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NARRATOR: Alone, a single fish
may be insignificant.

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00:00:21,745 --> 00:00:26,198
But together, they can hold
the fate of an entire coastline.

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In the deep, billions of sardines

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00:00:32,273 --> 00:00:35,069
begin a mass migration...

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00:00:35,104 --> 00:00:39,142
sparked by a whisper of cool water.

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It's the largest movement
of living things on Earth.

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00:00:44,389 --> 00:00:48,531
And it's about to become
nature's greatest ambush.

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♪

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Every predator along the coast
is counting on this event...

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...to feast on the abundance
the sardines bring...

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00:01:08,620 --> 00:01:11,519
...before they slip away
into the deep.

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00:01:11,554 --> 00:01:21,529
♪

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00:01:21,564 --> 00:01:28,122
♪

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00:01:28,157 --> 00:01:34,680
♪

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00:01:37,407 --> 00:01:39,375
[Waves crashing, wind blowing]

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NARRATOR:
Off the southern tip of Africa,

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00:01:46,968 --> 00:01:51,318
the frigid South Atlantic mixes
with the milder Indian ocean.

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00:01:54,044 --> 00:01:57,600
The waters are cold and rich
with plankton,

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00:01:57,634 --> 00:02:00,396
fed by upwellings
from the mighty Atlantic.

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00:02:03,502 --> 00:02:06,885
Perfect conditions
for a tiny fish to thrive.

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00:02:06,919 --> 00:02:13,857
♪

26
00:02:13,892 --> 00:02:18,345
Sardines by the billions
live here year-round,

27
00:02:18,379 --> 00:02:21,279
swimming and feeding together
in loose shoals

28
00:02:21,313 --> 00:02:23,971
of hundreds of thousands of individuals.

29
00:02:26,353 --> 00:02:31,289
Then in late April, ocean
currents undergo a subtle shift.

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00:02:31,323 --> 00:02:37,812
♪

31
00:02:37,847 --> 00:02:40,021
As the southern winter approaches,

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00:02:40,056 --> 00:02:43,439
upwellings and eddies force
a tendril of cold water

33
00:02:43,473 --> 00:02:46,959
toward the east.

34
00:02:46,994 --> 00:02:50,549
The warm Agulhas Current
moves further offshore,

35
00:02:50,584 --> 00:02:53,725
allowing the cold stream to gain momentum.

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00:02:56,314 --> 00:02:59,351
The cold-water sardines
instinctively cluster

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00:02:59,386 --> 00:03:01,250
in the chillier current.

38
00:03:01,284 --> 00:03:06,565
♪

39
00:03:06,600 --> 00:03:10,673
150 miles out to sea,
on the Agulhas Banks,

40
00:03:10,707 --> 00:03:13,158
schools begin to mass together...

41
00:03:15,125 --> 00:03:19,509
...until they form a mega shoal
20 miles long.

42
00:03:22,961 --> 00:03:25,239
Then the single superorganism

43
00:03:25,274 --> 00:03:28,000
pours into the cold-water highway

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00:03:28,035 --> 00:03:30,762
toward the coast and shallower water.

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00:03:34,490 --> 00:03:38,183
It's the biggest biomass
migration on the planet,

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00:03:38,218 --> 00:03:42,774
exceeding the great herds
of the Serengeti.

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00:03:42,808 --> 00:03:48,504
Yet, exactly why they do it
remains a mystery.

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The journey serves no apparent
benefit to the fish.

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It will inevitably dead-end in a warm sea,

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unsuitable for sardines.

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00:04:01,793 --> 00:04:04,796
How far they travel
depends entirely on the vagaries

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00:04:04,830 --> 00:04:06,901
of this year's cold current.

53
00:04:09,110 --> 00:04:10,698
But one thing is certain...

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00:04:10,733 --> 00:04:14,978
an entire food web is counting
on the sardines to make the run.

55
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[Birds squawking]

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Some predators will follow
the shoal for weeks.

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00:04:27,577 --> 00:04:31,409
Others wait for the feast
to pass close to shore.

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00:04:32,513 --> 00:04:35,861
Some even race hundreds of miles
to intercept it.

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To the multitude, this year's
sardine run can mean

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00:04:48,460 --> 00:04:52,222
the difference between
abundance and deprivation.

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All are at the mercy of the current.

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00:05:02,440 --> 00:05:05,719
If the water temperature
stays below 70 degrees,

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the sardines could travel 1,000 miles

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00:05:08,687 --> 00:05:11,311
up the Eastern coast of South Africa.

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00:05:12,898 --> 00:05:15,418
But if the tendril of cold water fades,

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the shoals will turn, disperse,
or disappear into the deep.

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♪

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The coastline waits.

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♪

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The first hazard for the fish
lies just 100 miles

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from the sardine's home turf...

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♪

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...a colony of some 4,000
Cape fur seals.

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They're local predators,

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00:05:54,043 --> 00:05:56,528
patrolling the shallows close to shore.

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00:06:02,085 --> 00:06:05,054
The pups need milk every four hours...

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00:06:07,470 --> 00:06:09,886
...so moms can't go far to hunt.

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And they're reluctant to leave the safety

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of coastal kelp forests.

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The towering plants offer protection

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from great white sharks.

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If the seals are to feast on sardines,

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they need the shoals to come to them.

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Mothers depend on the oily fish
to fuel their milk supply.

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And they're already pregnant
with next year's baby...

