Algae farm field in Indonesia.

Credit: dinozzaver / Adobe Stock

Seaweed Farming

Call to action:

Promote ocean farming by integrating seaweed and bivalves to increase wild fish stocks, absorb the pollution that leads to the formation of marine dead zones, and even reduce local ocean acidification. Growing more seaweed, in particular, will supply us with sustainable food for ourselves and our livestock and replace plastics and fuels.

Unlike agriculture on land, kelp and bivalve mariculture, sometimes called “marine permaculture,” does not require clearing land or using harmful inputs like pesticides and chemical fertilizers. Moreover, the benefits do not stop at having more highly nutritious sea vegetables and delicious protein. Farming the red algae Asparagopsis taxiformis can help us reduce methane emissions from cattle (see Asparagopsis Nexus). Kelp derivatives can help restore soil health and stimulate crop growth. Both seaweed and bivalves can help reduce runoff pollution that threatens coastal waterways and even reduce the acidity of seawater to help nearby species suffering from ocean acidification. Growing kelps at a commercial scale is also an important stepping-stone for an even more ambitious kelp-based climate solution (see Seaforestation Nexus).

Nexus Rating System^Beta

Solutions to the climate emergency have unique social and environmental effects, positive and negative. To develop a broader understanding of the solutions in Nexus, we rate each solution on five criteria.

Sources for each Nexus are graded numerically (-3 through 10), and the average is displayed as a letter grade. You can explore each source in depth by clicking “view sources” below. For more information, see our Nexus Ratings page.

Seaweed Farming

7.08

9.00

7.58

7.00

Social Justice
Culture
Women
Biodiversity
Carbon

Reference	Social Justice	Culture	Women	Biodiversity	Carbon
Seaweed as a Nature-Based Climate Solution	9.0			9.0
The Seaweed Manifesto	9.0			9.0
A New Leaf	7.0	7.0		8.0
The Climate-Friendly Vegetable You Ought to Eat	8.0
Facing Warming Waters Fishermen Are Taking Up Ocean Farming	9.0
Women Are Charting New Paths on Changing Waters	8.0		9.0
Tanzanias seaweed farmers on the frontlines of climate change	8.0	8.0	9.0
Seaweed farming for food and nutritional security climate change mitigation and adaptation and women empowerment: A review	9.0		9.0
Tropical seaweeds for human food their cultivation and its effect on biodiversity enrichment	8.0			9.0
Climate-resilient women: Seaweed farmers feed families and futures	9.0	9.0	9.0
Womens leadership in Indonesias modern seaweed processing industry	9.0		9.0
Empowering Women Boosting Economies: Seaweed Farmings Coastal Resilience Solution in Kenya and Tanzania	8.0	8.0	9.0
By cultivating seaweed Indigenous communities restore connection to the ocean	10.0	10.0		10.0
Does experimental seaweed cultivation affect benthic communities and shorebirds? Applications for extensive aquaculture	7.0			7.0
The Women-Led Indigenous-Owned Kelp Farm Restoring Long Islands Waters	9.0	8.0	8.0	8.0
Couples vision grows First Nations seaweed knowledge and business	9.0	9.0
In seaweed climate capitalists see green	1.0	1.0
Reclaiming Native Knowledges Through Kelp Farming in Cordova Alaska	8.0	8.0		8.0
Reducing global land-use pressures with seaweed farming	7.0			5.0
The Environmental Risks Associated With the Development of Seaweed Farming in Europe - Prioritizing Key Knowledge Gaps				6.0
Should Seaweed Farming be Better Regulated?	6.0	5.0
The Ocean Farmers Trying to Save the World With Seaweed	7.0	7.0		6.0
The role of women in seaweed aquaculture in the Western Indian Ocean and South-East Asia	9.0		10.0
The empirical evidence for the social-ecological impacts of seaweed farming	4.0	4.0		6.0
Womens well-being and household benefits from seaweed farming in Indonesia	9.0	8.0	9.0
Seaweed Farming - Project Drawdown					7.0
Carbon Sequestration by Seaweed Farming					7.0
Exploring the Depths of Water’s Role in Climate Change					7.0
	7.8	7.1	9.0	7.6	7.0

Action Items

Individuals

Learn what makes ocean farming easier than land-based agriculture. Ocean farming of seaweed and bivalves fundamentally differs from growing crops on land in terms of its impact on the environment and people.

