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Narrator: Among the ocean's most dangerous predators...
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Only one...
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Is bold enough to trespass...
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♪ ♪
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(scream)
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...Right where you live.
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♪ ♪
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♪ ♪
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Bull shark.
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The bad boy of the tropics...
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Has earned its reputation...
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For aggression.
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♪ ♪
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♪ ♪
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Man: Oh, my gosh!
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Man: Holy (bleep)!
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Woman: Oh, my gosh!
(bleep) oh, my gosh!
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(screams) oh, my gosh!
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(bleep)
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Narrator: Like humans, bull sharks prefer warm seas.
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The coastlines of brazil, florida, california.
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And they don't stop there.
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Unlike most sharks, they thrive in fresh water.
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Rivers, lakes, harbors, canals.
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Bulls will travel miles up the amazon.
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They've invaded new orleans,
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All the way to lake pontchartrain.
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Even 1,700 miles up the mississippi into st. Louis.
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And florida, with its network of manmade canals,
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Is swimming with bull sharks.
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Man: (screams) watch out, boy!
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Watch out!
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Oh!
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Ah, dude,
that's 400 pounds, bro.
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Look at the size
of this shark, guys!
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Narrator: They prowl backyards...
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Live and hunt among people.
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A bull shark will even eat another shark.
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Man: Oh, look at the shark
trying to eat that shark!
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Woman: Oh, my god, look at that.
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Man: Holy (bleep)!
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Woman: Oh, my god! Oh, my god!
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Man: Holy (bleep)!
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Woman: (screams) oh, my god!
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Man: Holy (bleep)!
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Pardon my language,
but holy (bleep)!
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Did you get that on video?
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Narrator: They're mysterious and can be deadly to humans.
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Here's what we know.
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Like bulls on land, their bodies are muscular and broad.
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The biggest, 11 feet long,
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700 pounds of muscle,
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And brazen enough to steal.
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♪ ♪
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These spearfishermen are used to competition.
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♪ ♪
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Trevallies.
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Prized game fish and a family meal.
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♪ ♪
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♪ ♪
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Bull shark won't let you have it.
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♪ ♪
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♪ ♪
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♪ ♪
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They'll move in at any opportunity
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With unpredictable speed.
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♪ ♪
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♪ ♪
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Great white, tiger and bull
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Are the three deadliest sharks on earth.
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The great white shark: All-star cold-water killer.
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It can be seven times as heavy as a bull shark, twice as long.
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Its favorite food: Seals.
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Great whites' hunting method is iconic.
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Scout out the weak...
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(seals barking)
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♪ ♪
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Save energy...
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♪ ♪
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♪ ♪
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...For the perfect moment.
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♪ ♪
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♪ ♪
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Jaws can hack a seal in half.
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But the bull shark's bite is even stronger.
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Bulls will eat anything
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From dolphins to turtles to other sharks.
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With over 1,000 pounds per square inch of force...
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...It's enough to break a leg.
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The next contender: Tiger shark.
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The trash cans of the sea.
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They'll eat just about anything,
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With rows of teeth like a couple of hacksaws.
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Bigger than bulls, tiger sharks are travelers.
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And a floating whale carcass in a tropical sea
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Attracts them in hordes.
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♪ ♪
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♪ ♪
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♪ ♪
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♪ ♪
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♪ ♪
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Bull sharks patrol these same warm oceans,
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But bulls have an added advantage.
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They can hunt where tigers and great whites can't.
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Bull sharks don't have to feed every day.
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They're opportunists,
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Seeking out easy meals that will sustain them for days.
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The east coast of south africa
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Is one of the most shark-infested coastlines
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In the world.
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A sardine buffet attracts a throng of a-list predators.
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♪ ♪
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Gannet dive-bombers assault from the air.
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(squawking)
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Common dolphins round up the feast.
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(dolphins whistling)
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Bryde's whales gorge.
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♪ ♪
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♪ ♪
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♪ ♪
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And sharks.
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Whalers, duskies and blacktips.
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♪ ♪
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♪ ♪
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♪ ♪
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♪ ♪
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But the bulls are awol.
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There's a reason.
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♪ ♪
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♪ ♪
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Unlike most sharks,
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Bulls can control the salt levels in their bodies.
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They're uniquely adapted to thrive
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In estuaries and freshwater environments.
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♪ ♪
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Meaning they can move freely between salt water and fresh...
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♪ ♪
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Invade hunting grounds far inland...
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Where people live...
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...And play.
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♪ ♪
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♪ ♪
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♪ ♪
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No one sees them coming.
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(scream)
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Man: There she is! (screams)
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Narrator: Giant sharks, miles from any ocean.
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Bull sharks infiltrate river systems all over the world.
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Man: There she goes.
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Narrator: The only lethal shark
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That's capable of living in fresh water.
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They're close to where we live,
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Yet we know so little about them.
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Dr. Ryan daly studies bull sharks in southern africa.
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He's on a mission to find out what makes bull sharks
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Such nimble survivors.
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Ryan specializes in shark migration,
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Where they feed and breed,
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And how that impacts their conservation.
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A day at the office for ryan means catching bulls
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And fitting them with tracking devices.
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Ryan daly:
We're tagging bull sharks
primarily to find out
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Where they go,
where they spend their time,
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So we can balance out
the refuges and the risks
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That they face
as they migrate and move.
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Narrator: It's his job to get close to a predator
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He wants humans to keep away from, and vice versa.
