A voracious predator has been prowling the oceans for millennia, in search of seafood. In recent decades, this predator has become adept at capturing, and killing, fish by the millions through the use of giant nets (sometimes extending tens of miles long), poisons, and explosives—aided in the pursuit by sonar, radar, GPS, and satellite surveillance.
For most of human history, it seemed inconceivable that our species could make an appreciable dent in the ocean's bounty. Surely we'd do nothing to jeopardize the principal source of animal protein for a billion people. Yet today, with millions of fishing vessels patrolling the seas and marine life decimated in their wake, ocean observers know the opposite to be true: In all the seas there are very few places left with undisturbed fish stocks, claims Boris Worm of Dalhousie University in Halifax, Canada. "The whole ocean has been transformed."
Indeed, a recent study in Science by a group of international ecologist and economists warned that the world will run out of seafood by the year 2048 if steep declines in marine species continue. A United Nations report classified 77% of the world's fish stocks as "fully exploited" or depleted. Simply put, we're removing fish from the seas faster than they can replenish themselves, often damaging their habitat in the process.
One difficulty facing ocean observers pertains to "shifting baselines." Although fish have been around for millions of years, scientific studies have far shorter attention spans, rarely detecting changes that occur over the course of centuries or generations. As a result, we may be seriously underestimating the losses sustained at sea.
There's an obvious solution to overfishing: Reap less today so there'll be something left for future generations. The goal can be furthered by imposing temporary fishing bans and by creating a network of permanent "no-take" zones. Implementing the solution, however, is far from simple. A March 2006 paper in Science compared some players in the global fishing industry to "roving bandits," who plunder the seas at will. "Harvesters have no incentive to conserve," the authors write. "Whatever they do not take will be harvested by others"—a practice that will continue, no doubt, until the establishment of a global management system that provides stronger incentives for conservation than for exploitation.
A single bluefin tuna, which can weigh more than 1,000 pounds, often fetches more than $10,000 in today’s market, and that financial incentive has contributed to the fish’s demise.