A new study reveals that small, unassessed fisheries are in even worse shape than we thought. But the research also provides hope that smarter management could stop the bleeding—and provide more sustainable seafood.

Dan Kitwood / Getty Images A man casts a net while fishing in the lagoon on his boat near Ganvie, Benin, Jan. 6, 2012.

The default law of the sea is lawlessness. Take fishing, by far the major human interaction with the three-quarters of the Earth‘s surface that is not dry land. There are perhaps 10,000 fishing areas around the world—from Alaska‘s multi-billion dollar fishery to near-shore African waters that are fished by hand for subsistence—and more than 80% of them are completely unregulated. Not only are there little to no laws controlling fish catches in those mostly smaller territories, scientists haven’t even been able to assess their status. Throughout much of the world, we don’t even know how much we’ve lost.

(MORE: Oceans: From Climate Change to Overfishing, Bad News for the Deep Blue)

That’s beginning to change. In a major new paper published in the September 27 Science, a team of researchers at the University of California-Santa Barbara (UCSB) and the University of Washington managed to assess the status of those smaller fisheries, which together comprise more than 80% of the global catch. And what they discovered offers plenty of reason to despair—and some hope as well. It turns out that those small, unregulated fisheries are doing worse—in some cases much worse—than the larger, better studied and regulated fisheries. That means the world’s oceans are even more overfished than we had feared.

But the study’s authors also found that those fisheries—if better managed—can be rebuilt quickly, and may be able to produce an even larger, more sustainable catch than they do now. “This report is a big deal,” says Brett Jenks, the CEO of the conservation non-profit RARE, which is involved in small-scale sustainable fisheries. “Some might see this as another dark cloud for fisheries, but there’s a silver lining.”

Because there literally is no one counting the full catch in small-scale fisheries, the researchers—led by Christopher Costello, an economist with the Bren School of Environmental Science at UCSB—used regression models to estimate the state of the smaller fisheries. They found out that smaller fisheries in the northeastern U.S. and Canada—where boats have been plying once-abundant waters for centuries—are in particularly bad shape, while the fisheries in the eastern Indian Ocean tended to be richer. But in general, the stats for those smaller, unassessed fisheries are not good. “Small-scale unassessed fisheries are in substantially worse shape than was previously thought,” Costello told reporters last week. “The longer we wait, the harder and most costly it will be [to revive them]. In another ten years, the window of opportunity may be closed.”

(MORE: Why the Future Belongs to Jellyfish)

The good news is that smart policy can help even those most depleted fisheries recover. One simple way is to provide more funds for scientists to assess smaller fisheries—after all, we need to be able to diagnose the problem before we can cure it. Once scientists can assess the state of a fishery, they can set quotas that prevent territories from being overfished. That’s helped in the U.S., where tighter regulations has translated into more sustainable catches, with U.S. landings of fish and shellfish hitting a 17-year high in 2011. Another option involves granting communities or even individual fishermen exclusive rights to catches in return for establishing no take zones that allow stressed species time to recover. “The silver lining is that we have proven solutions,” said Michael Arbuckle, a senior fisheries specialist with the World Bank. “Ending open access in favor of fishing rights is the key.”

Because the unassessed fisheries are so small, that means working community by community. To that end RARE has established 40 pilot sites in Asia and Latin America that use both catch shares and protected areas to help small fisheries recover. Jenks notes that an analysis by the University of Philippines found that fish stocks in 12 fisheries in the Philippines carrying out those strategies were growing by 40% on average in a single year. “We’re working with local mayors to preserve and protect those no take zones,” says Jenks. “The incentive for better management is to remove the tragedy of the commons and provide security for local fishermen.”

That better management can pay off. The Science study estimates that 64% of the small, unassessed fisheries could “provide increased sustainable harvest” if they came under better management. And that in turn could increased global fish abundance by 56%, which would translate into more seafood for the world. Given that global food demand is expected to double by the middle of the century, that could be quite the catch.

MORE: Why It’s a Bad Idea to Fish Out the Bottom of the Marine Food Chain