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After eight years of tracking,
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He's discovered that bull sharks travel
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Almost 1,000 miles each year.
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He suspects they often go much farther.
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Ryan's main study site is in southern mozambique.
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Three miles off the coast of ponta do ouro
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Is a global hot spot for sharks.
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A healthy reef full of food is a beacon for predators.
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And a perfect place to study sharks.
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Ryan's looking to identify a few unique individuals,
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So he can learn which ones take up residence here.
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Ryan: There's so many sharks
down there at the moment.
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Five blacktips,
couple tigers on the outside,
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And a whole shoal
of hammerheads.
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This place is on fire!
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Narrator: Ryan's after the bull sharks.
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Big ones.
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♪ ♪
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♪ ♪
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He records how they hunt,
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How they compete with one another.
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♪ ♪
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Now, ryan's taking his research a step further.
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Ryan: Getting an eye,
or a perspective of their world
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Is almost impossible.
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But what recent technology
has allowed us to do
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Is use cameras to attach
to these sharks
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And let them collect
the data for us.
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Narrator: First, he has to catch
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His new research assistant.
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Ryan: Catching bull sharks
is especially difficult,
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Because they seem to know
that you're after them.
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♪ ♪
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♪ ♪
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♪ ♪
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Narrator: A bite.
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♪ ♪
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♪ ♪
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In order for ryan to get a camera on,
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The shark needs to be tired out.
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♪ ♪
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♪ ♪
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He puts it in a trance-like state and collects data.
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♪ ♪
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♪ ♪
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Ryan: We just need
to flip her over
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And then you can
put the camera on.
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Okay, looking good.
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Narrator: Ryan takes a photo id before the animal disappears.
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The fin cam won't start to record
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Until the shark's activity returns to normal, in 12 hours.
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This will be the first time a bull shark's natural behavior
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Is recorded in the indian ocean.
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♪ ♪
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♪ ♪
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No human distractions.
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Just a window into what a bull shark sees.
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Checking out prey.
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♪ ♪
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♪ ♪
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Other sharks.
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Blacktips.
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♪ ♪
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Massive tigers.
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♪ ♪
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♪ ♪
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And finally, in another first,
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A bull shark films other bulls.
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♪ ♪
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All apex predators,
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Instinctively heading towards a massive quarry of food.
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♪ ♪
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5,000 giant trevallies.
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Expert predators and a formidable foe.
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At nearly 180 pounds apiece,
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They're not afraid of sharks.
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Trevallies use a shark's rough skin
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To shed parasites from their scales.
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♪ ♪
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They're fast, too.
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Not an easy catch.
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Every year, at exactly the same time,
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Just before the full moon,
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Trevallies gather in southern mozambique to breed.
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For ryan, this annual ritual offers a golden opportunity.
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♪ ♪
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♪ ♪
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♪ ♪
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Ryan: So many big fish
down there.
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Seeing them all in one place
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In a massive shoal like that
is just mind blowing.
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It'll never get old.
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Narrator: Thousands of trevallies
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Should be an all-you-can-eat buffet.
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♪ ♪
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So far, ryan sees no predation on the fin camera.
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He needs more footage,
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And there's an easier way to get it.
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Ryan: We've come up
with a new camera design
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That gives us
a unique perspective
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Of what the shark's seeing.
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We don't have to catch the shark
to attach this camera to it.
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All we need to do
is feed the shark bait
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And it'll tow the camera around
for about six hours.
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Narrator: A blacktip shark is the first to grab the camera
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And take off.
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♪ ♪
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Not what ryan expected.
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But a chance to see something brand new.
277
00:19:00,373 --> 00:19:05,676
♪ ♪
278
00:19:05,678 --> 00:19:08,212
Ryan: Footage from the tow cam
reveals how these sharks swim
279
00:19:08,214 --> 00:19:11,315
Side by side and sometimes
even ram into each other.
280
00:19:14,187 --> 00:19:16,988
Narrator: Sharks are highly competitive.
281
00:19:20,693 --> 00:19:23,794
But also strategic.
282
00:19:23,796 --> 00:19:26,564
♪ ♪
283
00:19:26,566 --> 00:19:33,471
♪ ♪
284
00:19:33,473 --> 00:19:38,009
Here come the bulls.
285
00:19:38,011 --> 00:19:40,811
Blacktips and bulls take up position
286
00:19:40,813 --> 00:19:45,082
Around the shoal of trevallies.
287
00:19:45,084 --> 00:19:49,086
The bulls are much bigger.
288
00:19:49,088 --> 00:19:53,291
Higher up the food chain.
289
00:19:53,293 --> 00:19:57,495
Like a police force on patrol.
290
00:19:57,497 --> 00:19:59,463
The blacktips stay close.
291
00:19:59,465 --> 00:20:04,335
♪ ♪
292
00:20:04,337 --> 00:20:11,108
♪ ♪
293
00:20:11,110 --> 00:20:12,176
Ryan: You get the feeling
that they're all waiting
294
00:20:12,178 --> 00:20:13,744
For something to happen.
295
00:20:13,746 --> 00:20:16,180
♪ ♪
296
00:20:16,182 --> 00:20:22,053
♪ ♪
297
00:20:22,055 --> 00:20:28,226
♪ ♪
298
00:20:40,073 --> 00:20:44,408
Narrator: Bull sharks, tigers, hammerheads, and blacktips
299
00:20:44,410 --> 00:20:46,944
Converge around a challenging predator:
300
00:20:46,946 --> 00:20:50,414
A shoal of 5,000 fat trevallies.
