No fish inspires the same terror as the shark.
You're in the monster's mouth getting thrown around.
Somebody's like a rag doll in its mouth getting thrown all over.
We've got sharks in australia that hit hard.
They don't leave anything.
But at least these killers are confined to the oceans.
Or are they?
It seems one species of shark has been trespassing
From saltwater into my territory... Freshwater...
Operating where people thought no danger existed.
Alan!
As an angler and biologist, my aim is to work out how this is possible
And just how far inland these sharks will bring their reign of terror.
My mission is to find out whether it's safe to get back in the water,
Even if you're miles from the sea.
I'm a specialist in hunting down giant freshwater animals.
Using a combination of logic, local intelligence, and intuition,
I face shoals of piranha in south america and man-Eating catfish in asia.
Sharks, though, are a different target altogether.
These creatures are the stuff of legend.
"jaws," the iconic '70s story,
Describes ferocious man-Eaters with a taste for human flesh.
But the report of a shark operating in an inland lake is truly terrifying.
To investigate, i'm heading to australia.
Midsummer on a brackish lake.
The temperature... Over 80 degrees.
A 23-Year-Old post-Doctorate student, beau martin, and his friend david
Are planning a cooling swim in miami lake.
I'm gonna flog you.
I'm gonna absolutely slay you in this place.
Put some money where it is.
50 bucks? 50 bucks, done.
Yeah, you need it. You need that for the race.
Yeah.
Going down.
Gonna beat you.
Whoa.
Hey, keys, keys, keys. Need keys.
Let's go.
Shirts off... Less drag. We're going. We're going.
They begin a swimming race across the 500-Yard-Wide lake.
Dave takes the lead...
And reaches the safety of the shore.
Beau, however, is still out on the lake.
In trying to catch up, he strays into deeper water.
Aah!
In an instant, he disappears.
Dave returns to the water, but there's no sign of his friend.
Beau's sudden disappearance had all the hallmarks of a shark attack.
But few could imagine this apparently safe backwater
To be a hunting ground for sharks.
Even here, where there are the deadliest snakes,
Massive crocs, the most poisonous spiders, this incident rang alarm bells.
We just don't expect to be attacked by a shark
On an inland lake in an urbanized area like the gold coast.
In australia, there are three species of shark
Commonly responsible for attacks on people... The great white, the tiger shark,
And the bull shark.
Australians know vic hislop as the shark man.
Like quint from "jaws,"
Hislop has fought a series of battles with sharks,
Including this 21/2-Ton great white.
We've got sharks in australia that hit and hit hard.
They don't leave anything.
They're so good at what they do, they pull somebody under, you don't see any more.
Someone's got to be looking at that exact spot to see it happen.
The great white is a notorious man-Eater, but some experts think the bull shark
Is a far more deadly threat altogether.
It's a very robust animal, very rough and tough.
Because of the structure of its teeth,
It can't just bite through a big chunk of meat.
It has to bite and start shaking like crazy.
And, of course, somebody's like a rag doll in its mouth getting thrown all over,
And that immediately also instigates all sorts of fear reactions.
You know, you're in the monster's mouth getting thrown around.
Stocky in shape, savage in character,
The bull shark is built like a street fighter, with a level of raging aggression
That gives it its name.
Pound for pound, it's top of the league of man-Eaters.
Statistically, a bull shark's attack
Is more likely to result in death than a great white's.
And the authorities believe that it's a bull shark
That killed beau martin in this canal system.
This complex of waterways was built during the '70s and '80s
And is bigger than venice, italy... 160 miles of canals and over 30 lakes.
This is an area with just thousands of apartments,
Houses right down on the waterfront.
And most of the people here just think of these canals
As a perfectly safe place to swim.
What puzzles me is how any shark could have made its way here,
So far from where we expect to find it... The open ocean.
To work that out, i'm heading 60 miles south to the coast.
There were 15 shark attacks in australia in 2008,
But there's one, well-Reported in the press, that is central to my investigation.
16-Year-Old brock curtis-Mathew is setting off with his friend peter edmonds
For some early-Morning bodyboarding.
We got there maybe a quarter to 8:00, 8:00-Ish.
They've chosen a location next to the mouth of the richmond river.
This is a popular surfing spot, often used by these close friends.