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00:06:53,551 --> 00:06:56,692
...a precarious position
when your food source is fickle.

87
00:07:01,110 --> 00:07:04,562
The colony is crowded.

88
00:07:04,596 --> 00:07:06,633
Pups cling to mothers.

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00:07:08,600 --> 00:07:09,636
[Seals barking]

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00:07:09,670 --> 00:07:11,258
Tempers fray.

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00:07:18,541 --> 00:07:21,648
But this year, the sea delivers.

92
00:07:25,790 --> 00:07:28,689
The cold current pushes clouds
of zooplankton

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00:07:28,724 --> 00:07:31,796
toward the coast and the seal colony.

94
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The little fish follow their food...

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...directly into the kelp beds.

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♪

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For the seals,
it's the moment of the year.

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♪

99
00:08:03,448 --> 00:08:07,314
Their front flippers are large
and incredibly powerful.

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00:08:07,348 --> 00:08:11,421
♪

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00:08:11,456 --> 00:08:15,909
Like paddles, they propel
the seals at 15 miles per hour.

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♪

103
00:08:22,363 --> 00:08:26,402
And they provide control when
maneuverability matters most.

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♪

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♪

106
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♪

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♪

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Every seal cooperates.

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00:09:02,611 --> 00:09:10,377
♪

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00:09:10,411 --> 00:09:12,759
The seals swallow fish whole...

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...even when they're underwater.

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♪

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♪

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♪

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00:09:40,510 --> 00:09:45,619
In the onslaught, the sardines
school in an ever tighter mass.

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It's a proven defense.

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00:09:49,105 --> 00:09:51,832
Every fish is equipped
with a lateral line...

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00:09:51,867 --> 00:09:55,422
sensory cells in its head,
trunk, and tail.

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00:09:57,010 --> 00:09:59,944
It's sensitive enough to pick up
the slightest change

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00:09:59,978 --> 00:10:01,497
in water pressure.

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00:10:04,673 --> 00:10:07,537
When a fish feels its neighbor move,

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00:10:07,572 --> 00:10:10,333
it instantly responds in kind.

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00:10:11,956 --> 00:10:16,719
Millions of tiny, synchronized
movements combine into one,

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00:10:16,754 --> 00:10:19,653
forming a superorganism that shape-shifts

125
00:10:19,688 --> 00:10:21,897
and slips just out of reach.

126
00:10:26,142 --> 00:10:29,145
The assault by thousands of hungry seals

127
00:10:29,180 --> 00:10:31,631
barely makes a dent in the giant shoal.

128
00:10:34,323 --> 00:10:36,843
The sardines make their getaway
up the coast,

129
00:10:36,877 --> 00:10:38,603
and the seals don't follow.

130
00:10:41,157 --> 00:10:43,539
They need to get back
to their hungry pups.

131
00:10:46,749 --> 00:10:50,546
The shoal always stays
in the cold current,

132
00:10:50,580 --> 00:10:52,997
covering up to 40 miles a day.

133
00:10:56,310 --> 00:11:00,073
Now the females drop eggs
as they move up the coast...

134
00:11:01,937 --> 00:11:03,490
...prompting some to suggest

135
00:11:03,524 --> 00:11:07,459
that this is an annual spawning run.

136
00:11:07,494 --> 00:11:11,325
Others say it's simply
driven by wind and cold water.

137
00:11:13,569 --> 00:11:17,607
With each mile, the water grows
imperceptibly warmer.

138
00:11:20,541 --> 00:11:23,683
There's no telling where or when,

139
00:11:23,717 --> 00:11:27,169
but the cold current
will eventually dissipate.

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00:11:27,203 --> 00:11:32,312
♪

141
00:11:32,346 --> 00:11:36,419
For now, it remains strong,
impelling the fish onward.

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00:11:36,454 --> 00:11:42,978
♪

143
00:11:43,012 --> 00:11:49,536
♪

144
00:11:49,570 --> 00:11:56,025
♪

145
00:11:58,131 --> 00:12:01,962
By early May, the sardines
approach another landmark...

146
00:12:04,171 --> 00:12:06,898
...400 miles east
of the seal colony.

147
00:12:10,799 --> 00:12:12,490
Bird Island.

148
00:12:12,524 --> 00:12:14,561
[Birds squawking]

149
00:12:18,599 --> 00:12:22,155
It's the world's biggest colony
of Cape gannets.

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For three months, the birds have been

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00:12:26,884 --> 00:12:29,093
feeding their growing chicks.

152
00:12:29,127 --> 00:12:34,029
♪

153
00:12:34,063 --> 00:12:36,548
They may be fierce ocean predators,

154
00:12:36,583 --> 00:12:38,930
but they're also devoted parents.

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00:12:38,965 --> 00:12:44,729
♪

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00:12:44,764 --> 00:12:46,006
They're monogamous,

157
00:12:46,041 --> 00:12:49,147
always returning to the same nest.

158
00:12:49,182 --> 00:12:51,080
[Birds squawking]

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It's crowded.

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00:12:55,084 --> 00:12:57,984
That means competition for real estate...

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00:12:58,018 --> 00:12:59,571
and food.

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00:13:07,303 --> 00:13:10,928
With over 200,000 birds in the colony,

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00:13:10,962 --> 00:13:15,484
they need 9,000 tons of fish
in one breeding season.

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00:13:26,633 --> 00:13:29,636
The gannets have pinned
their entire breeding cycle

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00:13:29,670 --> 00:13:32,777
on the unpredictable arrival of sardines.

