Original subtitles

MY NAME IS JEREMY WADE.

HERE WE GO. FISH ON.

FISHING IS MY PASSION.

TIME AND AGAIN, IT'S ENABLED ME TO SOLVE FRESHWATER MYSTERIES.

NOW I'M BACK IN AFRICA...

A SAVAGE HIT. LOOK AT THIS RUN!

...TO REOPEN A CASE I THOUGHT WAS CLOSED.

I WANT A DEFINITIVE ANSWER TO ONE QUESTION --

IS THE TIGERFISH A MAN-EATER?

TO FIND OUT, I'LL NEED MORE THAN A FISHING LINE.

I'LL TO CONFRONT THIS PACK-HUNTING PREDATOR

IN ITS OWN DOMAIN.

IN EFFECT, WHAT I'VE GOT TO DO,

I'VE GOT TO TURN MYSELF INTO HUMAN BAIT.

BY USING A TOTALLY NOVEL DIVE STRATEGY,

BASED ON NEW UNDERSTANDING OF THE RIVER'S PREDATORS,

I'M GOING TO GO WHERE VERY FEW HAVE GONE BEFORE.

-- Captions by VITAC -- www.vitac.com

CAPTIONS PAID FOR BY DISCOVERY COMMUNICATIONS

OF ALL THE RIVER MONSTERS I'VE EVER ENCOUNTERED,

ONE HAS GOT UNDER MY SKIN MORE THAN ANY OTHER...

...THE TIGERFISH.

TWO YEARS AGO, I CAME TO AFRICA TO INVESTIGATE A TRAGEDY

WHERE THE OCCUPANTS OF AN OVERTURNED BOAT

APPEARED TO HAVE BEEN EATEN BY UNKNOWN FISH.

WHAT I PULLED OUT OF THE RIVER THEN

WAS THE STUFF OF NIGHTMARES.

MUSCULAR AND PACKED WITH TEETH,

A SUPER-SIZED RELATIVE OF THE RED-BELLIED PIRANHA.

WELL, THIS IS THE FISH. THIS IS THE FISH.

THERE IS A PACK OF THEM DOWN THERE.

BUT IF THIS IS AFRICA'S PIRANHA, WHERE'S THE RAP SHEET?

WHY ARE THERE SO FEW VICTIMS?

THE FACT IS, SO LITTLE IS KNOWN ABOUT THIS FISH,

AND FOR ME, WHERE THERE'S MYSTERY, THERE'S DOUBT.

MAYBE BY GOING UNDERWATER,

I CAN PUT THIS ANIMAL'S FEARSOME REPUTATION TO THE TEST.

BUT IN DOING SO, WILL I BECOME PREY?

IN MOST AFRICAN RIVERS,

GOING UNDERWATER WOULD BE POINTLESS, IF NOT SUICIDAL.

IT'S NORMALLY TOO CLOUDY TO SEE ANYTHING,

AND ON TOP OF THIS, YOU RISK ENCOUNTERING CROCODILES.

BUT THERE'S ONE PLACE

WHERE I MIGHT BE ABLE TO OVERCOME THESE PROBLEMS...

IF I GET MY TIMING RIGHT.

THE OKAVANGO DELTA IN BOTSWANA IS A HUGE SWAMP

ON THE NORTHERN EDGE OF THE KALAHARI DESERT.

ONCE A YEAR, IT GETS A MASSIVE INFLUX OF RAINWATER

THAT RUNS OFF THE ANGOLAN HIGHLANDS.

IT'S AT THIS TIME, FOR JUST A FEW SHORT WEEKS,

THAT THE WATER CAN BE CLEAR ENOUGH

TO ACTUALLY SEE WHAT'S PROWLING AROUND.

ALTHOUGH I'VE BEEN HERE BEFORE,

I FEEL AS IF I'VE SCARCELY SCRATCHED THE SURFACE,

IN TERMS OF UNDERSTANDING THE FISH AND THE DELTA ITSELF.

SO BEFORE I EVEN ATTEMPT TO GET IN THE WATER,

I WANT TO REACQUAINT MYSELF WITH THE TIGERFISH.

THE DELTA LOOKS VERY DIFFERENT FROM WHEN I WAS LAST HERE.

IT'S NOW THE SOUTHERN AFRICAN WINTER,

AND THE WATER IS AT ITS HIGHEST --

SOME 13 FEET ABOVE ITS SUMMER LEVEL.

IT'S ALSO AROUND 30 DEGREES COLDER.

WHAT I DON'T YET KNOW IS HOW THESE SEASONAL CHANGES

MIGHT AFFECT THE BEHAVIOR OF THE TIGERFISH.

THOUGH CONDITIONS LOOK IDEAL, THE RIVER IS STRANGELY QUIET.

NOTHING AT ALL GOING FOR THAT. UM...

IT'S ALMOST AS IF THIS BIT OF WATER HERE

IS JUST DEVOID OF FISH.

UM...

SO, FOR ONCE, MY NORMAL SAMPLING TOOL -- A FISHING LINE --

IS JUST GIVING ME NO INFORMATION WHATSOEVER

ABOUT WHAT'S GOING ON,

WHAT'S LIVING UNDERNEATH THE SURFACE.

WITH SO MUCH FLOODWATER,

EVERYTHING IS SPREAD MORE THINLY.

IT LOOKS LIKE FINDING A PACK OF TIGERFISH IN THIS VAST SWAMP

IS GOING TO TAKE LONGER THAN I RECKONED.

NEXT MORNING, AS I HEAD UPRIVER,

I SPOT A PLUME OF SMOKE --

THE TELLTALE SIGN OF A FISHERMAN'S CAMP.

