35:15,776
{\an8}♪♪♪
357
00:35:15,800 --> 00:35:17,800
{\an1}It's the dolphin super pod...
358
00:35:21,200 --> 00:35:25,309
{\an1}...now grown to 20,000 strong.
359
00:35:25,333 --> 00:35:33,333
{\an8}♪♪♪
360
00:35:54,366 --> 00:35:57,809
The sardines now face
an unprecedented assault
361
00:35:57,833 --> 00:36:01,409
from a fleet
of swift ocean-going hunters...
362
00:36:01,433 --> 00:36:08,076
{\an8}♪♪♪
363
00:36:08,100 --> 00:36:12,076
{\an1}...and a far-flung deadly
air force assembling above.
364
00:36:12,100 --> 00:36:20,100
{\an8}♪♪♪
365
00:36:52,833 --> 00:36:56,609
The sardines turn
to the only defense they know...
366
00:36:56,633 --> 00:36:59,776
Schooling up
as tight as they can.
367
00:36:59,800 --> 00:37:03,976
{\an8}♪♪♪
368
00:37:04,000 --> 00:37:06,809
{\an1}One moves, and they all move.
369
00:37:06,833 --> 00:37:13,433
{\an8}♪♪♪
370
00:37:16,466 --> 00:37:22,209
{\an8}♪♪♪
371
00:37:22,233 --> 00:37:24,866
{\an1}But the dolphins are prepared
for this.
372
00:37:28,866 --> 00:37:32,376
{\an1}Their goal is to prevent
the shoal from diving deep.
373
00:37:32,400 --> 00:37:37,776
{\an8}♪♪♪
374
00:37:37,800 --> 00:37:41,766
{\an1}They coordinate their efforts,
blocking the sardines' evasion.
375
00:37:44,833 --> 00:37:46,242
{\an1}With surgical precision,
376
00:37:46,266 --> 00:37:49,276
they slice balls away
from the main shoal.
377
00:37:49,300 --> 00:37:57,142
{\an8}♪♪♪
378
00:37:57,166 --> 00:38:01,476
{\an1}They blow bubbles to corral any
fish that tries to break form...
379
00:38:01,500 --> 00:38:07,442
{\an8}♪♪♪
380
00:38:07,466 --> 00:38:10,733
{\an1}...forcing the fish tighter
and tighter together.
381
00:38:12,166 --> 00:38:14,309
{\an1}Every fish instinctively
tries to get
382
00:38:14,333 --> 00:38:16,033
{\an1}into the middle of the pack.
383
00:38:18,266 --> 00:38:22,109
{\an1}But now exhausted gills
struggle to suck oxygen
384
00:38:22,133 --> 00:38:24,042
from turbulent water.
385
00:38:24,066 --> 00:38:32,066
{\an8}♪♪♪
386
00:38:39,200 --> 00:38:43,933
{\an1}Ball after ball is dissected
from the shoal and obliterated.
387
00:38:45,700 --> 00:38:48,409
The dolphins get
what they've waited for.
388
00:38:48,433 --> 00:38:56,433
{\an8}♪♪♪
389
00:39:24,600 --> 00:39:26,876
{\an1}The toll is exponential.
390
00:39:26,900 --> 00:39:31,409
{\an8}♪♪♪
391
00:39:31,433 --> 00:39:34,809
{\an1}The dolphins are so effective
at herding the fish
392
00:39:34,833 --> 00:39:38,342
{\an1}that every other predator
is also more successful.
393
00:39:38,366 --> 00:39:46,366
{\an8}♪♪♪
394
00:40:09,200 --> 00:40:12,009
{\an1}As the fish are driven
to the surface,
395
00:40:12,033 --> 00:40:15,442
{\an1}gannets get easy access.
396
00:40:15,466 --> 00:40:23,466
{\an8}♪♪♪
397
00:41:12,733 --> 00:41:16,209
{\an1}Dark fledglings now hunt
like experts.
398
00:41:16,233 --> 00:41:24,233
{\an8}♪♪♪
399
00:41:53,133 --> 00:41:55,976
{\an1}Sharks follow and wait
for the perfect moment
400
00:41:56,000 --> 00:41:58,633
{\an1}to cash in on the tight balls.
401
00:42:00,800 --> 00:42:03,033
{\an1}They pick off the edges
at first...
402
00:42:06,333 --> 00:42:08,009
{\an1}...then they plough in.
403
00:42:08,033 --> 00:42:16,033
{\an8}♪♪♪
404
00:42:22,933 --> 00:42:25,276
{\an1}The dolphins are relentless.
