Transcriber: Lucy Arch Reviewer: David DeRuwe
We drove blue whales to the edge of extinction in the 20th century.
Imagine if we lost the largest animal that has ever lived.
I’m an ecologist, and for the last 25 years I’ve looked at our impacts
on different vulnerable ecosystems and different species,
and I’ve always felt tied to the ocean.
I grew up in this big old wooden house by the sea.
My bedroom looked across the bay,
and on the other side was an abandoned whaling station,
and I want to take you back to the early days of whaling.
So back to Melville’s time of Moby Dick
when the whalers worked in those open rowboats.
Back then, they left blue whales alone.
They’re really fast, but also they’re large and powerful,
but unlike other whale species that when they died, they’d float,
blue whales sink,
so they’d drag them down, so they left them alone.
They went largely unmolested in those early days.
But as soon as the whalers could move from sail ships to steamboats,
then they had the power, the grunt to be able to chase them
and work safely in remote locations,
like down in the Southern Ocean
where they chased the Antarctic blue whales,
the largest whale there is.
And they’d be there in summertime when they gorge on huge, huge,
huge swarms of fat-rich krill.
So blue whales had then lost the advantage,
and they were hunted, they were prized like no other
because one blue whale can yield 18,000 kilograms of whale oil.
In our money, that’s worth 60,000 dollars.
In the one summer of 1931, 30,000 blue whales were taken.
That’s a value of 1.8 billion dollars.
Over 30 years,
they’d taken 300 thousand blue whales from the Southern Ocean,
almost all of them.
They left 0.15% of the blue whales of the world.
It’s been 55 years since blue whales -
blue whales and other whales have been commercially hunted,
but unlike other species, the blue whales haven’t come back.
They haven’t bounced back as much.
These guys are really, really long-lived.
Some of the whales you see today are possibly the same whales
that escaped the early whalers.
So that’s why people were really, really worried
that commercial hunting stopped too late for the blue whale,
that their numbers were driven too low in the southern hemisphere.
As you can imagine, that’s why my colleagues and I
were super excited that we recently found two new groups of blue whales
that we didn’t realize were there.
You might be thinking, “How the hell did you miss a blue whale,
given they are the largest animal that has ever lived?”
But they’re actually, in some areas, really, really hard to study.
They’re reclusive, and they roam enormous areas,
and often in remote locations,
so how do we find them?
Well, it was their singing that gave them away.
All around the world, there are these listening stations.
They’re set up to stop us covertly developing nuclear bombs,
and it’s run by the Comprehensive Nuclear Test Ban Treaty.
So they’ve got hundreds of these listening stations all around the world
on land, but also many, many throughout the oceans.
They record 24 hours a day, and in some areas, for the last 20 years -
massive amounts of data!
They’re looking for bomb noises.
What do bomb sounds and whales have in common?
Well, blue whales produce very low frequency, very loud songs.
When you think of a whale song, you’re probably thinking of a humpback,
but humpbacks are like the jazz singers of the whale world.
Each year, they tinker and change their songs, and in some years, radically,
almost like us moving from classical to punk,
but blue whales, they don’t do that.
They’re incredibly traditional,
a nice way of saying they’re actually really boring.
But for us, that’s fabulous
because we can build algorithms to go look for those simple songs,
the massive amounts of data from these nuclear listening stations.
But it gets even better than that
because different blue whales from different populations,
they produce different songs, like a unique fingerprint.
We’ve looked at hundreds of thousands of hours of this underwater sea noise,
looking at all of these different blue whale populations,
and right in the middle of the Indian Ocean,
we found a song that dominates the area.
A colleague, she recorded that same song off Sri Lanka
being produced by a blue whale, but it’s not a Sri Lankan blue whale song
or any other song recognized to be a blue whale.
They thought, “Oh, it’s a young whale he’s just practicing;
it’s a bit of an aberration.”
But that song moves from the middle of the Indian Ocean,
it migrates to Sri Lanka across to Western Australia,
and back again into the Indian Ocean each year.
And for the last 20 years,
that song has dominated the middle of the Indian Ocean.
It’s a whole new population.
So maybe there are others there as well.
So, for whales, whaling is not an issue now.
They face new threats.
Did you know the ocean is like an enormous sponge?
It’s absorbing our extra carbon dioxide and heat from the atmosphere,
it’s buffering our fossil fuel use,
but that’s at a cost for the poor ocean because as it heats and it warms,
it’s causing massive problems.
The phytoplankton, the base of the food chain, is having issues.
That’s impacted, had a knock-on effect on the grazers,
things like krill that feed on the phytoplankton.
Krill is the food of blue whales, and many other marine species.
Blue whales are incredibly expensive feeders.
I want you to imagine this massive krill swarm.
You’re a blue whale, this long, slick thing.
You’re moving into this massive swarm.
As you open your mouth -
your mouth, when open, can engulf as much water as your whole body.
As it opens, it’s like a parachute.
It slows - your body almost stops.
When you get to go again, you’ve got to expend energy,
and so if you were feeding in an area
where there was really low densities of krill,
it’ll cost you more to feed than you actually feed in the first place.
The sad thing is that our warming oceans
are actually causing a drop in krill stocks
in the southern hemisphere,
and that's only getting worse and will into the future.
So I think it’s poetic that this system that was developed
for peace to stop us developing more nuclear bombs has been perfect for us,
not only for- we didn’t go out looking for new populations of blue whales.
We’re using the system to see how the whales are coping
with our drastically changing oceans.
So we stopped whaling just in time, really,
for the blue whales in the Southern Ocean to actually have recovered,
but that question about our time is true today as they face this new challenge.
We need to stop our harmful actions,
and in time, so that the environment can recover.
And that time ... gosh, it’s now, right?
While it still is possible.
Thank you.
(Applause)