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00:13:34,606 --> 00:13:40,923
♪

167
00:13:40,958 --> 00:13:44,616
Scouts return with full bellies
and good news.

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00:13:47,102 --> 00:13:49,069
The fish are coming.

169
00:13:49,104 --> 00:13:54,316
♪

170
00:13:54,350 --> 00:13:58,285
The sardine superorganism
is 20 miles offshore...

171
00:14:01,185 --> 00:14:04,015
...within striking distance
of the colony.

172
00:14:04,050 --> 00:14:10,366
♪

173
00:14:10,401 --> 00:14:16,856
♪

174
00:14:16,890 --> 00:14:21,101
The birds appear awkward
on the ground, even comical.

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00:14:21,136 --> 00:14:26,003
But once they achieve air speed,
they are all grace and danger.

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♪

177
00:14:32,802 --> 00:14:39,464
♪

178
00:14:39,499 --> 00:14:46,195
♪

179
00:14:46,230 --> 00:14:52,926
♪

180
00:14:52,961 --> 00:14:55,549
They soar 100 feet in the air.

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00:14:57,966 --> 00:15:01,003
They scan the shoal
with binocular vision...

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00:15:01,038 --> 00:15:08,735
♪

183
00:15:08,769 --> 00:15:16,467
♪

184
00:15:16,501 --> 00:15:18,020
...lock on to a target...

185
00:15:20,229 --> 00:15:23,163
...then dive.

186
00:15:23,198 --> 00:15:27,340
♪

187
00:15:27,374 --> 00:15:31,206
Gannets hit the water
at 60 miles per hour.

188
00:15:31,240 --> 00:15:39,904
♪

189
00:15:39,939 --> 00:15:43,045
Muscles lock their
neck vertebrae into place.

190
00:15:43,080 --> 00:15:51,709
♪

191
00:15:51,743 --> 00:15:55,161
Airbags in the face and chest
absorb impact.

192
00:15:55,195 --> 00:16:00,890
♪

193
00:16:00,925 --> 00:16:06,620
♪

194
00:16:06,655 --> 00:16:10,866
The sardines swim deeper to escape,

195
00:16:10,900 --> 00:16:13,524
but the birds' momentum
carries them down...

196
00:16:17,355 --> 00:16:21,187
...30 feet underwater.

197
00:16:21,221 --> 00:16:24,052
If a gannet misses the target,
it holds its breath

198
00:16:24,086 --> 00:16:27,779
and paddles, penguin-like,
for a second grab.

199
00:16:27,814 --> 00:16:35,649
♪

200
00:16:35,684 --> 00:16:43,450
♪

201
00:16:53,426 --> 00:16:56,360
This first hunt is all for the youngsters.

202
00:16:56,394 --> 00:16:58,569
Gannet parents load up their gizzards

203
00:16:58,603 --> 00:17:01,503
and return at high speed to Bird Island.

204
00:17:18,382 --> 00:17:22,282
Every parent knows
exactly where to find its chick.

205
00:17:36,124 --> 00:17:43,096
♪

206
00:17:43,131 --> 00:17:45,616
The food cargo is precious.

207
00:17:48,653 --> 00:17:51,760
A healthy sardine run
means more young gannets

208
00:17:51,794 --> 00:17:53,900
are given a chance to survive.

209
00:17:53,934 --> 00:17:58,111
♪

210
00:17:58,146 --> 00:18:01,149
But <i>this</i> is the fledglings'
last free meal.

211
00:18:04,152 --> 00:18:08,087
The parent birds will leave them
forever and follow the shoals.

212
00:18:11,573 --> 00:18:13,299
Any gannet that wants to eat

213
00:18:13,333 --> 00:18:16,302
must get on the wing and follow the fish.

214
00:18:16,336 --> 00:18:20,444
♪

215
00:18:20,478 --> 00:18:23,550
This is motivation for the chicks to fly.

216
00:18:23,585 --> 00:18:30,419
♪

217
00:18:30,454 --> 00:18:33,664
The hungrier they get,
the harder they try.

218
00:18:33,698 --> 00:18:43,156
♪

219
00:18:43,191 --> 00:18:45,158
The learning curve is steep,

220
00:18:45,193 --> 00:18:48,161
against howling wind and rough seas.

221
00:18:48,196 --> 00:18:54,892
♪

222
00:18:54,926 --> 00:19:01,657
♪

223
00:19:01,692 --> 00:19:04,833
Crash-landing in the waves
is their first pitfall...

224
00:19:13,082 --> 00:19:16,293
...but the wild surf
is not the real danger.

225
00:19:18,916 --> 00:19:21,919
Fur seals hunt these shores, too.

226
00:19:21,953 --> 00:19:30,410
♪

227
00:19:30,445 --> 00:19:38,901
♪

228
00:19:38,936 --> 00:19:47,393
♪

229
00:19:47,427 --> 00:19:55,884
♪

230
00:19:55,918 --> 00:20:04,341
♪

231
00:20:04,375 --> 00:20:12,901
♪

232
00:20:12,935 --> 00:20:15,731
Fledglings don't have
the strength or experience

233
00:20:15,766 --> 00:20:17,319
for a water take-off.

234
00:20:17,354 --> 00:20:22,048
♪

235
00:20:22,082 --> 00:20:24,533
Soaked feathers weigh them down.

