This is what the end of overfishing would look like

Two thirds of the world’s fisheries are in bad biological shape, and it is only going to get worse if we continue on our current path. But according to a study published recently in the Proceedings of the National Academy of Sciences, we can fix this mess—and fast. The study found that if sound management policies were put in place, it would take an average of ten years for the world’s fisheries to recover. By mid-century, the authors say, 98 percent of stocks could be healthy.

“There is hope for the world’s fisheries if we can enact the kinds of management policies that we know work and that have worked in parts of the world that were aggressive enough to pursue them,” says lead author Christopher Costello.

The authors assembled the largest-of-its-kind database of 4,713 fisheries, accounting for 78 percent of reported catch. Since abundance data exists for just 397 fisheries (or 43 percent of the fish in the database), the authors used a model they previously developed to estimate abundance for the remaining fisheries. Then, using this baseline estimate, they created bioeconomic models to project how each fishery would fare in terms of catch, profit, and biomass under three different management regimes through 2050. The first is the business-as-usual scenario. In the second, fishing is pursued in a way that maximizes long-term catch. The third is a rights-based fishing management policy, which is oriented at maximizing economic value over time.

The authors found that the rights-based management approach would result in the greatest levels of fish biomass. If it is applied only to fish of conservation concern, it would provide for annual increases of 2 million metric tons (MMT) in catch, $31 billion in profits, and 388 MMT in stocks. If all fish were managed this way, those numbers would be 16MMT, $53 billion, and 619MMT, respectively. The other approach, fishing to maximize long-term catch, would provide for smaller stock increases and fewer profits, but upon full recovery would generate the largest catch.

Dirk Zeller, senior scientist and executive director of the University of British Columbia’s Sea Around Us program, who was not involved in the research, said that while the paper is methodologically sound, its conclusions are rather far-fetched. “That’s like saying if all cars are suddenly (over the next few years) converted to electric, we can…likely achieve our carbon goal within 10 years,” he says. “Although a very appealing idea, it’s not a very likely, realistic scenario everywhere.”

Costello, who is a professor at the Brenn School of Environmental Science and Management at the University of California at Santa Barbara, admits that it would be extremely difficult in many places in the world to make the needed changes. But he hopes that by demonstrating the extent of what is possible, the paper will serve as an impetus to begin the process.

“If they are willing to take the short run costs of getting new rules through, countries can have more fish in the water and more catch for their country,” he says. “It’s powerful message.” —Catherine Elton | 15 April 2016

Source: Costello, C. et al. Global fishery prospects under contrasting management regimes (2016). Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.1520420113

Header image: shutterstock.com

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