But this morning, after several days of heavy rain,
They have the beach to themselves.
We were maybe like halfway to where we were gonna go in the water.
I turned around and came back in, and he kept going.
While brock covers their possessions in case of more rain, peter heads out.
He's around 35 yards from the surf line.
But as brock goes to rejoin his friend, he glimpses a dark shape.
I saw this big, round, weird, circle thing.
What brock had seen was a shark.
He has no idea it is attacking his friend.
All he can see from 25 yards away is some splashing.
I was just thinking, "oh, what's he doing?
Something's... Something's not right."
Brock approaches as quickly as he can.
When i got up, like, really close, i couldn't see any blood.
And then, like, once i grabbed him and stuff, i noticed his leg.
Risking his own life, brock carries his now unconscious friend toward shore.
He had taken a first-Aid course at school.
There was a slight pulse when i first checked it, like a beat... Beat... Beat.
Come on, pete!
In a state of shock, he calls the emergency services.
Emergency service.
Please, he's gonna die.
I just said, "can you come down here quickly?"
My friend's been attacked by a shark."
From the shape and the size of the wound to peter's thigh,
The attacker appears to be a bull shark...
Some 9 feet long.
After the attack, lifeguard stephen leahy was one of the first on the scene.
It was obvious that it was high-Impact, it was hard-Hitting,
And there was just a large amount of flesh removed from his upper thigh.
Leahy has worked to save lives on these beaches for over 15 years.
But in this case, tragically, peter had lost too much blood.
There was just absolutely nothing
That we were going to do that would save this boy's life.
Dr. Vic peddemors is the first person medical teams turn to
When they believe there's been a shark attack.
It's estimated that a shark bite applies a force of over 4 tons per square inch.
The most important thing for a shark is to get that lower jaw in
Because those are the hooking teeth that sort of latches in.
So, once it's got its lower jaw in, the upper jaw can clamp down.
If that lower jaw has got in properly, it only needs one bite,
And it'll take the muscle straight off.
Because of the site of this incident,
The lifeguard already had this attacker's identity in mind.
Knowing that the attack's happened just here,
We always had, in the back of our mind,
That this was going to be a bull shark incident.
It's likely that the shark had confused peter for its common prey, a large fish,
Perhaps even another shark.
Nothing can ever compensate a family or friends for such a cruel loss.
But if there is anything to be salvaged from this terrible episode,
It might be in identifying the warning signals that accompany a bull shark attack.
Bull sharks have been observed congregating around river mouths after heavy rain,
Attracted by the supply of freshwater fish being washed out to sea.
We know that bull sharks will always hang around the river mouth
After periods of heavy rain and when there are lots of fish around.
The beach where the attack occurred is only 60 meters away
From the entrance of that river mouth.
The bull shark that killed peter edmonds had been attracted to this shoreline
Because of its proximity to freshwater.
We're well and truly aware that there's just so much for the bull shark to live on
In our freshwater systems, and that's part of the uniqueness of the bull shark...
Can easily cope in saltwater and in our oceans,
But it's just as comfortable in our river systems.
Perhaps this knowledge might prevent others being caught,
Like peter, in the wrong place at the wrong time.
As a biologist, i want to better understand the physiology and particular affinity
Bull sharks have for freshwater.
I need to catch one.
I must have fished literally thousands of destinations all over the world,
But this time, i think i'm out of my depth.
I've never tried to catch any kind of shark, let alone a bull shark.
100 miles north of where peter was killed, in sight of land,
I join a fishing charter boat out after sharks.
With four rods set, i know i'm in with a good chance.
Oh, yeah.
Right. There we go.
There we go. That is a bull shark.
Hammered quite big mullets, couple-Of-Pound mullets, and just took off.
I think we're ready to bring it in the back of the boat, actually.
Okay.
This one's none too happy to see me.
But after the hook's out, it becomes easier to handle.
It's 41/2 feet long, around 1/3 of the length they can reach.
Boat's rolling around a little bit at the moment,
Side on to the tide and rolling a little bit.
So with something like this mouthful of teeth, got to be a wee bit careful.
The teeth are partially obscured by thick gums,
But the tips are as sharp as scalpels.
That's good to actually see one of these animals close up,
Get my hands on one... That's what i wanted.
