'Each year, hundreds
of the biggest great whites
on the planet gather in
southern New Zealand.
Between the males, a power struggle.
And the female great whites?
They're looking for the alpha male.'
It is an arena where
males come and compete.
And as the season goes on,
the males get bigger and bigger
and the competition gets
greater and greater.
'So what does it
take to be the alpha shark
among all these giants?'
By definition, the alpha male is
generally the most powerful,
the most aggressive, the most
testosterone, the best hunter,
but this has never been established
for a great white shark.
We're going to establish
who is the alpha male,
who is the boss shark?
'Stewart Island, New Zealand.
In a world-first,
Doctor Riley Elliott
and Marine Biologist,
Kori Burkhardt,
have come up with a
one-of-kind competition
to find out who's the alpha.'
We're starting to
gather social hierarchy
understanding of these animals
and a list of individuals.
And at the end of the day,
we will be able to determine
who is the alpha male.
'For several months,
great whites have been arriving
at Stewart Island after
an annual migration
of thousands of kilometres.
Satellite tags have
tracked them voyaging here
from across the South Pacific.
By late Autumn, the
population of Stewart Island
great whites grows to more
than a hundred sharks,
all packed into a few
square kilometres of water
and jostling to be at
the top of the hierarchy.
I'm a shark behavioural ecologist
that studies how dominance
shapes ecosystems
in the South Pacific.
This is a first of
its kind hands-on way
to study dominance in the
world of male white sharks.
'Of the many great whites
swimming the waters here,
Kori has identified
five main contenders
that have the size, strength
and attitude to be an alpha shark.
Happy, 3.7 metres long.
A young shark,
not scared of anything.
Brutus, the biggest
and oldest male.
Scrappy, covered in scars
and always ready to throw down.
Max, maximum speed,
maximum aggression.
Little Caesar, the
smallest of the contenders
with the most attitude.
These five players will
be put to the test.'
We've designed a
series of experiments
to investigate how these sharks
set up a hierarchy system
to see which one can
get the biggest and baddest female
at the end of the season.
'Speed measures
their athleticism and power.
Peacocking tests
their sexual fitness.
Predation reveals the
most deadly k*ller.
And fearlessness puts
their courage on trial.
The shark that
wins the most tests
will be crowned The Boss Shark.
The first experiment
measures speed,
to find out which shark can harness
its power the most effectively.'
To establish how powerful
each great white is,
we're going to measure
how fast it can swim.
With that, we get a metric of the
capability of each individual.
'Riley will draw each
shark into a vertical attack on bait
and record their peak speed.'
And this is how we're going
to do it, with a laser grid.
This thing is wicked.
How does it work?
We have two parallel lasers,
but we have six in a row here
and as the sharks pass through it,
take a screen grab,
get a measure of how fast they move
through each of these grids
to calculate their maximum speed.
'The lasers are
spaced 30 centimetres apart,
so the team can use the rig
to time how fast each shark
moves through the set distance
and then determine its velocity.
Sharks are allowed to
attack multiple times.
Only their highest
score is recorded.'
'In short bursts, great whites can
hit almost 50 kilometres per hour.'
'In this test, Riley
needs them to swim vertically
past his cage to ensure he
gets a clean reading
at a consistent distance.
Propelling their massive
bodies upwards against gravity,
they won't be as fast.
But these sharks are famous for
their vertical strikes on prey.
Their dark coloration helps
them hide in the depths
and choose the time and place
to launch a devastating
as*ault from below.
OK, bait's going down.
Stand by. Pull, pull, pull,
pull, pull, pull, pull.
OK, bait's going down.
'Happy hit
23 kilometres per hour
and is first on the board.'
OK, get ready.
Slow pull.
'At 25 kilometres per hour,
Scrappy's taken the lead.'
Alright deploy the
bait, deploy the bait.
Here he comes, here he comes!
Keep going, keep
going, keep going.
Oh my god!
'Despite the perfect form,
Max only clocks in at
19 kilometres an hour,
putting him in third place.'
'At four metres, Brutus is
the biggest and oldest male here.
On his first attempt,
he missed the bait
and hit the cage instead.
Now it's his shot at redemption.'
Here comes big Brutus.
Slow pull, slow pull, slow pull.
Pull, pull, pull, pull!
Keep pulling, keep pulling!
Keep pulling!
'29 kilometres per
hour puts Brutus in the lead.
Riley and Kori have
readings on every shark
but the smallest
one, Little Caesar,
so they'll target him
with the last bait.'
Deploy the bait.
