Why is our ocean at risk?

Emptying a mesh full of orange roughy into a trawler.

Overfishing, climate change, destruction of coastal habitats, pollution... these are among the threats that are pushing our ocean to the breaking point. What this means is simple – the way we exploit seas and coastal areas destroys not only their diversity, but also their ability to meet our most basic needs. As fish stocks crash and coral reefs die off, millions of people who depend on the ocean are at risk of losing their livelihoods and a critical food source.

Not just a problem for the ocean

The problems affecting the ocean are bad news for the 3 billion people who rely on fish (from marine and inland fisheries) as an important part of their diet, and more than 520 million more who rely on fishing-related activities for income and food. What's more:
Half of the world's population lives within 100km of the sea
Every year, millions of marine species are caught unintentionally by fishing boats, and many die as a result.

61% of fish stocks are fully fished (fishing pressure is close to, or at the maximum limit of what can be sustained before overfishing will likely occur) and 29% are overfished (which means they are taken out of the water at biologically unsustainable levels)
Less than 4% of the ocean benefits from some kind of protection

When multiple threats interact—some local (such as removing mangroves) with global ones (such as climate change)—the impacts can be disastrous. For example, “dead zones” (areas of very low oxygen content), are worsening because of steadily warming temperatures, acidification and pollution among others.

The ocean - warmer and more acid

The average sea surface temperature has increased over the past 50 years, as a result of human activities such as the burning of fossil fuels and deforestation. The warming of the ocean is felt through changes in weather patterns, and the frequency of extreme events, as well as sea level rise. More intense storm systems are increasing the energy of waves and winds in some regions, and consequently the stress on coastal ecosystems.

According to the scientific consensus of the Intergovernmental Panel on Climate Change (IPCC), the speed at which these changes are occurring has no parallel in at least the last 65 million years. Changes have been observed in almost every part of the ocean, with marine wildlife relocating to higher latitudes, consistent with warming trends.

Changes in ocean temperature are also altering the timing of key life history events such as plankton blooms, and the spawning and migratory behaviour of turtles, fish and invertebrates.

The domino effect of climate change

These changes are already affecting human systems and industries. Shelled molluscs (like clams and oysters), for example, are being harmed by an increase in water acidity. The oyster industry in the Pacific Northwest of the United States has already lost nearly US$110 million in revenue and some 3,200 jobs due to ocean acidification.
A growing amount of carbon dioxide in the atmosphere is entering the ocean and making it more acid. This is affecting negatively crustaceans and corals.