236
00:20:24,568 --> 00:20:33,266
♪

237
00:20:33,301 --> 00:20:41,999
♪

238
00:20:42,033 --> 00:20:50,732
♪

239
00:20:50,766 --> 00:20:59,534
♪

240
00:20:59,568 --> 00:21:03,676
Just as the gannets exacted
their toll on the sardines,

241
00:21:03,710 --> 00:21:07,852
the bird colony
now suffers its own losses.

242
00:21:07,887 --> 00:21:14,859
♪

243
00:21:14,894 --> 00:21:21,797
♪

244
00:21:21,832 --> 00:21:28,770
♪

245
00:21:28,804 --> 00:21:35,708
♪

246
00:21:35,742 --> 00:21:42,680
♪

247
00:21:42,715 --> 00:21:49,687
♪

248
00:21:49,722 --> 00:21:53,967
The lucky ones must dry
their feathers and try again.

249
00:21:56,625 --> 00:22:00,629
They can't miss out on the first
sardine hunt of their lives.

250
00:22:00,664 --> 00:22:07,740
♪

251
00:22:07,774 --> 00:22:14,885
♪

252
00:22:14,919 --> 00:22:22,030
♪

253
00:22:22,064 --> 00:22:29,140
♪

254
00:22:29,175 --> 00:22:36,320
♪

255
00:22:36,355 --> 00:22:40,048
The sardines move east
at 6 miles per hour.

256
00:22:42,844 --> 00:22:46,365
They're approaching the first
real crux of their journey.

257
00:22:49,954 --> 00:22:54,511
600 miles into the run,
the coastline bends north,

258
00:22:54,545 --> 00:22:57,203
and the continental shelf
starts to narrow.

259
00:22:59,792 --> 00:23:03,105
Their cold-water ribbon
is pinched against the coast

260
00:23:03,140 --> 00:23:05,660
by warm offshore currents.

261
00:23:07,524 --> 00:23:09,664
Billions of sardines must squeeze

262
00:23:09,698 --> 00:23:12,252
into the cold but narrowing channel.

263
00:23:16,153 --> 00:23:19,467
The shoal is stretched longer and thinner.

264
00:23:19,501 --> 00:23:21,745
The fish pack tighter together.

265
00:23:21,779 --> 00:23:28,441
♪

266
00:23:28,476 --> 00:23:32,687
This current delivers them to
a place called the Wild Coast.

267
00:23:34,896 --> 00:23:39,935
It's a 200-mile stretch...
a pristine, untouched transition

268
00:23:39,970 --> 00:23:43,007
between temperate and tropical biomes.

269
00:23:43,042 --> 00:23:49,151
♪

270
00:23:49,186 --> 00:23:52,085
It's not only a mix of water temperatures,

271
00:23:52,120 --> 00:23:55,848
it's also a crossroads for myriad species.

272
00:23:57,366 --> 00:24:00,715
It's June and humpback whales
pass from Antarctica

273
00:24:00,749 --> 00:24:02,820
to breeding grounds farther north.

274
00:24:02,855 --> 00:24:10,345
♪

275
00:24:10,379 --> 00:24:12,830
Others live here all year round.

276
00:24:12,865 --> 00:24:19,078
♪

277
00:24:19,112 --> 00:24:25,256
♪

278
00:24:27,880 --> 00:24:32,436
50 miles ahead of the shoal,
resident bottlenose dolphins

279
00:24:32,471 --> 00:24:34,231
relish winter's arrival.

280
00:24:40,548 --> 00:24:44,517
Dolphins live in social groups
of about 25 members.

281
00:24:49,142 --> 00:24:53,146
Their play reveals why
they're such formidable hunters.

282
00:24:57,496 --> 00:25:00,533
They're fast, they communicate,

283
00:25:00,568 --> 00:25:02,362
and they move as a unit.

284
00:25:05,193 --> 00:25:08,127
A real-life sardine nemesis.

285
00:25:10,025 --> 00:25:13,166
And this resident pod
is just the advance guard

286
00:25:13,201 --> 00:25:15,272
for an even greater army.

287
00:25:21,071 --> 00:25:25,247
♪

288
00:25:25,282 --> 00:25:27,215
Common dolphins.

289
00:25:27,249 --> 00:25:35,292
♪

290
00:25:35,326 --> 00:25:38,122
They spend most of their lives
in warmer waters

291
00:25:38,157 --> 00:25:41,574
along the coast.

292
00:25:41,609 --> 00:25:45,302
This time of year, their calves
are just beginning to hunt.

293
00:25:47,925 --> 00:25:51,998
Mothers need to wean them before
next spring's breeding season.

294
00:25:53,897 --> 00:25:57,003
A glut of fish would be
a crucial windfall.

295
00:25:57,038 --> 00:26:01,629
♪

296
00:26:01,663 --> 00:26:06,495
There's no guarantee
the sardine run will reach them.

297
00:26:06,530 --> 00:26:08,843
So they come to it.

298
00:26:08,877 --> 00:26:14,676
♪

299
00:26:14,711 --> 00:26:19,578
As they head south, hundreds
of small family pods converge.

300
00:26:19,612 --> 00:26:25,756
♪

301
00:26:25,791 --> 00:26:31,969
♪

302
00:26:32,004 --> 00:26:34,938
A dolphin super pod begins to form,

303
00:26:34,972 --> 00:26:37,630
streaming to intercept the shoal.

304
00:26:37,665 --> 00:26:47,640
♪

305
00:26:47,675 --> 00:26:53,128
100 miles to the south, the fish
pour along the Wild Coast...