405
00:42:25,300 --> 00:42:31,642
{\an8}♪♪♪
406
00:42:31,666 --> 00:42:35,942
{\an1}Youngsters take the cue and feed
on fish for the first time.
407
00:42:35,966 --> 00:42:43,966
{\an8}♪♪♪
408
00:42:58,233 --> 00:43:03,109
{\an1}Along miles of coastline,
every predator is synchronized.
409
00:43:03,133 --> 00:43:11,133
{\an8}♪♪♪
410
00:43:18,800 --> 00:43:22,109
Unlikely accomplices
of all stripes work together
411
00:43:22,133 --> 00:43:24,509
{\an1}toward one brutal goal.
412
00:43:24,533 --> 00:43:32,533
{\an8}♪♪♪
413
00:44:07,066 --> 00:44:09,133
[ Birds squawking ]
414
00:44:20,333 --> 00:44:22,376
And then,
with the fish exhausted
415
00:44:22,400 --> 00:44:25,642
{\an1}and thousands of predators
well fed,
416
00:44:25,666 --> 00:44:27,576
{\an1}the biggest arrives...
417
00:44:27,600 --> 00:44:35,600
{\an8}♪♪♪
418
00:44:36,166 --> 00:44:39,176
{\an1}...a 20-ton Bryde's whale.
419
00:44:39,200 --> 00:44:43,176
{\an8}♪♪♪
420
00:44:43,200 --> 00:44:47,576
{\an1}Thousands of sardines gone
in a single gulp.
421
00:44:47,600 --> 00:44:55,600
{\an8}♪♪♪
422
00:45:07,833 --> 00:45:10,409
{\an1}The feast goes on for days.
423
00:45:10,433 --> 00:45:14,476
{\an8}♪♪♪
424
00:45:14,500 --> 00:45:17,509
{\an1}The great shoal is in tatters.
425
00:45:17,533 --> 00:45:25,533
{\an8}♪♪♪
426
00:45:30,233 --> 00:45:34,166
{\an1}It's now a 3-mile buffet.
427
00:45:40,900 --> 00:45:46,142
{\an1}Too confused and spent
to reform their shoal,
428
00:45:46,166 --> 00:45:49,466
{\an1}they're almost 800 miles
from home.
429
00:46:00,233 --> 00:46:04,942
They've been duped
by the vanishing current.
430
00:46:04,966 --> 00:46:09,566
{\an1}Now they're lost and scattered
in a strange, warm ocean...
431
00:46:12,100 --> 00:46:14,433
{\an1}...simply food for others.
432
00:46:17,400 --> 00:46:19,842
{\an1}And yet it isn't over.
433
00:46:19,866 --> 00:46:23,909
{\an8}♪♪♪
434
00:46:23,933 --> 00:46:27,133
{\an1}The predator of all predators
arrives.
435
00:46:31,533 --> 00:46:33,242
Orcas.
436
00:46:33,266 --> 00:46:37,576
{\an8}♪♪♪
437
00:46:37,600 --> 00:46:41,009
{\an1}As smart and cooperative
as a common dolphin
438
00:46:41,033 --> 00:46:43,133
{\an1}and three times bigger.
439
00:46:46,133 --> 00:46:49,442
{\an1}Orcas never used to travel
for the sardine run,
440
00:46:49,466 --> 00:46:54,076
{\an1}but now they swim thousands of
miles to intercept the shoals.
441
00:46:54,100 --> 00:47:02,100
{\an8}♪♪♪
442
00:47:04,333 --> 00:47:07,009
{\an1}But it's not the sardines
they're after.
443
00:47:07,033 --> 00:47:15,033
{\an8}♪♪♪
444
00:47:16,966 --> 00:47:19,842
{\an1}They're here to hunt dolphins.
445
00:47:19,866 --> 00:47:27,866
{\an8}♪♪♪
446
00:47:29,400 --> 00:47:33,276
{\an1}Not chasing anymore but running.
447
00:47:33,300 --> 00:47:35,876
{\an1}The orcas are not only
more powerful,
448
00:47:35,900 --> 00:47:37,776
{\an1}they have more stamina.
449
00:47:37,800 --> 00:47:45,342
{\an8}♪♪♪
450
00:47:45,366 --> 00:47:48,242
Just as the dolphins
corralled the fish,
451
00:47:48,266 --> 00:47:51,233
now the orcas work the dolphins.
452
00:47:55,833 --> 00:47:58,176
{\an1}They isolate one from the pod.
