Technology companies have unveiled satellite systems which would allow governments to track fishing boats and crack down on illegal fishing

Governments should appoint ministers for the oceans and agree a global treaty to halt the despoiling of the seas, the former foreign secretary David Miliband said last night in a speech at the United Nations.

“Evidence of crisis is growing,” said Mr Miliband, a co-chair of the Global Ocean Commission, at an event designed to pressure member states to strike the first international treaty on the oceans in three decades.

The former minister, who bowed out of British politics in 2013 after losing the contest for the Labour leadership to his brother, said the large-scale depletion of sea-life and “much clearer” evidence of a connection between climate change and rising ocean acidity had made the case for a new overarching agreement more urgent, “if the