“The Bluewater Revolution” by Charles C. Mann, in Wired (May 2004), 520 Third St., 3rd fl., San Francisco, Calif. 94107–1815.

The world’s appetite for fish is growing so fast that the catch will have to increase nearly 50 percent by 2020 to meet rising demand. Yet almost 30 percent of the world’s fish stocks are “overfished” or nearing extinction. The futuristic solution: robotic fish-farming in the open seas.

“Already, a third of the annual global fish harvest comes from farms, both on land and in shallow water just offshore,” writes Mann, a Wired contributing writer. “But today’s methods won’t be able to produce the volume of fish needed for tomorrow—they’re too dirty, costly, and politically unpopular” (because the farms spoil waterfront views).

Nine miles off the New Hampshire coast is a fish farm on the open ocean, an experiment run by the University of New Hampshire. A metal cylinder crammed with electronics and extending 10 feet above the surface of the Atlantic is “the antenna, eyes, and brain of a sprawling apparatus suspended [below] like a huge aquatic insect, its legs of thick steel chain tethered to the ocean floor. The creature’s body is a group of three cages,” inside of which swim multitudes of halibut, haddock, and cod.

Similar experiments are underway in other countries. “In the future, ocean ranches will be everywhere, except they’ll be vastly bigger and fully automated—and mobile,” Mann predicts. “Launched with lab-bred baby fish, these enormous motorized pens will hitch months-long rides on ocean currents and arrive at their destinations filled with mature animals, fattened and ready for market.”

It’s not all clear sailing ahead. Obstacles include a “paltry” federal research budget ($780,000 this year), legal questions about such ocean-roaming objects, and environmentalists worried about the risk of genetic pollution from the interbreeding of escaped farmed fish and wild fish.

Like the Green Revolution of the 1960s and 1970s, this oceanic one “will probably have some negative environmental effects,” says Mann. “But it will also feed countless millions—and possibly stop humankind from plundering the seas bare.”