301
00:20:53,253 --> 00:20:55,519
A bull shark's food of choice.
302
00:20:59,225 --> 00:21:01,259
After almost a decade of research,
303
00:21:01,261 --> 00:21:04,362
Dr. Ryan daly knows that at least 20 bull sharks
304
00:21:04,364 --> 00:21:07,898
Make these mozambican waters a year-round home.
305
00:21:12,472 --> 00:21:17,408
But in summer, when trevallies spawn,
306
00:21:17,410 --> 00:21:21,245
A multitude of sharks move here to feast.
307
00:21:21,247 --> 00:21:24,282
♪ ♪
308
00:21:24,284 --> 00:21:30,721
♪ ♪
309
00:21:30,723 --> 00:21:37,662
♪ ♪
310
00:21:37,664 --> 00:21:41,098
Scalloped hammerheads outnumber the bulls.
311
00:21:41,100 --> 00:21:47,505
♪ ♪
312
00:21:47,507 --> 00:21:53,744
♪ ♪
313
00:21:53,746 --> 00:21:57,548
They're after smaller bonitos, not giant trevallies.
314
00:21:57,550 --> 00:22:02,853
♪ ♪
315
00:22:02,855 --> 00:22:05,423
But blacktips are.
316
00:22:05,425 --> 00:22:07,858
♪ ♪
317
00:22:07,860 --> 00:22:14,865
♪ ♪
318
00:22:14,867 --> 00:22:16,867
Bull shark jaws open wide enough
319
00:22:16,869 --> 00:22:22,073
To take much bigger prey, even smaller sharks.
320
00:22:22,075 --> 00:22:23,741
Ryan: It's incredible
to see all these sharks,
321
00:22:23,743 --> 00:22:27,144
But when the bulls step in, all
the other species step aside.
322
00:22:29,382 --> 00:22:32,283
Narrator: The bulls work the edges of the shoal.
323
00:22:35,355 --> 00:22:38,989
Pick an easy target.
324
00:22:38,991 --> 00:22:42,960
They only need one trevally per week to sustain themselves.
325
00:22:42,962 --> 00:22:48,399
♪ ♪
326
00:22:48,401 --> 00:22:51,535
Nowhere else are this many bulls swarmed
327
00:22:51,537 --> 00:22:54,038
By a potential feast like this.
328
00:22:54,040 --> 00:23:00,478
♪ ♪
329
00:23:00,480 --> 00:23:06,917
♪ ♪
330
00:23:06,919 --> 00:23:13,124
♪ ♪
331
00:23:13,126 --> 00:23:15,726
Predator versus predator.
332
00:23:18,998 --> 00:23:22,700
Any fish that breaks formation instantly gets eaten.
333
00:23:22,702 --> 00:23:27,405
♪ ♪
334
00:23:27,407 --> 00:23:30,708
It's not a frenzy, but an attack strategy.
335
00:23:30,710 --> 00:23:33,144
♪ ♪
336
00:23:33,146 --> 00:23:39,583
♪ ♪
337
00:23:39,585 --> 00:23:46,123
♪ ♪
338
00:23:46,125 --> 00:23:49,260
Survival of the fittest.
339
00:23:49,262 --> 00:23:50,961
Marine version.
340
00:23:54,667 --> 00:23:57,101
♪ ♪
341
00:23:57,103 --> 00:24:02,139
♪ ♪
342
00:24:02,141 --> 00:24:05,042
Fit trevallies get to breed.
343
00:24:05,044 --> 00:24:07,878
The old and sick get eaten.
344
00:24:07,880 --> 00:24:10,714
♪ ♪
345
00:24:10,716 --> 00:24:17,655
♪ ♪
346
00:24:17,657 --> 00:24:19,290
Without mercy.
347
00:24:19,292 --> 00:24:25,763
♪ ♪
348
00:24:25,765 --> 00:24:27,531
Ryan: Wow, seeing
a big bull shark
349
00:24:27,533 --> 00:24:31,602
Rip open a fish like that,
just so much power.
350
00:24:31,604 --> 00:24:35,506
Narrator: After they spawn, the trevallies dissipate.
351
00:24:35,508 --> 00:24:38,742
So do the sharks.
352
00:24:38,744 --> 00:24:43,047
The question is, where do they go?
353
00:24:44,951 --> 00:24:49,019
Ryan once tagged a bull shark here that traveled 1,000 miles
354
00:24:49,021 --> 00:24:52,223
To the north of mozambique and back.
355
00:24:52,225 --> 00:24:55,326
Another invaded south african waters.
356
00:24:58,498 --> 00:25:03,634
Even these powerful travelers run a gauntlet.
357
00:25:03,636 --> 00:25:05,302
Ryan: As these
bull sharks migrate,
358
00:25:05,304 --> 00:25:08,005
They come into contact with
so many different dangers,
359
00:25:08,007 --> 00:25:10,875
Ranging from long lines,
shark nets,
360
00:25:10,877 --> 00:25:13,344
Which are pretty much designed
to cull sharks,
361
00:25:13,346 --> 00:25:16,981
And targeted shark fishing.
362
00:25:16,983 --> 00:25:19,283
There's increasing pressure
to catch sharks
363
00:25:19,285 --> 00:25:21,385
Because of their valuable fins.
