China is Building a Blue Granary

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Hanson Lu/Aerial photography of fish farms

Off the coast of Zhejiang province, an unusual vessel plies the East China Sea. It could be mistaken for a cargo ship, but there are no containers on its deck. Its track is strange: instead of running between sequential ports of call, it bounces between points at sea for months at a time. However, its movements are anything but random.

The ship’s transponder identifies it as the Guoxin 2-1. It is moving with the tidal currents, seeking water at the right temperature for the cargo in its hull: vast tanks of large yellow croaker, raised from fry in the ship’s underbelly and destined for markets and restaurants from Shanghai to Suzhou.

Farther up the coast, off southern Shandong province, a crew in a small offshore boat works to sink a concrete block. Seagrass seeds have been tucked into nooks along its sides. These men are employed by a marine ranching initiative at Rongcheng, which is assembling artificial but productive coastal reefs from the seafloor up.

Some 200 kilometers northwest of Rongcheng, in the stretch of the Yellow Sea where Chinese and South Korean exclusive economic zone claims overlap, a South Korean research vessel and its coast guard escort approach a partly submerged steel cage as tall as a twenty-story building, along with a converted rig complete with a helipad. Two Chinese coast guard cutters and a rigid inflatable boat—ostensibly civilian, though the men aboard brandish knives—block their path. They are shielding the Deep Blue 2, a salmon farm China has parked in contested waters.

These are all stories about the same thing: aquaculture—the deliberate raising and farming of aquatic organisms—and its explosive growth in China. The Guoxin 2-1, the Rongcheng marine ranch, and the Deep Blue 2 are the products of a decades-long effort by the Chinese state and a legion of private entrepreneurs to build the world’s largest aquaculture industry—and, in doing so, to begin cultivating and terraforming the open ocean. A new frontier is opening, and its implications are as vast as the water it covers.

Aquatic Origins

Chinese aquaculture began in freshwater. China was among the first regions in the world to take up the practice, with farmers raising and harvesting fish in managed ponds by around 2500 BC. Writings from 2000 BC ascribed to Da Yu, the traditional founder of the Xia dynasty, describe picking “seeds”—common carp spawn—to “plant” in small ponds, along with laws specifying exactly when fish could be harvested. State involvement is nearly as old as the industry itself.

Modern aquaculture—artificial reproduction, hatchery-based farming, selective breeding—was developed mainly in Europe, but adopted in China toward the end of the twentieth century during the Reform and Opening Up period. China is now by far the largest producer of farmed aquatic animals in the world, accounting for roughly 55 percent of global output.

As of 2023, close to 60 percent of that output came from freshwater rather than marine environments. In recent years, the Chinese Communist Party (CCP) has pushed aquaculture investment into poorer interior regions like Xinjiang. More than just a form of economic stimulus, inland aquaculture is a source of domestic food security and, increasingly, of exports.

The caviar market shows what Chinese industry can do even to a gated, high-margin luxury good. After overfishing gutted the conventional, wild supply of sturgeon in Siberia during the mid-2000s, Chinese entrepreneurs, scientists, and fortune-seekers set their sights on the industry. Dozens of aquaculture operations sprang up around colder inland lakes to raise sturgeon and harvest their valuable eggs. Farmed sturgeon production grew roughly ninefold between 2003 and 2017, and Chinese cultured caviar output climbed from 0.7 to 135 metric tons between 2006 and 2018. Wholesale prices fell by roughly 50 percent between 2012 and 2018, turning caviar into an accessible luxury, while Chinese brands like Kaluga Queen became some of the world’s largest.

The remaining 40 percent of Chinese aquaculture occurs in marine environments: nearshore enclosure farms, net pens, and specialized aquaculture vessels. Particularly of note amongst these are China’s immense near-shore oyster rope-and-raft systems. The PRC accounts for nearly 85 percent of global oyster production, but they are more than just another protein source. Each oyster is capable of filtering 50 gallons of water a day, helping to remove pollutants from Chinese coastal waters. Partnerships in the Chinese Greater Bay Area–Hong Kong, Guangzhou, Shenzhen, and the surrounding cities–are working to restore the region’s old oyster beds. Recent measures by the party-state to protect and expand coastal fisheries have set off a boom in a related practice off Fujian, Shandong, and several other coastal provinces: sea ranching.

Sea ranches are built by seeding the seafloor with...