According to one of the most extensive surveys of sea life ever compiled, the populations of some marine species have declined by 49% in just 40 years. The Living Blue Planet Report, released by World Wildlife Fund (WWF) in partnership with the Zoological Society of London, has documented the extraordinary losses, which occurred from 1970 to 2012.

The report has found that some fish species have declined by nearly 75%. The report authors have attributed the dramatic drops in population to human-driven climate change and to habitat loss, overexploitation and pollution.

Mr. Brad Ack, senior vice-president for oceans at WWF, said in less than a human generation they have seen dramatic losses in ocean wildlife and their habitats have been degraded and destroyed.

He said, "Driving all these trends are humans actions: from overfishing and resource depletion, to coastal development and pollution, to the greenhouse gas emissions causing ocean acidification and warming".

During the study, researchers surveyed over 10,000 populations of 3,038 marine species, including fish, birds, mammals and reptiles. According to the report estimation, nearly one-third of the world's fish stocks are overfished, and one in four species of sharks, rays and skates are endangered with extinction.

Another main report finding is that three-quarters of the world's coral reefs are presently threatened. Keeping in mind the projected levels of warming and ocean acidification, all coral reefs are likely to be lost by 2050.