Seaweed aquaculture is a major part of China's coastal bioeconomy, yet farming space and seasonal windows are increasingly constrained in many established production areas.

To address this challenge, a research team led by Prof. PANG Shaojun from the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) has demonstrated that wakame (Undaria pinnatifida)—a kelp traditionally cultivated in temperate waters—can be grown to market size in subtropical Fujian Province using clonal sporophyte seedlings and a winter cultivation strategy.

Their findings were published in Aquaculture Reports on January 6.

In the pilot project, clonal wakame seedlings were propagated from male and female gametophyte strains of "Haibao No. 1", a nationally certified cultivar maintained at the CAS Seaweed Culture Collection Center. This clonal propagation method ensures consistent seedling quality and enables hatchery operations to be scheduled in alignment with the subtropical winter cultivation window, facilitating reliable offshore deployment.

During the winter cultivation period in Fujian, the clonal wakame exhibited rapid growth and developed into market-sized fronds—with an average length of approximately 1.9 meters by early March, according to the study. The team also evaluated different farming techniques and found that a cluster-based clipping approach yielded significantly higher biomass than an alternative method, highlighting a scalable operational solution for the industry.

Beyond growth performance, nutritional analysis revealed that the subtropically cultivated wakame blades met commercial quality standards. Notably, the study reported higher protein content and elevated levels of key umami-related amino acids, underscoring both the feasibility and market potential of the cultivation approach.

The researchers emphasize that Fujian's subtropical climate also mitigates ecological risks: summer seawater temperatures exceed the species' critical thermal threshold, preventing wakame (and kelps such as Saccharina japonica) from establishing self-sustaining wild populations locally and thus reducing the risk of naturalization. Nevertheless, the team recommends strict harvest-and-removal protocols and ongoing monitoring as cultivation scales up.

The pilot study provides field-validated evidence that the approach is technically feasible and that the harvested product meets core commercialization requirements.

"By integrating clonal seedling supply with the subtropical winter growing window, we have identified a practical pathway to expand wakame cultivation into southern China," said Dr. LI Xiaodong, first author of the study.

Full stage-covered U. pinnatifida seeldings and cultivation production cycle in north China. (a) Clonal hybrid breeding; (b) Traditional commercial cultivation sporophyte breeding. (Image by IOCAS)

U. pinnatifida under different farming methods in Fujian. a, b, cluster-clipping; c, d, individual-clipping. (Image by IOCAS)