Kuala Lampur, May 16 -- The ocean has always been largely taken for granted. But as we face a planetary ceiling on land - every arable acre spoken for, every forest shrinking, every city sprawling - we are finally turning our gaze seaward. The ocean is, indeed, the next frontier. Yet we arrive at this frontier as trespassers rather than stewards. The ocean is not healthy; it is overheated, acidifying, and choking with plastic. The question before us is not whether we should tap its potential, but how we can do so without committing ecological suicide.

For centuries, we have treated the ocean as a hunting ground. We have chased fish stocks to the edge of collapse. If we are to feed a growing population from the sea, we must transition to ...