Press Trust of India: Only four per cent of world’s oceans are undamaged by human activity, according to a study of man’s impact on marine life. A team of international researchers has found that almost half of the world’s marine regions have been seriously affected by over-fishing, pollution and climate change, the British media reported on Friday. "For the first time we have produced a global map of all of these different activities layered on top of each other so that we can get this big picture of the …