Start pulling, keep
going, keep going.
'In true alpha fashion,
Brutus has pushed the
smallest shark aside
and taken another
run at the bait,
maxing out at 35
kilometres per hour.'
The experiment was designed simply
and it worked perfectly.
Great white sharks getting airtime
measured with lasers,
calculating body length, speed.
And one thing became clear,
Brutus was number one.
'At four metres long
and with a maximum speed
of 35 kilometres per hour,
Brutus wins the competition.
Runner's up, 3.7 metre Scrappy,
who clocked in at 25
kilometres per hour.
Happy at 23 kilometres per hour.
And finally Max at 19
kilometres per hour.
Brutus has won the first test,
but he'll need more than speed
to become the alpha shark.
Riley and Kori will
be watching closely
how he performs in the next test.
So will the big females.
Their arrival marks the
beginning of the true battle
for these males, the chance to mate.
The females will be
the ultimate judges.'
So the mature female
great white sharks
have their own incredible story.
At the end of the season down here,
they actually migrate
thousands of miles north to the
Polynesian tropical islands
where the water is really warm,
and they spend six months of
their lives up there.
It makes sense.
White sharks, they have to regulate
their inner body temperature.
If you're a pregnant female,
you gotta have really nice energy
efficiency to brood those pups.
The warmer water is
gonna help with that.
The mature female, they can
have up to six pups inside of them.
They are seven feet long each and
they give birth to them live.
They come back to New Zealand
at the start of summer.
They drop them in the warm,
nursery grounds of estuaries
and harbours and then they
continue their migration south
down here to these
very, very cold waters.
And then you've got
the male sharks here
building up their social structure,
working out their hierarchy
so when those big females arrive,
they're ready to do that cycle all
over again and reproduce.
It sets the premise we're trying to
do and the importance of it.
Finding out how, why and who
becomes the alpha male that
that mature female picks.
We know great whites
are perfectly evolved.
They all look pretty much the
same, they're silver b*ll*ts.
In the animal kingdom, sexual
selection where females, as you know
pick males based on the biggest
lion's mane, biggest horns.
Male great white sharks don't
really have any of that flair,
except for two things
that stand out, claspers.
'For the non-scientists,
claspers are penises.
And great white sharks
are equipped with two.'
Males with the biggest testosterone
actually have bigger gonads
than lesser dominant males, and so
we could have overlooked something
just by pure awkwardness
of claspers.
And to investigate whether
there's a correlation there,
we're going to have to measure them.
OK, but surely you're not using this
as that's a bit unfair for our boys.
No Kori, I have set up a clasper
friendly sized laser rig.
These lasers are 12 inches
apart and with this,
we can measure the clasper
size, the body size,
put those things in proportion to
get a measure of this alpha trait.
OK, I don't think this
has ever been done before,
but let's go see if
size really matters.
'The Stewart
Island sharks are unique
because great whites of
all ages can be found here.
In most other locations,
they live a highly
segregated existence
with smaller sharks keeping
well clear of the bigger ones.
They co-exist at Stewart Island,
but to avoid conflict
they tend to divide
the water column.
The biggest and most powerful sharks
dominate the surface waters,
where large and dangerous prey
like seals are most easily found.
Smaller sharks lurk
in the deeper water
and at the periphery of the action.
They chase fish and
anything that drifts down
from the carnage above them
while avoiding
the bigger sharks.
Scientists believe that this
vertical distribution strategy
is an opportunity for
the younger sharks
to watch the older ones
above and learn from them.
For this reason,
Riley and Kori are positioning
this test at the surface,
where the boss shark is
most likely to be found.
The shark with the
biggest claspers
as a percentage of his body size
will win this challenge.
'Bait will be
used to lure the sharks close.'
'With cages in an
L-shaped configuration,
the sharks will be forced
into a 90 degree turn
as they strike the bait,
exposing their claspers
when they turn away
and putting Riley and
Kori in the firing line.'
That looks like Brutus.
That was perfect!
'Brutus has measured up
with 30 centimetre claspers,
but it remains to be seen if that's
enough to win this test.'
'With just
20 centimetre claspers,
Little Caesar is already
out of the running.'
'At 40 centimetres,
Happy has pulled ahead of Brutus.'
'With a pair
of 60 centimetre claspers,
Scrappy has knocked both Brutus
and Happy out of the race.
Riley's measured every
shark except Max.
But now, the males have backed off
and the waters have fallen quiet.'
'Like humans,
sharks are sexually dimorphic.
One sex is larger than the other.
But in sharks, it's the
females who are bigger.
