Original subtitles

This female salmon in a last act of resilience

gives her body back to the river.

Hidden in the pebbles near her decaying body are thousands of eggs.

Each glowing glow holds one of her precious babies

and the future of her species.

In these first weeks of life,

the newly hatched salmon are in their most vulnerable state.

They find safety within their nest of pebbles.

As the seasons change,

the young salmon grow confident and restless.

It's time to start the long migration out to sea.

Believing the safety of their birthplace is a perilous act

and only a handful of them will ever make it back home.

Tracking this female as she travels down the river

helps us map her epic journey.

Although the salmon have over 50 natural predators in the wild,

man is by far the deadliest.

As the river cuts through the land,

it widens and turns into an estuary,

the gateway to the open sea.

Here the female salmon will spend time

letting her body adjust to life in salt water.

Finally, after long months of travel,

she will arrive at her long-term habitat, the big blue.

Out at sea, she is free and wild.

It's here she will spend most of her life,

feeding and growing stronger,

preparing for the return journey home.

Overfishing has left the salmon population depleted

and brings her kind close to extinction.

These huge farms produce most of the salmon we eat,

but it comes at a grim price,

spreading disease and threatening the future of the wild salmon.

The female salmon has lived in the ocean for a few years

and now she is ready to start one of nature's most rigorous

and demanding journeys.

Back home.

Upriver to lay eggs in the exact same place

where she herself was born.

As she travels back,

the constant battle against the flow

and the sudden change to fresh water

takes a heavy toll on her body.

If the rainy season is delayed,

the salmon struggles to move upriver.

She pauses,

waiting for the rain.

When the water comes, they can set off again,

running the river.

No one knows exactly how the salmon find their birthriver.

It's as if within its DNA,

this fish holds great distant memories

of endless past journeys.

As the river narrows and turns into streams,

space becomes limited.

The drive towards the spawning ground

is very powerful now.

Heavily pregnant, starving and exhausted,

she is now nearing her limits.

Somehow, from a million rivers and streams,

she knows which turn to take,

which stream to run.

Until she finds the particular patch of gravel

she was born on.

She is finally back home.