China produces over half of the global total of seaweed (12.8m tonnes), while Indonesia is responsible for 27% - 6.5m tonnes. Other major producers include the Republic of Korea and the Philippines.
With the industry rapidly evolving, the UN University's Canadian-based Institute for Water, Environment and Health, and the Scottish Association for Marine Science, a UNU associate institute, have published policy advice to the burgeoning, multi-billion dollar sector to help it avoid expensive mistakes and pursue best practices, backed by relevant case studies involving crops like bananas and shrimp.
The authors note that seaweed farms now produce more than 25m metric tonnes annually. The global value of the crop, US$6.4bn, exceeds that of the world's lemons and limes.
Most of the seaweed produced is used for human consumption, either for food, nutraceuticals of pharmaceuticals, with much of the remainder used as a nutritious additive to animal feed or as a fertiliser.
Problems of rapid expansion
"The rapid expansion of any industry, however, can result in unforeseen ecological and societal consequences," according to the authors.
Communities that come to depend on a single crop for their livelihood become highly vulnerable to a disease outbreak, as happened in the Philippines between 2011 and 2013 when a bacteria that whitens the branches of a valuable seaweed species caused a devastating loss to the communities involved, estimated at over US$310m.
The authors say the industry needs to guard against non-indigenous pests and pathogens, to promote genetic diversity of seaweed stocks and to raise awareness of mistakes in farm management practices, such as placing the cultivation nets too close together, making the crop more vulnerable to disease transfer and natural disasters.
"In addition, the illegal use of algicides / pesticides, with unknown but likely detrimental consequences for the wider marine environment, user conflicts for valuable coastal resources and rising dissatisfaction over the low gate prices for the crop can all result in negative impacts on the industry."
The experts note that increasing demands being placed on the marine environment necessitates coordination and co-operation between different users, an ecosystem-wide management approach and marine spatial planning (MSP) for aquaculture, alongside regulation to protect the wider marine environment.
Conflict resolution
According to the report, the key points for the seaweed industry come down to:
- Biosecurity -- preventing the introduction of disease and non-indigenous pests and pathogens
- Investing in risk assessment and early disease detection
- Building know-how and capacity within the sector
- Cooperative planning to anticipate and resolve conflicts between competing interests in finite coastal marine resources, and
- Establishing management policies and institutions at both national and international levels
Vladimir Smakhtin, director, UNU-INWEH said: "The seaweed industry in Asia has been growing rapidly for the best part of 60 years, but Europe has only recently woken up to the economic potential of seaweed cultivation. Interest in the West has been sparked by the wide range of seaweed applications, from health foods through to fuel, that can be produced in a sustainable way and has little environmental impact. As the only marine science institute to have associated institute status with the UNU, we are proud to be involved with helping to lead the discussion on this increasingly important topic."