Only 11.4% of the Earth’s surface is suitable for crops or grazing, and only 3.4% is arable, compared to 70% of the Earth covered in oceans. Plus, there’s stiff competition for land between the needs for agriculture, buildings and roads, renewable energy production, and nature. Ocean farms avoid that competition for space.
Ocean farming of kelp also creates a useful habitat for a variety of species, from sea otters to squid. In the Pacific Northwest, the recovery of kelp forests led to a dramatic increase in salmon, cod, and rockfish populations.
On land, there are limits on available freshwater, and crops often need fertilizers and pesticides to survive, even though they cause major issues with pollution, have health consequences for people, and are linked to huge carbon footprints. None of these limitations exist in the coastal settings where ocean farming is set to take off.
Unlike farms on land, which can cause negative impacts on surrounding natural landscapes, growing seaweed and bivalves can benefit nearby marine ecosystems, from reversing ocean acidification in the surrounding water to removing excess nutrients that can bleach coral reefs.
The Seaweed as a Nature-Based Climate Solution vision statement produced by the Ocean Stewardship Coalition provides a useful overview of the role ocean farming can play going forward in addressing climate change.

Find seaweed products from marine permaculture farms. Despite a long history of cultivation by various groups, including Alaska natives, Hawaiians, and even early twentieth-century Californians, the resurgence of interest in seaweed cultivation in much of the West is in its initial shaky early stages. One of the best things you can do to support the expansion of marine permaculture is to become an early adopter of regionally-grown seaweed products. Here is a sample of companies and guides to seaweed products:

The New York Times guide to seaweed food products.
Blue Evolution is a California company selling seaweed-derived foods made from seaweed from Alaska down to Baja California and working closely with farmers to ensure they can access seed lines and other resources for establishing seaweed farms.
Dill kelp pickles and hot sauces from Barnacle Foods.
Seaweed seasonings from Daybreak Seaweed Company in the U.S. and SeaGrown in the U.K.
Kelp burgers and jerky from Akua.
Kelp Help, a bull-kelp-derived plant stimulant to improve soil health and crop growth from Pacific Northwest Organics.
Seaweed straws are a “hyper-compostable” alternative to plastic straws from Loliware.
Kelp plastic from Sway.
Sauce sachets, paper, and boxes from Notpla.
Liquid Kelp is a fertilizer and plant stimulant from GS Plant Foods.
Kelp powder is an ingredient for homemade soaps from Nature’s Garden.
Sargassum products, from C-Combinator,which harvests excess Sargassum from beaches in the Caribbean, where it would otherwise rot.

Learn more about Asparagopsis and seaforestation. Asparagopsis taxiformis is a type of seaweed that can reduce the methane released by cattle by 60 to 99 percent when it replaces even a few percent of their feed. Seaforestation is a term for growing new kelp forests in places that lack some or all of the conditions needed for kelp forests to grow naturally and then ensuring that much of the kelp (and the atmospheric carbon it contains) ends up thousands of feet deep on the seafloor, where the carbon will remain for more than a thousand years. See Asparagopsis Nexus and Seaforestation Nexus to learn more.

Become a seaweed farmer. There has been an explosion of interest among individuals recently in farming seaweed, especially alongside bivalves like mussels and oysters. Resources for becoming a marine permaculturist include:

GreenWave's training hub offers a zero-to-hero outline for becoming a regenerative marine farmer. With videos, infographics, and links, it walks you through what it takes in terms of initial investment, what goals to strive for, and what markets a farmer can connect to. It even discusses how some nonfood-grade seaweed can be used as feedstock for bioplastics.
The Alaska Mariculture Initiative offers a number of resources for becoming a kelp farmer in the state of Alaska.
The Pacific Seaweed Industry Association, based in Vancouver, offers training and consultations as part of their mission to promote regional seaweed farming.

