All language subtitles for Mystery In Yellowstone (2015)

Mystery In Yellowstone

Narrator:
INCOMPARABLE YELLOWSTONE,

A PANORAMA OF LIFE
AND A LANDSCAPE LIKE NO OTHER.

A PLACE WHERE ANCIENT CONFLICTS
PLAY OUT IN A FRAGILE BALANCE.

BUT SOMETHING HAS TILTED
THAT BALANCE DANGEROUSLY,

AND THE PARK'S MAGNIFICENT ELK
ARE DISAPPEARING.

BUT WHO IS THE CULPRIT?

THE WOLF,
REINTRODUCED 20 YEARS AGO,

RIGHT WHEN
THE ELK NUMBERS CRASHED?

GRIZZLIES,
WHO HAVE ALWAYS PREYED

ON THE YOUNGEST
AND MOST VULNERABLE ELK?

[THUNDER]

OR IS IT SOMETHING
MORE INSIDIOUS AND BAFFLING?

[BANG]

NOW SCIENTISTS ARE RACING
TO SOLVE THE MYSTERY

OF THE DISAPPEARING ELK IN...

MYSTERY IN YELLOWSTONE.

♪

[HELICOPTER]

♪

THE SEARCH FOR SUSPECTS
IN THIS MYSTERY

BEGINS WITH THE VICTIMS
THEMSELVES.

ONLY TWO DECADES AGO, THE PARK
WAS THICK WITH THESE ELK--

NEARLY 20,000 OF THEM.

NOW LESS THAN A QUARTER
OF THEM REMAIN.

[BANG]

WILDLIFE BIOLOGISTS NEED TO
MONITOR THE HERD'S EVERY MOVE

AND THE HEALTH OF ITS MEMBERS--

AND A ROUND-UP BY HELICOPTER

IS THE QUICKEST WAY TO CAPTURE
CRITICAL INFORMANTS.

IT LOOKS BRUTAL,
BUT THE SCIENTISTS HAVE LEARNED

THAT THIS IS ONE
OF THE LEAST TRAUMATIC WAYS

TO RECRUIT VOLUNTEERS
FOR THEIR MISSION.

THEY MOVE QUICKLY
TO RESTRAIN THE ANIMALS

AND GET THE SAMPLES THEY NEED.

BIOLOGIST ARTHUR MIDDLETON
HAS SPENT THE LAST FEW YEARS

WRESTLING WITH THE STRANGE
AND UNNERVING ELK DECLINE.

Arthur Middleton:
THE QUESTIONS WERE PRESSING,

THE PROJECT WAS ALREADY
READY TO GO,

AND SO I CAME ACROSS THE STATE
FROM THE UNIVERSITY

UP TO NORTHWEST WYOMING

AND I STARTED MY FIELD WORK.

Narrator:
AFTER MAKING SURE THE ELK COW
IS SAFELY RESTRAINED,

HE TAKES BLOOD SAMPLES
THAT WILL BE CHECKED FOR SIGNS

OF DISEASE, STARVATION, STRESS,
AND PREGNANCY.

THEN HE FITS THE COW
WITH A GPS COLLAR

THAT WILL TRANSMIT HER POSITION
EVERY THREE TO FIVE HOURS.

THE TEAM AIMS TO GET EVERY
ANIMAL CAPTURED AND RELEASED

IN LESS THAN 8 MINUTES
AND WITHOUT ANY SEDATION.

AND THEN THE NEWLY RECRUITED
INFORMANT IS FREE AGAIN...

UNAWARE JUST HOW MUCH
VITAL INFORMATION

SHE'LL BE GIVING MIDDLETON
AND HIS TEAM...

AND THAT SHE COULD HELP EXPOSE
THE KILLER OF HER KIND.

[BUGLING]

THERE ARE MANY
POTENTIAL CULPRITS

IN THE DECLINE OF THE HERD,

BUT THE FIRST ONE
ON EVERYONE'S MIND IS THE WOLF.

LONG MISSING FROM YELLOWSTONE,

THE WOLF ARRIVED
BACK ON THE SCENE

RIGHT WHEN THE ELK NUMBERS
BEGAN TO CRASH.

TOO MUCH OF A COINCIDENCE,
IN THE MINDS OF MANY.

BUT PINNING THE CRIME
ON THE RETURN OF THE WOLF

REQUIRES PROOF.

WOLVES, ONCE CONSIDERED
DANGEROUS VERMIN,

WERE SYSTEMATICALLY EXTERMINATED

FROM THE TIME THE PARK
WAS FOUNDED IN 1872.

BY THE 1920s, THEY WERE GONE,

AND THE PARK WAS TURNED INTO
A SAFER PLAYGROUND FOR TOURISTS.

Film narrator:
YOU'VE JUST ENTERED
YELLOWSTONE NATIONAL PARK.

YOU'RE A MILE AND A HALF
ABOVE SEA LEVEL,

AND THE AIR IS CLEAR
AND INVIGORATING.

ALL AROUND US IS THE EVIDENCE
OF THE PARK'S VOLCANIC ORIGIN.

ALL THE FLOWERS AND FORESTS AND
MOUNTAINS ARE RESERVED FOR YOU.

♪

Narrator:
THE YELLOWSTONE NATIONAL PARK
STRADDLES THE CONTINENTAL DIVIDE

OF THE NORTHERN ROCKY MOUNTAINS
IN WYOMING.

IT'S THE HEART OF THE GREATER
YELLOWSTONE ECOSYSTEM--

AN AREA OF ALMOST
30,000 SQUARE MILES.

[ELK BUGLING]

IT LOOKED PRISTINE--

BUT WITHOUT THE WOLF,

YELLOWSTONE WAS AN ECOSYSTEM
OUT OF BALANCE.

THE ELK POPULATION EXPLODED
TO UNSUSTAINABLE LEVELS.

BUT IN 1995, 70 YEARS AFTER
THE LAST WOLF HAD BEEN KILLED,

THE PARK DID SOMETHING RADICAL:

THEY IMPORTED A PACK OF WOLVES
FROM CANADA

AND RELEASED THEM
INTO YELLOWSTONE.

Middleton: THE WOLF HAD BEEN
REINTRODUCED IN THE MID 1990s,

AND IT WAS A HUGE SUCCESS
BIOLOGICALLY.

THEIR POPULATION NUMBERS
GREW VERY RAPIDLY,

AND THEY EXPANDED FAR
OUTSIDE OF YELLOWSTONE PARK

INTO THE SURROUNDING REGION.

Narrator: THE WOLVES
IMMEDIATELY SET ABOUT DOING

WHAT THE PARK BIOLOGISTS
HAD HOPED--

HUNTING THE OVERPOPULATED ELK
WITH A VENGEANCE,

BRINGING DOWN ELK NUMBERS

BUT ACTUALLY IMPROVING
THE HEALTH OF THE HERDS.

