A recent study for the conservation charities WWF and the Zoological Society of London (ZSL) shows populations of mammals, birds, reptiles and fish in global oceans declined by 49 per cent between 1970 and 2012, with some near extinction.
The new “Living Blue Planet” report blames over-fishing as the main driver of the loss of ocean life, but says climate change is accelerating the decline.
Environmentalists are warning the large-scale disappearance of sea life is disastrous both for the health of the planet and for people across the world who depend on the ocean’s resources.
They say the latest findings highlight the devastating impact of human activities and are calling for urgent action to safeguard the planet for the future.
The report states: “For centuries people have regarded the ocean as an inexhaustible source of food and a convenient dumping ground, too vast to be affected by anything we do. But in the space of just a few decades it has become increasingly clear that the ocean has limits and that in many important parts of our seas the sustainability thresholds have been well and truly breached.”
It concludes that global warming is causing oceans to change more rapidly now than ever before, with rising temperatures and acidification further weakening a system already damaged by over-fishing, habitat degradation and pollution. It continues: “Driving all these trends are human actions: from over-fishing and extractive industries, to coastal development and pollution, to the greenhouse-gas emissions causing ocean acidification and sea temperature rise.”
The authors warn that all coral reefs could vanish by 2050 if oceans continue to warm at the current rate. With more than a quarter of all marine species living in coral reefs, the loss of these habitats would be catastrophic. The study shows the family of fish that includes tuna and mackerel has shrunk by 74 per cent, with bluefin and yellowfin of particular concern. There have been dramatic declines in species found in UK waters, including the vulnerable porbeagle shark and critically endangered leatherback turtle.
Steep drops in the cover of mangroves and seagrasses have also occurred.
But experts believe action can be taken to reverse the trend.
WWF Scotland director Lang Banks said: “Our oceans and seas are some the most amazing parts of our planet, and this report is a stark reminder as to what would be at risk if we do not begin to turn things around.”
He said the creation of marine protected areas, where some damaging activities such as types of fishing are banned or limited, could play a key part in improving the health of the ocean.
Consumers can also ensure all seafood they eat is certified as sustainable by the Marine Stewardship Council, as well as reducing waste and litter that can end up in the seas.
“This is a wake-up call, but it is also an opportunity,” said Robin Freeman, head of indicators and assessments at ZSL.