[Narrator] There is a place...
on this blue planet...
unlike any other...
where ice retreated,
water flowed in...
and life exploded.
The first people here
called it "The Dawnland"...
the place
where the sun rose first.
This is the story
of how we used the treasure
of this place...
founded nations...
and devastated others.
Today, this sea within a sea
is warming faster
than 97% of the global ocean.
So, what happens here
in the Gulf of Maine
could happen everywhere,
for jobs,
for culture,
for every living thing.
But there is
a hidden strength here.
Fishers, scientists
and the first people here
believe answers
are in the sea...
a way forward...
to strike a balance
between people and nature.
It will happen here,
where we face the test
that will define us all...
in this place,
where the sun rises first.
[♪♪♪♪♪]
[Narrator] It's a place
that many people
think they know,
a proverbial vacation land,
from the sandy beaches
of Cape Cod
to the rugged coast
of Nova Scotia.
This stretch
of the Atlantic Ocean
is called the Gulf of Maine.
Drawn to its raw beauty,
most have only looked
at its surface...
but hidden beneath
lies an ecosystem
unlike any other on Earth...
home to more than 3,000 species.
That bounty has sustained
millions of people
for thousands of years,
but now the Gulf of Maine
is threatened.
[Brian Skerry]
I'm really worried
about the Gulf of Maine.
So many of the places
I used to go
just don't have
what they used to have.
[Narrator] This is the story
of the scientists
racing to understand
the threat...
[Doug Rasher]
Conserving ocean resources
is really essential
for conserving
our quality of life,
even on land,
whether you live
close to the ocean or not.
[Narrator] ...the fishers
who feel its impact...
We adapt to what can we catch,
do it sustainably,
and make a dollar at it.
I mean, at the end of the day,
we're trying to feed
our families, too.
[Narrator] ...and the creatures,
some thriving,
some struggling,
like us,
all trying to adapt
to a warming planet.
It's also the story
of a rare expedition
to a remote and dangerous place,
Cashes Ledge,
a seamount
that could hold secrets
to the survival of the Gulf.
[♪♪♪♪♪]
[Robbie Lamb] Cashes Ledge
is a magical place.
When you go down there,
there's no land around,
so you have
no frame of reference.
When you start to go down,
about 10, 15 feet,
you start to see the tips
of the kelp
waving back and forth
in the surge,
like it's beckoning you
to come down and explore.
It's just the most magical
thing in the world.
But Cashes Ledge,
it's not someplace
that everybody goes to.
It's 80 miles offshore.
It takes a lot
of infrastructure,
a lot of logistical planning.
It's hard to get there,
and it's hard to get down.
[Narrator] Because
it's 80 miles offshore,
it remains relatively unspoiled.
It also boasts
the largest kelp forest
on the East Coast,
and features
every subtidal ocean habitat
in the Gulf.
It's the perfect laboratory
to study the future
of this place.
[♪♪♪♪♪]
It's been seven years
since a scientific expedition
has been to Cashes,
and that same team
is heading out today.
- Hey, can I hand this to you?
- Yup.
It's heavy.
[Narrator]
Leading them is Jon Witman.
[Jon Witman] The first time
I dove on Cashes Ledge
was in 1977.
You know, I was
in this huge kelp forest,
it was absolutely
stunningly beautiful,
and that was it, I was hooked.
Hundreds of cod going by
in an hour, you know,
it's just spectacular.
[Narrator]
Joining Jon on this trip
is fish ecologist, Robbie Lamb.
[Lamb] We're mostly doing
an ecological assessment.
You know, how does
the ecosystem look
compared to when we were there
seven years ago?
Because Jon Witman
has been working here
since the '70s,
we can actually look
all the way back
to that point in time,
and see how kelp density,
and fish abundance,
and fish diversity has changed
in that period of time.
[Narrator] Kelp is a barometer
of ocean health,
and the Gulf has already lost
huge swaths of it,
especially close to shore.
Doug Rasher
has been witnessing kelp loss
for almost a decade...
Very heavy.
[Doug Rasher] I study
the ecology of kelp forests,
and how they're changing
as a result of climate change
and fishing pressure.
We've seen a lot
of rapid change along the coast
just in the last five years,
and so I would guess
that we're going to see
some similar sorts of changes
out on the ledge as well,
but we'll see.
[Narrator] Helping
document these changes
is National Geographic
photographer Brian Skerry.
Always helpful to have
a couple more days.