♪

[ELK BUGLING]

♪

BUT NOT EVERYONE WAS THRILLED.

HUNTERS WHO COMPETE
WITH WOLVES FOR ELK

AND RANCHERS WHO FEARED
FOR THEIR LIVESTOCK

PREDICTED THE WOLVES
WOULD CAUSE A CATASTROPHE.

♪

20 YEARS LATER,

IT WAS BEGINNING TO LOOK
LIKE THE WOLF-HATERS WERE RIGHT.

ELK NUMBERS
HAD PLUMMETED BY 80%.

AND AS A FEW DOZEN WOLVES
BECAME HUNDREDS,

PRESSURE GREW TO SHUT DOWN
THE RETURN OF THE WOLF.

Middleton: THE TIME DREW
CLOSER AND CLOSER

FOR THEIR PROTECTIONS
TO BE LIFTED,

AND THAT MEANS
THEIR MANAGEMENT SHIFTS

FROM A PROTECTION POSTURE
TO MORE OF A HARVEST POSTURE,

WHERE THE PUBLIC IS PERMITTED
TO HUNT WOLVES.

Narrator:
THE SITUATION WAS URGENT:

IF WOLVES COULD BE HUNTED AGAIN,

THE WHOLE SUCCESS
OF THE PARK'S ATTEMPT

TO RETURN YELLOWSTONE
TO ITS ORIGINAL BALANCE

WAS IN DANGER.

ENTER DR. MIDDLETON,

A YOUNG BIOLOGIST
SENT TO DETERMINE

WHETHER THE WOLF WAS NOT
JUST A SUPREME PREDATOR

BUT A MASS MURDERER.

Middleton: I CAME HERE TO FIND
THE ANSWER TO A QUESTION

THAT A LOT OF PEOPLE LOCALLY
AND A LOT OF SCIENTISTS

HAD ASKED, WHICH IS:

DOES THE PRESENCE OF WOLVES
SCARE ELK SO MUCH

THAT THEY'RE LOSING FAT,
THEY'RE STRESSED OUT,

AND THEY'RE NOT REPRODUCING?

SO I HAD TO GO OUT IN THE FIELD
AND STARE AT ELK.

Narrator: MONITORING THE HERD
THROUGH THE BRUTAL WINTERS

IN THEIR TERRITORY
IN THE LOWER NORTHERN RANGES

ISN'T EXACTLY ALL
IT'S CRACKED UP TO BE.

Middleton: CONTRARY TO WHAT
I WAS LED TO BELIEVE,

ELK DON'T REALLY DO VERY MUCH.

THEY'RE CERTAINLY NOT RUNNING
INTO WOLVES ALL THAT MUCH,

AND THEY'RE MOSTLY JUST DIGGING
AROUND IN THE SNOW FEEDING

ALL DAY.

Narrator: THE ELK CERTAINLY
DON'T LOOK STRESSED,

AND THEY BARELY GLANCE UP

AT ANY WOLF THAT ISN'T
WITHIN SPRINTING DISTANCE.

THE RESULT OF THE BLOOD TESTS

CONFIRM WHAT MIDDLETON
IS SEEING IN THE FIELD:

THE COW ELK ARE
IN EXCELLENT HEALTH,

AND OVER 70% OF THE FEMALES
ARE PREGNANT.

STRESS CAN PREVENT PREGNANCY
AND CAUSE MISCARRIAGE,

SO THAT DOESN'T SEEM
TO BE THE PROBLEM.

BUT ANOTHER RESULT
IS DISTURBING:

THE TESTED FEMALES
ARE OLDER THAN EXPECTED.

ONLY A HANDFUL
IS UNDER 9 YEARS OLD,

FAR PAST AN ELK'S PRIME.

THEY GENERALLY DON'T LIVE
PAST 15.

[BUGLING]

THE HERD ISN'T JUST SHRINKING;
IT'S BECOMING GERIATRIC.

IN WINTER, THE ELK HERD
SEEMS HEALTHY AND RELAXED--

JUST OLD.

SOMETHING MUST BE
HAPPENING TO THEM

AT SOME OTHER TIME OF THE YEAR,
KILLING OFF THE YOUNG ELK.

SPRING IS COMING,

MEANING THE MASS MIGRATION
OF PREY ANIMALS

IN SEARCH OF BETTER GRAZING.

MANY OF MIDDLETON'S COLLARED ELK

ARE HEADED TO THE HIGH PLAINS
IN THE INTERIOR OF THE PARK,

WHERE THERE WILL BE
RICH PASTURE,

JUST IN TIME FOR CALVING.

COULD SOMETHING BE HAPPENING

DURING THE LONG
AND ARDUOUS TREK?

Middleton: ONE OF THE MOST
IMPORTANT THINGS

THAT HAPPENS THIS TIME OF YEAR

IS THE MIGRATION
OF THE LARGE HERBIVORES--

THE ELK, THE MOOSE,
THE PRONGHORN ANTELOPE,

THE MULE DEER,
THE BIGHORN SHEEP.

ALL THOSE ANIMALS,
THOUSANDS AND THOUSANDS,

TENS OF THOUSANDS OF ANIMALS ARE
MOVING TO THEIR SUMMER HABITAT,

NEARER TO THE CORE
OF YELLOWSTONE,

AND ELK ARE THE DOMINANT
MIGRATORY ANIMAL.

Narrator:
AS THE ELK SLOWLY MIGRATE

BACK UP INTO
THE YELLOWSTONE NATIONAL PARK,

THEY PASS THROUGH DIFFERENT
WOLF TERRITORIES...

WITH MIDDLETON ON THEIR HEELS.

BUT ONCE AGAIN, HE FINDS OUT

THAT ENCOUNTERS
BETWEEN ELK AND WOLVES

REMAIN EXTREMELY RARE,

AND THE ELK SHOW
NO SIGN OF STRESS.

BY MAY, THEY REACH THE HIGH
PLATEAU IN THE INTERIOR,

WHERE NEW, RICH GRASSES
AND MILD TEMPERATURES

SET THE STAGE
FOR A NEW SEASON...

AND A NEW DRAMA.

[WOLF HOWLING]

AS NIGHT FALLS, THE FEMALES
SLIP AWAY FROM THE HERD

AND PREPARE TO WELCOME A SLEW
OF NEWCOMERS INTO THE WORLD

AND A WHOLE NEW SET
OF VULNERABILITIES.

[HOWLING]

THE NIGHT IS CALM,
BUT THE DAWN WILL BRING TROUBLE.

♪

DAYBREAK REVEALS
THE YEARLY MIRACLE--

OVERNIGHT, YELLOWSTONE COUNTRY
HAS BECOME A MASSIVE NURSERY.

