The ocean, seen from a beach or from a plane, seems vast, ancient and invulnerable. It’s hard to imagine that 90% of life on earth lives below the waves, across 1.3 billion cubic kilometres of water and across a seabed formed by mountain ranges, vast plains and trenches that reach 11,000 metres deep.

Every other breath we take is filled with oxygen that originates from photosynthesising marine life, the ocean provides billions of us with food, and in other ways provides a critical role in supporting the ecology of the planet. Yet much of this is simply not recognised, and certainly not valued.

Our relationship with the ocean has become abusive. Industrial fishing has led to a catastrophic collapse of both target species and those taken as by-catch. The number of many of the iconic ocean predators – tuna, swordfish, sharks, and even cod – have been reduced to less than 10% of their original abundance. The great whales were almost hunted to extinction by the mid-20th century, and some species still struggle to survive.

Seabirds, drowned or killed as collateral damage from fishing, die in their hundreds of thousands a year, pushing some towards extinction. Our inexorable appetite for profit from fisheries has led us to trawl deep and remote ecosystems for fish. Having evolved to survive at great depths where there is limited food, these fish can live for more than 100 years and reproduce slowly, and so are extremely vulnerable to overfishing. Even the method of fishing itself destroys habitats such as deep-sea coral reefs and sponge gardens which support an enormous diversity of life.

And of course the ocean is affected not just by what we take out, but by what we put in: pollution, particularly plastic debris, ocean acidification from the effects of climate change, and deoxygenation caused by nitrate fertiliser washed into the sea from fields also cause problems for marine life.

It’s easy to be overwhelmed by this tragic spiral of degradation, but it is still the greatest wilderness on Earth and in places teems with beautiful and majestic life. Many of the human activities damaging the oceans can be modified, reduced to promote recovery, or even eliminated. The latest report of the Global Ocean Commission is a “rescue package” of eight practical recommendations that can reverse this decline. It is nothing less than a Marshall Plan for the oceans, a reflection of the scale of the emergency we face.

Eight steps to save the ocean

The commission’s rescue package calls for a Sustainable Development Goal for the oceans, to emphasise the need to use the ocean’s resources sustainably, now and for the future.

It outlines steps that would make fisheries more sustainable. Some of these are incredibly simple. Requiring fishing vessels to carry a mandatory identification number, as other merchant vessels must, could make enforcing fishing regulations much easier. Better still, tracking vessels using Automated Identification Systems and other satellite tracking systems already in use would provide the means to know who is fishing where, and even what and how they are fishing.

These two simple steps would quickly make it very hard for illegal fishing vessels to go unnoticed in the vastness of the oceans. Combined with improved port state control of fisheries landings, this could eliminate illegally caught fish from supermarkets, destroying pirate fishers’ profits. Other recommendations address more difficult political issues such as overcapacity in fishing fleets, subsidies that lead to overfishing, and flag-state responsibility for the action of their vessels at sea.

Many of the commissioners’ recommendations are such clear and obvious choices that it’s reasonable to ask why they haven’t been implemented long ago. The ocean is governed mainly through the principles of the United Nations Convention on Law of the Sea, but its implementation is spread across many sector-specific organisations that leads to a disconnection between exploiting the oceans and the need to conserve them. This has made it easy for national and commercial interests to undermine ocean governance for collective benefit.

Nowhere has this been more acute that in the high seas, beyond the territorial area that extends 200 nautical miles from the coast that is subject to international regulation. The commission’s final recommendation is that, if we cannot clean up our act and manage the high seas better, they, or at least those portions that are unregulated, should be entirely closed to fishing to allow them to recover.

Two scientists, Crow White and Christopher Costello, recently modelled such a closure and found that it would lead to increasing fish stocks, and as a result greater and more sustainable fish catches. It would also deliver a more equitable sharing of the ocean’s resources, as the investment and technology to build large, ocean-going vessels is limited to the developed nations.

Given the degradation of the oceans and a burgeoning human population predicted to reach 9 billion or more by the middle of the century we cannot allow nineteenth-century-style politics to rule the waves. It is time to act collectively to rescue the oceans so that they continue to provide critical services and inspiration for our children and for generations thereafter.