364
00:25:21,387 --> 00:25:23,821
♪ ♪
365
00:25:23,823 --> 00:25:29,226
♪ ♪
366
00:25:29,228 --> 00:25:31,095
Narrator: As with predators on land,
367
00:25:31,097 --> 00:25:34,465
Humans are the bull sharks' greatest threat.
368
00:25:36,669 --> 00:25:40,170
But not the only one.
369
00:25:40,172 --> 00:25:45,109
As these adaptable hunters invade fresh water,
370
00:25:45,111 --> 00:25:49,013
They run into trouble, too.
371
00:25:49,015 --> 00:25:50,047
(hippo bellows)
372
00:25:55,922 --> 00:25:57,555
Narrator: These safari tourists
373
00:25:57,557 --> 00:26:01,659
Are about to get the sighting of their lives.
374
00:26:01,661 --> 00:26:04,061
(people screaming)
375
00:26:04,063 --> 00:26:06,497
Hippo versus bull shark.
376
00:26:06,499 --> 00:26:09,900
♪ ♪
377
00:26:09,902 --> 00:26:14,338
♪ ♪
378
00:26:14,340 --> 00:26:16,740
(grunting)
379
00:26:16,742 --> 00:26:19,777
The strongest bite force of all mammals...
380
00:26:19,779 --> 00:26:24,181
♪ ♪
381
00:26:24,183 --> 00:26:28,485
...Faces off with the strongest bite force of all sharks.
382
00:26:28,487 --> 00:26:33,190
♪ ♪
383
00:26:33,192 --> 00:26:39,430
♪ ♪
384
00:26:39,432 --> 00:26:42,933
Just 150 miles south of ryan's study site,
385
00:26:42,935 --> 00:26:46,370
At st. Lucia estuary,
386
00:26:46,372 --> 00:26:50,674
One of africa's largest tidal wetlands,
387
00:26:50,676 --> 00:26:53,377
A watery mix of fresh and salt.
388
00:26:55,648 --> 00:26:57,815
Shallow.
389
00:26:57,817 --> 00:27:00,384
Warm.
390
00:27:00,386 --> 00:27:02,853
Just right for bull sharks.
391
00:27:05,358 --> 00:27:10,394
And a once-in-a-lifetime encounter on safari.
392
00:27:10,396 --> 00:27:13,297
♪ ♪
393
00:27:13,299 --> 00:27:17,901
(bellowing)
394
00:27:17,903 --> 00:27:22,339
♪ ♪
395
00:27:22,341 --> 00:27:28,746
♪ ♪
396
00:27:28,748 --> 00:27:32,816
(bellows)
397
00:27:32,818 --> 00:27:38,856
♪ ♪
398
00:27:38,858 --> 00:27:41,358
This shark was probably chasing a fish
399
00:27:41,360 --> 00:27:45,396
When it caught the hippos by surprise.
400
00:27:45,398 --> 00:27:48,465
Africa's deadliest large land animal.
401
00:27:50,736 --> 00:27:54,438
And a clue to a mystery.
402
00:27:54,440 --> 00:27:57,875
We know bulls infiltrate rivers like these to feed.
403
00:28:03,582 --> 00:28:05,582
And there's no shortage of rivers
404
00:28:05,584 --> 00:28:07,985
On the east coast of south africa
405
00:28:07,987 --> 00:28:11,455
For a bull shark to invade and disappear.
406
00:28:14,026 --> 00:28:17,961
Tucked away on the wild coast,
407
00:28:17,963 --> 00:28:19,930
A pristine wilderness.
408
00:28:24,203 --> 00:28:28,706
Undisturbed from sea to source.
409
00:28:28,708 --> 00:28:30,574
(birds squawking)
410
00:28:31,844 --> 00:28:35,746
Such a forested retreat
411
00:28:35,748 --> 00:28:38,816
Is an unlikely place to find any marine creature.
412
00:28:38,818 --> 00:28:40,818
(birds cawing)
413
00:28:43,823 --> 00:28:45,889
(bird screeching)
414
00:28:47,793 --> 00:28:50,828
And a long shot for a shark scientist.
415
00:28:53,232 --> 00:28:56,734
But ryan knows there's a visitor from the ocean here
416
00:28:56,736 --> 00:28:59,970
That might bring him closer to bull sharks.
417
00:28:59,972 --> 00:29:05,676
♪ ♪
418
00:29:05,678 --> 00:29:11,715
♪ ♪
419
00:29:11,717 --> 00:29:14,885
It's not uncommon to see trevallies in rivers.
420
00:29:16,855 --> 00:29:20,591
They may use systems like this one as a nursery,
421
00:29:20,593 --> 00:29:22,493
Or take advantage of fresh water
422
00:29:22,495 --> 00:29:24,561
To kill off marine parasites.
423
00:29:27,133 --> 00:29:32,669
But seeing 200 of them together is peculiar.
424
00:29:32,671 --> 00:29:34,471
Ryan: Not only do giant trevally
occur there,
425
00:29:34,473 --> 00:29:37,474
But they seem to shoal
in the unique way
426
00:29:37,476 --> 00:29:39,343
That we just don't see
anywhere else.
427
00:29:39,345 --> 00:29:42,079
The reason the giant trevallies
are a bit of a mystery,
428
00:29:42,081 --> 00:29:43,881
To be honest.