[Narrator] Since Brian
and the rest of the team
were last at Cashes in 2016,
the Gulf has endured
several extreme heat waves...
[Skerry]
Anywhere out of the way,
and I'll
straighten it out later.
[Skerry] I started diving
on Cashes Ledge
a little over a decade ago,
and it was, to me,
like going back in time.
I mean, it wasn't like
even anything I'd seen
in the last four decades.
I know what's happening
along the coast.
I just can't imagine
that Cashes isn't
going to be damaged as well.
[Narrator]
It will take the crew all night
to go the 80 miles
out to Cashes,
which sits in the middle
of the Gulf of Maine.
The Gulf is really
a sea within a sea,
semi enclosed
by large underwater banks
that rise from the sea floor
more than a thousand feet.
Just outside
is where
two major currents meet,
the cold Labrador
from the Arctic,
and the warm Gulf Stream
from the Gulf of Mexico.
Until recently,
the Labrador kept
much of the warm water out,
fertilizing the Gulf
with a steady flow
of cold water,
loaded with oxygen
and nutrients.
As it circulates
across the Gulf,
it hits Cashes Ledge,
an underwater mountain range.
All that oxygen and nutrients
are then forced
up to the surface,
where the sun triggers
photosynthesis,
and life explodes.
As the planet warms
and glaciers melt,
fresh water is making
the Labrador less salty,
weakening it,
and allowing the warm
Gulf Stream to push in...
but what kind of impact
is that warming having
on places like Cashes Ledge?
Once on site,
and with the weather
cooperating,
the team gets in
and takes their first look.
[Skerry] I'm really excited
about this Cashes Ledge trip,
but I'm nervous about
what we might find there.
This is, in my mind,
our last hope...
but I don't know what
I'm going to find out there,
so fingers crossed.
[Narrator] The crew hopes
to find an intact ecosystem,
with a bounty that was created
by the Gulf's own
unique formation,
about 14,000 years ago.
Over millions of years,
massive ice sheets repeatedly
expanded and contracted
across the northern hemisphere,
as Earth alternately cooled
and warmed.
At some point,
so much of the planet's water
was frozen
that the ice covered
the entire Gulf in sheets.
In some places,
those sheets
were more than a mile thick.
As it contracted,
the ice served
as a massive grinder,
chewing the bedrock
into a mix of gravel and sand,
then rivers of glacial melt
pushed it all
hundreds of miles downstream,
and out to sea,
shaping the Gulf's unique floor.
The conditions
helped marine life thrive.
Lobsters
took to the rocky crevices.
Kelp and underwater plant life
took hold,
providing food and shelter
for the Gulf's
smaller creatures.
Thousands of species
drifted in and flourished,
from present-day Cape Cod
to the northernmost corner
of the Gulf of Maine,
the Bay of Fundy.
This is one of the coldest parts
of the Gulf.
That, combined
with unparalleled tides,
powers an ecosystem
that benefits
many of the animals that live
and visit here.
Because of its unique
funnel-like shape,
the world's
most extreme tides flow here.
In parts of the Bay of Fundy,
between tides,
the difference in water levels
can reach over 50 feet.
Every day, there are
two high tides and low tides.
When high tides flood in,
they carry about
of cold, nutrient-rich water.
As the bay empties,
miles of seafloor are exposed,
revealing a feast.
The creatures here
have come to rely on it...
like these periwinkles.
These sea snails
are after one thing...
algae.
Carried in on the tide
or grown here
when the sun hits the water,
periwinkle numbers suggest
there is plenty to feed on
as they graze the mudflats.
Marine snails have a structure
in their mouths,
kind of like our tongue,
but theirs is covered
by rows of teeth,
which they use to rake in
and eat algae.
There's competition out here
for that algae,
and it comes from below.
Little mud shrimp,
the size of a grain of rice,
spend much of the year
in the mud...
but the summertime
is mating season,
so they leave
the safety of the mud,
and seek out partners
on the surface.
Their natural drive to reproduce
can carry a high cost.
Higher up the food chain,
hundreds of thousands
of semipalmated sandpipers
descend on the Bay of Fundy.
They're coming from the Arctic,
some having flown
more than a thousand miles,
and they're hungry.
Weighing less
than a chicken egg,
they're here to bulk up
for the next,
longer leg of their journey,
a 2,000-mile flight
down to South America.
To do that, they'll have to
double their weight,
to around two ounces.