THIS IS AN OPPORTUNITY FOR ME

TO FIND OUT MORE ABOUT TIGERFISH,

IN PARTICULAR, WHETHER THE PEOPLE WHO LIVE HERE

SEE THEM AS A THREAT.

JUDGING BY THE NUMBERS OF BREAM AND CATFISH

THAT ARE BEING SMOKED,

THERE'S CERTAINLY PLENTY OF FOOD IN THIS AREA

FOR A TOP PREDATOR.

SO THIS TIGERFISH, IT WAS INSIDE THE NET.

YOU TRIED TO --

TWO MONTHS TO HEAL.

SO IT WAS A DEEP CUT.

DID THIS ONE -- DID IT JUMP OUT OF THE WATER?

Man: YEAH.

THIS FISH IS SEEN AS A MALEVOLENT PRESENCE

IN THE RIVER,

SO IT'S DEFINITELY A FISH

THAT EVERYBODY HERE TREATS WITH A CERTAIN AMOUNT OF RESPECT.

ALL THE FISHERMEN HERE HAVE THEIR OWN ACCOUNTS

OF BEING BITTEN BY TIGERFISH,

BUT ALWAYS WHEN THEY'RE DEALING WITH THEM IN THEIR NETS.

WHAT THEY DON'T HAVE

ARE STORIES OF ATTACKS IN OPEN WATER.

BUT PERHAPS THIS ISN'T SURPRISING.

MOST PEOPLE IN THE DELTA

KNOW BETTER THAN TO JUMP OUT OF THEIR CANOES.

THE PRESENCE OF CROCODILES IS MORE THAN ENOUGH TO DETER THEM.

BUT IF I'M GOING TO UNDERSTAND

THE TRUE NATURE OF THE TIGERFISH,

THEN SOONER OR LATER,

I'LL HAVE TO PLUCK UP MY COURAGE AND GET IN THE WATER.

FIRST, THOUGH, I'M STOPPING OFF

TO MEET A MAN NAMED FRANCOIS JACOBS.

HE'S ONE OF THE VERY FEW SCIENTISTS

WHO ARE TRYING TO STUDY TIGERFISH.

THE TIGERFISH IS ONE OF THE --

WELL, ONE OF THE MOST PREDACIOUS FISH SPECIES ON EARTH.

WHEN THEY LOCK ON TO SOMETHING, IT SEEMS THAT THEY JUST --

THEY JUST FULLY, FULLY GO OUT FOR THEM.

IF THEY SEE SOMETHING IN DISTRESS,

EVEN IF IT'S BIGGER THAN THEM, THEY'LL GO FOR IT.

WHY IS IT THAT THERE'S SO LITTLE KNOWN

ABOUT TIGERFISH AND THEIR BEHAVIOR?

IT'S MOSTLY BECAUSE THEY'RE IN CROCODILE-INFESTED WATERS.

CROCS...EVERYWHERE.

BECAUSE OF THE DANGERS OF WORKING IN THESE ENVIRONMENTS.

WHAT I WANT TO DO IS ACTUALLY GET UNDER THE WATER

AND LOOK AT TIGERFISH.

WOULD YOU HAVE ANY GENERAL ADVICE?

YOU'RE GETTING IN THE WATER WITH CROCODILES.

THEY'RE KNOWN TO HUNT HUMANS,

SO IF YOU'RE ASKING ME IF I WANT TO SWIM WITH CROCODILES,

THE ANSWER'S NO. GOOD LUCK.

FRANCOIS HAS CONFIRMED THAT TIGERFISH, LIKE PIRANHAS,

WILL ATTACK ANIMALS MUCH BIGGER THAN THEMSELVES.

AND HE'S REMINDED ME, AS IF I NEEDED IT,

THAT TO PUT THIS TO THE TEST,

I'LL ALSO HAVE TO DEAL WITH CROCODILES.

MY IMMEDIATE OBJECTIVE, THOUGH, IS TO FIND THE TIGERFISH.

WHAT I'M DOING IS FISHING A VERY FLASHY LURE

THAT WILL CATCH THE SUNLIGHT -- ALSO CAUSE VIBRATIONS --

AND THE KIND OF PLACES I'VE BEEN LOOKING OUT FOR

ARE WHERE YOU'VE GOT A BEND.

AND WHAT THE BEND WILL DO,

IT WILL SORT OF CREATE A SANDBAR,

FOLLOWED BY A DROP-OFF,

AND THAT'S EXACTLY THE KIND OF PLACE

WHERE PREDATORS LIKE TO LURK

AND WAIT FOR SMALLER FISH TO PASS IN THE CURRENT.

BY LATE AFTERNOON, I'M STILL EMPTY-HANDED.

A LITTLE EDDY OVER THERE. LET'S JUST TRY THAT.

IF THERE ARE TIGERFISH HERE, THEN THEY'RE VERY WARY.

NO. THOUGHT SOMETHING WAS ON THERE.

MY MIND IS STARTING TO PLAY TRICKS ON ME.

IT'S SOMETIMES HARD TO TELL IF I'M GETTING A KNOCK ON THE LURE

OR JUST SNAGGING ANOTHER WEED.

WHEN IT COMES, THOUGH, THE STRIKE IS UNMISTAKABLE.

A SAVAGE HIT.

LOOK AT THIS RUN! LOOK AT THIS RUN!

IN THE HEART OF BOTSWANA'S OKAVANGO DELTA,

I'M HUNTING DOWN THE TRUTH

ABOUT AN ANIMAL WITH A FEARSOME REPUTATION...

THE TIGERFISH.

IF THEY REALLY ARE MAN-EATERS, I INTEND TO FIND OUT.

