Seaweed 101: The Potential of Seaweed Aquaculture in the Blue Economy

Vanessa Fajans-Turner, Investable Oceans Fisheries & Aquaculture

Seaweed 101: The Potential of Seaweed Aquaculture in the Blue Economy
Courtesy of Paul Nicklen

For many North Americans, direct interaction with seaweed products has largely been limited to sushi and high-end beauty products. No longer. Over the last decade, seaweed cultivation has emerged as an area of growth and innovation, with applications ranging widely from culinary to climate solutions.

Already a multi-billion-dollar global industry1, seaweed is an ingredient in everything from food to fertilizers and medicines to fuel. In addition to its expanding product applications, seaweed is increasingly recognized as a sustainable solution for water quality improvement, carbon sequestration, and even art.

The explosion of commercial uses for seaweed has generated accelerating interest from and opportunities for investors, researchers, and policymakers. This Seaweed 101 overview was prepared by our Investable Oceans team with invaluable contributions from key leaders in the sector (thanked by name below) as a primer for those interested in learning more about this emergent pillar of the Blue Economy.

Seaweed Aquaculture: Key Takeaways

The Basics: There are over 10,000 species of seaweed globally divided across three main types: red, brown and green. The current seaweed industry farms 31 million metric tons of seaweed per year, primarily from small farms and industry. Notable exceptions are in larger-scale commercial food markets predominantly in Asia. Some seaweed will grow 30 cm/day, an impressive yield from one of the lowest man-power crops.2

Seaweed Vs. Kelp: Seaweed is an umbrella term used to describe many different marine-based species of plants and algae. Kelp is the largest subgroup of brown seaweeds, and is a non-plant (specifically, a heterokont) with unique properties that make its commercial applications distinct from other types of seaweed.

The three major groups of seaweed, which include kelp, all have significantly different biological profiles and commercial-use applications.

  • Brown kelp and other brown seaweeds (Phaeophyta) can contain double the protein of their green counterparts, currently the most widely-used type of seaweed in food products. Brown seaweed’s high protein composition means it has, among other things, significant promise as an alternative source of plant-based protein and alternative packaging material.
  • Red seaweed (Rhodophyta) has, among other things, notable potential as a salt/MSG replacement, and could be used to supplement the green seaweed market.
  • Green seaweed (Chlorophyta) has a long history of use in food products thanks to its high nutritional value. It also has a high tolerance for cultivation in the presence of pollutants.

Recent Developments

Oceans 2050 Seaweed Project
Oceans 2050 founder Alexandra Cousteau and Professor Carlos Duarte have partnered to lead efforts to quantify seaweed farming’s capacity to sequester carbon, results which will help validate and monetize the carbon sequestration impact of ocean farming.

Jeremy and Hannelore Grantham Environmental Trust (GET) and Ocean Visions Inc. (OVI) GET and OVI have partnered to identify and test technology-based ocean-climate solutions. ​

Bezos Earth Fund and WWF
Jeff Bezos’ $100M donation in 2020 to the WWF will be used for three areas of activity, one of which is “the seaweed solution.

Only One's Green Seas Journey
Started by a powerful collective of ocean change makers, the Only One platform engages audiences around the world in ocean conservation. Inspirational storytelling is at the core of this exciting new initiative, and its Green Seas Journey focuses on protecting and restoring mangroves, seagrasses, salt marshes, and yes... seaweed forests.


Commercial Potential: 85% of the seaweed harvest each year is used for human consumption3. In addition, seaweed can be found in food additives, food thickeners, medicines (Western and non-Western), animal and fish feed, cosmetics, biomass for fuel, plastics and disposable packaging, fertilizers4, a variety of health products, and even alcoholic beverages5.

Farming Basics and Industry: Seaweed farming is still labor intensive and primarily conducted on a relatively small scale with favorable economics. Low input farming means lower labor costs compared with terrestrial farms. Industrial seaweed farming continues to expand across Asia, Europe and (more slowly) the Americas. But as industrial farming expands, there may be impacts on the economics and viability of smaller operations. Data on current operations is limited, and larger entities will need to put in the legwork to understand the output and framework of regions where farming is already taking place.

Regional Trends: The geographic focal points for the cultivation of and demand for seaweed is expanding, but nascent beyond Asia. Outside of Asia, the global seaweed industry is relatively underdeveloped, fragmented and regionalised in many places. Different initiatives and applications are perceived as disconnected. Pioneering companies might experience competitive relationships and there is limited sharing of good practices.”6

Asia: While there is a firmly established capacity for seaweed cultivation across Asia, the market continues to expand with new uses beyond seaweed as food (eg- seaweed’s potential as a plastic alternative). Asia may also serve as a model for global seaweed endeavors as the home of most of today’s only large-scale seaweed cultivation operations. Production in Asia is split between North Asia (Korea, Japan and China) where seaweed are used as a local food with high value added and South East Asia (Phils & Indonesia) exporting their massive red seaweed production as a commodity for the hydrocolloids industry in North America, China and Europe.