306
00:26:53,163 --> 00:26:55,303
unaware of what lies ahead.

307
00:26:57,512 --> 00:27:00,929
As the narrowing current
pushes them to the shallows,

308
00:27:00,964 --> 00:27:04,346
the shoal fragments.

309
00:27:04,381 --> 00:27:10,076
Smaller, isolated bait balls
offer a new opportunity...

310
00:27:10,111 --> 00:27:11,733
for sharks.

311
00:27:11,768 --> 00:27:17,532
♪

312
00:27:17,566 --> 00:27:20,811
These migratory blacktips and dusky sharks

313
00:27:20,846 --> 00:27:24,401
have moved down from
the warmer waters farther north.

314
00:27:26,679 --> 00:27:28,992
Little is known of their lives,

315
00:27:29,026 --> 00:27:31,926
but shark nurseries
have been discovered nearby,

316
00:27:31,960 --> 00:27:33,479
suggesting that the sharks...

317
00:27:33,513 --> 00:27:35,584
like other creatures along the coast...

318
00:27:35,619 --> 00:27:39,002
may time their breeding cycle
to the sardine run.

319
00:27:42,937 --> 00:27:46,665
Tiny fish face off with dozens of sharks.

320
00:27:50,289 --> 00:27:54,327
It seems an unfair match...

321
00:27:54,362 --> 00:27:57,537
but the sardines launch
their schooling defense.

322
00:27:57,572 --> 00:28:02,991
♪

323
00:28:03,026 --> 00:28:08,479
♪

324
00:28:08,514 --> 00:28:12,691
As the sharks move, they send a
pressure wave through the water.

325
00:28:14,416 --> 00:28:17,972
The fish detect it through
their sensitive lateral lines.

326
00:28:21,630 --> 00:28:24,116
Just one moves out of harm's way,

327
00:28:24,150 --> 00:28:26,981
and every fish around it follows.

328
00:28:27,015 --> 00:28:33,159
♪

329
00:28:33,194 --> 00:28:35,299
It's incredibly effective.

330
00:28:35,334 --> 00:28:41,789
♪

331
00:28:41,823 --> 00:28:44,792
The sharks simply can't turn
and bite quick enough.

332
00:28:44,826 --> 00:28:54,249
♪

333
00:28:54,284 --> 00:29:03,707
♪

334
00:29:03,742 --> 00:29:06,606
The predators change tactics.

335
00:29:06,641 --> 00:29:14,822
♪

336
00:29:14,856 --> 00:29:18,377
With sudden bursts of speed,
they try and carve the shoal

337
00:29:18,411 --> 00:29:20,620
into even smaller balls...

338
00:29:23,727 --> 00:29:26,385
...but they just don't
coordinate enough.

339
00:29:26,419 --> 00:29:35,981
♪

340
00:29:36,015 --> 00:29:39,708
A school of 60-pound tuna
gets in on the action.

341
00:29:39,743 --> 00:29:43,747
♪

342
00:29:43,782 --> 00:29:46,508
Normally the sharks hunt tuna,

343
00:29:46,543 --> 00:29:49,546
but they seem to know help
when they see it.

344
00:29:50,892 --> 00:29:55,000
The smaller tuna are much more agile.

345
00:29:55,034 --> 00:29:59,245
Within seconds, they slice
a bait ball from the shoal

346
00:29:59,280 --> 00:30:01,351
and trap it against the surface,

347
00:30:01,385 --> 00:30:03,802
where it's easier for everyone to feed.

348
00:30:03,836 --> 00:30:11,982
♪

349
00:30:12,017 --> 00:30:20,163
♪

350
00:30:20,197 --> 00:30:28,447
♪

351
00:30:28,481 --> 00:30:32,485
Game fish and sharks
enjoy a temporary truce

352
00:30:32,520 --> 00:30:35,040
as they feast on the same prey.

353
00:30:35,074 --> 00:30:44,981
♪

354
00:30:45,015 --> 00:30:54,887
♪

355
00:30:54,922 --> 00:31:04,828
♪

356
00:31:04,863 --> 00:31:14,803
♪

357
00:31:14,838 --> 00:31:24,744
♪

358
00:31:24,779 --> 00:31:27,402
The main shoal flees north,

359
00:31:27,437 --> 00:31:30,992
leaving this fragment behind
to be obliterated.

360
00:31:50,667 --> 00:31:53,290
Even the gulls get their share.

361
00:31:53,325 --> 00:32:01,264
♪

362
00:32:01,298 --> 00:32:09,168
♪

363
00:32:16,313 --> 00:32:20,973
♪

364
00:32:21,008 --> 00:32:24,908
The mega shoal is now way
out of its home habitat.

365
00:32:27,152 --> 00:32:31,294
As long as it's cold,
they swim blindly along.

366
00:32:31,328 --> 00:32:34,469
They're heading toward a feature
of the South African coast

367
00:32:34,504 --> 00:32:37,265
that will prove the most
consequential milestone

368
00:32:37,300 --> 00:32:40,855
of their journey...

369
00:32:40,889 --> 00:32:44,410
a sandstone buttress
called Waterfall Bluff.

370
00:32:44,445 --> 00:32:51,279
♪

371
00:32:51,314 --> 00:32:55,387
This rocky promontory shoves
the cold current eastward

372
00:32:55,421 --> 00:32:58,390
to collide with the warm water
just offshore.