They grow to almost
twice the size of males
and can have twice the attitude.'
'Despite a massive
female amping up the boys,
Riley has captured the
last clasper measurement.
What's already apparent is
that Riley's hunch is correct.
There's a wide variation
in clasper size
and they don't
correlate to body size.
A smaller shark can have
much larger claspers.'
That was a legitimate boys club.
Insanity.
But... levelled the playing field
when that big female turned up.
That is just a whole other beast,
and you see why...
these great whites have
to be such alphas
in order to take on something that
big. It's twice their size.
I know, it felt a little silly.
We were so focused on claspers,
like oh, who's got the biggest.
And then the female,
no claspers comes in,
and the boys didn't even exist.
'With two challenges down,
the competition between the great
white sharks is heating up.
Scrappy comes out on top
with 60 centimetre claspers
on a 3.7 metre body.
Runners up were... Happy.
Two and a half metre, Little Caesar.
And Max.
Big Brutus sits in
last place in this test
with 30 cm claspers.
After 20 minutes of
shark on shark action,
Scrappy has tied the game with
his 60 centimetre claspers,
putting him neck and
neck with Brutus.
But with two tests left to go,
the competition for the alpha
shark is still wide open.'
'This cluster of islands at
the bottom of New Zealand
has become a famous hot
spot for great white sharks
because the big sharks
gather here in huge numbers.
They're here to mate, but
they also need to eat,
and the Southern Ocean provides.'
Kori, I know that you've never
been to New Zealand before,
but you didn't have to take
long to realise that it's cold.
It's cold, but the upwelling
brings a lot of nutrients.
There's an abundance of life
and it's a harsh environment,
but lots of food.
'Southern New Zealand
sits deep in the roaring 40s,
a windswept band of ocean
that circles Antarctica.
It's famous for its cold,
nutrient-rich currents.
The nutrients feed enormous
populations of plankton and krill,
the foundations for a
marine ecosystem
which is one of the most
productive on earth.'
About 80% of the
world's seabirds here,
albatross, petrels, penguins.
But also a wide range of
fish that feed on that.
And the fish ultimately
drive all that food chain... to,
believe it or not, thousands
and thousands of seals
that are hidden in
the rocks just there.
And then what's on top?
The great white shark
is a perfect resource
for them, full of food.
These seals in these numbers
are why this is one of
the best places on Earth,
if not the best, for great
white sharks in the world.
'Riley and Kori need to
test the potential alphas
to see which one is
the best hunter.'
Experiment number three
is predation.
To become an alpha, you've
got to fuel your big,
powerful body, and to
do that, you got to eat.
So we are going to measure
which of these male
great white sharks is
the ultimate predator.
'Stewart Island
is home to thousands
of New Zealand fur seals.
They're common prey
for great white sharks.
In this test, Riley and Kori
will measure the sharks'
predatory instincts
by towing a seal decoy,
hoping to trigger an attack.
Every hit on the bait
will earn a point.
I'm going to put out this tow cam
that's going to let us see
what's happening between us,
the seal,
and what's going on underneath.
This is going to give us a live feed
straight to the monitor of
what sharks are showing up
and what's happening underwater.
Wow, that seal looks so real.
That is such a bizarre
thing to see underwater.
Like, if we think that looks
real, hopefully the sharks do.
These seals swim
pretty quick normally, so...
go a little bit faster.
Back starboard.
OK, we've got a shark,
we've got a shark.
I think it's Brutus.
Oh my god, he's
still shaking on it.
'Brutus scores a point for
the first hit on the seal decoy.'
Oh, that was a big shark man.
Oh, there he is.
Here we go. KORI: Got it.
Holy cow, look at that!
All the teeth in there.
The precision though,
it didn't grab a head or a tail,
like, it went straight
for the core of the body.
'Despite the damage to the bait,
it's still usable.
Time for another try.
Shark, shark, shark!
Oh, shark on it, shark on it.
Oh, behind it, behind it.OK.
Oh, he's chasing it.
You see it now? No.
OK, yeah, I see the shark coming,
it's coming. BOTH: Oh!
That's Scrappy. It's Scrappy,
it's Scrappy. Is it? Yeah.
Oh, he's going back!
Oh!
Oh my god, he's still going at it!
He's going back for it.
No, don't do it!
Oh, there he is.
They're coming from under the
boat is the hard thing.
Grab it, grab it.
I don't think you should grab it.
I don't think you should grab it.
'While retrieving the decoy,
Kori almost becomes
Scrappy's next meal.