AND I THINK I'VE JUST GOT ONE ON MY LINE.

LOOK AT THIS RUN! LOOK AT THIS RUN!

[ GRUNTS ]

A SAVAGE HIT ON THE LURE. SAVAGE HIT.

RIGHT. WE HAVE A FISH. I DIDN'T SEE IT VERY --

IT JUST JUMPED OUT OF THE WATER JUST THEN.

DIDN'T SEE IT TOO CLEARLY.

I THINK IT'S A TIGERFISH.

RIGHT. I'VE GOT A LANDING NET THERE.

THIS TOOTHY FIGHTER IS A YOUNG ADULT.

RIGHT.

SO, THERE WE GO. THAT'S A TIGERFISH.

WHY ARE THEY CALLED TIGERFISH?

WELL, IT COULD BE BECAUSE OF THE STRIPES.

IT COULD BE BECAUSE OF THE TEETH,

AND THOSE TEETH ARE -- WHOOPS! --

ABSOLUTE SIGNATURE OF THE SPECIES.

SO, FROM THE GILLS BACK,

IT'S THIS VERY PRETTY, STREAMLINED FISH,

AND THEN THE HEAD IS ALMOST LIKE SOMETHING OUT OF YOUR --

YOUR WORST NIGHTMARES.

SO I THINK WE CAN CATEGORICALLY SAY NOW

THAT WE'RE IN TIGER COUNTRY.

BUT HOW MANY OF THEM ARE OUT THERE?

HAVE THEY SPLIT UP INTO ONES AND TWOS...

OR COULD THERE BE A WHOLE PACK OF THEM RIGHT UNDERNEATH ME?

THAT'S A FISH.

THIS ONE IS MUCH BIGGER THAN MY FIRST CATCH.

ONE VERY SIGNIFICANT THING ABOUT THIS FISH

IS THE -- THE HINGING IN THE MOUTH.

YOU'VE ACTUALLY GOT A DOUBLE HINGE THERE.

YOU'VE ACTUALLY GOT ONE HINGE HERE,

AND THEN YOU'VE GOT A SECOND HINGE UP HERE.

WHAT THIS MEANS IS THAT IT CAN OPEN ITS JAWS

A LOT WIDER THAN OTHER FISH.

AS A RESULT, ITS BARE TEETH POINT FORWARDS WHEN IT STRIKES,

ENABLING IT TO CUT LARGE CHUNKS OUT OF ANIMALS

MUCH BIGGER THAN ITSELF.

RIGHT. SO I THINK IT'S TIME TO GET THIS ONE BACK IN THE WATER.

I FISH ON TILL DUSK,

TRYING TO WORK OUT

IF I REALLY AM IN THE MIDST OF A TIGERFISH PACK.

WHAT HAPPENED JUST NOW IS VERY INTERESTING.

THERE WAS A KNOCK ON THE LURE, ANOTHER ONE, ANOTHER ONE.

NOW, IT COULD'VE BEEN THIS SAME FISH CHASING IT.

IT COULD'VE BEEN A GROUP OF THEM DOWN THERE.

FROM WHERE I AM ON THE BOAT,

THERE'S ACTUALLY NO WAY OF TELLING.

TIGERFISH CLEARLY HAVE THE HARDWARE

TO DO SOME SERIOUS DAMAGE.

BUT WHAT IF I WAS TO JUMP IN?

WOULD THEY ACTUALLY ATTACK ME?

ONE RECENT STORY FROM ZIMBABWE MAKES ME WONDER.

IN SEARCH OF WORK,

TWO YOUNG MEN DECIDE TO ENTER SOUTH AFRICA ILLEGALLY.

TO AVOID A BORDER POST, THEY MUST SWIM ACROSS A RIVER.

BUT WITHIN MINUTES,

THEY'RE ATTACKED BY SOMETHING IN THE WATER.

AAH!

BY ALL ACCOUNTS, THE WOUNDS ON THE MEN'S HANDS AND FEET

WERE UNMISTAKABLY THE WORK OF TIGERFISH.

NOW, I LOVE FISHING,

BUT THERE'S A LIMIT TO WHAT FISHING CAN TELL YOU.

BASICALLY, IT TELLS YOU THAT A CERTAIN FISH

WAS IN A CERTAIN PLACE, AND IT WAS FEEDING.

BUT TO TRULY UNDERSTAND THIS FISH,

I'VE GOT TO GET BENEATH THE SURFACE WITH IT,

UNDERWATER, IN ITS DOMAIN.

IN EFFECT, WHAT I'VE GOT TO DO,

I'VE GOT TO TURN MYSELF INTO HUMAN BAIT.

THAT'S EASIER SAID THAN DONE.

BEFORE I CAN GO EYE-TO-EYE WITH TIGERFISH,

I FIRST NEED TO GET PAST THE CROCODILES.

TO FIND OUT HOW, I'M MEETING BRAD BESTERLINK,

A MAN WHO'S GROWN UP IN THE DELTA.

IF ANYONE CAN MAKE SURE I DON'T END UP AS REPTILE FOOD,

IT'S BRAD, BUT THERE ARE NO GUARANTEES.

SO, WHAT ABOUT THE LARGE ANIMALS THAT EXIST HERE --

THE ELEPHANTS, THE HIPPOS, THE CROCS?

HOW DO YOU WORK AROUND THEM?

CROCS ARE MUCH HARDER TO ANTICIPATE,

AND THAT'S JUST SOMETHING

THAT WE HAVE TO DEAL WITH IN THE WATER.

SO WHEN YOU SAY "DEAL WITH IN THE WATER,"

WHAT DOES THAT INVOLVE?

YOU KNOW, THAT SOUNDS PRETTY DANGEROUS.

