Living Blue Planet
Crisis in global oceans as populations of marine species halve in size since 1970
Marine species around the world are in potentially catastrophic decline.
Our Living Blue Planet report - an updated study of marine mammals, birds, reptiles and fish - shows that marine populations have declined by 49% between 1970 and 2012.
As well as being disastrous for ecosystems, these findings on the state of the ocean spell trouble the world over, especially for people in the developing world who depend heavily on the ocean’s resources.
All life on earth depends on healthy oceans
“In the space of a single generation, human activity has severely damaged the ocean by catching fish faster than they can reproduce while also destroying their nurseries. Profound changes are needed to ensure abundant ocean life for future generations.”
The analysis included almost twice as much data as past studies and tracked 5,829 populations of 1,234 species, from sea birds to sharks to leatherback turtles.
The findings are based on the Living Planet Index - a database maintained and analysed by researchers at the Zoological Society of London (ZSL).
This follows alarming statistics raised in our Living Planet Report in 2014 which revealed huge declines in vertebrate populations around the world.
The Living Blue Planet Report studies how overfishing, damage to habitat and climate change are affecting marine biodiversity.
Populations of leatherback turtles in the Eastern
Pacific have declined by 97% in the past three generations
Image: © naturepl.com / Doug Perrine / WWF
Species under threat
Many species essential to the global food supply have become significantly depleted due to over fishing.
Global population sizes of the family of food fish that includes tunas, mackerels and bonitos have fallen by 74%. Declining numbers of bluefin and yellowfin are particularly concerning.
Some species found in UK waters, including the vulnerable porbeagle shark and the critically endangered leatherback turtle, have also undergone dangerous declines.
The size of the populations of marine species have declined by 49%.
Status of species populations:
FISH
Nearly a third (29%) of commercial fish stocks are now classed as over exploited and 61% as fully exploited.
SHARKS & RAYS
Global catches have increased by 300% and a quarter of shark, rays and skates are now threatened with extinction.
MARINE TURTLES
Four of the seven sub-populations of leatherback turtles are critically endangered.
DEEP SEA FISH
There has been a 72% decline in deep sea fish populations over the last 40 years.
Image: © Brent Stirton / Getty Images
marine habitats in danger
The report shows steep worldwide declines in the cover of coral reefs, mangroves and seagrasses that support fish species and provide valuable services to people.
It is very possible that we could lose coral reefs from most areas by 2050 as a result of climate change. With over 25 per cent of all marine species living in coral reefs and about 850 million people directly benefiting from their economic, social and cultural services, the loss of these reefs would be catastrophic.
CORAL REEFS
25% of all marine species live on coral reefs. However they cover less than 1% of the ocean.
This is especially distressing as three quarters of the world’s coral reefs are currently threatened and coral reef cover has decreased by more than 50% over the last 30 years.
At the currently projected levels of ocean warming and acidification, coral reefs could be lost altogether by 2050.
SEAGRASS
Seagrass stores 83,000 tons of carbon per square km. That's more than double terrestrial forests. However there's been a 30% decline in cover over the last century.
MANGROVES
Mangrove cover equivalent to an area half the size of Scotland has been lost between 1980 and 2005. That's 20% of the global cover!
Why the oceans are in such a perilous state
While over-exploitation is identified as the major threat to ocean biodiversity, the study finds that climate change is causing the ocean to change more rapidly than at any other point in millions of years.
Rising temperatures and increasing acidity levels caused by carbon dioxide are further weakening a system that is already severely degraded through overfishing, habitat degradation and pollution.
“As well as being a source of extraordinary natural beauty and wonder, healthy seas are the bedrock of a functioning global economy. By over-exploiting fisheries, degrading coastal habitats and not addressing global warming, we are sowing the seeds of ecological and economic catastrophe."
OVERFISHING
The average consumption of fish has roughly doubled since 1960s. To meet demand the global fishing fleet has now increase to a point where it is two to three times larger than the ocean can sustain.
CLIMATE CHANGE
Oceans have absorbed 30% of the carbon caused or produced by humans and 90% of excess heat. This has caused ocean acidification to increase at a faster rate than any other period.
Image: © Brian J. Skerry / National Geographic Stock / WWF
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