373
00:32:58,424 --> 00:33:07,778
♪

374
00:33:07,813 --> 00:33:13,612
Some years the cold water
can blast beyond this point...

375
00:33:13,646 --> 00:33:15,165
but not this year.

376
00:33:15,200 --> 00:33:17,996
The vital current thins to a trickle.

377
00:33:21,240 --> 00:33:25,486
The sardines follow into
the bottleneck as if spellbound.

378
00:33:28,075 --> 00:33:31,561
Every single fish follows
the same mission...

379
00:33:31,595 --> 00:33:34,426
stick with the school
and stay in the middle.

380
00:33:34,460 --> 00:33:36,738
But in the fading current,

381
00:33:36,773 --> 00:33:40,949
the already fractured shoal
breaks up even further.

382
00:33:40,984 --> 00:33:44,919
Small schools follow shifting
pockets of cool water

383
00:33:44,953 --> 00:33:46,438
into oblivion.

384
00:33:50,649 --> 00:33:53,583
The great journey stalls for the fish

385
00:33:53,617 --> 00:33:56,931
and conditions align for every predator.

386
00:33:56,965 --> 00:34:01,004
♪

387
00:34:01,039 --> 00:34:04,283
A familiar enemy has
trailed them all this way.

388
00:34:06,596 --> 00:34:09,323
Some gannets will fly for 24 hours

389
00:34:09,357 --> 00:34:12,636
to intercept the bottleneck...

390
00:34:12,671 --> 00:34:15,915
and there are plenty more
roosting on the nearby coast.

391
00:34:18,642 --> 00:34:21,438
It's a true test for the rookies.

392
00:34:21,473 --> 00:34:26,547
♪

393
00:34:26,581 --> 00:34:28,859
The sharks are back for more, too.

394
00:34:32,863 --> 00:34:36,108
Until now, the sardines
have managed to slough off

395
00:34:36,143 --> 00:34:40,595
small bait balls as sacrificial decoys.

396
00:34:40,630 --> 00:34:44,461
But now they're more vulnerable
than they've ever been.

397
00:34:47,602 --> 00:34:50,018
The high-flying gannets
are the first to spot

398
00:34:50,053 --> 00:34:51,641
a stalling shoal.

399
00:34:51,675 --> 00:34:56,301
♪

400
00:34:56,335 --> 00:34:58,682
The birds stand out against the sky

401
00:34:58,717 --> 00:35:02,307
like a homing beacon, guiding in an army.

402
00:35:02,341 --> 00:35:06,311
♪

403
00:35:06,345 --> 00:35:08,209
It's the dolphin super pod...

404
00:35:11,833 --> 00:35:15,941
...now grown to 20,000 strong.

405
00:35:15,975 --> 00:35:25,571
♪

406
00:35:25,606 --> 00:35:35,271
♪

407
00:35:35,305 --> 00:35:44,970
♪

408
00:35:45,004 --> 00:35:48,456
The sardines now face
an unprecedented assault

409
00:35:48,491 --> 00:35:51,942
from a fleet
of swift ocean-going hunters...

410
00:35:51,977 --> 00:35:58,639
♪

411
00:35:58,673 --> 00:36:02,608
...and a far-flung deadly
air force assembling above.

412
00:36:02,643 --> 00:36:11,790
♪

413
00:36:11,824 --> 00:36:21,075
♪

414
00:36:21,109 --> 00:36:30,947
♪

415
00:36:30,981 --> 00:36:37,195
♪

416
00:36:37,229 --> 00:36:43,408
♪

417
00:36:43,442 --> 00:36:47,274
The sardines turn
to the only defense they know...

418
00:36:47,308 --> 00:36:50,380
schooling up as tight as they can.

419
00:36:50,415 --> 00:36:54,522
♪

420
00:36:54,557 --> 00:36:57,353
One moves, and they all move.

421
00:36:57,387 --> 00:37:03,876
♪

422
00:37:07,052 --> 00:37:12,885
♪

423
00:37:12,920 --> 00:37:15,371
But the dolphins are prepared for this.

424
00:37:19,478 --> 00:37:22,964
Their goal is to prevent
the shoal from diving deep.

425
00:37:22,999 --> 00:37:28,418
♪

426
00:37:28,453 --> 00:37:32,250
They coordinate their efforts,
blocking the sardines' evasion.

427
00:37:35,391 --> 00:37:36,909
With surgical precision,

428
00:37:36,944 --> 00:37:39,878
they slice balls away from the main shoal.

429
00:37:39,912 --> 00:37:47,782
♪

430
00:37:47,817 --> 00:37:52,028
They blow bubbles to corral any
fish that tries to break form...

431
00:37:52,062 --> 00:37:58,068
♪

432
00:37:58,103 --> 00:38:01,175
...forcing the fish tighter
and tighter together.

433
00:38:02,763 --> 00:38:04,868
Every fish instinctively tries to get

434
00:38:04,903 --> 00:38:06,456
into the middle of the pack.

435
00:38:08,907 --> 00:38:12,738
But now exhausted gills
struggle to suck oxygen

436
00:38:12,773 --> 00:38:14,671
from turbulent water.

437
00:38:14,706 --> 00:38:22,230
♪

438
00:38:22,265 --> 00:38:29,859
♪

439
00:38:29,893 --> 00:38:34,415
Ball after ball is dissected
from the shoal and obliterated.

440
00:38:36,348 --> 00:38:39,040
The dolphins get what they've waited for.

