(CNN) -

The human footprint on the ocean, from the shoreline to the deepest abyss, is growing.

It is evident in over-exploited and collapsing fish stocks, it washes up as oil and garbage on our beaches, and even ends up contaminating the fish on our plates.

The idea that our seas are so vast that they will absorb anything we throw into them and replenish anything we take out of them must be consigned to history.

Today, the health of the ocean is in decline. We urgently need to clean up our act, and restore and protect the ocean.

Understanding the depth of the problem

The high seas are responsible for 50% of the biological productivity of the ocean, and what happens here affects the entire marine ecosystem, and every one of us, according to the Global Ocean Commission.

Previously invisible services such as the storage of 500 million tons of carbon every year, which our studies estimate is worth up to $222 billion annually, are now being seen and understood. The value of the ocean is far greater than just the fish we catch. We rely on it for the air we breathe, to provide protein and energy, and to maintain our weather systems.

With agricultural land under threat from climate change, it has never been more vital to our long term food security that we combat chronic overfishing, illegal fishing and worsening pollution that are pushing fish stocks to the point of collapse.

Evidence of the consequences of fisheries mismanagement is not hard to find. Overfishing in the Philippines has caused a steady drop in the fish protein available to local people according to the UN Food and Agriculture Organization.

Globally, illegal fishing takes 20% of the total marine catch, deprives communities of food and income, and connects with other heinous crimes including slavery.

On the high seas, two-thirds of the fish caught are from stocks that are already dangerously depleted, and this lawless race to the bottom also affects coastal fisheries.

Unless we take decisive action to turn the tide on ocean decline we risk a future where the essential services provided by the ocean are threatened.

This is not a future anyone should accept.

How to stem the ocean's decline

The Global Ocean Commission put forward a set of eight proposals for action tackling the main drivers of ocean decline.

This offers a way forward to ensure the ocean is able to provide a growing global population with a healthy, safe source of nutrition for generations to come.

It focuses on the long-neglected high seas -- the 64% of the ocean beyond national jurisdiction -- where governance is weak and fragmented, and resources are vulnerable to over-exploitation.

The action plan calls for a five-year phase-out of government high seas fishing fuel subsidies from a handful of nations -- including the U.S., EU, Japan and China -- that fuel overfishing to the tune of $30 billion.

It also calls for all high seas fishing vessels to carry mandatory identification numbers to prevent illegal fishing, and for seafood retailers to insist on full traceability of the products from "bait to plate."

High seas fishing needs to be brought into line before we irreversibly squander our last great common resource, and lose the fish so vital to our diets and our culture. It is equally important that the fish that reaches our markets is not only sustainably caught, but safe to eat.

The situation is critical as millions of tons of plastics end up in the ocean and enter the food chain every year.

Experts believe that up to 33 billion tons of plastic will accumulate by 2050, a large percentage of which will find its way to the ocean. Much of it -- 70 percent - will sink to the ocean floor and some of the rest break down to form a soup-like mass of tiny microplastic particles.

We know that plastics ingested by marine species cause the bioaccumulation of toxic chemicals higher up the food chain. Larger species consume both plastics and other animals that are already contaminated. Microplastics have been found in mussels, oysters and lobsters, among other species. We must address this problem before it spreads as a danger to human health, food security, and the fishing industry.

As 80% of the plastic in the ocean originates on land, increased recycling and environmentally sound waste management is at the core of any solution. The Commission is calling for a host of measures, including minimizing single-use plastics by direct government intervention and creating incentives to boost recycling.

Japan is rightly proud to lead the world in plastic recycling rates. Reaching 77% in 2010, Japan's rate is about twice that of the UK, and nearly four times the 20% figure for the U.S., though there is room for improvement, particularly in the over-use of plastic food packaging, according to Japan's Plastic Waste Management Institute.