An agricultural revolution at sea
Before the 1950s, China’s supply of kelp, a large brown seaweed, depended entirely on wild harvesting. The primary species, Laminaria japonica, was introduced from Japan in the late 1920s but could only grow naturally in a few cold-water areas. This scarcity had significant consequences for a population where iodine deficiency was a widespread health issue. Kelp is a rich source of iodine, and its limited availability restricted a dietary tool for preventing goiter and other related conditions. The total annual production of kelp hovered around 60 metric tons, a tiny amount for a large nation.
The Qingdao Marine Biology Laboratory, founded in 1950 and later expanded into the Institute of Oceanology, Chinese Academy of Sciences (IOCAS), addressed this problem. Led by the pioneering phycologist C.K. Tseng (Zeng Chengkui), often called the "Father of Chinese Oceanography," researchers at the station began the difficult process of domesticating a wild sea plant. Tseng and his team developed three foundational techniques. First was the floating raft method, a new form of aquaculture where kelp is attached to ropes suspended from rafts, allowing it to grow at optimal depths regardless of tides. Second, they created a system for cultivating sporelings indoors in cooled water (below 10°C) during the hot summer months when the kelp could not survive in the open sea. Finally, they devised methods for applying fertilizer directly to the raft farms in the nutrient-variable open ocean.
From tons to millions of tons
These innovations fundamentally changed kelp farming. By the early 1950s, scientists at the station successfully produced Laminaria on floating rafts, a first for the country. This success allowed cultivation to expand far beyond its limited natural habitat. Following successful experiments in 1956, kelp farms were established along the coast of Zhejiang Province, proving the seaweed could be grown in warmer southern waters. The results were dramatic. Between the 1950s and 1980s, China's annual dried kelp production exploded from about 60 to over 250,000 metric tons. Today, China is the world's largest producer of seaweed, and the industry is a part of its marine economy.
The work at Qingdao extended beyond cultivation techniques. Scientists engaged in genetic breeding, developing new strains of Laminaria and other seaweeds like Porphyra (laver). The institute today holds the CAS Mariculture Core Gene Bank, which preserves 60 species of marine algae and over 1,000 culture systems, supporting the entire aquaculture industry. The impact is economic. Seaweed farms are carbon sinks, absorbing immense amounts of CO2 from the atmosphere. They also improve water quality by filtering excess nitrogen and phosphorus. The industrial utility of seaweed extracts like alginate, used as a thickener in everything from ice cream to toothpaste, has also created a global industry based in Qingdao.