429
00:29:46,585 --> 00:29:51,955
♪ ♪
430
00:29:51,957 --> 00:29:53,757
Narrator: The mystery goes beyond
431
00:29:53,759 --> 00:29:57,661
Why an ocean dweller adapts to a saline-free habitat.
432
00:29:57,663 --> 00:30:00,097
♪ ♪
433
00:30:00,099 --> 00:30:05,169
♪ ♪
434
00:30:05,171 --> 00:30:08,405
To get here, the trevallies battle tides
435
00:30:08,407 --> 00:30:12,042
And swim against shallow rapids 3 miles inland.
436
00:30:14,046 --> 00:30:15,512
It would be impossible
437
00:30:15,514 --> 00:30:18,282
For a big predator to follow the bait.
438
00:30:21,520 --> 00:30:23,587
But not a small one.
439
00:30:31,197 --> 00:30:32,963
They're here.
440
00:30:35,201 --> 00:30:37,000
Baby bull sharks.
441
00:30:37,002 --> 00:30:43,974
♪ ♪
442
00:30:43,976 --> 00:30:50,714
♪ ♪
443
00:30:50,716 --> 00:30:53,217
Ryan: This is fascinating,
because it is essentially
444
00:30:53,219 --> 00:30:56,520
In the forests, above rapids,
445
00:30:56,522 --> 00:31:01,358
Just right up at the top
of this river system.
446
00:31:01,360 --> 00:31:05,229
Narrator: How did juvenile sharks reach so far inland?
447
00:31:05,231 --> 00:31:07,664
♪ ♪
448
00:31:07,666 --> 00:31:13,570
♪ ♪
449
00:31:13,572 --> 00:31:15,472
After a 10-month pregnancy,
450
00:31:15,474 --> 00:31:18,308
Female bull sharks drop one to three pups
451
00:31:18,310 --> 00:31:20,110
At the mouth of a river.
452
00:31:20,112 --> 00:31:22,512
Her job is done.
453
00:31:22,514 --> 00:31:25,482
The baby sharks instinctively swim upriver,
454
00:31:25,484 --> 00:31:28,919
Away from ocean predators.
455
00:31:28,921 --> 00:31:33,690
All they have to do now is fatten up.
456
00:31:33,692 --> 00:31:35,726
True to their mysterious nature,
457
00:31:35,728 --> 00:31:39,596
Bull sharks are hard to find.
458
00:31:39,598 --> 00:31:43,433
So this is another first.
459
00:31:43,435 --> 00:31:44,768
Ryan: Yes, I've been
studying bull sharks
460
00:31:44,770 --> 00:31:46,436
For over a decade now,
461
00:31:46,438 --> 00:31:50,040
But I've never seen juvenile
sharks in a forested river,
462
00:31:50,042 --> 00:31:53,110
Miles away from the ocean,
in such a pristine environment.
463
00:31:53,112 --> 00:31:58,248
Just the perfect habitat for
them to grow up, grow strong.
464
00:31:58,250 --> 00:31:59,650
Narrator: Ryan has just confirmed
465
00:31:59,652 --> 00:32:02,286
A new nursery ground for his study.
466
00:32:02,288 --> 00:32:04,955
When these baby bulls are big and tough enough,
467
00:32:04,957 --> 00:32:06,957
They will head out to sea.
468
00:32:11,196 --> 00:32:13,997
Where will they invade next?
469
00:32:20,205 --> 00:32:21,838
Narrator: Bull shark.
470
00:32:21,840 --> 00:32:23,907
Among the three deadliest sharks in the world.
471
00:32:23,909 --> 00:32:28,512
The great white and tiger are more famous.
472
00:32:28,514 --> 00:32:30,514
But bull is the only shark
473
00:32:30,516 --> 00:32:33,116
That regularly invades human habitats.
474
00:32:33,118 --> 00:32:35,118
Man: (screams) watch out, boys!
475
00:32:35,120 --> 00:32:37,254
Watch out!
476
00:32:37,256 --> 00:32:41,224
Narrator: Stealing fish...
477
00:32:41,226 --> 00:32:46,229
And growing up in fresh water, miles upriver.
478
00:32:46,231 --> 00:32:51,568
Opportunistic, unpredictable, misunderstood.
479
00:32:51,570 --> 00:32:54,838
Dr. Ryan daly is in the bull shark's corner.
480
00:32:54,840 --> 00:32:59,376
He wants to know where they travel, feed and breed,
481
00:32:59,378 --> 00:33:01,945
So that he can help keep them out of trouble.
482
00:33:01,947 --> 00:33:03,313
Ryan: Bull sharks may be
perceived as these
483
00:33:03,315 --> 00:33:04,915
Sort of killing machines,
484
00:33:04,917 --> 00:33:08,885
But they are key predators
in our marine ecosystems,
485
00:33:08,887 --> 00:33:12,723
And we need them to keep
our ecosystems in balance.
486
00:33:12,725 --> 00:33:14,925
Narrator: He knows bull sharks travel every summer
487
00:33:14,927 --> 00:33:17,527
To mozambique to feed.
488
00:33:17,529 --> 00:33:22,332
But even for a shark, travel comes with risk.
489
00:33:22,334 --> 00:33:25,102
Threats are everywhere.
490
00:33:27,306 --> 00:33:31,008
How are these sharks so successful at moving around?
491
00:33:31,010 --> 00:33:33,677
And what is the bull shark's range?