He earns two points for
striking the seal decoy twice.'
I was like, just grab it.
It was too far.
I was hoping it was going
to rub against the side,
but I'm not reaching
over that far.
Oh my god, man, that
shark was full circling it.
And no wonder, that is full
predation. Look at that thing.
It wasn't just one hit.
It came back for more.
The shark just came from behind,
just starting on the nose,
full face behind the seal,
dropped out of sight.
And then full vertical side, smash.
'Scrappy's destroyed the seal
before the other
contenders can get a shot.
To complete the test, Riley
and Kori will use fresh tuna.'
Deploy the tuna.
Let's see how this thing goes.
'Fish makes up to
70% of the Stewart Island
great whites' diet.
As juveniles, they
eat fish and rays,
but as they grow larger,
great whites need more energy.'
'Seals have thick layers of
fat that fuels the sharks.
It gives them faster response
times and greater strength,
a turbo boost they
regularly use to hunt tuna,
one of the fastest
fish in our oceans.'
'Riley's predation test is
where the Stewart Island
great whites can put their instant
acceleration on full display.'
'The scoring in this
test remains the same.
Each shark gets one point
for every hit on the bait.'
Shark, shark, shark!
Riley, there's Max.
Oh!
He's got it.
Oh, my god.
Dude, the tuna's still on
there. Keep going, keep going,
He's coming back,
he's coming back!
Oh, my god
Oh, my god.
He got it.
Oh, my god.
'Max has just
put two points on the board
during the predation event.'
RILEY: Clearly tuna's on the menu.
'Max and Scrappy
are now tied with two points,
with Brutus trailing
behind with one point.
Alright Kori,
let's deploy the tuna.
We've got a shark right
underneath. Shark, shark, shark!
It's Brutus!
That was sick.
Oh my god, back for more, OK.
'Brutus registers
two points on that run.
But not to be outdone,
Scrappy returns!'
And he's coming
up, he's going to hit it.
Oh, go, go, go, go!
He's got the head.
He's coming back for more,
he's coming back for more.
That was a full mouth shot
I just looked straight down
the barrel of him, wow.
'Scrappy now has four points,
putting him in the lead.'
KORI: Bombs away.
'The team decides to
do one final pass with the tuna
to see if any other
shark wants to step up.'
Shark, shark, shark!
It's Brutus again!
Oh, my god.
That was a full breach!
OK, that was an epic one.
Oh, he's still on it.
He's shaking it, he's shaking it.
Oh, my god.
'With another successful hit,
Brutus ties with Scrappy
with four points each.'
There was no warning.
You didn't even give a warning,
it was just full
vertical breach.
Kori, yeah, dude,
tuna on the menu. Holy cow!
'The predation
test ends in a tie.
Brutus and Scrappy both
earned four points,
proving they own
the hunting ground.
Max sits in third place for
his two big hits on the bait.
Three challenges down,
Brutus and Scrappy
refuse to give up ground.
Brutus carried away
the power challenge
with a 35 kilometre per
hour burst of speed.
Scrappy strutted to
victory in peacocking
with 60 centimetre claspers.
And they tied the predation round,
giving them two wins
each on the leaderboard.
With three experiments down,
it's given Kori
enough data to analyse
and a good understanding of
what's really going on
between these sharks.
Hey Riley, I want to show
you something real quick.
Wicked, what's that?
So this is a social network analysis
of our sharks based
off the photo ID's.
It's originally made for human
networking and things like that,
but the application for animals
and behavioural science
has been really great.
So I used the photo ID's
to connect all of our sharks
into a social network.
Basically this is the
mapping you see here.
So what do all the lines mean?
So all the different lines
are associations between
two individuals.
So if you see a connection,
that means those two sharks
have some sort of association.
The thickness of the line
is what is the strength
of the association,
whereas the really thin lines..
Those sharks may not like each
other, or they're so competitive
they avoid each other.
Basically they haven't associated
much with each other.Possibly.
And the really fun part is...
seeing who was kind of at
the centre of the network,
I guess, like the most popular of
the bunch. And guess who?
Brutus and Scrappy right in the
centre of this entire network.
Wow, that's incredible, eh?
It's pretty cool.
It's nice to see how they...
Well, interact,
but also show dominance,
show socialisation.
Probably linked to a variety
of things, like, er,
prey that they're equally after,
or they actually
enjoy each other's company.
Like we always said, Scrappy...
and Happy were kind of like
brothers, but it's interesting.