At this critical time
of their lives,
only two things matter,
feeding and resting.
Feed during low tide,
rest during high tide.
When waters recede,
sandpipers follow the tideline,
and work the flats
for the next six hours.
It's estimated
that one sandpiper
can dig out 20,000 mud shrimp
in a single day.
They want to stay as close
to the food as possible,
so when the water comes back in,
they just bunch up on the beach,
even if it means sharing it
with 100,000 others.
Crowding at the beach
until next mealtime
doesn't seem to bother them,
but maybe it should,
because in the Gulf of Maine,
when you come for the food,
at some point,
you may become it.
High tide serves up
an all-you-can-eat buffet.
The peregrine falcon
is the fastest creature
in the animal kingdom,
clocking in
at over 200 miles per hour
when diving.
These sandpipers
may not be as fast,
but they are agile,
and there is safety in numbers.
Like schools of fish,
a flock of thousands
can change direction
in an instant,
evading the straight-line flyer.
The sandpipers
are no longer individuals,
but a hypnotizing mass
that contorts
its shape and shade
to confuse the hunter.
This group-think
does come at a cost.
The energy spent here
could be used
for their 2,000-mile journey...
but it's energy well-spent,
because for the falcon,
the fine print
on this tide's buffet
reads "all-you-can-catch."
Tired after a long feed,
and fending off a falcon attack,
the sandpipers bunch up
once again
to rest and wait
for the next ebb tide.
The appeal of 100,000
bite-sized edibles
isn't lost on another bird.
Consider the seagull,
a shoreline regular,
not really noticed,
but always lurking
in the background,
watching and waiting
for a beach snack.
Without the talons
or blinding speed of a falcon,
the seagull just blends,
a predator
hiding in plain sight.
Maybe the sandpipers
don't take gulls seriously,
maybe
they're in a shrimp coma...
but they allow a fatal distance.
The spellbinding synchronization
of thousands of birds
has no effect on the seagull.
Persistence pays,
and the slowest sandpiper
won't be leaving
the Gulf of Maine.
At just one to two ounces each,
it'll take a few sandpipers
to satisfy the seagull.
As the tides retreat once again,
the birds return to the flats
to get their fill
for their journey south.
Most of these seasonal tourists
will get what they came for
this year...
but 300 miles south,
will the crew at Cashes Ledge
find an ecosystem as intact?
Fog has moved in,
and all diving
has come to a standstill.
This is why diving out here
at Cashes
is particularly dangerous.
Here,
it's kind of like
being on the moon,
or on Mars.
It kind of all looks the same.
It's kelp everywhere you look.
That up and down mooring line
is your lifeline
because if something happens,
you've got to get back
to that line,
and if you can't find it,
you have to punch out,
and just come up to the surface.
You're out in the thick fog.
This boat may not
be able to find you.
So you have to be prepared
for what Cashes
can throw at you,
and knowing that we may only
have another day or two max
means that we're trying
to ramp it up
and get it all done.
[Narrator] The fog delay
means they've lost four dives
worth of potential data,
but finally, it clears enough
to get back in the water.
[♪♪♪♪♪]
Kelp forests are critical
for keeping
everything down here alive.
They're connected
to the sea floor
by an ingenious feature
called a "holdfast".
Once these tendrils attach,
they grow upward
towards the sun,
harnessing its energy
in the same way plants
and trees do.
Just like forests on land,
kelp forests provide food,
produce oxygen,
and filter water,
everything their inhabitants
need to survive.
They also provide shelter
from predators
and rough seas.
Take this critter.
Not only do these folds of kelp
buffer strong currents
down here,
a six-inch blade of kelp
can shield a three-inch
Jonah crab
from a hungry lobster,
and this juvenile codfish
gets a covered highway
to adulthood.
Without kelp,
we lose pretty much
everything down here...
and that's
what we are starting to see
closer to shore.
When Doug Rasher
began studying coastal waters
almost ten years ago,
he could already see
kelp forests struggling...
very patchy,
covered with parasites,
or shot through with holes.
of intense human development,
fishing, and pollution
had taken its toll.
Over the past five years,
rapid warming has further
reduced what remained.
Warmer waters opened the door
to an invasive algae species
which outcompetes
the weakened kelp.
As the coastal kelp disappears,
so goes the habitat
that supports so much life.
We have healthy kelp forests
in the north,
collapsed kelp forests
in the south,
so where Cashes Ledge lies
relative to the story
along the coast
is something
I'm really excited to see.
