Bertie Gregory

They can be 200 to 300 kilos, these fish.

They're enormous.

uh yeah so a thousand fish in one net guess how much food you have to feed 1 000 bluefin tuna per day oh tons and tons i'm sure six to ten tons of fish per net this one ranch had 24 nets

That means they are feeding that farm up to 240 tons of prey fish per day.

Where does that come from?

It comes from anywhere in the ocean around the world.

So once a week, this enormous ship would turn up with herring from Norway, anchovies from the coast of Chile, sardines from the coast of South Africa, wherever it was cheap.

And these fish would get poured into these nets,

We were catching fish to feed fish.

Right.

Because there's enough depressing stuff in the world.

Well, I mean, a really...

Staying with the theme of the ocean, the really amazing thing about the ocean is that if you give it the chance, it comes back on an unbelievable scale, the speed.

So a really awesome conservation success story.

There's a place called Raja Ampat in Indonesia.

It's this amazing archipelago.

It looks like something out of a storybook.

It's all these little islands covered in green jungle.

And around those islands underwater,

is some of the most amazing coral reef.