But what sets this species of shark apart is its extraordinary ability
To operate in both salty and fresh water.
The bull shark is the only species of shark that can do this.
Some scientists speculate that the bull shark is capitalizing on this adaptation
To dominate new feeding grounds inland.
The bull shark is unique because it's actually much more capable than other sharks
In regulating the amount of salts and urea in its body tissues.
Bull sharks constantly test the salt content of the water
With tiny sensors mounted all over the body,
Similar to the way we use our taste buds.
Then, a special organ, the rectal gland, acts like an on/off valve,
Releasing or retaining salt as required.
It's really incredible how capable they are at doing that.
But it's obviously, energetically, very costly,
And that's why we tend to find the bigger animals capable of changing very quickly,
Whereas the smaller animals
Tend to stay within a relatively narrow band of salinity.
This amazing adaptation gives the bull shark
A deadly access-All-Areas freedom to roam, bringing its violence
To our once-Peaceful inland waters... A predator that can operate
In rivers and adjoining lakes all around the world,
Responsible for fatal attacks from australia to south africa,
From florida to new jersey.
Here, in 1916, four people were killed and one was severely mutilated
In a 10-Day spree of attacks.
This provided the inspiration for the most famous shark story of all, "jaws."
But what is so terrifying is that two of these deaths
Occurred 15 miles up an estuary... At matawan creek...
In a place that everyone thought was safe.
Man-Eaters are supposed to be found in untamed places, but this unstoppable predator
Seems to be bringing its savagery into the very heart of our civilized world.
Aah!
Is there nothing in place to stop these deadly predators?
I'm here to meet tony ham.
G'day, jeremy. How you going?
He manages the shark control program on the gold coast in australia.
Got the bait on board.
We're planning to make an inspection of the shark nets just off the main beach.
This section of the beach is called main beach on the other side of the spit.
That's a fairly heavily populated beach.
In summer, you'd have anywhere upward of 50,000, 60,000 people
Between here and surfers paradise, and then, from surfers down further,
Probably double that number.
It's a big beach just running up with sort of all the hotels
And some of the tourist amenities behind that.
Exactly, but branching off here are a number of canal estates and large lakes.
And what's happened is it's basically extended the river habitat.
And so we have bull sharks here pretty constantly.
Right up inland?
Yeah, so bull sharks will actually live all the way up
And including into freshwater reaches of some rivers.
So they're definitely in there,
And when you get in the water, if you get in the water,
You could only be just a matter of yards away from one, i suppose.
Literally, feet, and you wouldn't know they were there
Unless, you know, you actually see it or it bumps into you
Or actually does have a bite at you.
Around the spit, at about 500 yards off the beach, the swell has picked up.
This shark net is pretty much the only line of defense
Along a 21/2-Mile-Long beach.
The idea is to remove sharks that come in close to the shore.
But looking at it, i can see no reason why bull sharks
Wouldn't easily go under it or around it
And then head on, relentlessly, into the canals.
After all, the net is only 200 yards long and just 20 feet high.
Some think that these measures are, in fact, literally worse than useless.
Shark nets in australia are a false sense of security for tourism.
They kill everything we love out there.
They kill dolphins, turtles, dugong.
But more important, the big sharks have learned to feed off those nets.
They're now a feeding ground.
Cost millions of taxpayers' dollars
For a waste of time, just a false sense of security.
It's a joke.
If hislop is correct, bull sharks are being lured towards the shore
And then inland into the canals and lakes.
And because, inevitably, they'll meet more people inland,
This species has to be a far greater threat
Than other man-Eating sharks which remain out at sea.
On miami lake, the day after beau martin's disappearance,
The search begins, led by beau's father.
Exhaustively, he combs the perimeter of the lake.
For two days, there is no sign of beau.
On the morning of the third day, after the police have given up the hunt,
He begins to search from his kayak.
He happens upon the body of his son, part in and part out of the water.
The only reason his body had surfaced... The gases resulting from decomposition,
Causing his body to inflate.
The autopsy revealed that beau had been struck three times... By a bull shark...
One devastating bite on his left thigh proving fatal.
This predator had slipped with ease
From the sea into the brackish water of miami lake.
Once inside, it had been free to go about its business unseen
Until the killing of beau martin revealed its deadly presence.
