They have scales and fins and don't say much, but the world would be a lonely place without fish – and possibly hungrier.

Documentary film 'A Sea Change: Imagine a World Without Fish' will be shown at the Bermuda Institute for Ocean Sciences (BIOS) today.

It looks at the implications of rising acidity in the world's oceans due to global warming, and the potential impact on fish stocks and human health – one billion people in the world depend on fish as their main source of protein.

The night will include a lecture by retired history teacher Sven Huseby who made the film with his wife, filmmaker Barbara Ettinger of Niijii Films.

Mr. Huseby decided to make the film after reading Elizabeth Kolbert's book 'The Darkening Sea'.

Mr. Huseby and his wife have spent the last nine months touring the United States with the film and they now intend to take it globally.

During their tour they have met with thousands of people, talked with government officials and even made an appearance on Martha Stewart's show.

In the film, Mr. Huseby meets with oceanographers, marine biologists, climatologists, and artists from around the world to discuss the ocean's rising acidity.

He discovers that global warming is only half the story of the environmental catastrophe that awaits us.

"Excess carbon dioxide is dissolving in our oceans, changing sea water chemistry," said Mr. Huseby.

"The more acidic water makes it difficult for tiny creatures at the bottom of the food web to form their shells. The effects could work their way up to the fish one billion people depend upon for their source of protein."

Bermuda's own BIOS has been a pioneer in studying ocean acidification through its Bermuda Atlantic Time Series (BATS) programme. For many years, BIOS has been taking measurements in the open ocean off of Bermuda at regular intervals.

'A Sea Change' is also a touching portrait of Mr. Huseby's relationship with his grandchild, Elias.

During the film, he keeps a correspondence with the little boy, and mulls over the world that he is leaving for future generations. 'A Sea Change' has been referred to as "a disturbing and essential companion piece to 'An Inconvenient Truth'."

"The film brings home the indisputable fact that our lifestyle is changing the earth, despite our rhetoric or wishful thinking," said Mr. Huseby.

'A Sea Change' is thought to be one of the first documentaries about ocean acidification.

It is chock full of scientific information, and is also a beautiful tribute to the ocean world and an intimate story of the Husebys, a Norwegian-American family whose heritage is bound up with the sea. The film has won several awards including Best Green Film, at the Kosovo International Documentary Film Festival; Grand Prize, Feature Documentary, at the Fica International Environmental Film Festival; and the Dumosa Award for Best Coastal Film, at the Cottonwood Environmental Film Festival, among many other awards.

'A Sea Change' will be shown at BIOS tonight. There will be a cash bar at 6 p.m. and the film starts at 6.30 p.m. It will be followed by a panel discussion with the Husebys.

Entrance is $20 for BIOS members and $25 for non-members. For more information see the film's website at http://aseachange.net.