'' OCEAN '' FILM'S HONOUR : SIR DAVID ATTENBOROUGH

Sir David Attenborough's nature documentary OCEAN reveals, in horrifying detail, how bottom trawling is hurting sea life.

! SAVING OUR SEAS ! : IN one of the most powerful scenes of Sir David Attenborough's new film Ocean, the audience sees industrial fishing from a fish's perspective.

Confronting a bottom trawl as it thunders across the seabed, terrified fish scatter in desperate but futile attempts to escape the vast net swallowing them.

The heavy chain that holds the trawl down sweeps away sponges, corals, sea-grass and other seabed life, leaving behind utter devastation.

Attenborough's latest nature documentary is a visually magnificent and highly personal mediation on the relationship humans have with the sea. It is the most important part of our world, he says. But we have taken it for granted.

A century of intensifying and destructive fishing has culminated in bottom trawl nets, some as big as cathedrals and weighing many tonnes, being towed along the seabed to catch fish.

To allow them to fish more effectively in areas of rough seabed, which is where most marine life is found, fishers in the 1920s invented '' rock-hopper '' gear : rollers placed along the foot rope that touches the bottom, allowing the net to bounce over obstacles.

This innovation followed the trajectory of many fishing methods, which was to become more destructive over time to sustain the size of the catches in the face of declining fish stocks.

Shellfish dredging, another fishing method that destroys as it catches, is shown in a second horrifying scene.

To catch scallops, steel dredges, armed with spikes [ imagine the harrows farmers use to break up soil on ploughed fields] drag along the seabed, smashing and pummelling everything.

In minutes, seabed life of astonishing diversity and beauty is erased.

TOGETHER, Attenborough explains, bottom trawling and dredging wreak their havoc across an area of seabed larger than the Amazon rainforest every year.

Attenborough invites viewers to wonder how on Earth these fishing methods are still allowed when the damage is so obvious.

Viewers may be even more surprised, and very probably angry, to learn that most marine protected areas in Europe, and indeed worldwide, permit bottom trawling and dredging between their boundaries.

The World Students Society thanks Callum Roberts, a Professor of Marine Conservation at the University of Exeter in the UK.