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Far offshore are the high seas—waters beyond any country’s jurisdiction and the focus of a contentious debate. The high seas, which cover nearly two-thirds of the ocean’s surface, have recently seen an increase in fishing and other activities, such as deep-sea mining. To protect the biodiversity of this vast environment, delegates attending a meeting currently underway in New York are negotiating for a new international treaty, an addition to the United Nations Convention on the Law of the Sea.
At this, the first in a series of meetings, some activists and scientists are urging the United Nations to discuss regulating, and perhaps even banning,* fishing and other activities on the high seas.
Currently, high-seas fishing is mainly managed by regional organizations, such as the Western and Central Pacific Fisheries Commission. But some scientists and conservationists say a global agreement is needed to protect this critical habitat from destructive activities. Deep-sea fishing often involves bottom trawling, which can kill life on the seafloor, threatening, for example, deep-water coral ecosystems. By-catch is a problem, too, and the lack of adequate regulation and enforcement also threatens vulnerable species. While stocks of some target fish such as tuna remain mostly healthy, some are overfished.
But some scientists and fisheries experts are concerned that restricting high-seas fishing will strain an already stretched global food supply and are questioning any fisheries restrictions.
A new study, however, suggests that prohibiting fishing wouldn’t affect the world’s seafood supply much at all.
“If you’re worried about food security as a reason not to limit access to the high seas, your concerns are unfounded,” says Laurenne Schiller, a doctoral candidate at Dalhousie University in Nova Scotia, whose recent analysis of global fisheries data shows that high-seas fishing accounts for about 4.32 million tonnes of seafood annually—just 2.4 percent of global seafood production (including farmed and freshwater sources).
Not only is that a relatively small slice of the world’s demand, Schiller says, but most of the catch goes to wealthier nations, which aren’t starved for protein.
But not everyone agrees with these conclusions. The study paints a picture that the catch from the high seas is largely comprised of luxury goods such as bluefin and bigeye tuna, says Ray Hilborn, an ecologist at the University of Washington. “Fish caught on the high seas aren’t all high-end fish destined for rich people.”
In fact, he says, the majority of high-seas fish are relatively low-end, such as skipjack tuna, which is canned and a source of inexpensive protein. Restricting high-seas fishing might just send people searching for cheap protein elsewhere, he says—shifting, rather than reducing, the damage done to ecosystems.
In a blog post responding to Schiller’s research (on a site for which Hilborn is the editor in chief), Johann Bell, the senior director of Pacific tuna fisheries at the nonprofit Conservation International, points out that in some lower-income countries, such as Pacific Island nations, people depend on canned tuna that comes from the high seas.
But the study’s conclusion, says Schiller, isn’t that all high-seas catch is expensive seafood. It’s that most of the catch—even canned tuna—ends up in wealthier countries, including Japan, the United States, and Europe, where, in principle, even low-income people have alternatives for inexpensive protein, such as legumes.
The study is the latest in a series of recent papers suggesting that eliminating or restricting high-seas fishing would not have a major impact on food security or economies. For example, one study published earlier this year found that most high-seas fishing is propped up by government subsidies, without which it would not make economic sense to fish more than half of the high-seas fishing grounds.
Some researchers have suggested that restricting high-seas fishing would allow stocks of some migratory species to grow. These fish could then move into countries’ domestic waters, boosting production. But a 2016 analysis by Louise Teh, a fisheries researcher at the University of British Columbia, found that a ban wouldn’t improve food security in low-income countries by much. Still, Schiller’s new paper complements this study, says Teh, in showing that while a ban on fishing would likely protect biodiversity in the high seas, it wouldn’t have much of an impact on food security.
*Correction: An earlier version of this article implied that the current intergovernmental conference on the United Nations Convention on the Law of the Sea is discussing a fisheries ban on the high seas. While this is a proposal being advocated by some scientists and activists, it is not one that is currently under discussion.