Perhaps the best way to fight the decades-long decline of fish populations, primarily from overfishing, is to give the fishing industry clearer incentives to preserve them. That conclusion leapt from a recent analysis of the effect of “catch share” incentives by resource economist Christopher Costello and others at the University of California, Santa Barbara.

The researchers analyzed more than 11,000 fisheries over 50 years and found that those being managed using catch shares were about half as likely to collapse as those without catch shares. And when fisheries switched to catch shares, fish populations stopped declining and, according to some analyses, may have reversed course. “I’ll be honest,” Costello says, “I was really surprised” by the size of the effect.

The system of catch shares works somewhat like a stock market: individual fishers can net a designated percentage of the total amount of a species set aside for fishing annually. The cap on each fish type is adjusted yearly by the government according to how the species is faring. If the population increases, the shares increase in value, too. And fishers can buy and sell shares to one another.

Catch shares give fishers a financial motive to treat the ocean with care, because they are literally invested in the future of their quarry. Costello compares the difference between catch shares and traditional fishing licenses (which expire yearly) to the difference between renting and buying a house. “When you own a house, you have a strong incentive to invest in it,” he points out. “The fishermen have an incentive to grow the fish stock” by fishing responsibly.

Boris Worm, a marine biologist at Dalhousie University in Halifax, Nova Scotia, who two years ago predicted the collapse of seafood as a food source by 2048, says Costello’s work is noteworthy but adds that catch shares will work better when combined with other tools, such as banning fishing in sensitive areas.