[GEESE HONKING]

♪

THE CALVES CAN STAND
WITHIN HOURS,

BUT THEY WON'T BE ABLE TO RUN
WITH THE HERD FOR TWO WEEKS.

SO THEIR MOTHERS KEEP THEM APART
AND KEEP A CLOSE EYE ON THEM.

♪

THE SHEER NUMBER OF ELK CALVES,
ALMOST ALL IN GOOD HEALTH,

CLEARLY SHOWS
THAT THE ELK PREGNANCIES

HAVE NOT BEEN AFFECTED
BY THE PRESENCE OF WOLVES.

BUT THE PREDATORS SENSE
A NEW OPPORTUNITY--

THERE ARE YOUNG
PREY ANIMALS EVERYWHERE.

WOLVES ARE DEVOTED PARENTS;

THE WHOLE PACK WILL DO
WHAT IT CAN TO FEED THEIR PUPS.

BEAR FAMILIES HAVE EMERGED
FROM HIBERNATION,

AND THE MOTHERS
HAVEN'T EATEN IN MONTHS.

EVEN SCAVENGERS
WILL TURN INTO HUNTERS

WHEN SPRING CALVES
ARE EVERYWHERE FOR THE PICKING.

BUT THE HUNTERS NEED TO CHOOSE
THE HUNTED CAREFULLY.

BISON CALVES WOULD SEEM RIPE
FOR THE PICKING,

BUT THEY'VE ALREADY
JOINED THE HERD

AND ARE PROTECTED BY GIANTS.

ELK CALVES ARE SMALLER

AND STILL DON'T HAVE
THE PROTECTION OF THE HERD.

ELK MOTHERS, TOO,
ARE EXTREMELY PROTECTIVE...

BUT YOUNG MOTHERS
CAN MAKE MISTAKES.

MOM KNOWS THAT WATER
MEANS SAFETY

FROM ALMOST ALL PREDATORS...

BUT THE LITTLE CALF ALSO KNOWS

THAT HE'S NO MATCH
FOR RAGING MELTWATER.

IT COULD BE A COSTLY MISTAKE.

WOLVES ARE ON THE LOOKOUT
FOR UNPROTECTED YOUNGSTERS.

[WOLF HOWLING]

BUT MOTHER SOON REALIZES
HER MISTAKE;

SHE HEADS BACK ACROSS THE RIVER.

♪

FORTUNATELY FOR HER,

HER CALF HAS HIS OWN DEFENSE
THAT FOILS THE WOLF.

♪

HE, LIKE ALL NEWBORN ELK CALVES,
HAS ALMOST NO SCENT--

AND EVEN THE KEEN-NOSED CANINE
CAN'T SMELL HIM.

IT'S A BRILLIANT DEFENSE,

ALLOWING THE MOTHER
TO WANDER AND GRAZE

WHILE HER CAMOUFLAGED BABY
HUNKERS DOWN

AND DISAPPEARS
INTO THE LANDSCAPE.

AND MEANWHILE MOTHER ISN'T
GIVING AWAY WHERE HER BABY IS.

IF WOLVES GET
TOO CLOSE FOR COMFORT,

SHE'LL GET RIGHT IN THEIR FACES
TO LEAD THEM AWAY FROM HER CALF,

KNOWING SHE'S FAST ENOUGH

TO REACH THE SAVE HAVEN
OF WATER...

AND GUTSY ENOUGH
TO KEEP THEM AT BAY.

Middleton: ELK ARE
VERY SOPHISTICATED ANIMALS,

SO EVEN WHEN WOLVES SHOW UP,
THEY CAN RUN AWAY,

THEY CAN STAND THEIR GROUND,

THEY CAN ASSESS
HOW VULNERABLE AM I?

HEY, I'M FIVE YEARS OLD;
I'M IN TOP SHAPE.

MY LEGS ARE FINE;
MY HEALTH IS FINE.

I DON'T HAVE ANYTHING
TO WORRY ABOUT.

[BIRDS CHIRPING]

Narrator: AS SUMMER APPROACHES,

THE DECLINE OF THE ELK
IS STILL A MYSTERY.

THE INVESTIGATORS ARE ABOUT
TO COUNT THE CALVES AGAIN.

AND THE RESULT IS DISTURBING.

Middleton: YOU COULD HAVE
AS MANY CALVES AS COWS

BECAUSE EVERY COW
CAN HAVE ONE CALF,

SO, IN LATE SUMMER,
ONLY A FEW MONTHS AFTER CALVING

WE COUNT HOW MANY CALVES
THERE ARE,

AND IF THERE'S VERY FEW CALVES,

THEN SOMETHING
DURING THE SUMMER,

UP ON THE SUMMER RANGE,

IS CAUSING THE LOSS
OF THOSE CALVES.

Narrator: BY SUMMER'S END,

ONLY A THIRD OF THE CALVES
ARE STILL ALIVE.

ARTHUR MIDDLETON
NEEDS TO REASSESS.

THE ELK COWS WERE
IN GOOD PHYSICAL CONDITION

IN THE WINTER,

WITH MOST OF THEM PREGNANT

AND SHOWING NO SIGNS
OF WOLF-INDUCED STRESS.

THE HERD IS OLD, BUT THEY'RE
CARRYING THE CALVES TO TERM

AND GIVING BIRTH
TO HEALTHY YOUNG.

BUT THEN THEY START
TO DISAPPEAR,

AND, EVEN THOUGH THE ELK NUMBERS
WENT INTO FREE FALL

AT THE SAME TIME AS
THE REINTRODUCTION OF THE WOLF,

THERE'S NO SMOKING GUN HERE--

FOR THE SCIENTISTS REALIZED,
THROUGH MONITORING BOTH SPECIES,

THE WOLVES AREN'T TAKING
NEARLY ENOUGH OF THEM

TO ACCOUNT
FOR THE ELK'S DECLINE.

[HOWLING]

Middleton: WOLVES ARE ONLY
ONE OF FIVE PREDATORS--

ACTUALLY SIX
IF YOU COUNT HUMANS--

THAT EAT ELK, AND THEY WERE NOT
AFFECTING THESE ELK

AS STRONGLY AS EVERYBODY
SAID THEY WERE.

AND SO I SPENT A LOT OF TIME

FINDING OUT
WHAT WAS NOT GOING ON;

I NEEDED TO FIND OUT
WHAT WAS GOING ON.

♪

Narrator: SINCE HUNTING
WITHIN THE PARK BOUNDARIES

IS PROHIBITED

AND OTHER PREDATORS

SUCH AS MOUNTAIN LIONS
AND WOLVERINES ARE RARE...

♪

BEARS ARE PRIME SUSPECTS.