492
00:33:37,316 --> 00:33:41,785
To find out, ryan travels to the most southwesterly end
493
00:33:41,787 --> 00:33:44,654
Of the bull shark's range in africa.
494
00:33:44,656 --> 00:33:49,292
♪ ♪
495
00:33:49,294 --> 00:33:53,196
The sleepy town of infanta,
496
00:33:53,198 --> 00:33:56,933
On the busy breede river.
497
00:33:56,935 --> 00:34:00,337
Home to at least 30 bull sharks in summer.
498
00:34:03,308 --> 00:34:06,910
People vacation here.
499
00:34:06,912 --> 00:34:09,146
This could be new york's long island
500
00:34:09,148 --> 00:34:12,149
Or the outer banks, north carolina.
501
00:34:12,151 --> 00:34:13,817
Ryan: It's crazy,
all these people,
502
00:34:13,819 --> 00:34:16,353
All these sharks
in the same place.
503
00:34:16,355 --> 00:34:19,222
It's incredible that
everything is so peaceful,
504
00:34:19,224 --> 00:34:21,658
And I hope it continues
as it is;
505
00:34:21,660 --> 00:34:25,228
Sharks minding their business,
people minding their business.
506
00:34:25,230 --> 00:34:27,431
Narrator: Ryan is here to catch a shark
507
00:34:27,433 --> 00:34:31,802
And fit it with a long-term tracking device.
508
00:34:31,804 --> 00:34:35,038
Ryan: This can stay on the shark
for six months to a year.
509
00:34:35,040 --> 00:34:38,442
Pop up on a specified date,
come to the surface,
510
00:34:38,444 --> 00:34:40,110
Transmit all the data to us.
511
00:34:40,112 --> 00:34:42,079
So hopefully we're gonna be able
to answer some of the questions
512
00:34:42,081 --> 00:34:44,114
Around where they go.
513
00:34:44,116 --> 00:34:47,684
Narrator: Time to go shark fishing again.
514
00:34:47,686 --> 00:34:50,454
Ryan teams up with dr. John filmater,
515
00:34:50,456 --> 00:34:53,123
Marine scientist and local expert.
516
00:34:53,125 --> 00:34:59,596
♪ ♪
517
00:34:59,598 --> 00:35:02,165
They have a tough job on their hands.
518
00:35:05,471 --> 00:35:09,139
Ryan: Yeah, this is
pretty much shark food.
519
00:35:09,141 --> 00:35:11,408
So the waiting game begins.
520
00:35:11,410 --> 00:35:13,844
♪ ♪
521
00:35:13,846 --> 00:35:19,883
♪ ♪
522
00:35:19,885 --> 00:35:23,720
Narrator: A big shark takes the bait.
523
00:35:23,722 --> 00:35:26,289
Ryan: Ooh, it's nice, putting
a bit of extra pressure on him.
524
00:35:26,291 --> 00:35:27,424
Perfect.
525
00:35:27,426 --> 00:35:29,559
Ooh, it might be wrapped
a little bit.
526
00:35:31,563 --> 00:35:33,663
It's definitely angry.
527
00:35:33,665 --> 00:35:36,967
Yeah, it's got a lot
of energy still.
528
00:35:36,969 --> 00:35:42,205
Narrator: He can't pull it in safely until he's tired it out.
529
00:35:42,207 --> 00:35:44,608
Ryan: Yo.
530
00:35:44,610 --> 00:35:47,844
Narrator: A formidable predator with a temper...
531
00:35:47,846 --> 00:35:53,216
♪ ♪
532
00:35:53,218 --> 00:35:56,219
...That can snap in a second.
533
00:35:57,756 --> 00:35:59,956
Man: Oh, my god!
534
00:35:59,958 --> 00:36:02,993
Narrator: Until the shark is secured next to the boat,
535
00:36:02,995 --> 00:36:06,563
Anything can happen.
536
00:36:06,565 --> 00:36:09,599
Ryan: (laughs) that's right.
537
00:36:09,601 --> 00:36:10,834
John filmater:
Think he'll get angry.
538
00:36:10,836 --> 00:36:12,369
Ryan: The head shakes
are proper.
539
00:36:12,371 --> 00:36:13,904
Watch, watch, watch!
540
00:36:18,877 --> 00:36:19,910
Male shark.
541
00:36:19,912 --> 00:36:20,911
John: Yeah.
542
00:36:20,913 --> 00:36:23,847
Ryan: Head shakes are violent.
543
00:36:23,849 --> 00:36:25,248
Tail up.
544
00:36:25,250 --> 00:36:31,021
♪ ♪
545
00:36:31,023 --> 00:36:33,123
Yes, it's a monster, this thing.
546
00:36:33,125 --> 00:36:35,559
♪ ♪
547
00:36:35,561 --> 00:36:40,530
♪ ♪
548
00:36:40,532 --> 00:36:44,234
(grunts)
549
00:36:44,236 --> 00:36:49,673
♪ ♪
550
00:36:49,675 --> 00:36:55,946
♪ ♪
551
00:36:55,948 --> 00:36:58,348
Yes, well done. Very nice.
552
00:36:58,350 --> 00:37:04,254
♪ ♪
553
00:37:04,256 --> 00:37:05,989
We always monitor the shark
554
00:37:05,991 --> 00:37:08,959
And make sure it's got water
pumping over its gills.