[Narrator]
If the kelp forest is strong,
then this system has a chance
against the changes
the Gulf faces.
[♪♪♪♪♪]
In 1987,
Jon Witman
created a data baseline here
by laying down one-metre-square
grids on the seafloor,
and collecting the kelp
and everything else in them.
Today, the team
is doing the same thing,
at the same coordinates,
establishing
a new reference point.
This expedition will add
more information
to Cashes' health chart,
helping scientists understand
what changes have taken place.
[exhaling]
Well, it's as advertised.
It's amazing down there.
The things that stand out here
relative to the coast
is just the sheer amount
of kelp in the forest,
how dense it is,
how tall the plants are,
and the sheer amount
of fish here...
and the size of those fish,
it's just unbelievable.
[Jon Witman] It's another
metre-square scraping of kelp
for biomass and density.
It gives us a lot
of information.
[Narrator] Each bag
is filled with answers
to one big question...
how is Cashes Ledge doing?
By calculating length
and weight of kelp blades,
as well as density
in each square metre,
they get a snapshot
of Cashes' health right now.
We're looking at a kelp forest
in one square yard.
It's actually one metre
about this big.
These are our trees,
I mean, look how many
are in a small patch
of underwater habitat.
This is a long single blade.
That's Saccharina longicruris,
and then we've got
the multi-bladed one
that looks like fingers.
This is called "finger kelp".
This is Saccharina digitata.
Longicruris,
because it's so much longer.
This is kind of the redwood
of the forest.
[Rasher] It historically,
was really
important ecologically.
It was a big part
of our coastal kelp forest
in the past.
Not so much today.
That's why it's so heartening
to see that there's a lot of it
here at Cashes Ledge.
We need data.
We need hard numbers
to quantify the state
of the kelp forest,
and the abundance
of animals that live there,
and that's what we're doing,
whether it's algae that lives
on the seafloor like kelp,
or fish that use
the kelp forest as habitat.
They've shown in Norway
that juvenile cod actually
grow up in kelp forests,
so they're very important
nursery habitats.
Its mass is 161.
It's all fun.
You know,
diving is great and all,
but actually
seeing the numbers come in,
and understanding what kind
of change we're seeing,
or lack thereof,
is equally as exciting,
because we're all driven
by these questions.
[Narrator] At first glance,
the news is encouraging...
and as if on cue,
one of the Gulf's
iconic predators shows up...
a humpback whale.
[Witman] There it is.
[Rasher]
Oh, it's getting closer.
- Humpback. Nice.
- Nice.
It's that kind of a day.
For sure.
There it is!
Do you see it, Steve?
[Narrator] The relative health
they're seeing at Cashes
is in large part
due to something
that feeds and drives
the entire Gulf,
its unique currents.
When water from
the Labrador current enters,
the Gulf's shape forces it
into the Bay of Fundy first
and deflects
everything else west.
As the water circulates
in a counter-clockwise pattern,
and their nutrients
pour into this bathtub,
adding the final element
to the Gulf's unique blend...
one that created
a dynamic ecosystem
that supported
more than 3,000 species.
It allowed those species
to thrive in huge numbers,
leading the global fisheries
that have fed millions of people
for hundreds of years,
but today,
warming waters are threatening
many of these species,
and the jobs
that depend on them.
Like most creatures here,
sea scallops make their living
off the Gulf's currents
and tides.
The tide is essentially
a conveyor belt
of plankton and algae,
so eating can be as simple
as opening wide.
All scallops propel themselves
by ejecting water out of valves
next to their hinge,
and they do it by pumping
their one single muscle.
It's that muscle that ends up
on the dinner table...
and that's what David Tarr
is after.
He spends every winter
diving for scallops.
In this part of Maine,
he can only harvest by hand
for a maximum
of 70 days per year.
[David Tarr] No visibility.
[Narrator] A massive storm
two days ago
is making things difficult.
I can see about
two or three feet down there.
We had our third pretty major
southeast storm here
in the last month or so.
The peak winds were probably,
oh, 70, 80 miles an hour,
a lot of rain with it
right at high tide.
So the problem with that
is not only are we
dealing with the big seas
churning up the bottom,
we're dealing with the runoff
running off the land,
and then...
and it takes days
for it to settle down.
So that's just kind of
screwed up today.
So I gotta rethink things here
a little bit.