441
00:38:39,075 --> 00:38:48,084
♪

442
00:38:48,118 --> 00:38:57,093
♪

443
00:38:57,127 --> 00:39:06,136
♪

444
00:39:06,171 --> 00:39:15,214
♪

445
00:39:15,249 --> 00:39:17,527
The toll is exponential.

446
00:39:17,562 --> 00:39:22,118
♪

447
00:39:22,152 --> 00:39:25,397
The dolphins are so effective
at herding the fish

448
00:39:25,432 --> 00:39:28,952
that every other predator
is also more successful.

449
00:39:28,987 --> 00:39:36,615
♪

450
00:39:36,650 --> 00:39:44,347
♪

451
00:39:44,382 --> 00:39:52,079
♪

452
00:39:52,113 --> 00:39:59,845
♪

453
00:39:59,880 --> 00:40:02,572
As the fish are driven to the surface,

454
00:40:02,607 --> 00:40:06,058
gannets get easy access.

455
00:40:06,093 --> 00:40:15,585
♪

456
00:40:15,620 --> 00:40:25,146
♪

457
00:40:25,181 --> 00:40:34,639
♪

458
00:40:34,673 --> 00:40:44,200
♪

459
00:40:44,234 --> 00:40:53,727
♪

460
00:40:53,761 --> 00:41:03,322
♪

461
00:41:03,357 --> 00:41:06,774
Dark fledglings now hunt like experts.

462
00:41:06,809 --> 00:41:13,056
♪

463
00:41:13,091 --> 00:41:19,200
♪

464
00:41:43,811 --> 00:41:46,573
Sharks follow and wait
for the perfect moment

465
00:41:46,607 --> 00:41:49,127
to cash in on the tight balls.

466
00:41:51,439 --> 00:41:53,476
They pick off the edges at first...

467
00:41:56,893 --> 00:41:58,550
...then they plough in.

468
00:41:58,585 --> 00:42:06,040
♪

469
00:42:06,075 --> 00:42:13,565
♪

470
00:42:13,600 --> 00:42:15,912
The dolphins are relentless.

471
00:42:15,947 --> 00:42:22,332
♪

472
00:42:22,367 --> 00:42:26,578
Youngsters take the cue and feed
on fish for the first time.

473
00:42:26,613 --> 00:42:34,034
♪

474
00:42:34,068 --> 00:42:41,420
♪

475
00:42:41,455 --> 00:42:48,876
♪

476
00:42:48,911 --> 00:42:53,674
Along miles of coastline,
every predator is synchronized.

477
00:42:53,709 --> 00:43:01,544
♪

478
00:43:01,579 --> 00:43:09,448
♪

479
00:43:09,483 --> 00:43:12,762
Unlikely accomplices
of all stripes work together

480
00:43:12,797 --> 00:43:15,178
toward one brutal goal.

481
00:43:15,213 --> 00:43:23,635
♪

482
00:43:23,670 --> 00:43:32,126
♪

483
00:43:32,161 --> 00:43:40,618
♪

484
00:43:40,652 --> 00:43:49,074
♪

485
00:43:49,109 --> 00:43:57,600
♪

486
00:43:57,635 --> 00:43:59,567
[Birds squawking]

487
00:44:10,924 --> 00:44:13,029
And then, with the fish exhausted

488
00:44:13,064 --> 00:44:16,274
and thousands of predators well fed,

489
00:44:16,308 --> 00:44:18,207
the biggest arrives...

490
00:44:18,241 --> 00:44:26,767
♪

491
00:44:26,802 --> 00:44:29,805
...a 20-ton Bryde's whale.

492
00:44:29,839 --> 00:44:33,843
♪

493
00:44:33,878 --> 00:44:38,227
Thousands of sardines gone
in a single gulp.

494
00:44:38,261 --> 00:44:44,958
♪

495
00:44:44,992 --> 00:44:51,654
♪

496
00:44:51,689 --> 00:44:58,385
♪

497
00:44:58,419 --> 00:45:00,974
The feast goes on for days.

498
00:45:01,008 --> 00:45:05,047
♪

499
00:45:05,081 --> 00:45:08,084
The great shoal is in tatters.

500
00:45:08,119 --> 00:45:14,504
♪

501
00:45:14,539 --> 00:45:20,821
♪

502
00:45:20,856 --> 00:45:24,722
It's now a 3-mile buffet.

503
00:45:31,625 --> 00:45:36,803
Too confused and spent
to reform their shoal,

504
00:45:36,837 --> 00:45:39,978
they're almost 800 miles from home.

505
00:45:50,851 --> 00:45:55,580
They've been duped
by the vanishing current.

506
00:45:55,614 --> 00:45:59,998
Now they're lost and scattered
in a strange, warm ocean...

507
00:46:02,690 --> 00:46:04,865
...simply food for others.

508
00:46:07,972 --> 00:46:10,422
And yet it isn't over.

509
00:46:10,457 --> 00:46:14,599
♪

510
00:46:14,633 --> 00:46:17,671
The predator of all predators arrives.

511
00:46:22,193 --> 00:46:23,884
Orcas.

512
00:46:23,919 --> 00:46:28,268
♪

513
00:46:28,302 --> 00:46:31,685
As smart and cooperative
as a common dolphin

514
00:46:31,719 --> 00:46:33,687
and three times bigger.

515
00:46:36,863 --> 00:46:40,176
Orcas never used to travel
for the sardine run,

516
00:46:40,211 --> 00:46:44,767
but now they swim thousands of
miles to intercept the shoals.