555
00:37:13,065 --> 00:37:14,798
Narrator: Time to flip it.
556
00:37:14,800 --> 00:37:20,570
♪ ♪
557
00:37:20,572 --> 00:37:24,374
The nearly 10-foot shark instantly calms.
558
00:37:29,982 --> 00:37:31,047
Ryan: It's a big shark.
559
00:37:31,049 --> 00:37:32,749
Ooh, okay. Wait a bit?
560
00:37:32,751 --> 00:37:35,018
John: Yeah.
561
00:37:35,020 --> 00:37:37,420
Ryan: Ah, 297.
562
00:37:37,422 --> 00:37:39,723
John: Okay. Jeez.
563
00:37:39,725 --> 00:37:45,929
♪ ♪
564
00:37:45,931 --> 00:37:49,499
Narrator: A small incision for an internal acoustic tag.
565
00:37:51,403 --> 00:37:52,836
John: Happy?
566
00:37:52,838 --> 00:37:54,704
Ryan: Okay, tag that as well.
567
00:37:54,706 --> 00:38:01,344
♪ ♪
568
00:38:01,346 --> 00:38:03,546
Narrator: And as long as the shark is on its back
569
00:38:03,548 --> 00:38:05,115
It's in a trance.
570
00:38:05,117 --> 00:38:08,818
But if it flips over too soon, there's trouble.
571
00:38:08,820 --> 00:38:09,753
John: Yo. Watch! Watch!
572
00:38:16,128 --> 00:38:20,797
Narrator: A 9 1/2-foot bull shark in a busy river.
573
00:38:22,701 --> 00:38:26,002
Dr. Ryan daly wants to know its migratory patterns
574
00:38:26,004 --> 00:38:28,338
And exactly where it will travel.
575
00:38:28,340 --> 00:38:34,711
♪ ♪
576
00:38:34,713 --> 00:38:38,748
Ryan: It's awake.
That's a good sign.
577
00:38:38,750 --> 00:38:40,984
Narrator: A satellite tag on the dorsal fin
578
00:38:40,986 --> 00:38:43,286
Will track his movements for up to a year.
579
00:38:43,288 --> 00:38:44,487
Ryan: It's gonna switch itself
on automatically
580
00:38:44,489 --> 00:38:46,923
When it gets to 5 meters deep.
581
00:38:46,925 --> 00:38:52,829
♪ ♪
582
00:38:52,831 --> 00:38:56,633
Narrator: The release is done from the water.
583
00:38:56,635 --> 00:38:58,101
Ryan: Okay, there we go.
Turn it over.
584
00:38:58,103 --> 00:38:59,536
John: No, right there.
585
00:38:59,538 --> 00:39:00,804
Ryan: Oh.
586
00:39:05,210 --> 00:39:07,243
John: Don't turn it over.
Tell me when to turn it over.
587
00:39:07,245 --> 00:39:08,778
Ryan: Yeah.
588
00:39:08,780 --> 00:39:11,214
Narrator: Ryan guides the shark back.
589
00:39:11,216 --> 00:39:15,652
♪ ♪
590
00:39:15,654 --> 00:39:22,092
♪ ♪
591
00:39:22,094 --> 00:39:28,531
♪ ♪
592
00:39:28,533 --> 00:39:35,071
♪ ♪
593
00:39:35,073 --> 00:39:37,941
John: Watch, watch, watch!
594
00:39:37,943 --> 00:39:39,909
Narrator: Over the course of seven days,
595
00:39:39,911 --> 00:39:42,445
The team successfully tags and releases
596
00:39:42,447 --> 00:39:45,315
Four big male bull sharks.
597
00:39:51,123 --> 00:39:53,623
Ryan: Tagging these bull sharks
here has allowed us to discover
598
00:39:53,625 --> 00:39:57,527
That they travel
at least 20 miles upriver,
599
00:39:57,529 --> 00:40:00,096
Up and down, almost every day.
600
00:40:00,098 --> 00:40:02,098
Narrator: Bull sharks patrolling a river
601
00:40:02,100 --> 00:40:05,301
Surrounded by farms and vacation homes.
602
00:40:05,303 --> 00:40:10,507
♪ ♪
603
00:40:10,509 --> 00:40:12,809
Triggered by winter's cooler temperatures,
604
00:40:12,811 --> 00:40:16,279
The sharks break for open ocean.
605
00:40:16,281 --> 00:40:18,415
Ryan: We expected them
to stop off
606
00:40:18,417 --> 00:40:22,652
At known bull shark aggregation
sites as they went up the coast.
607
00:40:22,654 --> 00:40:24,254
In fact, they did the opposite.
608
00:40:24,256 --> 00:40:26,556
Once these bull sharks
left the breede river,
609
00:40:26,558 --> 00:40:28,591
They just beelined it
for northern mozambique,
610
00:40:28,593 --> 00:40:31,327
Almost 2,000 miles away.
611
00:40:31,329 --> 00:40:34,230
Narrator: Ryan has made a remarkable discovery.
612
00:40:34,232 --> 00:40:36,699
Rather than go it alone,
613
00:40:36,701 --> 00:40:40,503
The sharks leave the river together.
614
00:40:40,505 --> 00:40:42,305
Like bulls on a stampede,
615
00:40:42,307 --> 00:40:46,576
They swim almost 2,000 miles over three months,
616
00:40:46,578 --> 00:40:49,579
All the way to northern mozambique.