Europe: While Asia accounts for 99% of all global seaweed production, Europe currently accounts for half of the world import value (USD 1.3 billion) of seaweed-based thickeners (United Nations, 2020) alone, suggesting a market that will continue to grow exponentially as regulation and development catch among European governments. Recent developments along these lines are being spearheaded by the United Nations’ Global Compact, Lloyd's Register Foundation and the newly created Global Safe Seaweed Coalition, aimed at examining how best to shift seaweed farming on a global scale in order to minis disruption to ocean environments and ecosystems, as well as to examine the relationship between seaweed’s utility as a carbon sink, and the safety of consuming a product which readily absorbs ocean toxins.

Africa: The lack of land requirements is opening up seaweed opportunities in unlikely farming zones, and, with seaweed and kelp’s potential for carbon sequestration, this is propelling the involvement of some surprising industry leaders. Kelp Blue, run by the former XY of Shell, is working towards planting “huge underwater forests of seaweed off the coast of Namibia, covering some 70,000 hectares.” Forests of this magnitude mean big potential to address food scarcity, atmospheric carbon, and low regional job opportunities, all in one fell swoop. Seaweed is already an established industry in part of East Africa (Tanzania) for hyrocolloids.

The Americas: North American cultivation is nascent, as evidenced by the fact that the first license for a North American kelp farm was only granted in 20107. To date, expansion has been inhibited by the lack of an existing framework for permitting and licensing seaweed farm operations. Until further data develops at scale, market trends are enticing but nebulous, with real questions concerning how much seaweed product can sell beyond countries which have traditionally utilized it as a food source. The US Department of Energy has actively supported offshore seaweed cultivations over the last few years through the MARINER project, investing $50M+ to create a seaweed industry in North America. Initially mostly focused on seaweed as a source of fuel, the project has been gradually redirected to other seaweed applications.

Environmental Benefits: Seaweed is increasingly recognized for its efficacy in tackling climate change and environmental degradation. Seaweed farming has been shown to improve water quality, reduce ocean acidification, and sequester phosphorus, nitrate and carbon. Additionally, it has been known to decrease harmful, bottom-trawling fishing techniques8.

Among Seaweed’s most buzzworthy applications is its promise as a climate solution by popular publications such as Paul Hawken’s Drawdown. The scale of its impact is dependent on the scale of its cultivation. Were seaweed production to increase 40x over current levels, the World Bank predicts that “achieving a global yearly seaweed production of 500 million tons would absorb 30% of the nitrogen entering the ocean and 33% of the phosphorus used for fertilizers”9.

Environmental and Social Impacts: Possible to Mitigate but Tough to Quantify. Low data is a hurdle here, as much research is underway concerning the environmental downsides to larger-scale production. Larger ecosystems of coral, mangroves and seagrasses could be affected by larger farms10 and, when seaweed improves water quality, it does so by absorbing impurities, a phenomenon with implications for sales and usage. More data is needed, not only to examine the impacts of seaweed cultivation on local farmers and local ecosystems, but on the best way to structure an industry growing faster than the framework needed to support and grow it thoughtfully and efficiently.

Key Contributors
The Investable Oceans team extends a special thanks to the following individuals and institutions that contributed to this document’s development, particularly: Vincent Doumeizel and Lloyd’s Register Foundation, authors of the UN Global Compact’s Seaweed Manifesto, Duke University’s Center for Energy, Development, and the Global Environment (EDGE), especially Dan Vermeer, Alex and Julie Wallace, Paul Nicklen and Cristina Mittermeier, and many others.

Want to learn more about seaweed? Browse our collection of Quick Dips (short articles) and Deep Dives (longer articles) in the Investable Oceans Seaweed Zone. Please also share additional content about the growing seaweed sector with us by emailing


1S. Bernstein, PE.

2Seaweed Revolution: A Manifesto For a Sustainable Future

3S. Bernstein, PE citing Ferdouse. F. The Global Status of Seaweed Production, Trade and Utilization

4S. Bernstein, PE citing McHugh, 2003.

5Seaweed and Alcohol: Biofuel or Booze?

6Seaweed Revolution: A Manifesto For a Sustainable Future

7S. Bernstein, PE. citing Grebe et. al. 2019.

8S. Bernstein PE citing Bjerregaard et al. 2019


10Rolin, C., Inkster, R., Laing, J., Hedges, J., McEvoy, L. (2014). SEAWEED CULTIVATION MANUAL, Shetland Seaweed Growers Project 2014-16 . NAFC Marine Centre - University of the Highlands and Islands

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