WE CAN MANAGE INTERACTIONS WITH CROCS ON THE BOTTOM.

ON THE SURFACE, THAT'S WHERE YOU DIE.

BRAD HAS FIGURED OUT THAT, FOR A FEW WEEKS EVERY WINTER,

THE WATER TEMPERATURE IS LOW ENOUGH

TO SLOW DOWN THE COLD-BLOODED CROCS.

IN EFFECT, THEY ENTER A BRIEF HIBERNATION

WHEN THEY CEASE TO HUNT.

SO FAR, SO LOGICAL,

BUT I'M FEELING ANYTHING BUT REASSURED.

THE ENORMITY OF WHAT MIGHT BE HAPPENING TOMORROW

IS STARTING TO SINK IN.

I COULD BE WITHIN TOUCHING DISTANCE

OF ONE OF THESE ANIMALS IN ITS ELEMENT.

NOW, I'VE SEEN THE DAMAGE THAT CROCODILES CAN DO TO PEOPLE,

AND IT'S VERY HARD TO ACTUALLY PUT THAT FROM MY MIND.

ANOTHER THING THAT'S ACTUALLY SURFACING IN MY MIND RIGHT NOW

IS A SAYING THAT THE TRIBESPEOPLE HAVE HERE.

WHAT THEY SAY IS THIS -- "I AM THE RIVER.

MY SURFACE GIVES YOU LIFE. BELOW IS DEATH."

NEXT MORNING, BRAD AND I HEAD OUT TO OUR FIRST DIVE LOCATION,

CLOSE TO WHERE I WAS FISHING.

I'M HOPING TO ENCOUNTER THE SAME TIGERFISH

THAT WERE ATTACKING MY LURE.

NO ONE HAS EVER DIVED WITH TIGERFISH BEFORE

BECAUSE MOST DIVERS CONSIDER THESE WATERS TOO DANGEROUS.

THE WATER'S LOVELY AND CLEAR.

UM...

ALMOST LIKE AN AQUARIUM.

IT ACTUALLY LOOKS VERY BENIGN,

BUT THE KNOWLEDGE THAT THERE COULD BE CROCODILES DOWN THERE

PUTS A RATHER DIFFERENT LIGHT ON PROCEEDINGS.

OKAY. I THINK I'VE LOADED THAT ALL IN.

IT -- IT -- IT MAKES SORT OF LOGICAL SENSE.

IT'S JUST SORT OF PROCESSING IT EMOTIONALLY

THAT THERE COULD BE SOMETHING --

THAT'S THE HARDEST THING.

IF THERE IS A CROC DOWN BELOW,

I'M HOPING IT'S NOT HUNGRY.

Woman: 3...2...1...GO.

I'M IN THE OKAVANGO DELTA IN BOTSWANA

TO FIND OUT IF TIGERFISH REALLY ARE MAN-EATERS.

TO TEST THIS, I NEED TO GET IN THE WATER,

BUT THE WATER HERE IS ALSO STALKED BY CROCODILES.

Woman: ...1...GO.

I'M MOST VULNERABLE AT THE SURFACE,

WHICH BRAD CALLS THE KILL ZONE.

TO A LURKING CROC,

MY SILHOUETTE WOULD PRESENT A CLEAR AND TEMPTING TARGET.

SO TO MINIMIZE THE RISK OF AN ATTACK,

I DESCEND QUICKLY TO THE RIVERBED.

I'VE GOT A CAMERA AFFIXED TO MY DIVE STICK

TO RECORD ANY ENCOUNTERS WITH EITHER TIGERFISH OR CROCODILES.

AND MY MASK HAS A BUILT-IN MICROPHONE,

HARDWIRED TO A RECORDER ON MY BACK.

I CAN ALSO TALK TO THE DIVE BOAT,

BUT COMMUNICATIONS MUST BE KEPT TO A MINIMUM,

AS THE SOUND WAVES COULD ATTRACT CROCODILES.

IT'S A TOTALLY DIFFERENT WORLD FROM HOW YOU IMAGINE IT.

SEE HOW IT WOULD BE VERY EASY TO BLUNDER INTO SOMETHING.

THEY DO SAY ABOUT CROCODILES,

IT'S THE ONES YOU CAN'T SEE YOU SHOULD WORRY ABOUT.

SO, EYES PEELED.

IT'S HARD TO STAY RELAXED IN THIS NERVE-RACKING SITUATION.

BUT IF I BREATHE TOO HARD, I'LL QUICKLY USE UP MY AIR SUPPLY.

THE FIRST SIGNS OF LIFE ARE SOME SQUEAKER CATFISH,

NAMED AFTER THE STRANGE NOISES THEY MAKE.

NICE TO SEE SOME OF THE FISH DOWN HERE.

THEY STICK CLOSE TOGETHER, PARTLY FOR PROTECTION,

BUT WHETHER FROM TIGERFISH OR CROCS, I'M NOT SURE.

IT'S ALMOST LIKE... BEING IN A PLANE

AND FLYING INTO A THUNDERSTORM.

IT'S ALL BRIGHT AROUND YOU, AND YOU'RE JUST BEING TAKEN,

IN THIS CASE BY THE CURRENT, TO THIS AREA OF DARK.

BUT ACTUALLY, AS YOU APPROACH, IT LIGHTENS UP.

BUT YOU'RE ALWAYS RATHER CONCERNED

ABOUT WHAT MIGHT BE THERE.

I HAVE TO REMIND MYSELF THAT I'M HERE TO FIND TIGERFISH.

SO FAR, THERE'S NO SIGN OF THEM,

AND MY DIVE TIME IS RUNNING OUT.