That's about 40 feet.
I'm gonna have you just
set me up on a little shoal
right on that rockpile.
[Marshall Lebel] Yep.
So we do it all again.
Take two.
[Lebel] That tank's no good
to put back on?
[Tarr] Yeah,
I got about half a tank,
so no more than two bags.
[Lebel] Yep.
I probably was about that tall.
He could put me
up on the bulkhead.
I think... How old was I?
Five, six?
[Tarr] His dad
worked with me for years.
So Marshall has been around
this boat and me
for most of his life.
[chuckling]
[Lebel]
It's work, but I love it.
He keeps an eye on me.
I mean, I could...
You know, I could die out here,
so I want someone I can trust.
Yeah, I'm all set.
All right.
We'll put him on a spot.
About right here?
[Tarr] I want to just be in
over that bank,
right over this way.
Right on a bed of scallops,
okay?
[Lebel] I'll try!
[chuckling]
- 50 feet?
- Yep.
Good luck!
[Narrator]
David's been doing this
for the past 40 years,
but there's always risk
when diving alone
in 40-degree water.
[Lebel] I usually
just keep an eye on him,
watch his bubbles,
see what he's doing.
Like, usually,
I'll watch his bubbles.
If he's moving like that,
he's looking,
but if he's usually
sitting in one spot,
he's got something.
Pretty easy,
just sit here and watch.
[chuckling]
This year's just been kinda,
between the weather
and the tide and everything,
it's been kinda hard
to get a good day
where you actually
can find scallops.
He's moved probably
almost 200 yards now.
Usually, when he's moving
that much, he's looking still.
Maybe he's finding a patch
here and there,
but I like it when his bubbles
aren't moving.
That usually is a good sign,
means he landed right on 'em.
[Narrator]
But he's not on 'em,
and he needs to move
to a different spot.
[Lebel]
Ah, he's coming up.
Especially that long,
that was almost 20 minutes
he was down there.
Ah, that's not good.
[Narrator]
They're two dives in,
without much to show for it.
[Tarr] The silt that I make
combined with the silt
that is already there.
Part of what happens to me
down here
is I'm really limited.
I can only work into the tide
because I need what silt
I'm stirring up behind me,
and it limits where I can go,
even if I see something,
and I think I want to go
with the tide, say,
I just, I can't.
I'm not giving up yet.
I've moved a little bit.
We're going to try
another spot here.
If I don't find something
on this tank,
I may not finish it.
If I don't find something
pretty soon,
it's just going to be
late in the day when I get done.
It's my, uh,
and I got a little
celebration planned.
I'm not gonna be out here
that much longer.
[chuckling]
I forgot about that.
[Narrator] Fishing regulations
this time of year
allow David to dive
three days a week.
With storms on either side,
today's his only chance.
[Lebel] Try right there!
[Narrator]
This is grinding work.
It's five to eight dives
down to 30-60 feet
over a few short hours.
It takes a toll on the body.
David spends the other
half of his week in the boat,
dragging for scallops
using a steel net,
which comes
with its own set of dangers.
He's one of thousands of people
on these shores
who pull their living
from the Gulf.
Whether it's shellfish,
groundfish, or aquaculture,
the strength of this ecosystem
has a direct impact
on whether these folks
can make a living,
and David has witnessed
the system changing.
[Tarr] We've got
these Sea Squirts here now
that are causing a lot of grief
for some of these
bottom dwellers like scallops.
I don't know
where they come from,
but we've had 'em,
at least on the mid-coast,
quite a lot
in the last five years.
[Narrator] Sea Squirts
are a kind of invertebrate,
invasive in the Gulf.
Like scallops,
they're filter feeders,
but their babies become adults
and reproduce themselves
in just a matter of months,
easily outcompeting scallops
for food, oxygen,
and real estate.
[Tarr] They can be
six or eight inches deep
on the bottom,
and they pretty much smother out
whatever else is there.
They're filter feeders
just like those scallops are,
so they're eating the same food
the scallop wants.
Just makes it hard
for them to get by.
[Narrator] For now,
Sea Squirts
have not had a huge impact
on scallop numbers
where David dives,
but that could change,
because they thrive
in warmer waters.
[Tarr] Somehow, those things
got introduced to our waters,
probably from the ballast
from a ship or something,
and so we're stuck with them.
It's like Zebra mussels
in the Great Lakes, same idea.