AND YELLOWSTONE IS HOME
TO TWO KINDS--

BLACK AND GRIZZLY BEARS.

IS EITHER OF THESE BEARS TO
BLAME FOR THE DISAPPEARING ELK?

♪

Middleton: WOLVES EAT SOME ELK,
OF COURSE THEY DO,

BUT GRIZZLY BEARS ARE ESPECIALLY
GOOD AT FINDING NEWBORN CALVES.

HUNTING AROUND LIKE BIRD DOGS
ON THE LANDSCAPE,

FINDING THEIR SCENT,
CATCHING THEM AND EATING THEM,

AND THEY DO IT IN THE FIRST FEW
WEEKS OF THE LIFE OF AN ELK CALF

BEFORE IT'S EVEN UP,
RUNNING AROUND.

AND THAT'S HOW MOST ELK CALVES
THAT DIE FROM PREDATION DIE.

Narrator: THIS CALF,
KILLED EARLIER BY A GRIZZLY,

IS STILL GUARDED BY ITS MOTHER.

GRIZZLIES HAVE
THE KEENEST SENSE OF SMELL

OF ALL YELLOWSTONE'S PREDATORS.

THEY CAN DETECT
THE NEARLY SCENTLESS CALVES

THAT OTHER PREDATORS CANNOT.

[HOWLING]

THE COW ELK TRIES
TO DISTRACT THE BEAR

AWAY FROM HER DEAD YOUNGSTER.

BUT SHE'S HELPLESS
BEFORE THE MASSIVE GRIZZLY.

♪

[RAVEN SQUAWKING]

♪

[RAVEN SQUAWKING]

♪

BUT IF THE BEAR IS RESPONSIBLE

FOR THE ELK'S
PLUMMETING NUMBERS,

THERE MUST BE SOMETHING ELSE
AT PLAY HERE.

BEARS WERE AROUND
HUNTING ELK CALVES

WHILE THE ELK HERDS
WERE STILL ENORMOUS,

EVEN OUT OF CONTROL.

[RAVEN SQUAWKING]

IS SOMETHING TURNING
YELLOWSTONE'S GRIZZLY BEARS

INTO ELK MASS MURDERERS?

AND THE GRIZZLIES NOW BECOMING
THE LEAD SUSPECT,

IT'S TIME FOR SOME SERIOUS
BEAR EXPERTISE.

FRANK VAN MANEN
AND HIS COLLEAGUES

FROM THE INTERAGENCY
GRIZZLY BEAR STUDY TEAM

KNOW THE BEARS
OF YELLOWSTONE COUNTRY

BETTER THAN ANYONE ELSE.

Man: HELLO!

Frank van Manen: GRIZZLY BEARS
ARE THE ICONIC SPECIES

IN THIS ECOSYSTEM.

IT'S AN ANIMAL
THAT IS VERY POWERFUL.

YOU KNOW WHEN YOU'RE WALKING
IN GRIZZLY BEAR COUNTRY

THAT YOU'RE NOT
THE MOST POWERFUL CREATURE

IN THAT LANDSCAPE,

AND THAT'S A SENSE OF HUMILITY
THAT I ALMOST ENJOY.

HEY, BEAR!

AND IF WE CAN FIND A WAY TO
COEXIST WITH ANIMALS LIKE THAT,

I THINK WE'VE
ACCOMPLISHED A LOT.

Narrator: THE SCIENTISTS NEVER
ENTER GRIZZLY TERRITORY ALONE.

IN TEAMS, THEY SET OUT

TO CHECK ON THEIR
SPECIALLY DEVELOPED BEAR TRAPS--

A LITTLE LOW-HANGING BARBED WIRE

SURROUNDING A COCKTAIL
OF ANIMAL BLOOD.

THE BARBS SNAG BITS OF BEAR FUR
FOR THEM TO ANALYZE,

AND CAMERAS WILL CATCH THEM
IN THE ACT.

THE CAMERA TRAP SHOWS
A FAMILY OF THREE

PASSING THROUGH
JUST 24 HOURS AGO.

AND SURE ENOUGH, THEY'VE LEFT
CRUCIAL HAIR SAMPLES

FOR DNA ANALYSIS.

THE RESEARCHERS HOPE TO IDENTIFY
EACH AND EVERY BEAR

AND THEIR PREFERRED MENU.

Van Manen: WE CAN GET A LOT
OF INFORMATION

FROM THESE,
WHAT WE CALL HAIR TRAPS,

BECAUSE WE'RE COLLECTING
DNA SAMPLES.

THAT'S BASICALLY
LIKE GENETIC FINGERPRINTING.

WE CAN IDENTIFY THE INDIVIDUAL,

AND THERE'S SOME INCREDIBLY
INTRIGUING PATTERNS

THAT COME OUT OF THAT.

Narrator:
ONCE BEARS ARE IDENTIFIED,

THE SCIENTISTS CAN BEGIN
TO FIGURE OUT

WHERE THE BEARS ARE GOING
IN SEARCH OF FOOD--

BOTH INSIDE
AND OUTSIDE THE PARK.

ANALYSIS OF THE ANIMALS' SCAT

TELLS THEM EXACTLY
WHAT THE BEARS ARE EATING.

Van Manen:
GRIZZLY BEARS ARE DISTRIBUTED

IN ABOUT 50,000
SQUARE KILOMETERS OF HABITAT,

AND IT IS LISTED
AS A THREATENED POPULATION

UNDER THE U.S.
ENDANGERED SPECIES ACT.

SO OUR TASK AS A STUDY TEAM

IS TO HELP SPECIES
AND POPULATIONS RECOVER.

Narrator:
BUT HAIR TRAPS ARE NOT ENOUGH.

TO REALLY FIGURE OUT
WHAT'S GOING ON,

THEY NEED TO RECRUIT THE BEARS
THEMSELVES AS INFORMANTS.

ONCE A BEAR IS TRAPPED
AND SEDATED,

HE GETS A THOROUGH MEDICAL EXAM

BEFORE BEING FITTED
WITH A GPS RADIO COLLAR.

AN EXPERIENCED VET
FROM THE PARK MANAGEMENT

HELPS WITH MEASURING,
WEIGHING AND BLOOD DRAWING.

SO FAR, THE GPS DATA
HAS BEEN STARTLING.

Van Manen:
WE HAVE SEEN MOVEMENTS

DURING THE MIDDLE OF THE DAY,
BASED ON OUR GPS LOCATIONS,

OF TEN KILOMETERS OR MORE,

THROUGH A LOT OF AREAS WHERE
THERE WAS A LOT OF HUMAN USE

AND NOBODY EVER REPORTED
SEEING HIM,

NOBODY HAD ANY IDEA

THIS ANIMAL WAS CROSSING
THIS LANDSCAPE

AMONG ROADS AND PEOPLE,
BIKES AND CARS.