Donate to or volunteer with groups on the cutting edge of ocean farming. A number of organizations working at the forefront of marine permaculture are limited in their work by a lack of funding. Organizations that could use additional financial support include:

GreenWave is a nonprofit dedicated to training and supporting new seaweed farmers in the U.S.
The Climate Foundation, an Australia-based NGO with global ambitions on the cutting edge of marine permaculture efforts, is looking for volunteers and donors.
The Running Tide Foundation (alongside their for-profit company) is working to advance marine permaculture and kelp-mediated carbon drawdown in the U.S.

Invest in ocean farming. There are a number of companies, from tiny start-ups to major players, that are seeking investments to improve the way we use ocean resources. Investable Oceans is a hub for connecting investors (especially accredited investors) to environmentally friendly and socially responsible business opportunities across the Blue Economy, including a curated list of opportunities in the fisheries and aquaculture space.

Speak up. Write an op-ed to a newspaper or social media site promoting marine permaculture or public investments in seaweed farming (including streamlining permitting processes). Here are some examples of specific calls to action:

Getting a kelp farm permitted can take up to two years of navigating the leasing and permitting agencies in Alaska and much longer in California. Consider writing your state lawmakers to ask for more streamlined processes.
Promote foods, products, or companies derived from or engaged in regenerative ocean farming through public reviews.

Follow the latest from marine permaculture advocates on social media. Accounts include:

GreenWave on Facebook and X
The Climate Foundation on Facebook and X
Running Tide on X
Seaweed Solutions on Facebook
Greenwave Aotearoa - LinkedIn

Groups

Mariculturists

Grow polycultures. Mariculturists often focus on just one crop, but evidence shows there is high value in growing crops like seaweed, oysters, mussels, and other bivalves together. These polycultures require zero inputs and can even reduce pollution from sources like finfish farms or agricultural runoff. Primers on regenerative mariculture can be found online (Sea Grant, GreenWave, NOAA).

Join a collaborative or regional association of seaweed growers. Regional networks such as the Alaska Mariculture Alliance, the Pacific Seaweed Industry Association, and GreenWave are emerging to support marine permaculturists.

Obtain ASC-MSC sustainability certification. The Aquaculture Stewardship Council and the Marine Stewardship Council partnered to create a best-practices standard for sustainably produced seaweed products. Each company that obtains this certification will pressure the industry to ensure best practices are followed for growing and harvesting seaweed in the most environmentally friendly ways possible.

Companies

Become a seaweed buyer. GreenWave’s Seaweed Source allows a variety of businesses or other entities to source seaweed from small-scale producers.

Use marine permaculture inputs for animal agriculture, bio-stimulants, plastics, cosmetics, and biofuels. Small seaweed food companies have proliferated in the West, trying to play catchup with other parts of the world with long histories of large-scale consumption of seaweed products. Bigger food corporations in the West need to get on board. But beyond food, kelp can supply more sustainable versions of a number of other products. All straws could be made out of kelp-derived bioplastics, a much more sustainable option than either petroleum-based plastics or paper. Perhaps the biggest untapped opportunity is for kelp biofuels to replace both gasoline and diesel as well as first-generation biofuels like sugarcane or corn-derived ethanol, which have large carbon footprints and compete with food crops for limited space on terrestrial farms.

Assist in the development of blue carbon markets that support regenerative seaweed farming practices. Carbon offsets and credits have been around for many years, but carbon credits from seaweed farming have not been incorporated into major carbon markets. Companies can play a key role in shaping blue carbon credits through participation in voluntary carbon markets and through net-zero pledges.

Support marine permaculture through private capital. Financial partnerships between investors, nonprofits, private companies, and the public sector can help meet climate challenges faced by vulnerable communities.

Invest in R&D for seaweed bioplastics and biofuels. The market for seaweed products will likely expand dramatically as more efficient processes are developed to turn seaweed into biodegradable plastic alternatives and truly sustainable biofuels. Getting there will require additional investments from the private sector in research and development. For example, the company Sea6 Energy recently raised $9 million for the development of a “sea combine” that would decrease the labor needed for harvesting seaweed grown commercially in Indonesia.