The lines aren't actually that
strong. Yeah, and it's quite cool
because since we're using the same
site every day for these sharks,
it's almost like a sense
of territory mapping
as well because it's
showing you those animals
with the strongest associations.
Brutus and Scrappy
are kind of always present at this
site, so they're the core of that.
They're expanding out, connecting
with these other animals
that may be just passing through.
And really interesting to see
then the females in here.
They're on the periphery.
They're coming in and getting a
snapshot of each of these males,
kind of like the judges.
Leading into the final experiment,
fearlessness, it's neck and neck.
But this experiment will dictate
who ultimately becomes the
alpha, who is the boss shark.
Kori, the experiments
are going so well.
We're starting to really understand
the male hierarchy down here.
Brutus and Scrappy are
clearly the dominant sharks,
but Happy, Max and Caesar are all
aggressive enough to be an alpha.
One thing that's a big misconception
with great white sharks
is that they're mindless,
biting machines.
Absolutely, white
sharks, they're cautious,
they're calculated,
but they've got to bite
into the neck of a
female twice their size.
That requires an alpha
trait of fearlessness.
'Shark courtship is violent.
The male bites the female's
back, flanks and fins,
inflicting serious wounds as
he tries to attach himself.
Doing that to an apex predator
upwards of twice the size
requires a lot of courage.'
To measure fearlessness, I'm going
to try something that's...
pretty dangerous.
It's never been done before,
but it's a true measure
of fearlessness. And that is...
I'm going to hand feed the great
white sharks with this pole.
A shark that comes and
feeds from a human hand,
which is one of the most dangerous
things a shark can encounter,
well, that shark is truly fearless.
'The shark
that strikes the most often
will win this challenge.
It's going to be a
dangerous operation.
To hand feed great white sharks,
Riley will have to open his cage,
exposing himself at the
moment of peak predation.'
They're all here,
Scrappy, Brutus,
Max, and Happy.
'Riley's holding
a tasty 20 kilo tuna.'
'Brutus just
earned himself a point,
but this competition
is far from over.'
'The score is now tied,
one point each for
Brutus and Scrappy.'
Go, go. Go, go!
'With a second hit on the bait,
big Brutus is now in the lead,
but there's a new arrival.'
'A five metre
female has pushed her way
to the centre of the pack.
We need to get him out.
Get him out, get him out.
Oh, my god.
Oh, man!
That shark just came and
smashed straight into the cage,
ruptured my secondary air supply.
Bro, that was insane,
the bubbles everywhere.
She smashed your cage.
I thought she had you.
'A massive female great white
has just forced her
way into Riley's cage,
severing his air supply,
a perfect example
of why her potential
suitors need to be fearless.'
Holy that was intense going.
That big mature female,
it's changed the dynamic.
I feel like I want to get back in
there, get a new tank
because something special is about
to happen, it feels like.
We need to reset everything,
just hop in as quick as possible.
Alright, cool. Grab another tank,
let's do this.
'Riley gets back in the
water to continue the competition
and see how the females
affect the male's performance.
Right now, Brutus is in the lead
with two hits to Scrappy's one.'
Scrappy's back!
'The female
shark is circling the cages,
and both males
have taken notice.
This may be the beginning
of great white courtship,
something that has never
been fully documented.
From mating behaviour
through to birth,
the reproductive lives
of great white sharks
are still a mystery
to scientists.
But based on the behaviour
of other shark species,
Riley and Kori have a good
idea what to look for.
And Brutus and Scrappy are
showing all the right signs.
'Shark mating
begins with the male shark
biting the female to
see if she is receptive.
If she doesn't fight
back, she's willing.'
'At the completion
of the fearlessness test,
Brutus got two hits
and Scrappy had one.
Brutus takes the fearlessness test
and the competition 3-2.
But the ultimate proof
of this experiment
came when Brutus delivered
a courtship bite.
Riley and Kori came here to
see if they could use science
to identify an alpha
great white shark.
By winning the competition,
and the female,
Brutus has delivered
the evidence
the two scientists
were searching for.'
Throughout this experiment,
we saw one individual
shine near the top or at the
top the entire time.
That shark then truly
showed he was the alpha
when we saw him in a
very rare encounter...
Riley: Oh my god, did you see that?
Trying to mate with
one of the big females.
I've really enjoyed
watching these white sharks
compete here in New Zealand.
We've learned so much
about the social structure
of these males here.
But the competition
was super close,
but we do have a clear winner.
At the end of the day, there
can only be one alpha male.
And down here, the boss shark,
well, that was big boy Brutus.
Got to get her out!
Oh my god!
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Boss Shark (2024)
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