London - Populations of marine wildlife have plummeted by half over the past 40 years, with some species suffering far greater declines as a result of habitat loss, overfishing, rising sea temperatures and worsening ocean acidity, a major report has found.
The scale of the crisis is documented in detail by the study which claims that marine species, including some that are critical to human food security, are in potentially catastrophic decline.
Unprecedented pressures on the global ocean ecosystem from several directions are combining to threaten virtually everything that lives in the sea, says the WWF's Living Blue Planet report.
There has been significant declines in habitats such as mangroves and seagrasses, on which many other species depend, while numbers of commercially valuable fish, such as mackerel and tuna, have plummeted by as much as three quarters since the 1970s, the report found.
Many coral reefs, often described as the tropical rainforests of the oceans because of their rich diversity of life, could be threatened with extinction by mid-century if ocean acidity continues to worsen as a result of rising levels of CO2 in the atmosphere - which causes a corresponding rise in carbonic acid in the sea.
Louise Heaps, chief adviser on marine policy at WWF-UK, helped to compile the report. She said: “By over-exploiting fisheries, degrading coastal habitats and not addressing global warming, we are sowing the seeds of ecological economic catastrophe.”
The report is one of the most detailed surveys of marine wildlife ever undertaken. It found that seagrass coverage had declined by about 30 percent over the past century while the total area covered by mangroves has dropped by 20 percent between 1980 and 2005, primarily as a result of prawn farming and other forms of aquaculture.
“In the space of a single generation, human activity has severely damaged the ocean by catching fish faster than they can reproduce while destroying their nurseries. Profound changes are needed to ensure abundant ocean life for future generations,” said Marco Lambertini of WWF International.
Some of the most dramatic declines have been in species fished for commercial gain. The populations of some mackerel, tuna and sardine species have fallen by 74 percent between 1970 and 2010, with no signs of recovery, the report says.
“We are in a race to catch fish that could end with people starved of a vital food source and an essential economic engine... with the poorest communities that rely on the sea getting hit fastest and hardest,” Mr Lambertini said.
The report says that one in four species of sharks, rays and skates is now threatened with extinction
Professor Ken Norris of the Zoological Society of London, said: “These devastating figures reveal how quickly human beings are changing the wildlife in our oceans and are a stark warning of the problems we might face as a result.”
The Independent