Quotes of the Day

The oceans are being emptied of fish. A forthcoming United Nations report lays out the stark numbers: only around 25% of commercial stocks are in a healthy or even reasonably healthy state. Some 30% of fish stocks are considered collapsed, and 90% of large predatory fish — like the bluefin tuna so prized by sushi aficionados — have disappeared since the middle of the 20th century. More than 60% of assessed fish stocks are in need of rebuilding, and some researchers estimate that if current trends hold, virtually all commercial fisheries will have collapsed by mid century.

"Fisheries across the world are being plundered, or exploited at unsustainable rates," said Achim Steiner, the executive director of the United Nations Environment Programme.

In some respects, Steiner could have stopped at "plundered," because as much damage as the legal, commercial fishing trade has wrought on the oceans, it's the illegal trade that could spell their doom. Legal fishermen — the everyday farmers of the seas — have licenses they must protect and laws they must obey. But illegal fishing — often done on the high seas where regulations are lax and catch limits can be exceeded with impunity, or in the coastal waters of developing nations, which lack the ability to fight back — abides by rules of its own. Now, a team led by Stefan Flothmann of the Pew Environment Group has published a study in the May 20 issue of Science showing just how hard stopping the illegal fishing scourge will be.

There are a lot of factors driving the rising global demand for fish. A growing global population needs ready sources of protein, and fish — generally low in fat and high in nutrients — is a natural. Plus, the worldwide explosion in the popularity of sushi means that even people who never liked fish before have developed a taste for it. Global seafood consumption has doubled over the past 40 years, and the sushi boom has tracked that trend.

But there's also a major problem with overcapacity — or the simple excess of fishermen — thanks to the $27 billion in subsidies given to the worldwide fishing industry each year. Those subsidies — especially the billions that go to cheap diesel fuel that makes factory fishing on the high seas possible at all--have created an industry bigger than the oceans can support. The U.N. estimates that the global fleet consists of more than 20 million boats, ranging from tiny subsistence outfits to massive trawlers. Together they have a fishing capacity 1.8 to 2.8 times larger than the oceans can sustainably support. Our tax money is essentially paying fishermen to strip mine the seas.

Cutting the subsidies or restricting the boats would go a long way toward solving the problem — but not if the illegal trade, which accounts for anything from 11 to 26 million tons of fish a year, or about one-fifth of the reported legal catch, can't also be brought under control. Steps in that direction have been taken. In November 2009, the U.N. Food and Agriculture Organization (FAO) adopted the Port State Measurement Agreement (PSMA), which requires countries to close their ports to ships involved in illegal or unregulated fishing. The idea is simple: if illegal boats are denied ports where they can sell their catch and refuel, black market fishing should dry up.

The effectiveness of the PSMA is what Flothman and his colleagues investigated in their paper, crunching data on port visits by boats between 2004 and 2009 that had been listed as possibly involved in illegal fishing and that had been targeted for sanctions. What they found did not impress them. The ports' records were in woeful shape, tracking the movement of only one-third of those boats during the six-year research period. The vessels frequently changed their names to elude regulators, and even if they were caught, port states enacted sanctions only about one out of every four times. On those occasions that ports in one region did crack down in any systematic way, the boats just moved to another region — a phenomenon known as leakage. "This illustrates that if port measures remain regional, the problem will shift elsewhere," the Science authors write.

Flothmann and his colleagues argue that much greater transparency is needed if illegal fishing is going to be stopped, and that may begin with getting even greater control over the legal fleet. Right now, for example, fishing boats aren't required to have an identification code from the International Maritime Organization, the only globally recognized identifier for shipping. Establishing the requirement would help distinguish the good guys from the bad guys, particularly if the information is shared among all ports. "Accountability," Flothmann writes, "requires transparency."

He's right — but his work also shows why even in the best of situations, saving wild fish will be so challenging. The oceans present the ultimate problem of the commons — they're vast, and most of the marine world lies beyond the control of any one country. Yet we're all dependent on the productivity of the oceans. "The connection between our health and the health of the oceans is clear," says Julie Packard, the executive director of the Monterey Bay Aquarium. "We have to commit to saving them." And the commitment to save the oceans begins with a recognition that we all share them.

• Bryan Walsh