Right now,
beneath a shimmering blue sea,
millions of fish are having sex.
(Cheers)
And the way they're doing it and strategies they're using
looks nothing like what we see on land.
(Laughter)
Take parrotfish.
In this species, all fish are born female,
and they look like this.
Then later in life,
she can transition into a male and she'll look like this.
But it's not just a spectacular wardrobe change.
Her body can reabsorb her ovaries and grow testes in their place.
In just a few weeks,
she'll go from making eggs to producing sperm.
It's pretty impressive,
and in the ocean it's also pretty common.
In fact, I'll bet nearly all of you have at some point had a seafood dish
made up of an individual that started life as one sex
and transitioned to another.
Oysters?
Grouper?
Shrimp?
Seeing some heads nodding, yeah.
But not all fish that change sex start as females.
Those clownfish we know from "Finding Nemo"?
They're all born male.
So in the real world,
when Nemo's mother died,
Nemo's dad Marlin would have transitioned into Marlene
(Laughter)
and Nemo would have likely mated with his father turned mother.
(Laughter)
You can see -- (Laughter)
Yeah.
You can see why Pixar
took a little creative license with the plot line, right?
(Laughter)
So sex change in the ocean can happen in either direction
and sometimes even back and forth,
and that's just one of the many amazing strategies animals use
to reproduce in the ocean.
And trust me when I say
it's one of the least surprising.
Sex in the sea is fascinating,
and it's also really important,
and not just to nerdy marine biologists like me
who are obsessed with understanding these salty affairs.
It matters for all of us.
Today, we depend on wild caught fish
to help feed over two billion people
on the planet.
We need millions of oysters and corals to build the giant reefs
that protect our shorelines from rising seas and storms.
We depend on medicines that are found in marine animals to fight cancer
and other diseases.
And for many of us,
the diversity and beauty of the oceans is where we turn for recreation
and relaxation and our cultural heritage.
In order for us to continue to benefit from the abundance
that ocean life provides,
the fish and coral and shrimp of today
have to be able to make fish and shrimp and coral for tomorrow.
To do that, they have to have lots and lots of sex.
And until recently,
we really didn't know how sex happened in the sea.
It's pretty hard to study.
But thanks to new science and technology,
we now know so much more than even just a few years ago,
and these new discoveries are showing two things.
First, sex in the sea is really funky.
Second, our actions are wreaking havoc on the sex lives of everything
from shrimp to salmon.
I know. It can be hard to believe.
So today, I'm going to share a few details about how animals do it in the deep,
how we may be interrupting these intimate affairs,
and what we can do to change that.
So, remember those sex-changing fish?
In many places in the world,
we have fishing rules that set a minimum catch size.
Fishers are not allowed to target tiny fish.
This allows baby fish to grow and reproduce before they're caught.
That's a good thing.
So fishers go after the biggest fish.
But in parrotfish, for example, or any sex changer,
targeting the biggest fish means that they're taking out all the males.
That makes it hard for a female fish
to find a mate
or it forces her to change sex sooner
at a smaller size.
Both of these things can result in fewer fish babies in the future.
In order for us to properly care for these species,
we have to know if they change sex,
how, and when.
Only