Depth Charges

Sophisticated fish-harvesting technology, coupled with over-fishing and poor ocean management, appears to have caught up with the ocean's ability to renew itself.

The scientific journal Nature finds an astonishingly dramatic reduction in populations of popular commercial fish species. It notes that large ocean predators - such as tuna, cod, halibut, marlin, and swordfish, among others - have declined some 90 percent from historic levels in five of the earth's oceans.

Such fish are, of course, an especially vital part of the sea's food chain. Their decimation could have a profound impact on the ocean environment and human food supplies.

The Nature statistic is so startling, in fact, that a second study is probably warranted. But researchers argue that even if the number is off by half, the problem remains huge.

The study should serve as one of the most serious and sober warnings to policymakers yet that the ocean's ecosystem is fragile, and those who harvest its bounty must be better guardians of its resources.

And it should alert consumers to adjust the type of seafood they eat. An online guide can be helpful: www.mbayaq.org/cr/seafoodwatch.asp.

The news should also spur all countries to sign the UN Sustainable Development declaration and work to restore depleted fisheries by 2015.