COULD THE TIGERFISH HAVE MOVED ON, I WONDER,

OR IS MY PRESENCE DOWN HERE MAKING THEM WARY?

CROC!

JUST HIT A CROC. JUST HIT A CROC.

THIS LOOKS QUITE BIG.

JUST LOWERED RIGHT DOWN ONTO A CROCODILE.

AH!

IT LOOKS RIGHT AT ME...

...AND KEEPS MOVING.

I FOLLOW IT, TRUSTING IN BRAD'S THEORY

THAT THE WATER IS STILL TOO COLD

FOR THIS LARGE REPTILE TO BE IN FEEDING MODE.

BUT EVEN IF THIS IS TRUE,

THE CROC WILL STILL BITE ME IF I GET TOO CLOSE TO ITS HEAD.

AND WITH A LARGE, STRUGGLING OBJECT CLAMPED IN ITS JAWS,

IT COULD THEN THROW ITSELF INTO A DEATH ROLL,

SPINNING ITS BODY WITH ENOUGH FORCE TO DISMEMBER ME.

I AM WITHIN ABOUT A FOOT OF ITS TAIL.

UNBELIEVABLE.

UNBELIEVABLE THAT I CAN GET THIS CLOSE...

AND EVEN TOUCH IT.

I JUST TOUCHED ITS TAIL.

WHO WOULD'VE THOUGHT THIS WAS POSSIBLE?

HOLDING THE TAIL OF A CROCODILE --

A LIVE CROCODILE -- UNDERWATER.

BUT ACTUALLY, IN THEORY, IT MAKES PERFECT SENSE.

WHEN THEIR BODY TEMPERATURE IS LOW,

AND WHEN WE ARE ON THE BOTTOM LIKE THIS,

NOT CREATING A SILHOUETTE AGAINST THE SURFACE,

THEY DON'T SEE US AS A THREAT, AND I CAN DO THIS.

UNBELIEVABLE.

TALK ABOUT PUTTING THEORY INTO PRACTICE.

BUT IT WON'T BE LONG BEFORE THE WATER

AND CROCS LIKE THIS ONE ARE GETTING DANGEROUSLY WARM.

FOR NOW, THOUGH, THE BEAST'S INTENTIONS SEEM BENIGN...

AND WE'RE ABLE TO SWIM SAFELY BACK TO OUR BOAT.

[ BREATHES DEEPLY ]

JUST GETTING BREATH BACK A LITTLE BIT.

NOT NECESSARILY ALL DOWN TO EXERTION.

UM...

THAT WAS ME TOUCHING A CROC -- A LIVE CROC.

I WAS TRYING TO PUT IT INTO WORDS

WHILE I WAS DOWN THERE WHAT THAT FELT LIKE.

I WAS PARTLY QUITE DETACHED AND THEORETICAL ABOUT IT.

I KNOW WHAT BRAD HAS TOLD ME

ABOUT THESE BEING VERY SPECIAL CIRCUMSTANCES HERE.

THEIR BODY TEMPERATURE IS RIGHT DOWN.

WE'RE APPROACHING THEM IN A WAY

WHICH DOESN'T MAKE US LOOK LIKE PREY

BECAUSE WE'RE ON THE BOTTOM.

WE'RE NOT SILHOUETTED ABOVE IT.

BUT EVEN SO, ACTUALLY PUTTING THAT INTO PRACTICE...

HAVING EXPERIENCED THAT,

I THINK -- I FEEL THAT WAS AN IMPORTANT HURDLE TO GET PAST.

SO IF WE DO RUN INTO ONE AGAIN, I'M GONNA BE CALM.

AND THE THING IS, I FEEL I CAN NOW FOCUS MORE

ON LOOKING FOR THE TIGERS THAN CONTINUALLY LOOKING AROUND,

"WHERE'S THE CROC GONNA BE?"

CONDITIONS ARE CLEARLY CRUCIAL

FOR TRIGGERING PREDATORY BEHAVIOR IN CROCODILES,

AND I'M STARTING TO WONDER

IF THE SAME COULD BE TRUE FOR TIGERFISH.

THE TIGERFISH THEMSELVES, HOWEVER, SEEM TO HAVE VANISHED,

AND TIME IS NOT ON MY SIDE.

I'M KEEPING A CLOSE WATCH ON THE WATER TEMPERATURE,

AND MY THERMOMETER READINGS AREN'T ENCOURAGING.

THEY'RE APPROACHING THE CRITICAL THRESHOLD

OF 66 DEGREES,

THE POINT AT WHICH CROCODILES, ESPECIALLY THE LARGER ONES,

START TO BECOME ACTIVE.

BEFORE MY NEXT DIVE,

I DECIDE TO TALK TO A MAN NAMED LLOYD WILMOT,

A VETERAN OF THE DELTA.

GOOD MORNING.

BACK IN THE 1970s,

LLOYD ACTUALLY EXPERIENCED A TIGERFISH ATTACK,

AND I'M HOPING THAT HIS ACCOUNT MIGHT PROVIDE SOME INSIGHT

INTO WHAT MAKES THESE FISH SO POTENTIALLY DANGEROUS.

WHAT NEW AND VERY SURPRISING HUNTING BEHAVIOR

HAVE SCIENTISTS RECENTLY WITNESSED IN TIGERFISH?

THE ANSWER RIGHT AFTER THIS.

IN BOTSWANA'S OKAVANGO DELTA,

I'M DETERMINED TO FIND OUT IF A PACK OF TIGERFISH

WOULD EVER ATTACK AND KILL A HUMAN.

A MAN NAMED LLOYD WILMOT

BELIEVES HE CAME CLOSE TO FINDING OUT

WHEN HIS PADDLE WAS REPEATEDLY ATTACKED

BY A SWARM OF THESE HYPER-AGGRESSIVE FISH.