Governance

Pass legislation that legalizes and/or supports seaweed farming. In many states, farming seaweed was recently or is currently prohibited. But even where allowed, nascent seaweed farming efforts can use a helping hand to grow into mature industries. Some have proposed tax credits, but there are a variety of steps that could be taken. Here are some specific examples of helpful steps taken by governments that could be replicated:

The Alaska Mariculture Task Force was created by administrative order of the state’s governor. It has been instrumental in promoting seaweed farming in the state and has identified key issues that need to be addressed to put Alaska on track to make seaweed mariculture a $100 million-a-year industry by 2040.
The New York Legislature recently passed the “Kelp Bill,” allowing the commercial farming of sugar kelp in two Long Island bays that were recently opened to shellfish farming. Governor Andrew Cuomo, however, resigned before signing the bill into law.

Invest in recording Indigenous knowledge about seaweed cultivation and uses. Many coastal Indigenous communities have long histories of harvesting, cultivating, and using different types of macroalgae in the ocean. Often, this knowledge is held by elders within communities. Providing resources to carefully document and spread this form of traditional knowledge is vital for making sure it is not lost.

Enter into partnerships with universities, NGOs, and private businesses to facilitate marine permaculture work. Multistakeholder alliances are often enhanced with governmental partnerships, particularly given that the seascapes that could house marine permaculture arrays or seaweed farms are public resources managed by government entities. Compared to terrestrial crops, the cultivation of which is supported by agricultural extension and considerable research, much less is known about the basics of how, when, and where to grow seaweed. The Seaweed Manifesto points out that there is a need for further research on “Seaweed biology, genetics, and metabolomics . . . to support informed choices about species selection, breeding, disease management, sustainability, and diversity.”

Develop and harmonize standards for seaweed production and products and national and international levels. For seaweed production to reach its full potential, a clear and simple set of policies, standards, and regulations need to be established to ensure product safety, ease local permitting restrictions, and facilitate cross-border trade. Particularly useful would be the inclusion of seaweed farm suitability assessments as part of routine marine mapping exercises, as well as clear standards for seaweed-derived packaging and plastics alternatives.

Key Players

Organizations That Support Ocean Farming

GreenWave (U.S.) has a 10-year goal to provide training, tools, and support to a baseline of 10,000 farmers to catalyze the planting of regenerative ocean crops and yield meaningful economic and climate impacts.

Greenwave Aotearoa (New Zealand) is partnered with GreenWave to adapt its highly successful model.

Safe Seaweed Coalition (France) is an entity established to promote clear and universal standards and practices for safely growing the seaweed industry globally.

Pacific Seaweed Industry Association (Canada) is a non-profit, member-driven, industry association that works to develop awareness around the benefits and diverse uses for seaweed.

The Climate Foundation (U.S.) is an international organization working on large-scale climate solutions including marine permaculture.

Sea6 Energy (India) is a company developing new technologies to improve ocean farming.

The Department of Energy’s ARPA-E (Advanced Research Projects Agency-Energy) is a major funder of research into both scaling seaweed farming and deriving biofuels from seaweed, particularly through their MARINER (MacroAlgae Research Inspiring Novel Energy Resources) initiative.

Catalina Sea Ranch (U.S.) is the first ocean-farming initiative in federal waters.

Ocean Rainforest (U.S.) demonstrates the economic feasibility of commercial-scale seaweed cultivation in an offshore environment.

Cascadia Seaweed (Canada) creates seaweed-derived products for crop and cattle farmers, providing nature-based solutions toclimate change and food security.

Leaders

Bren Smith is an aquaculturist professional pioneering Regenerative Ocean Farming with his non-profit GreenWave.

Kendall Barbery holds a master’s degree in environmental science from Yale School of the Environment and developed GreenWave's training, support, and innovation programs.

Marty Odlin is the CEO and Founder of Running Tide, a company developing innovative solutions to combat climate change, such as leveraging aquaculture expertise to grow kelp.

Margaux Filippi uses data science and machine learning for sustainability and oceanography.

Ricardo Radulovich is advancing and promoting aquatic food production alternatives for development (seaweed farming, aquatic agriculture, low-trophic fish mariculture).

Julia Marsh is the CEO and Co-founder of Sway, a seaweed bioplastics company.