In assessing the true impact that nations have on the seas, the team needed to look not just at what a given nation caught but also at what the citizens of that nation ate. "A country can acquire primary production by fishing, or it can acquire it by trade," Pauly says. "It is the sheer power of wealthy nations to acquire primary production that is important."
Nations with money tend to buy a lot of fish, and a lot of the fish they buy are large apex predators like tuna. Japan catches less than five million metric tons of fish a year, a 29 percent drop from 1996 to 2006. But Japan consumes nine million metric tons a year, about 582 million metric tons in primary-production terms. Though the average Chinese consumer generally eats smaller fish than the average Japanese consumer does, China's massive population gives it the world's biggest seafood print, 694 million metric tons of primary production. The U.S., with both a large population and a tendency to eat apex fish, comes in third: 348.5 million metric tons of primary production. And the size of each of these nations' seafood prints is growing. What the study points to, Pauly argues, is that these quantities are not just extremely large but also fundamentally unsustainable.
Exactly how unsustainable can be seen in global analyses of seafood trade compiled by Wilf Swartz, an economist working on SeafoodPrint. Humanity's consumption of the ocean's primary production changed dramatically from the 1950s to the early 2000s. In the 1950s much less of the ocean was being fished to meet our needs. But as affluent nations increasingly demanded apex predators, they exceeded the primary-production capacities of their exclusive economic zones, which extend up to 200 nautical miles from their coasts. As a result, more and more of the world's oceans had to be fished to keep supplies constant or growing.
Areas outside of these zones are known in nautical parlance as the high seas. These vast territories, the last global commons on Earth, are technically owned by nobody and everybody. The catch from high-seas areas has risen to nearly ten times what it was in 1950, from 1.6 million metric tons to around 13 million metric tons. A large part of that catch is high-level,high-value tuna, with its huge seafood print.
The wealthier nations that purchase most of the products of these fisheries are essentially privatizing them. Poorer countries simply cannot afford to bid for high-value species. Citizens in these nations can also lose out if their governments enter into fishing or trade agreements with wealthier nations. In these agreements local fish are sold abroad and denied to local citizens—those who arguably have the greatest need to eat them and the greatest right to claim them.