IT'S REALLY FASCINATING HOW
THESE ANIMALS USE THE LANDSCAPE

AND BASICALLY GO UNDETECTED.

HEY-O!

Narrator: THE COLLARS CONFIRM

WHAT THE SCIENTISTS
HAVE ALWAYS SUSPECTED.

BEARS ARE SMART ANIMALS
THAT ARE HAPPY TO MAKE USE

OF HUMAN-CREATED SHORTCUTS.

THEY USE THE SWATHS CREATED
FOR ELECTRICAL LINES

AS URSINE HIGHWAYS,

PERFECT FOR COVERING LONG
DISTANCES WITHOUT BEING SEEN.

AND THEY USE THE TELEPHONE POLES
AS SCRATCHING POSTS,

AS WELL AS LEAVING
CHEMICAL MESSAGES ON THEM

FOR OTHER BEARS.

Man: THERE WE GO.

[BEEP]

Narrator: THE FINDINGS
ARE GREAT NEWS FOR BEARS.

Van Manen: FROM ALL OUR
DEMOGRAPHIC ANALYSIS,

WE'VE SEEN THAT THIS POPULATION
INCREASED

BY BETWEEN
ABOUT 4 TO 7% ANNUALLY

FROM 1983 TO ROUGHLY ABOUT 2000.

AND WHAT WE'VE SEEN SINCE THEN

IS THAT THE POPULATION GROWTH
HAS SLOWED DOWN A LITTLE BIT,

BUT THERE'S CERTAINLY
NO INDICATION OF DECLINE.

SO WE ARE NOW LOOKING
AT A POPULATION

IN MUCH BETTER SHAPE
THAN THEY WERE IN THE 1970s.

Narrator:
BUT IS GOOD NEWS FOR BEARS

THE CAUSE OF THE TERRIBLE NEWS
FOR THE ELK?

WITH THEIR NUMBERS GROWING
STEADILY IN THE LAST 30 YEARS,

COULD GRIZZLIES BE OUR KILLERS
OF YOUNG ELK CALVES?

CLEARLY THE NUMBER
OF MANY MORE GRIZZLIES

WOULD HAVE SOME IMPACT
ON THE SURVIVAL OF THE ELK,

ESPECIALLY CALVES.

BUT THERE'S A PROBLEM.

THE MOST DRAMATIC DECLINE
OF THE MIGRATING ELK HERD

HAS TAKEN PLACE
IN THE LAST 10 YEARS--

AND DURING THAT TIME THE GRIZZLY
POPULATION HAS HELD STEADY.

SO NOW IT'S EVEN HARDER
TO PIN THE ELK MURDER MYSTERY

ON A SINGLE PREDATOR,

AND THE PROFILES OF OUR
POTENTIAL SERIAL KILLERS

GET MURKIER.

[BIRD SQUAWKING]

[BEAR GROWLING]

IN A WOLF-BEAR STANDOFF
OVER A CALF KILL,

THE BEAR IS ALMOST ALWAYS
GOING TO WIN.

BUT THAT DOESN'T
NECESSARILY TRANSLATE

INTO AN ELK-HEAVY,
ALL-CARNIVORE DIET

FOR THE BEARS.

THE ANALYSIS OF THEIR HAIR
AND SCAT SAMPLES SHOW OTHERWISE.

Van Manen: BASICALLY,
WHAT WE FOUND OUT

WAS THAT IT WAS
INCREDIBLY DIVERSE.

GRIZZLY BEARS CONSUMED 266
DIFFERENT SPECIES OF ORGANISMS.

PLANTS, A NUMBER OF DIFFERENT
MAMMALS, FISH, INSECTS--

IT'S AN INCREDIBLE VARIETY
OF SPECIES.

WE CALL THEM OPPORTUNISTIC
OMNIVORES FOR A GOOD REASON.

Narrator: AFTER THE 3 TO 5
MONTHS OF HIBERNATION

THEY EVEN EAT DIRT--
VOLCANIC SOIL--

TO JUMP-START
THEIR DIGESTIVE SYSTEMS.

THE POTASSIUM AND MAGNESIUM

MAY HELP KILL OFF PARASITES
THAT CAUSE DIARRHEA.

BUT THEY NEED HUGE AMOUNTS
OF PROTEIN AND FAT AS WELL,

AND A SURPRISING AMOUNT
OF THESE NUTRIENTS

COMES FROM THE TINIEST OF PREY
IN THE STRANGEST OF PLACES.

DURING THE SUMMER MONTHS,

GRIZZLIES CLAMBER UP
PAST 9,000 FEET

TO REACH PRECARIOUS SLOPES
OF LOOSE ROCK,

OFTEN WITH YOUNG IN TOW.

THEY'RE LOOKING
FOR LITTLE PACKETS OF FAT

HIDING FROM THE SUN
AMONG THE ROCKS: MOTHS.

ARMY CUTWORM MOTHS...

COMMONLY KNOWN AS MILLER MOTHS.

IN YELLOWSTONE, THE MOTHS
CAN MATE AND SPENT THE SUMMER

IN THE SHADE
OF THE ROCKY MOUNTAINS.

DURING THEIR STAY
THE MOTHS FATTEN UP

ON THE NECTAR
OF THE RICH ALPINE MEADOWS...

AND HIDE ON THE SLOPES.

A SINGLE GRIZZLY BEAR CAN EAT
OVER 40,000 MOTHS A DAY.

THAT'S ACTUALLY
20,000 CALORIES OF FAT!

HOWEVER, THE LOOSE ROCK CAN MAKE
THIS AN UNNERVING FEAST...

♪

BUT GRIZZLIES CANNOT LIVE
BY MOTHS ALONE.

Van Manen:
WE SEE DIET DIFFERENCES
BASED ON INDIVIDUALS.

EACH INDIVIDUAL
IS SLIGHTLY DIFFERENT.

WE SEE DIFFERENCES BASED ON
WHERE YOU ARE IN THE ECOSYSTEM.

WE SEE DIFFERENCES
BASED ON TIME,

SO FROM ONE DAY TO THE NEXT

THEY COULD BE CONSUMING
SOMETHING VERY DIFFERENT,

FROM ONE SEASON
TO THE NEXT SEASON

AND EVEN FROM ONE YEAR
TO THE NEXT YEAR.

Narrator: WITH SO MANY
FOOD SOURCES TO CHOOSE FROM,

WHY WOULD GRIZZLIES BE TAKING
MORE AND MORE ELK CALVES?

IS SOMETHING IMPORTANT
ON THEIR MENU DISAPPEARING?

IN YELLOWSTONE'S
WHITEBARK PINE FORESTS,

SQUIRRELS ARE BUSY PREPARING
FOR THE LONG WINTER.