WHAT ON EARTH WAS GOING ON?

I'M WONDERING IF IT'S ONE OF THOSE THINGS

WHERE IT'S NOT NORMAL BEHAVIOR,

BUT POSSIBLY AS SOON AS ONE FISH DOES SOMETHING,

THE OTHERS ALL GET THAT CONFIDENCE

AND THEY ALL START DOING THE SAME THING.

SO THE ONLY WAY TO ACTUALLY BE CERTAIN

WHETHER THEY WOULD ACTUALLY GO FOR A PERSON

IN THIS RATHER UNUSUAL CIRCUMSTANCE

WOULD BE TO GET IN THE WATER.

LLOYD IS THE FIRST PERSON I'VE MET

WHO'S ACTUALLY EXPERIENCED TIGERFISH AGGRESSION FIRSTHAND.

AND ALTHOUGH HIS ENCOUNTER WASN'T A BLOODY ONE,

IT'S PLANTED AN UNNERVING THOUGHT IN MY MIND.

THESE FISH APPEAR TO OPERATE ON A HAIR TRIGGER,

PRIMED TO ATTACK ANYTHING THAT LOOKS LIKE PREY.

AND ONCE ONE OF THEM BITES,

IT SEEMS THE REST OF THEM QUICKLY PILE IN.

IF I'M GOING TO PROVE THAT TIGERFISH TARGET HUMANS,

THEN I NEED TO GET BACK IN THE WATER

AND OFFER MYSELF AS LIVE BAIT.

SO FAR, THOUGH, THE FISH ARE PROVING ELUSIVE,

AND MY WINDOW OF OPPORTUNITY IS CLOSING.

IF THE WATER GETS TOO WARM, THE CROCS WILL ATTACK.

EARLY START TODAY BEFORE THE SUN GETS TOO HIGH.

NO TIGERFISH YESTERDAY, AND SO WHAT THAT MEANS

IS WE'RE GOING MORE INTO THE MAIN CHANNELS,

BUT THERE'S MORE CHANCE THERE OF ENCOUNTERING A CROC,

AND THE WORRY AT THE MOMENT

IS THE TEMPERATURE'S ACTUALLY GETTING WARMER DAY BY DAY.

THE WATER IS VISIBLY GOING DOWN,

AND IT'S COMING BACK INTO THE CHANNEL, WHICH IS GOOD,

BECAUSE THE FISH ARE GOING TO BE MORE CONCENTRATED,

MORE PRESENT IN THE CHANNELS,

BUT THE OTHER THING THAT'S HAPPENING

IS THE WATER IS WARMING UP, AND WHEN THE WATER WARMS UP,

THE CROCODILES WARM UP, AND IT'S GONNA HIT A POINT

WHEN IT'S ACTUALLY NO LONGER SAFE TO GET IN THE WATER.

SO WHAT WE'RE HAVING TO DO NOW IS GET OUT EARLIER IN THE DAY.

WE STILL WANT LIGHT TO SEE BY,

BUT OUR AVAILABLE TIME

TO POSSIBLY SEE TIGERFISH IS LIMITED.

I HAVEN'T GOT A LOT OF TIME.

I'VE NOW MADE OVER A DOZEN DIVES

WITHOUT ENCOUNTERING A SINGLE TIGERFISH.

WHAT SEEMED STRAIGHTFORWARD WITH A ROD AND LINE

IS PROVING MUCH MORE DIFFICULT WITH A DIVE SUIT AND AIR TANKS.

BECAUSE SO LITTLE IS KNOWN

ABOUT THE MOVEMENTS OF TIGERFISH,

IT'S NOT EVEN CLEAR WHERE I SHOULD BE FOCUSING MY SEARCH.

BUT HAVING COME SO FAR TO GET AN ANSWER, I'M NOT GIVING UP.

IT'S TIME TO DIVE DEEPER, INTO AN UNEXPLORED HIDING PLACE.

THE THING IS, WHEN YOU GET IN THE WATER HERE,

YOU REALIZE THERE'S SO MUCH MORE TO THE RIVER

THAN WHAT YOU SEE JUST BETWEEN THE BANKS.

THERE ARE THESE OVERHANGS AND WHAT LOOK LIKE CAVES,

IN FACT, UNDER THE VEGETATION, UNDER THE FLOATING VEGETATION.

SO IT'S POSSIBLE THAT THE ROOTS OF THOSE WEEDS

COULD PROVIDE SHELTER FOR SMALL FISH,

AND IF THE SMALL FISH ARE THERE, THE PREDATORS COULD BE, AS WELL.

SO TODAY, IT'S ALL ABOUT

SPECIFICALLY GETTING UNDER THE BANKS,

UNDERNEATH THE FLOATING VEGETATION,

SEE WHAT WE CAN FIND THERE.

THIS WILL BE A RISKY DIVE INTO PITCH-BLACK WATER

WITH LITTLE ROOM TO MANEUVER.

AND THE DENSE VEGETATION

COULD ALSO LIMIT COMMUNICATION WITH THE BOAT.

BUT MOST IMPORTANT, I'VE GOT TO KEEP A CLOSE EYE

ON THE RISING WATER TEMPERATURE.

JUST DOING A QUICK TEMPERATURE CHECK.

IT'S 65 DEGREES, SO WE'RE SORT OF BORDERLINE,

IN TERMS OF CROCODILE BEHAVIOR.

SO WE'RE ON THAT POINT, UH --

THAT POINT WHERE THERE IS A KIND OF TRIGGER,

WHERE THE CROCODILE'S BEHAVIOR FLIPS FROM ONE THING TO ANOTHER.

