The Blue Planet

It's only in the last 50 years, with the invention of the aqualung

that we've gone underwater

and see some of the animals that live there.

We all love dolphins,

They're the playful, popular face of the ocean,

But most of what lives underwater is out of sight,

and so, out of mind.

Even in the 20 years that I've been diving,

there have been big changes in our seas,

It's clear that our oceans are now in real danger,

Flying over miles and miles of ocean, you get the impression

that things aren't too bad,

but below the surface there's a multitude of man-made problems,

Of all of them, probably the most destructive is fishing,

and it's the way we catch fish that's the problem.

Blue fin tuna, king of the sea.

They are exquisitely designed for the open ocean.

They can grow up to three-quarters of a tonne,

and can swim at 50 miles an hour,

faster than any other creature in the sea...

apart from us,

They have few natural predators when fully grown.

It is believed that these blue fin are now endangered.

There's no place in the ocean where we can't pursue them.

They just can't escape us.

Fishing has become incredibly hi-tech,

so much so that we can pretty much capture anything

anywhere in the world nowadays.

These blue fin tuna boats beneath me have every mod con.

They have incredibly big engines. They're using depth sounders, GPS,

and they even have spotter planes spotting the fish for them.

Yeah, Paul, I got about eight fish over here.

They just went down.

They're on my left side.

So the blue fin tuna, travelling at 50 miles an hour,

hasn't really got much of a chance,

The moment it comes to the surface, somebody is gonna spot it.

Come left...

There you go, 12 o'clock. Five or six boats.

Here they're being hunted on one of their major migration routes.

It's thought they swim from the Gulf of Mexico

up the eastern seaboard of the United States to Canada each summer.

Their routes are so predictable,

that fisherman can catch them year after year.

While these fisherman are still catching them,

there are scientists who are tagging the fish,

trying to discover how many separate populations there are,

what their movements are,

and just how many fish are left.

Marine scientist and keen sports fisherman Carl Safina

fishes off Long Island, New York.

He loves fishing for blue fin,

but these days he has to target other species.

I've been fishing off shore since I was 12

with my fathers and my uncles,

and we used to see lots of blue fin tuna,

a lot of small ones and a lot of big ones.

Now, er.. There are so few tuna,

that people... sport fish for sharks now.

Safina is so concerned by this decline in numbers

that he's campaigning with the National Audubon Society

to fry and save these tuna.

What we do know about blue fins in the western part of the Atlantic,

in other words, a part of the Atlantic off the U.S. and Canada,

is that, er... from the mid 1970s

until the late 1990s,

the population has declined by roughly 85 per cent.

In New England, where most of the Western Atlantic blue fin

are caught commercially,

fishermen just don't believe these government figures.

They claim there are mistakes in the analysis,

so they're naturally very skeptical about the quotas the government imposes.

Scientific research in the ocean is expensive,

and the politics surrounding this fish are complicated,

but one thing is indisputable,

these fish sell for vast amounts of money.

The blue fin tuna was worth a few cents a pound

and often sold as cat food until some people realised

that if they airlifted them to Japan,

if they sent them to Japan in airplanes,

the price would go from a few cents

to many dollars per pound.

Tsukiji market in Tokyo is the biggest fish market in the world.

Before I came to Japan, I'd heard a lot about it.

But I just wasn't prepared for the scale of it,

This warehouse is just the frozen section.

In another section, there are rows and rows of fresh tuna,

and amongst these are a frightening quantity of blue fin.

The Japanese are by far the biggest importers of blue fin tuna

in the world.

This is big business.

These blue fin are fetching £60 a kilo,

so in today's auction, a dealer would expect to get £12,000

for this one fish alone.

But the market fluctuates madly,

and some blue fin here

that have fetched more than £100,000.

Tuna fisherman don't accept the blue fin numbers are right down,

but most scientists firmly believe that they are.

Many people want blue fin tuna listed as CITES Appendix I,

in other words, a total ban on all fishing of them.

Unless this is done, there is no way

the fishermen, the wholesalers

everybody involved in the market will give up,

there's simply too much in it for them.

This market is not just about tuna.

There's every conceivable type of fish here.

Nearly 50 per cent of the food eaten in Japan

comes from the sea,

compared with the world's average of about 15 per cent.

They eat enormous quantities of fish, of every species imaginable,

but unfortunately, some of those species are in deep trouble.

This is a swordfish.

In the Atlantic, its numbers have more than halved since the 1960s,

as a result many restaurants have now taken it off the menu.

Marlin are a favourite amongst game fishermen,

and some species are down by 90 per cent.

While shark meat is on sale in many Japanese markets,

by far the biggest trade is in shark fins,

and that trade is Asia-wide.

About 100 million sharks

are caught every year.

Admittedly, this IS the biggest market,

but there are hundreds of markets all over the world

selling huge quantities of fish,

and it's not just one day a week, it's day after day after day.

You might find some really strange creatures here,

ones which are totally unfamiliar to us,

but that's not the issue,

it's often the more common species that are threatened,

and those you can find on sale at home.

This is Billingsgate Market,

the largest fish market in London.

Here you can buy all the familiar fish which we love to eat,

but in the UK, everyday we're eating fish

whose stocks are dangerously low.

Most of us have no idea that these fish are in trouble,

even the most common ones such as cod.

At the moment, the worst problem is with cod in the Irish Sea

which is really in a very, very depressed state indeed.

The north-east Arctic stock off the coast of Norway

is not in very good shape.

The Canadian stock is not in good shape.

The North Sea stock is not in good shape.

About the only one that's doing reasonably well is in Iceland.

And if that one goes the same way,

there will be no Atlantic cod.

There simply will not be any cod for sale.

So is this a normal size for a cod these days?

That's an average size, yeah.

When you buy fish, uh,

in the supermarket or, uh, the fish and chip shop,

you generally as a consumer you have no way to tell

whether this is come from a stock that is overfished or stock that isn't.

- And where are these ones from? - These are from Aberdeen?

- They're from Scotland North Sea? - Yeah, they're Scottish.

We know that fish stocks do collapse,

uh, and sometimes they recover,

the herring collapsed and recovered.

There was a stock of mackerel in the North Sea in the 60s and 70s

that collapsed under very heavy fishing pressure by purse-seiners,

and it has not come back. In 30 years, it has not come back.

Sole and plaice are fully exploited

and could not really sustain any further fishing pressure.

The herring also is fully exploited.

There's no room for expansion.

Now, with so much fishing pressure in surface waters,

fishermen are going deeper and deeper to find fish for the market.

We're seeing things here that we'd never have heard of 20 years ago.

This is a black scabbard

and it lives at about 1,000 metres.

So are these fish in trouble? It's hard to say really,

because like everything else that lives in the deep,

very little is known about it.

And that's the problem with deep sea fishing.

The scientists don't really know what's going on down there,

and they're only just beginning to find out.

Scientists from Tasmania

are now using hi-tech cameras

mounted on submersibles

to study the effects of fishing on the deep sea.

Only in the last 30 years

have we had the technology to fish the deep.

But in many places, the fishing pressure has been intense.

This particular fish is now on our menus.

These white fish

are the fillets of a deep sea fish called orange ruffie.

You may have noticed them

at your local fishmonger or supermarket recently.

They can live at up to depths of 1,500 metres,

and like a lot of deep sea fish,

they live a very long time.

These ones could have been born during World War |I.

They could even have been around during the Victorian era.

It's believed that orange ruffie

can live to a staggering 150 years old.

As well as living longer, these fish mature later

at about 30 years old.

If you take them out before this age,

they won't be able to reproduce.