They can outcompete
the natural population
sometimes,
so we're constantly adapting
to what's going on
in this environment,
just trying to fit in
with all of that,
not wipe something out,
but being able to make a living
at it at the same time.
[Narrator]
David's found a decent spot,
and even filled a bag.
He hasn't moved a lot.
Okay, he's gonna need a bag.
All right,
we'll clip a bag on there.
Yeah, just watch.
See where his bubbles are?
There it is.
[laughing]
[Narrator]
Fishing's a lot more fun
when you're catching.
[Lebel] That's a full bag.
It'd make me feel really good
if he gets another bag.
[Narrator]
Marshall can finally get
to the other part of his job.
I usually just pick my head up,
look, see what he's doing
once in a while,
and then I just shell a bunch.
[Narrator]
Cleanly shelling a scallop
is a knife skill
you learn on the job.
[Lebel] I've shelled a lot.
Add it out, I bet I'm close
to 10-, 12,000 pounds
somewhere in that range,
I've shelled my whole life.
Take your knife,
pinch just like that.
I got another bag, sweet.
[Narrator]
These are called "diver"
or "dayboat scallops".
Shelling them immediately
keeps them from freezing
on cold winter days,
and when you're on a good spot,
it's all about speed
because the scallops
keep coming.
All right,
I need to get that bag.
[♪♪♪♪♪]
[Lebel]
Is that a wrap? [laughing]
[Tarr] Yeah.
[Lebel] Figured.
That's an orange scallop.
To me, they're
the sweeter ones to eat.
If I'm gonna eat one raw,
that's probably
the best one to have
is the orange ones.
That's good.
That's really good.
If I'm going to have one
from my dinner,
I prefer one about that size
and not the big one.
But the best way to eat 'em
is just like that.
That's perfect.
[Narrator] After six dives,
they've harvested and shelled
about 700 scallops,
less than half
of their total allowable catch.
[Lebel]
Washing the scallops out,
so they can be ready
to be sold on the market.
[Tarr] How'd we make out?
[Lebel chuckling]
Okay, I guess.
[Tarr] Around five gallons.
Quite a difference
in size there.
This stuff's worth
a little more money.
That stuff is still
plenty good to eat, delicious.
I'd say $800.
You take the expenses
out of that.
Marshall gets a share of it,
and I'll still have
some money in my pocket.
A little dinner,
a little bit of scallops
for my birthday dinner tonight.
So I know where they came from.
Pretty sure they're fresh.
It is an honest day's work,
and a hard day's work,
but it's enjoyable.
[Narrator] For David,
it's a decent haul
after a slow start,
but just 40 years ago,
annual scallop landings in Maine
could be up to three times
what they are today.
Back then,
unregulated fishing brought in
so much from the Gulf
that it seemed to feed
the entire world,
and one of the main draws
was Atlantic cod.
[Lamb] There are stories
that you could lower a basket
weighted down with some rocks,
and pull it up
wriggling with cod.
Now we've got to work
quite a bit harder
to catch them.
[chuckling]
[Narrator]
That's because Atlantic cod
has been all but fished out
over the centuries.
Long gone are the cod days,
where fish were routinely
coming up five feet long,
or weighing more than
Today, even places like Cashes
sustain only
a remnant population
of the once-mighty cod.
Though far fewer in number,
cod is still
a top predator here,
so knowing what it's eating
tells us what the food chain
below it looks like.
[Lamb] Part of the science
that we're doing
is looking at
their gut contents,
trying to figure out
what they're eating out here.
[Narrator] That will help them
better understand
the health of the entire system.
But they're not catching
any cod,
only pollock.
[Lamb] Another nice,
beautiful Atlantic pollock.
That's the biggest one
we've caught so far.
[Narrator] Though cod numbers
have crashed,
pollock still seem abundant.
Sampling more predator species
provides
a more complete picture.
[Lamb] I feel like we could be
pulling these up all day
and never get a cod.
[Rasher] Yeah, well,
I think we should stop,
[but we have an N] of 3 now
of large pollock,
which I think is good.
[Narrator] Since the cod
aren't coming to them,
they have to go to the cod.
[♪♪♪♪♪]
[Lamb] We have hand spears,
which we use underwater.
That way, you can see the fish
that you're trying to catch.
The problem is the cod
are a bit flighty.
They don't let us
get that close.
So it's a real challenge,
really hunting underwater.
[Narrator]
With cod finally in the bag,
their scientific investigation
continues on deck.