THE WATER MAY BE CLEAR,

BUT BENEATH THE FLOATING PAPYRUS, THERE IS NO SUNLIGHT.

GOING INTO THE CAVE.

NOW THIS IS WHERE VISIBILITY IS REALLY SHUTTING DOWN.

TOPSIDE. TOPSIDE, DIVER ONE -- DO YOU RECEIVE, OVER?

WITHIN SECONDS OF ENTERING THIS UNDERWORLD,

I'VE LOST ALL CONTACT WITH THE SAFETY BOAT.

I NEED TO STAY ALERT.

IF I RUN INTO THE WRONG END OF A CROC,

I WON'T HAVE THE SPACE OR TIME TO ESCAPE.

A SHAFT OF SUNLIGHT PIERCES A SMALL GAP IN THE REEDS,

REVEALING A LITTLE MORE OF THIS STRANGE, PARALLEL UNIVERSE.

THIS IS AN AMAZING -- AN AMAZING LANDSCAPE.

YOU JUST WOULDN'T SUSPECT THIS EXISTED AT ALL.

OH, THERE'S SOME BREAM BEHIND US -- SHOAL OF BREAM.

WE'RE QUITE A LONG WAY UNDER.

INCREDIBLE, SPOOKY ATMOSPHERE. INCREDIBLE.

A FEW HUNDRED FEET IN,

I FEEL LIKE I'VE BEEN LURED INTO A DEADLY LABYRINTH.

SUDDENLY REALLY CLOSING IN AROUND US.

WE'VE GONE INTO SORT OF A CHAMBER NOW.

SMALL ENTRANCE, WHICH HAS OPENED OUT.

THIS IS A COMPLETELY DIFFERENT WORLD HERE.

BUT VERTICALLY, IT'S VERY TIGHT.

FLOOR IS VERY CLOSE.

FULL OF SOFT VEGETATION.

AND THE CEILING'S VERY CLOSE,

SO IT'S -- IT'S QUITE CLAUSTROPHOBIC, IN FACT.

I'M STARTING TO FEEL UNEASY

AND TO WISH I WAS SOMEWHERE ELSE.

THEN...SOMETHING BIG COMES LOOMING OUT OF THE SHADOWS.

OH.

IN MY SEARCH FOR A PACK OF TIGERFISH,

I'M RUNNING OUT OF TIME.

AT 65 DEGREES, THE WATER IS ALMOST WARM ENOUGH

TO FLIP THE CROCODILES INTO FEEDING MODE.

AND IN THE CLAUSTROPHOBIC UNDERWORLD

BENEATH THE FLOATING REED BEDS,

I'VE JUST RUN INTO SOMETHING BIG.

OH.

THERE'S A MONSTER CATFISH HERE.

JUST SAYING A MONSTER CATFISH.

A CATFISH THIS SIZE WOULD NORMALLY BE BEAST ENOUGH FOR ME.

HERE, IT'S JUST ONE OF SEVERAL FORMIDABLE PREDATORS,

AND IT'S NOT THE ONE I'M AFTER.

SUDDENLY, IT'S OPENING OUT. I'VE NO IDEA WHERE I AM.

IT'S ACTUALLY QUITE A RELIEF TO BE OUT OF THOSE CAVES.

IT'S VERY SPOOKY IN THERE.

THIS IS THE REMAINS OF A WOODEN CANOE

DOWN HERE ON THE BOTTOM OF THE RIVER.

I WONDER WHAT STORY THIS HAS GOT TO TELL.

THEN, SILENTLY GHOSTING INTO VIEW,

THE VERY FISH I'VE COME TO MEET.

I'VE JUST SEEN A TIGERFISH. I'VE JUST SEEN A TIGERFISH.

IT'S CHECKING ME OUT.

THAT WAS A BIG TIGERFISH.

JUST SWAM RIGHT IN FRONT OF ME.

AND RIGHT ABOVE ME IS A SIGHT

THAT POSSIBLY NO ONE HAS EVER SEEN BEFORE.

THERE'S FISH ABOVE US,

AND THOSE ARE DEFINITELY TIGERFISH.

JUST BIG TIGERFISH THERE.

THEY'VE APPEARED FROM NOWHERE,

AND THEY'RE BARELY 20 FEET AWAY.

VERY RECOGNIZABLE BECAUSE OF THAT DEEP-FORKED TAIL.

SHOAL OF TIGERFISH.

THERE MUST BE AT LEAST 50 ADULTS IN THIS PACK,

ALL OF A SIMILAR SIZE.

AND THOSE ARE JUST THE ONES I CAN SEE.

WOW. THAT IS A LOT OF TIGERFISH.

THEY'RE IN MORE NUMBERS THAN I THOUGHT POSSIBLE.

THEY'RE STILL COMING. THEY'RE STILL COMING.

AND I FINALLY FOUND THE TIGERFISH.

THERE ARE PACKS OF THEM.

THIS IS REALLY QUITE INCREDIBLE.

I'M VERY AWARE

THAT THE TIGERFISH ARE BETWEEN ME AND THE BOAT.

BUT SO FAR, THEY'RE KEEPING THEIR DISTANCE.

MAYBE THEY'RE BIDING THEIR TIME.

IF THEY REALLY ARE SUPER-AGGRESSIVE,

THEN WHY ARE THEY HOLDING BACK?

PERHAPS WHAT'S MISSING

IS SOMETHING TO PROVOKE THAT FIRST CRUCIAL BITE,

THE BITE THAT UNLEASHES THE REST OF THE PACK.

SOUNDS CRAZY, BUT MAYBE I NEED TO PROVIDE A TRIGGER.

