China wants to restore the sea with high-tech marine ranches

Chinese universities are world leaders in applied sciences, from agricultural research to materials science. But fundamental questions aren’t always easy to answer in China’s “quite unique” research and development environment, says Neil Loneragan, president of the Malaysia-based Asian Fisheries Society and a professor emeritus of marine science at Murdoch University in Australia. 

The central government’s controlling influence on the development of ranching, Loneragan says, means researchers must walk a tightrope between their two bosses: the academic supervisor and the party chief. Marine biologists want to understand the basics, “but researchers would have to spin that so that it’s demonstrating economic returns to industry and, hence, the benefits to the government from investment,” he says. 

Many efforts aim to address known problems in the life cycles of captive-bred fish, such as inadequate breeding rates or the tough survival odds for young fish when they reach the ocean. Studies have shown that fish in these early life stages are particularly vulnerable to environmental fluctuations like storms and recent ocean heat waves. 

One of the most radical solutions, which Zhongxin Wu is testing, would improve their fitness before they’re released from breeding tanks into the wild. Currently, Wu says, fish are simply scooped up in oxygenated plastic bags and turned loose in ocean nurseries, but there it becomes apparent that many are weak or lacking in survival skills. In response, his team is developing a set of “wild training” tools. “The main method is swimming training,” he says. In effect, the juvenile fish are forced to swim against a current, on a sort of aquatic treadmill, to help acclimate them to the demands of the wild. Another technique, he says, involves changing the water temperature and introducing some other species to prepare them for seagrass and kelp forests they’ll meet in the world outside.

Wu says better methods of habitat enhancement have the greatest potential to increase the effectiveness of marine ranching. Today, most ranches create undersea environments using precast-con­crete structures that are installed under 20 meters of water, often with a rough surface to support the growth of coral or algae. The typical Chinese ranch aims for 30,000 cubic meters of artificial reefs; in the conservation-­focused ranching area around Wuzhizhou Island, for instance, 1,000 cast-concrete reef structures were dropped around the tropical island’s shores. Fish populations have multiplied tenfold in the last decade.