617
00:40:49,581 --> 00:40:52,982
This is much farther than ryan thought.
618
00:40:52,984 --> 00:40:55,351
Then, the four sharks turn around in time
619
00:40:55,353 --> 00:40:58,154
To make the trevally feast off the south coast.
620
00:41:01,793 --> 00:41:04,160
The previous record for bull shark migration
621
00:41:04,162 --> 00:41:06,830
Was 2,000 miles.
622
00:41:06,832 --> 00:41:10,166
The four tagged sharks have already covered 3,000 miles
623
00:41:10,168 --> 00:41:13,336
To reach the trevally spawn.
624
00:41:13,338 --> 00:41:15,872
A new record.
625
00:41:15,874 --> 00:41:19,509
Ryan has no idea if his research subjects have survived
626
00:41:19,511 --> 00:41:21,277
Or if they'll return to the breede river
627
00:41:21,279 --> 00:41:22,645
Where they started.
628
00:41:27,452 --> 00:41:31,754
The only way to find out
629
00:41:31,756 --> 00:41:33,289
Is for ryan and john to go back
630
00:41:33,291 --> 00:41:36,159
To where they tagged the sharks 12 months ago...
631
00:41:36,161 --> 00:41:40,396
♪ ♪
632
00:41:40,398 --> 00:41:42,131
...In hopes they pick up a signal
633
00:41:42,133 --> 00:41:44,200
From one of the transmitters.
634
00:41:48,073 --> 00:41:50,974
Ryan: Alright,
we're in the spot.
635
00:41:50,976 --> 00:41:53,343
John: See if there's
a shark here.
636
00:41:53,345 --> 00:41:59,916
♪ ♪
637
00:41:59,918 --> 00:42:01,618
Narrator: A hydrophone will listen
638
00:42:01,620 --> 00:42:04,020
For acoustic tags nearby.
639
00:42:04,022 --> 00:42:08,525
♪ ♪
640
00:42:08,527 --> 00:42:13,563
John: If there's a shark within
400 meters of us, we'll know.
641
00:42:13,565 --> 00:42:15,064
Ryan: Alright.
642
00:42:17,903 --> 00:42:19,536
Come on, shark.
643
00:42:19,538 --> 00:42:23,506
John: So the tags are pinging
every 40 seconds or so.
644
00:42:23,508 --> 00:42:25,942
♪ ♪
645
00:42:25,944 --> 00:42:30,780
♪ ♪
646
00:42:30,782 --> 00:42:34,150
Ryan: Oh, is that something?
647
00:42:34,152 --> 00:42:35,852
False alarm.
648
00:42:38,857 --> 00:42:40,657
(clicking)
649
00:42:40,659 --> 00:42:43,459
Oh, there's a detection.
650
00:42:43,461 --> 00:42:44,394
And that's one of the sharks.
651
00:42:44,396 --> 00:42:45,995
John: Five-oh. No ways!
652
00:42:45,997 --> 00:42:48,498
Ryan: What? That's one
of the male zambezi sharks.
653
00:42:48,500 --> 00:42:54,737
It was 286 centimeters, so just
under 3 meters, or about 9 feet.
654
00:42:54,739 --> 00:42:56,639
So it's one of
our big male sharks.
655
00:42:56,641 --> 00:42:59,676
Unreal. Okay, so that means
that that shark has gone
656
00:42:59,678 --> 00:43:03,212
At least 1,800 miles up the
coast to northern mozambique,
657
00:43:03,214 --> 00:43:06,282
Turned around, swam all the way
back to the same place.
658
00:43:06,284 --> 00:43:08,785
Must be a round trip
of over 4,000 miles.
659
00:43:08,787 --> 00:43:10,920
Just under a year, it's come all
the way back to the same place.
660
00:43:10,922 --> 00:43:12,522
(clicking)
there it is again!
661
00:43:12,524 --> 00:43:16,759
John: That is absolutely insane.
662
00:43:16,761 --> 00:43:20,763
Narrator: All four tagged males are detected in the river.
663
00:43:20,765 --> 00:43:23,166
The data reveals that two of them arrived
664
00:43:23,168 --> 00:43:25,935
Within 30 hours of each other.
665
00:43:25,937 --> 00:43:30,073
They traveled 4,000 miles together.
666
00:43:30,075 --> 00:43:33,876
The longest bull shark migration ever recorded.
667
00:43:36,548 --> 00:43:39,148
Double the previously published record.
668
00:43:39,150 --> 00:43:43,286
♪ ♪
669
00:43:45,657 --> 00:43:49,258
Bulls travel from sea to river
670
00:43:49,260 --> 00:43:53,329
And back to sea every day
671
00:43:53,331 --> 00:43:58,301
And in coordinated migratory patterns.
672
00:43:58,303 --> 00:44:02,305
Are bull sharks a species uniquely lethal to humans?
673
00:44:04,943 --> 00:44:07,644
Or an apex predator under threat
674
00:44:07,646 --> 00:44:11,848
In every habitat it invades?
675
00:44:11,850 --> 00:44:13,816
Running the gauntlet of competition
676
00:44:13,818 --> 00:44:16,786
And other predators,
677
00:44:16,788 --> 00:44:19,489
To feed and to breed,
678
00:44:19,491 --> 00:44:23,926
This year and every year, all over the world.
679
00:44:23,928 --> 00:44:25,061
Captioned by
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52619
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