WHAT I HAVE IN MIND

MAY JUST BE THE RISKIEST THING I'M EVER LIKELY TO DO.

BUT IT'S NOW OR NEVER.

THIS IS VERY MUCH UNKNOWN TERRITORY WE'RE GOING INTO,

TRYING TO ENCOUNTER TIGERFISH UNDERWATER.

BECAUSE TIME IS SHORT, WHAT I'M DOING,

I'M EFFECTIVELY GONNA CHUM THE WATER

WITH SOME OF THE TIGERFISH'S NORMAL DIET -- SMALL FISH.

SO I'VE GOT A FEW HANDFULS OF THIS,

AND I'M GONNA THROW THAT INTO THE WATER

AND SEE HOW THEY RESPOND.

AND I'LL BE IN THE WATER WITH THEM.

I'VE NO IDEA HOW CHUMMING THE WATER

WILL AFFECT THE TIGERFISH,

BUT I'M HOPING THEY'RE STILL HERE.

IF THEY DO TURN NASTY, I'M READY TO RUN FOR THE BOAT.

I DON'T HAVE TO WAIT LONG.

TIGERFISH RIGHT NEXT TO THE BOAT.

AMAZINGLY CLOSE TO SOME TIGERFISH.

WILL ONE OF THEM BE FIRST TO STRIKE?

IN A REMOTE CORNER OF A REMOTE SWAMP,

I'M TURNING MYSELF INTO HUMAN BAIT.

I'VE FINALLY CAUGHT UP WITH A LARGE PACK OF TIGERFISH,

BUT SO FAR, THEY'VE DECLINED TO ATTACK ME.

SO I'VE DECIDED TO CHUM THE WATER.

THIS IS VERY MUCH UNKNOWN TERRITORY WERE GOING INTO.

AND IT'S NOT JUST THE TIGERFISH I HAVE TO WORRY ABOUT.

WITH WATER TEMPERATURES CLIMBING INTO THE HIGH 60s,

IT WON'T BE LONG BEFORE THE CROCODILES WARM UP

AND COME LOOKING FOR PREY.

I'M STARTING TO WONDER WHAT WILL ATTACK ME FIRST.

AMAZINGLY CLOSE TO SOME TIGERFISH.

BUT ALMOST AS SOON AS I SEE THEM...

THEY'RE GONE.

I'M JUST LOOKING AT THE WATER TEMPERATURE.

IT'S 66, WHICH IS ACTUALLY NOT GOOD NEWS.

ACCORDING TO BRAD, THE TEMPERATURE

WHERE THE CROC STARTS TO WAKE UP A LITTLE BIT IS 64.

SO WE'RE SLIGHTLY ON THE EDGE OF WHAT WE SHOULD BE DOING.

I'M PUSHING MY LUCK,

BUT I WANT TO KNOW IF TIGERFISH ARE MAN-EATERS,

AND I'M TOO CLOSE TO PULL OUT NOW.

JUST OPENING THE FISH BAG.

I DO WONDER ABOUT THE ADVISABILITY OF BEING DOWN HERE

WITH A BAG OF BLOODY, CHOPPED-UP FISH.

WITHIN MINUTES, THE TIGERFISH ARE BACK.

AND THIS TIME, THEY'RE COMING IN TO CHECK ME OUT.

THEY'RE GETTING CLOSER.

THEY'RE GETTING CLOSER AND CLOSER ALL THE TIME.

I BRACE MYSELF FOR THE JAWS.

AND THEN...

...NOTHING.

I'M IN PLAIN SIGHT OF PERHAPS 50 HUNGRY TIGERFISH,

YET THEY'RE REFUSING TO TOUCH ME.

THIS IS REALLY QUITE INCREDIBLE.

THEY'RE SO BOLD UNDERWATER, COMING SO CLOSE.

IT REALLY SHOWS THAT HUNGER OVERRIDES ALL OTHER EMOTIONS.

IN THEORY, I'M AN EASY MEAL,

BUT THE FISH SEEM MORE CURIOUS THAN MURDEROUS.

THEY'VE GOT THE JAWS AND TEETH TO ATTACK ME,

BUT PLAINLY, THEY DON'T SEE ME AS FOOD.

I'M SIMPLY NOT ON THEIR MENU.

SO WHAT ABOUT THOSE RARE STORIES

WHERE PEOPLE HAVE BEEN ATTACKED?

THE VICTIMS OF THE OVERTURNED BOAT

AND THE MIGRANT WORKERS MAULED IN THE RIVER?

SO, IN OTHER CONDITIONS, COULD TIGERFISH TAKE DOWN A PERSON?

THE ANSWER MAY LIE IN THE RIVER ITSELF.

MY EXPERIMENT TELLS ME THAT AS LONG AS TIGERFISH

CAN CLEARLY SEE WHAT THEY'RE DEALING WITH, WE'RE SAFE.

BUT VISIBILITY IS RARELY SO GOOD.

IMAGINE MORE CLOUDY WATER CONDITIONS,

WHEN THEY CAN'T MAKE OUT AN ENTIRE HUMAN SHAPE,

JUST DISEMBODIED HANDS OR FEET

FLASHING THROUGH THE WATER IN FRONT OF THEM.

FACTOR IN THE WAY THEY HUNT IN PACKS,

THEIR INSTINCT TO BITE FIRST AND ASK QUESTIONS LATER,

AND THEIR BOLDNESS TO ALL PILE IN

ONCE THE FIRST FISH HAS TAKEN THE FIRST BITE.

IN THOSE CONDITIONS, I THINK IT'S TRUE TO SAY

THAT I WOULDN'T FEEL SO HAPPY TO BE IN THE WATER WITH THEM.