But just how much further inland into freshwater
Are these predators capable of going?
80 miles inland from the ocean, trainer alan treadwell is taking
His finest trotting horse, glen-Burns arm, for exercise in the river.
I'd swum there for eight, nine years, never a problem.
It's a very popular picnic spot.
This part of the river is a secluded oasis,
Popular with families as a swimming hole.
But on this day, treadwell has the river to himself for his training program.
He wants to build up his horse's muscle strength without straining its legs.
Glen-Burns arm, a 6-Year-Old gelding weighing 1,000 pounds,
Has won 7 times over a 3-Year career.
With the help of his stable hand, alice holden,
Treadwell ties a half-Inch rope to the horse's halter.
With it, he can control the horse from the bridge.
As far as treadwell can see from 20 feet up on the bridge,
Everything appears to be going to plan.
The horse was swimming. I had control of the horse.
But suddenly something startles it.
The horse looks like it's gonna drown.
Then, all of a sudden, i saw something hanging off the back of him.
Alan!
As the horse rolled over, the color lightened,
And it went to a white underneath, whatever it was.
Whatever this creature is, it has the force to hold on to
And the power to submerge a 1,000-Pound horse.
The horse is in trouble. We had a problem.
I've got to get this horse out of there.
Whatever's wrong, if i can get him out of the water, i can control it.
He won't drown.
If we hadn't have gotten him out, i don't believe he would have survived.
Trainer alan treadwell was able to pull his horse to safety.
If the victim had been a human, 1/5 of the size of his horse,
There would be no hope of surviving the attack.
The horse, glen-Burns arm, was treated by a veterinary surgeon...
Who photographed the wound.
I want to meet up with alan treadwell
To find out if this attack can be attributed to a bull shark.
Hello, alan.
G'day. How are you? I'm well, thanks.
This is the boy, is he? Yeah, this is him.
Can i say hello? Say hello.
Hey.
So he's not just an ordinary horse, is he?
He's a bit of an athlete. Bit of an athlete... Yeah, he has been. Or used to be.
Yeah. Yeah.
Can we see the wound at all?
Can you show me where it was?
Yeah, i can do.
It's healed pretty well.
Yeah.
That's where it was, on the flat there.
Right, so, looking at him now, you wouldn't... He looks fine. He looks fine.
But, i mean, did he recover fully, or... No, i don't think so.
Actually, he swells up in the fetlock after a hard run... Right.
Which virtually makes it impossible to race him.
So, in effect, this actually finished his career.
It has done, yes.
It still seems to be a bit awkward in that one back leg.
I don't know what happened to it. It's impossible to say.
So, possibly, there's some sort of, you know, deep muscle damage, something.
Yeah, it could be. That's exactly right, yeah.
Although there had been no reports of sharks
This high up the brisbane river before,
Alan treadwell believes that what he saw was a shark.
Yet he only glimpsed the white shape for a fraction of a second.
I want to take a logical approach to discover exactly what happened here.
My first strategy is to measure the salt content
At this stretch of the brisbane river.
The water's saltiness lessens the further upriver you go.
I've taken a reading of seawater with this machine,
And the reading i get is about 17.
Down the other end of the scale, anything less than about 1 is freshwater,
So the fact that i've just got a reading of less than.5... This is freshwater.
I know bull sharks can get into freshwater.
Everything points to this being a shark attack... Except for one thing.
There's a good reason why i don't think
They could be responsible for this particular incident.
Look at this... Just 5 miles down the river is this man-Made barrier
That just goes right across the river.
Mount crosby weir is a dam that has been in place for over a hundred years.
The difference in height between the water on the ocean side
And the upriver side is 12 feet.
Now, i can understand how something might possibly get up from the sea to here,
But how's it gonna get over that?
So, what else could it be?
I think there might be a clue in something alan treadwell told me.
Although on the surface, the wound to glen-Burns arm has healed,
Underneath the skin, there is such profound muscle damage
That he can no longer race.
That is exactly the case with attacks made by another animal entirely...
The saltwater crocodile.
When a crocodile bites its victim, it deposits bacteria in the wound
That cause long-Term muscle damage.
The most distinctive thing about a saltwater croc is that big, gnarly head
With those big, actually blunt but long, penetrating teeth.