AND THE SMART BEARS KNOW IT.

WHILE SQUIRRELS FRENETICALLY
COLLECT AND STORE

THE ENERGY-RICH SEEDS
OF THE WHITEBARK PINES,

THE GRIZZLIES SIMPLY WAIT

AND THEN DIG UP THEIR BURROWS
TO STEAL THE SEEDS.

♪

Van Manen: WHITEBARK PINE
IS AN IMPORTANT FOOD SPECIES

FOR GRIZZLY BEARS.

THEY ACTUALLY FEED ON
THE BIG SEEDS OF WHITEBARK PINE

THAT ARE VERY RICH IN PROTEINS
AND FATS DURING THE FALL TIME,

SO IT'S ALSO A FOOD SOURCE
THAT IS AVAILABLE

DURING AN IMPORTANT TIME OF YEAR
FOR GRIZZLY BEARS,

BECAUSE THAT'S WHEN THEY PREPARE
FOR HIBERNATION.

Narrator: BUT THE WHITEBARK PINE
FORESTS ARE DYING.

72% OF THE BIG TREES ARE GONE,

MANY KILLED BY THE VORACIOUS
MOUNTAIN PINE BEETLE,

WHICH IS THRIVING
BECAUSE OF GLOBAL WARMING.

♪

BUT PINE NUTS ARE IMPORTANT
TO THE BEARS ONLY IN THE FALL,

BEFORE HIBERNATION,

AND NOT IN THE SPRING,

WHEN THE ELK CALVES
ARE DISAPPEARING.

STILL, THE DECLINE
OF THE WHITEBARK PINE

DOES PROVIDE AN IMPORTANT CLUE
IN THE PUZZLE:

IT SHOWS HOW GRIZZLIES REACT
TO A VANISHING FOOD SOURCE.

Van Manen:
WE WERE ABLE TO DEMONSTRATE

THAT THEY'RE NOT USING
WHITEBARK PINE HABITATS

AS MUCH AS THEY USED TO.

SO WE HAVE SEEN
A RESPONSE TO THAT,

BUT WE HAVEN'T SEEN
THAT THEY INCREASED

THEIR HOME RANGES
OR THEIR MOVEMENTS,

AND INSTEAD WHAT WE FOUND

WAS THAT THEY SEEM TO BE FINDING
ALTERNATIVE FOOD SOURCES

WITHIN THEIR
REGULAR HOME RANGES.

Narrator: THE UPSHOT--
WHEN FACED WITH A FOOD CRISIS,

BEARS DO NOT CHANGE
WHERE THEY EAT...

THEY CHANGE WHAT THEY EAT.

SO THE QUESTION BECOMES:
HAS SOMETHING DISAPPEARED

FROM THE BEARS'
SPRING AND SUMMER MENU

THAT'S MAKING THEM
TURN ELSEWHERE FOR FOOD,

ESPECIALLY AMONG THE BEARS
THAT ENCOUNTER THE ELK HERDS

JUST AS THE ELK
ARE GIVING BIRTH?

THE ANSWER: A STUNNING YES.

VAN MANEN FINDS A HUGE CLUE
TO THE ELK MYSTERY.

THEY SHOW THAT BEARS
AROUND YELLOWSTONE LAKE

AREN'T EATING THE FISH THAT
USED TO DOMINATE THESE WATERS

AND THEIR SPRING DIETS.

Van Manen: FOR THOSE BEARS
NEAR YELLOWSTONE LAKE,

CUTTHROAT TROUT WERE CERTAINLY
A PORTION OF THE DIET.

AND NO DOUBT THAT THAT USE
DECLINED SUBSTANTIALLY.

Narrator: IN THE LAST DECADE,
IT HAS BECOME CLEAR

THAT SOMETHING HAS GONE
TERRIBLY WRONG

IN YELLOWSTONE LAKE.

ROBERT GRESSWELL
OF THE U.S. GEOLOGICAL SURVEY

KNOWS THE FISH OF YELLOWSTONE
BETTER THAN ANYONE.

AND HE'S BEEN WITNESS
TO A TRUE ECOLOGICAL CALAMITY--

THE DISAPPEARANCE
OF THE NATIVE CUTTHROAT TROUT.

Robert Gresswell: IN THE 1960s
THERE WERE THOUSANDS OF PEOPLE

THAT WOULD SHOW UP TO FISH
ON FISHING BRIDGE.

AND IT WAS DANGEROUS.

I REMEMBER IN 1969,
WHEN I WORKED HERE,

YOU DIDN'T DRIVE ACROSS THE
BRIDGE WITH YOUR WINDOW DOWN,

BECAUSE YOU MIGHT GET HOOKED
BY SOMEBODY CASTING.

Narrator: FISHING IS NOW
FORBIDDEN AT FISHING BRIDGE...

BUT EVEN IF IT WEREN'T

IT WOULD BE A MIRACLE
TO CATCH A CUTTHROAT TROUT.

ISOLATED FROM OTHER CUTTHROAT

WHEN THE LAST ICE AGE CREATED
THE IMPASSABLE LOWER FALLS,

YELLOWSTONE'S CUTTHROAT
BECAME GENETICALLY DISTINCT

AND THE FOUNDATION
OF A THRIVING ECOSYSTEM.

FOR MILLENNIA, MILLIONS
OF YELLOWSTONE CUTTHROAT

HAVE MIGRATED
UP THE LAKE TRIBUTARIES

TO SPAWN IN LATE SPRING.

AS MEMBERS OF THE SALMON FAMILY,

THEY LIVE AND REPRODUCE
IN SHALLOW WATERS,

WHICH MAKE THEM EASY TARGETS
NOT ONLY FOR HUNGRY BEARS.

Gresswell:
THE YELLOWSTONE CUTTHROAT TROUT

HAS A HUGE ROLE
IN THIS ECOSYSTEM

AS A KEYSTONE SPECIES,

AS A KEYSTONE PART
OF THE FOOD WEB.

THERE ARE NUMEROUS,
IN ONE ESTIMATE 42 ANIMALS,

THAT AT SOME POINT IN THEIR LIFE

MAY FEED ON
YELLOWSTONE CUTTHROAT TROUT.

Narrator: SPAWNING TIME
IS IN LATE MAY AND EARLY JUNE--

PERFECT FOR
THE FAMISHED GRIZZLIES

EMERGING FROM HIBERNATION
TO GET SOME PROTEIN.

♪

♪

BUT SOMETHING SIGNIFICANT MUST
HAVE CHANGED IN THE LAST YEARS.

BEARS AREN'T EATING

ANYWHERE NEAR THE NUMBER
OF FISH THEY USED TO.

WILDLIFE BIOLOGIST TODD KOEL
FROM THE NATIONAL PARK SERVICE

HAS BEEN MONITORING THE NATIVE
CUTTHROAT TROUT FOR YEARS.

