GREAT BARRIER REEF - Off Australia’s east coast, you will find the Blue Outback, a kaleidoscope of life that is the Great Barrier Reef, the world’s biggest structure built by living organisms. But it is under siege from climate change and warming waters that have twice bleached its spectacularly colored corals white.

Overfishing further depleted U.S. fish populations in 2006, a government report said on Friday, a finding that prompted conservation groups to call for catch limits and tougher enforcement.

According to researchers, the largest and most highly prized fish species are down to 10% of their normal levels, and could be wiped out in a matter of decades.