Last week the Permanent Court of Arbitration in The Hague ruled overwhelmingly in favor of the Philippines in its case against China’s South China Sea (SCS) claims. The nearly 500 page ruling undercut Beijing’s claims to control all the land features and water inside China’s nine-dash line and concluded that the disputed land features are either rocks that generate small (12 nautical miles) territorial seas or low-tide elevations that convey no exclusive rights to exploit resources. Although the ruling—and much of the surrounding analysis—has necessarily placed considerable emphasis on sovereignty disputes in the SCS, less attention has been given to the underlying incentives that drive claimant positions and behaviors.

Given its power and recent assertiveness in the South China Sea, China’s interests deserve special attention. Aside from enlarging China’s security perimeter, China’s regional interests can be roughly lumped into three “P”s—politics, petroleum, and proteins (fish). The last of these interests, competition over dwindling SCS fisheries, may be most consequential in driving competition, but has not received sufficient analytic attention.

Although the SCS covers only 2.5 percent of the Earth’s surface, it is home to some of the world’s richest reef systems and over 3,000 indigenous and migratory fish species, comprising some 12 percent of the total global fish catch. Unfortunately, the region’s fisheries are in serious jeopardy. As of 2008, virtually all SCS fishery stocks are collapsed (roughly 25 percent), over-exploited (roughly 25 percent), or fully-exploited (roughly 50 percent). The situation is only worsening.

The most important aspect of the Spratly Island disputes is not oil or sovereignty—it is whether or not SCS fish continue to appear on Asia’s menus. Four trends in particular are important: sustainability, economic importance, rising demand, and declining access.