Saltwater crocodiles will live
In freshwater, saltwater, brackish water, mineral water.
They don't care.
Once a crocodile reaches 13, 14 feet, and up, you're dealing with an animal
That can take down a one-Ton water buffalo.
It seems more likely that the creature which attacked glen-Burns arm
Is not a shark but a crocodile.
What they prefer is deep, dark, murky water
Because they are the masters of camouflage.
That's how they get their prey.
They will launch from an invisible position up out of the water,
Grab whatever it is they're targeting,
Drag it back into the water in the blink of an eye.
Just the kind of water where the attack happened.
There's one problem with this idea.
While crocs were once found this far south,
None have been seen any closer than 150 miles away in the last 20 years.
I would be surprised that a crocodile who is big enough to take on a horse,
A, would go unnoticed for long periods of time, you know, way outside of its range,
And, b, in that situation, would miss.
You know, if it's in deep water, it's a large animal,
And it's going in to really have a go, you'd be the luckiest horse alive.
When all avenues seem closed, i turn to the least unlikely option
In my pursuit of the truth.
If the attacker wasn't a crocodile, it has to be a shark.
Yet i need to be certain.
If this is the truth, it has far-Reaching repercussions.
It would show conclusively that savage bull sharks
Can and will launch attacks in freshwater.
It would mean there is no kind of water that's safe from these predators.
But i'm looking for proof.
I want to show scientist vic peddemors the wounds inflicted on this racehorse.
He's one of the world's leading experts on shark bites.
So, what do you make of that?
Well, i'd definitely say it looks like a shark bite of some description
Because of these gaps between the tooth and the way that it seems
To have scratched down the hindquarter of the horse.
That is the bite in more context.
Wow.
I think this is just a hit with the upper jaw and a slip down.
Can you get any idea from that roughly how big the shark might have been?
This isn't much of a crescent,
Which suggests that the jaw must have been fairly big.
Assuming that that was the sort of... This part of the jaw that hit it like that.
So, the curve is quite gentle.
The curve is very gentle.
So, if you think of it as hitting like that... Mm-Hmm.
Now, if you look at this tooth there, that tooth there... It's a fairly close match.
That's not too far off a match.
And this is 2.75 meters in length.
8 or 9 foot.
It's a very similar sort of curvature.
And it links in with our knowledge of bull sharks.
We... One would expect a bigger bull shark
Up in a very freshwater component of the river.
This evidence suggests that the creature that attacked alan treadwell's horse
Is a bull shark... Over 8 feet long.
And by hunting through the government archives...
I know now how these animals managed to get over the weir.
The brisbane river has flooded repeatedly, with one extreme occurrence in 1974.
The city itself was inundated, but so, too, was the surrounding area...
Including the mount crosby dam.
It seems that, as the flood subsided, a colony of bull sharks,
Some growing to over 8 feet long, were locked in far upriver.
And if this can happen here, it can happen anywhere that bull sharks roam.
The danger they present isn't restricted to australia.
Bull sharks have been observed moving up the mississippi river as far as st. Louis.
And there has even been an attack reported in lake michigan.
To fully understand this threat, i want to get my hands
On one of these big predators in freshwater.
But to do that, i need to learn some specialist techniques
From an expert in catching big sharks.
Hello, there. You terry?
How you doing? Terry. Nice to meet you.
I'm ben.
Hello, there.
On march 14, 2007, just here in the river mouth, terry hesse caught
A 91/2-Foot-Long female bull shark estimated to weigh over 500 pounds.
This all looks like pretty serious stuff.
Yeah, well, for our rods and reels, we use one of these.
Right... Completely blown away with the idea of using a...
Needing to use that in a river.
These guys are serious. I'm impressed.
They're fishing in this busy working port
On the frontier between sea and freshwater.
One thing i'm noticing already is the attention to detail.
They've got a comprehensive plan to outwit the supersensory capacity of this shark.
Bull sharks, like all sharks, have tiny pinholes in their snout
Called the ampullae of lorenzini, used for detecting electrical fields.
They're so sensitive that they can detect
The electrical impulses of a fish's heartbeat.
Sharks with wider heads, like the bull shark, have more of these pinholes,
And therefore, they can lock onto prey more accurately.