[Lamb] So this is
what we came out here to find.
This is cod,
Gadus Morhua.
This is the fish
that was the mainstay
of New England's economy
for centuries,
and in the late '80s and '90s,
it was completely overfished
to the point of collapse
of the fishery.
It's got
a pretty healthy population
out here at Cashes Ledge,
and we think that it has
the potential
to even repopulate other areas
in the Gulf of Maine
if we allow them that space
to grow and reproduce.
[Narrator] It's hard to believe
that just 60 years ago,
fisherman were pulling in cod
weighing 50 to 60 pounds
on the regular.
Just a little more
than the one-to two-pounders
Robbie and Doug caught.
This is what 500 years
of relentless fishing
can lead to.
[Lamb] So fork length is 30.5.
Total length is 31.
Weight is 760 grams.
[Narrator] After weighing
and measuring their samples,
the team takes
an even closer look.
[Rasher] And now we're going
to be doing stomach contents.
Did you get a bag ready?
[Lamb] So this is the stomach
of the cod.
We're going to find out
what's inside of it.
Look at that.
Crab.
- No way.
- Yeah.
Oh, my gosh.
So that's either a Jonah
or a rock crab
- about halfway digested.
- Wow.
We don't really see
many crabs underwater,
and the ones that we do see
are hiding
in dead mussel shells.
So it's clear
that they're under extremely
high predation pressure
because of these abundant cod
out here at Cashes Ledge.
That's one of the really
obvious differences
between the coast and out here.
On the coast,
we see cancer crabs,
and lobsters, and urchins
roaming around freely
on the bottom
through the kelp forest,
and they're quite large,
and they're quite abundant,
with the exception of urchins,
and that to me suggests
that there isn't
a whole lot of fear of predation
in the coastal system,
whereas here we see,
you know, quite the opposite.
Very few individuals
walking around,
and the crabs that we do find
are quite small,
so very different world
out here.
[Narrator] Healthy ecosystems
have all of their pieces.
At Cashes,
it's all about predators.
Cod might be more familiar to us
as fish and chips,
but to baby crab, lobster,
and smaller fish,
they are a ferocious predator.
Without them,
the system unravels.
Imagine the teeming savannah
of Africa without lions,
or Yellowstone without wolves.
When top predators
like cod disappear,
prey species
lower on the food chain,
like lobsters and crab,
explode in number,
changing the seascape
and potentially allowing
other species to move in.
[Rasher] So this piece
of white muscle tissue
from the Atlantic cod
will tell us a story
about what the cod
has been feeding on
over about the last six months,
and so this allows us
to have a deeper view
into understanding the food web,
and the predator-prey
interactions
that are happening out here
over longer timescales
than we can observe.
[Narrator] Even
the limited presence of cod
may be helping maintain balance
in the system.
Amazingly,
there's new science
that lets us look well beyond
the tissue sample.
You just take off your gloves,
take out the tube,
and then you just fill that...
[Narrator] Shane Farrell's
a marine chemical ecologist.
He studies DNA
found in the water,
and can find traces
of every animal
that moves through here.
[Shane Farrell]
It may not look like much,
but in one small litre of water,
we can tell what animals
and other organisms are there,
from bacteria
all the way
to whales and sharks.
The power of environmental DNA.
[Narrator] One of the things
Shane can see
without a microscope
disturbs him.
He suspects
this is an invasive species
of red turf algae.
It's already wreaking havoc
on coastal kelp,
and Shane has brought
an invention
to help him investigate
how it causes trouble.
He calls it "BOMS",
short for "benthic
organic matter suckers."
These suckers allow him
to sample the water
right next to the red algae.
Shane thinks it might be
exuding something
that undermines kelp.
There's been this proliferation
of this red algae,
and it's taken over the bottom,
and it's created
these very lush, thick carpets.
Very, very detrimental.
We can only visually identify it
really under a microscope,
and what I'm looking for
is a proliferation of cells
around the main axis,
but then at the tips,
it becomes uniseriate,
where there's only one cell,
so it's very distinct.
This is, in fact,
Dasysiphonia japonica.
Wow.
Even out here.
- So...
- Yeah.
- Nowhere is safe.
- Nowhere is safe.
[Narrator] The reason
this is so worrying
is a survival tactic
that this species brings.
[Farrell]
I'm studying how these algae
might have nasty
internal chemicals
that they exude into the water
or onto their surfaces.