517
00:46:44,802 --> 00:46:49,841
♪

518
00:46:49,876 --> 00:46:54,950
♪

519
00:46:54,984 --> 00:46:57,642
But it's not the sardines they're after.

520
00:46:57,676 --> 00:47:07,514
♪

521
00:47:07,548 --> 00:47:10,413
They're here to hunt dolphins.

522
00:47:10,448 --> 00:47:19,975
♪

523
00:47:20,009 --> 00:47:23,944
Not chasing anymore but running.

524
00:47:23,979 --> 00:47:26,498
The orcas are not only more powerful,

525
00:47:26,533 --> 00:47:28,397
they have more stamina.

526
00:47:28,431 --> 00:47:36,025
♪

527
00:47:36,060 --> 00:47:38,925
Just as the dolphins corralled the fish,

528
00:47:38,959 --> 00:47:41,755
now the orcas work the dolphins.

529
00:47:46,484 --> 00:47:48,831
They isolate one from the pod.

530
00:47:48,866 --> 00:47:54,595
♪

531
00:47:54,630 --> 00:48:00,394
♪

532
00:48:00,429 --> 00:48:04,122
Once they've locked onto
their target, they tag-team...

533
00:48:06,849 --> 00:48:08,437
...chasing it...

534
00:48:08,471 --> 00:48:11,889
♪

535
00:48:11,923 --> 00:48:15,237
...exhausting it...

536
00:48:15,271 --> 00:48:17,929
then... ramming it.

537
00:48:17,964 --> 00:48:27,939
♪

538
00:48:27,974 --> 00:48:37,949
♪

539
00:48:37,984 --> 00:48:47,959
♪

540
00:48:47,994 --> 00:48:57,106
♪

541
00:48:57,141 --> 00:49:01,662
♪

542
00:49:01,697 --> 00:49:03,871
They attack again and again

543
00:49:03,906 --> 00:49:07,220
until the dolphin can no longer swim.

544
00:49:07,254 --> 00:49:17,264
♪

545
00:49:17,299 --> 00:49:24,789
♪

546
00:49:24,823 --> 00:49:32,383
♪

547
00:49:32,417 --> 00:49:35,800
Before they can feast, they drown it.

548
00:49:49,365 --> 00:49:53,611
♪

549
00:49:53,645 --> 00:49:57,028
The orcas have scattered
the dolphin super pod.

550
00:49:59,410 --> 00:50:02,309
Without the organizing force
of the dolphins,

551
00:50:02,344 --> 00:50:07,694
the sardines regroup and
slip away into deep, cold water.

552
00:50:10,421 --> 00:50:14,149
The massive cloud of fish
that dominated the coastline

553
00:50:14,183 --> 00:50:18,049
suddenly vanishes,
as if absorbed by the sea.

554
00:50:18,084 --> 00:50:25,850
♪

555
00:50:25,884 --> 00:50:29,888
As July concludes,
the sated hunters disperse.

556
00:50:32,891 --> 00:50:36,378
Gannets proceed to travel up
to 60 miles a day

557
00:50:36,412 --> 00:50:38,449
searching for more food.

558
00:50:41,797 --> 00:50:44,593
Sharks continue their migrations,

559
00:50:44,627 --> 00:50:47,147
fully fed and stronger for it.

560
00:50:47,182 --> 00:50:54,741
♪

561
00:50:54,775 --> 00:50:58,676
Dolphins have successfully
weaned their calves.

562
00:50:58,710 --> 00:51:04,958
♪

563
00:51:04,992 --> 00:51:08,548
Super pods thin out
as family units regroup

564
00:51:08,582 --> 00:51:11,516
and return to their
regular hunting grounds.

565
00:51:11,551 --> 00:51:15,796
♪

566
00:51:15,831 --> 00:51:18,040
The cold current has delivered the feast

567
00:51:18,075 --> 00:51:20,353
that all the animals were counting on.

568
00:51:24,184 --> 00:51:28,809
Now it fades away, mixing
with the warm Indian Ocean.

569
00:51:28,844 --> 00:51:35,747
♪

570
00:51:35,782 --> 00:51:39,268
Some believe the sardines
ride the current down

571
00:51:39,303 --> 00:51:41,891
to secretly spawn in the deep.

572
00:51:43,514 --> 00:51:46,033
Others say they follow it
all the way back,

573
00:51:46,068 --> 00:51:49,175
1,000 miles to their home off the Cape.

574
00:51:52,281 --> 00:51:55,077
Next year the cold current will reform,

575
00:51:55,112 --> 00:51:59,150
stronger or weaker than the last...

576
00:51:59,185 --> 00:52:00,738
and billions of little fish

577
00:52:00,772 --> 00:52:03,706
will be driven to follow its call,

578
00:52:03,741 --> 00:52:09,816
to face hardship and sacrifice,
toward a purpose yet unknown.

579
00:52:09,850 --> 00:52:13,889
♪

580
00:52:16,581 --> 00:52:24,589
♪

581
00:52:24,624 --> 00:52:32,632
♪

582
00:52:32,666 --> 00:52:40,709
♪

583
00:52:40,743 --> 00:52:48,786
♪

584
00:52:48,820 --> 00:52:50,719
♪

585
00:52:50,753 --> 00:52:52,203
♪

586
00:52:52,238 --> 00:52:54,309
♪

587
00:52:54,343 --> 00:52:55,344
♪