Another one there, or... To avoid giving off any electrical signals to the shark,
Terry masks all but the metal hook point in plastic and cable-Ties this to the eel.
Next, terry's making sure he capitalizes
On the shark's smell sense by using fresh bait.
2/3 of the shark's brain is devoted to sniffing out prey.
And by fishing at night,
We're choosing the most likely time for sharks to go hunting.
It's in the dark when the supersensory bull shark
Has the edge over fish that rely more on vision.
Terry begins the journey across the river mouth to place the baits.
Bull sharks have been reported to ram kayaks,
Taking the paddle splash and rudder movements
For the thrashing of a fish in distress.
Terry's okay, but in getting these baits set in the dark,
I've injured my index finger.
It's going to make things difficult.
I'm just hoping that this and the disturbance from the busy port
Doesn't damage my chances.
Pick it up! Pick it up!
At 2:30 a.M... Fish on!
With the tide high, the line begins to run.
We're on.
Let's actually put that on.
No, off. It's all right.
Yep.
Starts slowing down.
At the moment, it just feels like there's a boat on the end.
There's just a dead weight.
I'm just changing the ratio there.
Yeah, that... Yeah, that's pulling, that's pulling, that's pulling.
It is coming my way.
And with nearly 200 yards of line taken in, whatever it is reaches the shore.
Holy what is it? That is huge!
Like something from "20,000 leagues under the sea,"
It certainly isn't a shark.
But what on earth is it?
It's not a shark, but it is an exceptional fish.
It's just remarkable.
That is something, isn't it?
I've never seen anything like this in my life before.
It's what they call a queensland grouper.
This is a monster.
It's not the monster i was after, but this is a monster.
We're looking at 6 feet and 3 inches.
What about the girth?
Yeah.
2'1". Its girth is 4'3"... 4'3".
This is a protected marine fish normally found on reefs.
But they're known to come into river mouths like this on rare occasions.
Look at that.
This fish... Even terry and ben haven't seen anything like this
Anywhere like this size, you know.
So it's just an amazing catch and particularly from a river.
Just, you know, this thing really is a river monster.
Groupers have an extraordinary trick.
This 250-Pound male actually started life as a female.
When there are too few males in a spawning group,
A female will switch sex to keep breeding numbers up.
Oh. Ha!
Time, though, for this gender bender to head back home.
To me, that just underlines even more than before
That, you know, we just have no idea at all what is down there in our rivers.
It feels amazing to catch a fish like that, but it's not what i'm here for.
Armed with the knowledge i've gained from terry, i'm driving 50 miles upriver
From brackish water to freshwater.
I'm fishing at night.
I'm fishing with the freshest bait.
So... And i'm putting out two rods.
Here we go. Look.
Something... Something had that.
But it didn't have the hook in its mouth.
So, whatever it was, it's still out there, and i'm running out of bait now, so...
It's annoying.
Finally, i'm in luck.
I've got a take on the other rod.
And keep it away from some trees and stuff on the side there.
Yeah, it's a shark. It's a shark.
Up we come.
This is a shark in a river. Okay.
This may be a small one, but for me, this is, in some ways, more unsettling.
Up onto the grass.
I already know there are big females in this river.
Catching one like this implies they're breeding here.
That body is just solid muscle. You just feel it.
When it decides to flex, that's just got so much strength there.
This one didn't swim all the way from the ocean.
It was most likely born in brackish water just downstream.
And while only 18 months old, it seems to be thriving in freshwater.
It's a scary thought that this river
Will be its hunting ground for life... Another 15 years.
"at 3'6" long and 15 pounds in weight,
This one could triple in length and become 30 times heavier.
I'm just trying to imagine this thing two or three times the length in this water.
It's quite a frightening prospect in a river, a small river.
Anyway, this one's going back.
Well, i've been able to prove, without question,
That bull sharks are trespassing on my patch, in freshwater,
More than 80 miles up an australian river.
But critically, what i've learned is that they have the capacity for brutal attacks
In freshwater almost anywhere.
There are few limits to where this shark will operate.
More and more, it seems that this freshwater jaws
Is bringing its savagery into our once-Tame backyard.
Along metropolitan canals, up quiet rivers, and on tranquil lakes,
The bull shark is looking for its next meal.
It's just a question of who and when.