[Narrator] The red algae,
in effect,
are waging chemical warfare
on the largest kelp forest
on the East Coast
of the United States.
When it comes to this newcomer,
the kelp is just not equipped
for this battle,
and neither is
the rest of the system.
[Farrell] We don't know much
about its chemical makeup.
Other species that have entered
the Gulf of Maine
from the Pacific
have shown that they are
very chemically potent,
and have compounds
that make it not great to eat.
[Narrator] It's not
part of the food chain,
so nothing naturally removes it.
If Shane's hunch is right,
it could be a one-two punch,
but it'll be months
before he gets back his data.
Meanwhile,
in spite of the presence
of an invasive
like red turf algae,
Cashes may still offer Brian
the opportunity to showcase
some of the Gulf's bright spots.
We're getting ready
to go diving.
[Skerry] I've been working
on this Gulf of Maine project
for about four years now,
and during that time,
it's been very frustrating
photographically,
because so many of the subjects
that I sort of
naturally expected to be there
just were not there,
even simple things
like invertebrates,
and I was desperately hoping
to find sea stars,
you know, these beautiful, big,
somewhat colorful sea stars,
but over these last four years,
I just wasn't seeing it.
[Narrator]
After four long years,
Brian's luck has finally turned.
[Skerry] You know, if I were
to try to explain to somebody
what the Gulf of Maine is,
what it what it looks like,
what it feels like,
it would be this,
it would be a single frame,
a single photo
that shows an expl*si*n of life.
All of these animals, you know,
fish and invertebrates,
and kelp in the background,
all these things in one place.
It's a Garden of Eden,
and that, hopefully,
will translate visually
so that people understand.
[Narrator] To the naked eye,
this scene is dreamy,
but not for the mussels
attached to the rock.
What you can't see
is the sea star
prying open the mussel's shell
with its suctioned feet,
and that's not the worst part.
The sea star then sends
its stomach
full of digestive enzymes
out its own mouth
to dissolve and eat its meal.
When you speed things up,
it's a feeding frenzy.
Most of the seats at this diner
are taken,
and the sea stars on the move
hunt for another spot.
[Skerry] I've been literally
looking for a scene like this
for three or four years
since I've been working
on this project,
and haven't found
anything close to this.
We did see
this invasive red algae,
which has done so much damage
along the coastal kelp forest,
and that gives me great concern
for Cashes,
but, you know,
by the same token,
I see that all the pieces
are otherwise in place.
Cashes still remains
largely healthy.
There are fish,
there are invertebrates,
there is healthy kelp.
I suppose anything can happen,
but I'm certainly in the...
in the corner of resilience.
[Narrator] That's supported
by Shane's
environmental DNA research.
It shows that Cashes
does still have all its pieces,
despite warming waters
and harmful invasive species.
The water collected
revealed the presence
of 20 different fish species,
from Atlantic cod to wolffish,
to pollock to cunner.
Passing through
are large schools of fish,
such as Atlantic herring,
and mammals
like humpback whales.
[♪♪♪♪♪]
Compared to an expedition
in 1987,
the kelp has retained
its density, weight and length.
Cashes Ledge is still intact,
its kelp forest resilient
and relatively healthy.
For Jon Witman,
who first started
researching here
some 40 years ago,
the expedition has instilled
a lot of hope.
[Witman]
This is what I dreamed of.
The kelp forest
looks pretty good.
We don't see these sorts
of densities along the coast
that indicate higher resilience.
It may actually serve
as a climate refuge
for intense warming effects
in the coast.
If there is a place
that should be protected
in the Gulf of Maine,
this is it.
[Narrator] Cashes' variety,
its biodiversity,
is the promising marker
of its health,
and the hope,
not just here,
but for the global oceans.
[Skerry] If you look at Earth
from space,
we very much live
on a water world,
and every other breath
that we take
comes from the sea.
This oasis
that is still largely intact,
it will pay dividends,
it will pay you interest.
Those fish and those animals
will thrive,
and that will spill over
so that the entire Gulf
will benefit from it,
and as a result we will, too.
♪ ♪
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51x09 & 51x10 & 51x11 - Sea Change: Bounty in the Gulf of Maine Parts 1-3
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Nova often includes interviews with scientists doing research in the subject areas covered and occasionally includes footage of a particular discovery.
Nova often includes interviews with scientists doing research in the subject areas covered and occasionally includes footage of a particular discovery.