HE TAKES ONE OF HIS SONS
WITH HIM

TO VISIT A SPAWNING GROUND
NAMED CLEAR CREEK,

WHERE HE'S INSTALLED
A COUNTING STATION.

THE CHANGES ARE
SIMPLY DEVASTATING.

Todd Koel: A DECADE AGO
WHEN I ARRIVED

TO THESE SPAWNING STREAMS
HERE AROUND YELLOWSTONE LAKE,

WE WOULD STILL SEE THOUSANDS
OF CUTTHROAT TROUT

MIGRATING UP THEM
IN THE SPRING TO SPAWN.

AT THAT TIME, YOU'D SEE
OSPREYS FLYING BY

WITH CUTTHROAT TROUT
IN THEIR TALONS.

IT WAS COMMON, ALL THE TIME.

BUT EACH YEAR WHEN WE WOULD
RETURN AND MONITOR THE FISH,

WE WOULD SEE LESS
AND LESS AND LESS.

AND SO, DESPITE SPENDING
A LOT OF TIME OUT HERE,

I HAVEN'T SEEN AN OSPREY
ON YELLOWSTONE LAKE NOW

IN SEVERAL YEARS.

Narrator: THE NUMBERS
CONFIRM THE AWFUL TRUTH.

JUST 20 YEARS AGO,

THERE WERE 50,000 CUTTHROAT
PASSING THROUGH CLEAR CREEK.

IN 2014, THERE WERE ONLY
ABOUT 100 INDIVIDUALS.

AND ROBERT GRESSWELL
SAW IT COMING.

Gresswell: IN 1994
ONE OF THE RANGERS CAME UP,

AND HE HAD A LAKE TROUT
IN HIS HANDS,

AND HE SAID, "THIS LAKE TROUT
WAS JUST BROUGHT TO ME

BY SOME ANGLERS
IN YELLOWSTONE LAKE,"

AND I FELT LIKE SOMEBODY HAD
JUST PUNCHED ME IN THE STOMACH.

Koel: LAKE TROUT ARE NON-NATIVE
TO YELLOWSTONE LAKE,

AND THEY'RE
A VERY PREDATORY SPECIES.

THEY'RE SORT OF LIKE WOLVES
ON THE LANDSCAPE,

BUT IN A PLACE IN THE WATER

WHERE THEY'RE NOT
SUPPOSED TO BE.

Narrator: THE INVADING
AMERICAN LAKE TROUT IS HUGE,

MUCH BIGGER
THAN THE NATIVE CUTTHROAT,

AND INSATIABLE.

A SINGLE LAKE TROUT CAN EAT
MORE THAN 40 CUTTHROAT A YEAR.

AND NOW THEY'VE BROUGHT
THE YELLOWSTONE CUTTHROAT

TO THE BRINK OF EXTINCTION.

Koel: IN OTHER LAKES WHERE
LAKE TROUT HAVE BEEN INTRODUCED,

THE NATIVE SPECIES
CAN BE EXTIRPATED COMPLETELY--

BECOME EXTINCT--

AND SO WHEN THE LAKE TROUT
WERE FIRST DISCOVERED HERE

TWO DECADES AGO,

THAT CAUSED HUGE ALARM

BECAUSE OF WHAT WE'VE SEEN
HAPPEN AROUND US ALREADY

IN THESE OTHER PLACES.

Narrator: BUT HOW DOES THIS FIT
INTO THE MYSTERY?

WHY WOULDN'T BEARS SIMPLY SWITCH
FROM ONE TROUT TO ANOTHER?

THE ANSWER, AND THE FINAL CLUE
IN OUR MURDER MYSTERY,

WAS WITHIN
THE SCIENTISTS' GRASP.

HAS LED THE PARK MANAGEMENT

DEEP UNDER THE SURFACE
OF YELLOWSTONE LAKE.

THE INVASIVE TROUT LIVE
AND REPRODUCE DEEP IN THE LAKE

AND NEVER MIGRATE
TO SHALLOW WATERS.

SO BALD EAGLES, OSPREYS,
AND BEARS CAN'T GET TO THEM.

BUT IT HAS PROVIDED A VITAL CLUE
IN THE ELK MURDER MYSTERY:

IF GRIZZLIES, EMERGING
FROM HIBERNATION IN THE SPRING,

FIND THAT THEIR EASIEST
AND RICHEST SOURCE

OF FAT AND PROTEIN
HAS DISAPPEARED,

WHAT DO THEY DO?

THEY WON'T MIGRATE
IN SEARCH OF OTHER FISH.

THE BIOLOGISTS' STUDIES
HAVE SHOWN THAT.

INSTEAD THEY'LL
STAND THEIR GROUND, ADAPT,

AND FIND ANOTHER
RICH FOOD SOURCE ON LAND.

[WOLF HOWLING]

AND WHAT IS HAPPENING AROUND
YELLOWSTONE LAKE IN LATE SPRING,

WHEN THE FISH FAIL TO APPEAR?

THE MIGRATORY ELK HERDS
HAVE RETURNED

TO THE LUSH HIGH MEADOWS
TO GIVE BIRTH.

AND THE GRIZZLIES,

FAR MORE ADEPT
AT HUNTING ELK CALVES

THAN WOLVES
OR ANY OTHER PREDATOR,

HAVE HAD NO CHOICE BUT TO
UP THE ANTE ON THE NEWBORNS...

AND THE ELK POPULATION CRASHED.

♪

♪

♪

AND SO IT APPEARS
THAT THE LOWLY LAKE TROUT,

NOT THE GREAT BEARS AND WOLVES,
ARE OUR SERIAL KILLERS.

THE PARK MANAGEMENT

HAS BEEN REMOVING
THE INVASIVE KILLERS EVER SINCE.

LARGE GILL NETS,

ADJUSTED TO THE SIZE
AND BEHAVIOR OF THE LAKE TROUT,

ARE DEPLOYED DEEP IN THE WATER.

THE LARGE MESH SIZES

LET THE SMALLER CUTTHROAT TROUT
PASS THROUGH UNHARMED.

♪

EACH YEAR TENS OF THOUSANDS
OF LAKE TROUT

HAVE BEEN REMOVED
FROM YELLOWSTONE LAKE,

BUT THE CUTTHROAT NUMBERS
STILL COLLAPSED.

IN 2007,
A SCIENCE PANEL CONVENED,

HOPING TO AVERT DISASTER.

Gresswell:
THE PANEL UNANIMOUSLY SUPPORTED
THE CONTINUATION OF THE PROGRAM

AND IN FACT RECOMMENDED

THAT THE PARK SERVICE INCREASE
THE GILL-NETTING EFFORT.