453
00:47:58,200 --> 00:48:06,200
{\an8}♪♪♪
454
00:48:09,800 --> 00:48:13,666
{\an1}Once they've locked onto
their target, they tag-team...
455
00:48:16,300 --> 00:48:17,876
chasing it...
456
00:48:17,900 --> 00:48:21,242
{\an8}♪♪♪
457
00:48:21,266 --> 00:48:24,609
exhausting it...
458
00:48:24,633 --> 00:48:27,309
then... ramming it.
459
00:48:27,333 --> 00:48:35,333
{\an8}♪♪♪
460
00:49:11,066 --> 00:49:13,209
{\an1}They attack again and again
461
00:49:13,233 --> 00:49:16,609
until the dolphin
can no longer swim.
462
00:49:16,633 --> 00:49:24,633
{\an8}♪♪♪
463
00:49:41,700 --> 00:49:45,266
{\an1}Before they can feast,
they drown it.
464
00:49:58,700 --> 00:50:02,909
{\an8}♪♪♪
465
00:50:02,933 --> 00:50:06,500
{\an1}The orcas have scattered
the dolphin super pod.
466
00:50:08,700 --> 00:50:11,642
{\an1}Without the organizing force
of the dolphins,
467
00:50:11,666 --> 00:50:17,133
{\an1}the sardines regroup and
slip away into deep, cold water.
468
00:50:19,700 --> 00:50:23,442
{\an1}The massive cloud of fish
that dominated the coastline
469
00:50:23,466 --> 00:50:27,376
suddenly vanishes,
as if absorbed by the sea.
470
00:50:27,400 --> 00:50:35,109
{\an8}♪♪♪
471
00:50:35,133 --> 00:50:39,333
As July concludes,
the sated hunters disperse.
472
00:50:42,166 --> 00:50:45,742
{\an1}Gannets proceed to travel up
to 60 miles a day
473
00:50:45,766 --> 00:50:47,900
{\an1}searching for more food.
474
00:50:51,066 --> 00:50:53,909
Sharks continue
their migrations,
475
00:50:53,933 --> 00:50:56,476
{\an1}fully fed and stronger for it.
476
00:50:56,500 --> 00:51:04,076
{\an8}♪♪♪
477
00:51:04,100 --> 00:51:08,076
{\an1}Dolphins have successfully
weaned their calves.
478
00:51:08,100 --> 00:51:14,276
{\an8}♪♪♪
479
00:51:14,300 --> 00:51:17,909
Super pods thin out
as family units regroup
480
00:51:17,933 --> 00:51:20,842
and return to their
regular hunting grounds.
481
00:51:20,866 --> 00:51:25,076
{\an8}♪♪♪
482
00:51:25,100 --> 00:51:27,342
{\an1}The cold current has delivered
the feast
483
00:51:27,366 --> 00:51:29,833
that all the animals
were counting on.
484
00:51:33,500 --> 00:51:38,176
{\an1}Now it fades away, mixing
with the warm Indian Ocean.
485
00:51:38,200 --> 00:51:45,076
{\an8}♪♪♪
486
00:51:45,100 --> 00:51:48,642
{\an1}Some believe the sardines
ride the current down
487
00:51:48,666 --> 00:51:51,366
{\an1}to secretly spawn in the deep.
488
00:51:52,866 --> 00:51:55,309
{\an1}Others say they follow it
all the way back,
489
00:51:55,333 --> 00:51:58,666
1,000 miles
to their home off the Cape.
490
00:52:01,633 --> 00:52:04,442
{\an1}Next year the cold current
will reform,
491
00:52:04,466 --> 00:52:08,576
stronger or weaker
than the last...
492
00:52:08,600 --> 00:52:10,076
{\an1}and billions of little fish
493
00:52:10,100 --> 00:52:13,042
will be driven
to follow its call,
494
00:52:13,066 --> 00:52:19,209
{\an1}to face hardship and sacrifice,
toward a purpose yet unknown.
495
00:52:19,233 --> 00:52:23,333
{\an8}♪♪♪
496
00:52:31,100 --> 00:52:39,100
{\an8}♪♪♪
497
00:53:03,233 --> 00:53:04,942
{\an8}To learn more
about what you've seen
498
00:53:04,966 --> 00:53:06,676
{\an7}on this "Nature" program,
499
00:53:06,700 --> 00:53:09,042
{\an8}visit pbs.org.
500
00:53:09,066 --> 00:53:15,200
{\an8}♪♪♪