Koel: WE BEGAN GETTING
BIGGER BOATS,

MORE NETS, LARGER CREWS.

IT'S REALLY TURNED
INTO QUITE A MASSIVE EFFORT,

AN AGGRESSIVE EFFORT, ACTUALLY,
TO BATTLE THESE LAKE TROUT.

♪

Narrator: THE SCIENTISTS
NEEDED TO FIND OUT

WHERE THE LAKE TROUT
WERE COMING FROM.

SO, THEY SAMPLED THE EAR BONES

FROM THE OLDEST AND BIGGEST
OF THE LAKE TROUT.

UNDER THE MICROSCOPE,

THE EAR BONES SHOW GROWTH RINGS,
LIKE TREES--

SHOWING HOW OLD
THE INVADERS WERE

AND WHERE THEY CAME FROM.

Gresswell: WHAT THEY FOUND

WAS THAT THE CHEMICAL SIGNATURE
ACTUALLY CHANGED,

AND THE OLDEST PART WAS SIMILAR
TO LEWIS LAKE,

SO THESE FISH WERE ACTUALLY BORN

AND LIVED THEIR EARLY LIFE
IN LEWIS LAKE,

AND THEN APPARENTLY WERE MOVED
AT SOME POINT IN TIME

INTO YELLOWSTONE LAKE.

Narrator: BECAUSE NO RIVERS
CONNECT YELLOWSTONE LAKE

TO LEWIS LAKE,

THE INVASIVE TROUT COULDN'T HAVE
GOTTEN THERE ON THEIR OWN.

THE CHEMICAL SIGNATURE SHOWED
THAT THEY'D BEEN DUMPED THERE

SOMETIME IN THE MID-1980s.

[THUNDER]

NO ONE KNOWS WHO DUMPED THE FISH
IN THE LAKE OR WHY.

IT MAY HAVE BEEN
SPORT FISHERMEN,

LOOKING FOR BIGGER FISH TO FRY.

IRONICALLY, THOUGH,
THE GUILT REACHES FURTHER BACK--

TO WHEN THE U.S. FISH COMMISSION

FIRST BROUGHT LAKE TROUT
INTO LEWIS LAKE

MORE THAN A CENTURY AGO.

Koel: THE FISH COMMISSION SAW IT

AS AN OPPORTUNITY
TO BEGIN STOCKING.

AT THE TIME THEY CALLED IT

PLANTING OF FISHES
IN THESE FISHLESS WATERS.

AND THIS WAY IS HOW LAKE TROUT
WERE INTRODUCED

TO YELLOWSTONE NATIONAL PARK.

Narrator: SO FAR,
MORE THAN ONE MILLION

OF THE INVADING TROUT
HAVE BEEN NETTED AND KILLED.

FOR DECADES IT HAS SEEMED
A LOSING BATTLE--

AND THE CUTTHROAT
WERE DECIMATED.

WITH TIME RUNNING OUT,
AND THE WHOLE ECOSYSTEM AT RISK,

THE BIOLOGISTS NEEDED
A MORE AUDACIOUS PLAN.

SO GRESSWELL AND HIS TEAM TAG
LAKE TROUT WITH GPS TRANSMITTERS

AND FOLLOW THEM
TO THEIR SPAWNING GROUNDS.

Gresswell: AS WE IDENTIFY WHERE
THESE LAKE TROUT ARE SPAWNING

IN YELLOWSTONE LAKE,

THEN WE CAN FOCUS
ON THOSE SPAWNERS

DURING THAT PERIOD OF TIME.

Narrator:
AFTER ONE YEAR OF TRACKING,

THE RESEARCHERS FINALLY HONE IN
ON A MAJOR SPAWNING GROUND

IN THE WATERS
OFF CARRINGTON ISLAND.

AND A SPECIALLY DEVELOPED
DIVING ROBOT IS SENT IN

TO DRIVE THE YOUNG FISH
INTO THE OPEN WATER

USING MILD ELECTRO SHOCKS.

MILLIONS OF NEARLY INVISIBLE
HATCHLINGS, WHEN GROWN,

WILL EAT EVERYTHING IN SIGHT,

AND THERE IS NO NATURAL PREDATOR
HERE THAT EATS THEM.

Man: STOP.

Gresswell: THIS IS ALL
REALLY IMPORTANT RESEARCH,

BECAUSE ALL THE INFORMATION
WE HAVE NOW

COMES FROM THE GREAT LAKES,

AND THERE THERE ARE MANY MORE
EGG AND LARVAL FISH PREDATORS

IN THE SYSTEM.

AND EVERY INDICATION WE HAVE
IS THAT ONE OF THE REASONS

WHY WE UNDERESTIMATED SO GREATLY

THE POTENTIAL FOR THE LAKE TROUT
TO AFFECT THE CUTTHROAT TROUT

IS THAT WE JUST HAD NO IDEA

HOW FAST THAT POPULATION
WOULD EXPAND

BECAUSE SURVIVAL OF YOUNG

SEEMS TO BE MUCH, MUCH HIGHER
IN YELLOWSTONE LAKE

BECAUSE THERE ARE
NO OTHER PREDATORS.

Narrator: NOW THAT THEY'VE FOUND
THE SPAWNING GROUND,

IT'S TIME TO BRING IN
THE HEAVY ARTILLERY:

ELECTRIC PULSES KILL THE FRY,

BEFORE THEY GROW LARGE ENOUGH
TO EAT THEIR WAY THROUGH

TO THEIR NATIVE
CUTTHROAT COUSINS.

♪

AND NOW, FOR THE FIRST TIME,

THERE MAY BE REAL REASON
FOR HOPE ON THE HORIZON.

SLOWLY, THE INVASIVE LAKE TROUT
NUMBERS ARE FALLING.

[OSPREY CHIRPING]

♪

AND THIS YEAR, ELK NUMBERS
ARE UP SIGNIFICANTLY--

STILL NOWHERE NEAR
THE POPULATIONS OF 20 YEARS AGO,

BUT THE HERD IS GROWING.

IT'S TOO EARLY TO SAY
IF THE CONNECTION

LEADS DIRECTLY FROM THE FISH
TO THE BEARS TO THE ELK MURDERS.

BUT ONE THING IS SURE:

NO SINGLE PREDATOR IS
MORE GUILTY IN THIS CURIOUS CASE

THAN HUMANS.

♪

AND PERHAPS,
WITH A LITTLE BIT OF HELP,

THE ANCIENT WISDOM
OF YELLOWSTONE

IS ALREADY TURNING THE TIDE
AGAINST OUR SHORT-SIGHTEDNESS...

AND THE WORLD'S
FIRST NATIONAL PARK

WILL RETURN TO ITS
PRIMAL RHYTHMS ONCE AGAIN.

♪

♪

♪

♪