Wild harvesting
Cutting seaweed from natural beds.
- Offers
- No infrastructure, low cost, consistent supply
- Watch
- Availability, boat pollution
- Best practice
- Quotas, grid rotation, leaving the young to grow
Notpla · Our feedstock
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Seaweed, explained
Where our hero ingredient comes from, why it can scale where other bio-based materials cannot, and how we buy it.
01 · A short history
A short history of seaweed
From the first photosynthesis to your ice cream.
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Deep time
Human history
3.5bnyears agoBlue bacteria invent photosynthesis
1bn+years agoThe first seaweeds appear on Earth
500myears agoGreen algae come ashore and become every land plant
14,000years agoFirst Americans eat seaweed at Monte Verde, Chile
701Japan accepts seaweed as tax
c.180050,000 Scots burn kelp to make glass and soap
1811Iodine discovered in seaweed ash
1881Seaweed's gelling extracts discovered
1916California kelp turned into gunpowder in World War I
1949Kathleen Drew-Baker unlocks nori farming
1989Zanzibar's women start farming seaweed
02 · Already everywhere
40Mtonnes of seaweed
used every year
used every year
Seaweed is already in everyday products, usually in tiny amounts, which is why you never hear about it. You had it in your toothpaste this morning.
Instead of making a toothpaste grade of seaweed, we are making a packaging grade.
Ice cream
Face masks
Beer foam
Antacids
Ketchup
Wound dressings
Shampoo
Plant milks
Toothpaste
Textile printing
Dental moulds
Pet food
On a food label, seaweed extracts are
E400E401E402E403E404E405E406E407
03 · Not one material
Seaweed is not one material
Seaweeds have evolved separately for hundreds of millions of years, so each species is made of different building blocks. Very few research centres study seaweed as deeply as land crops, so we are still scratching the surface.
Species of seaweed1
In three familiesBrown, red and green
Split by more than a billion years of separate evolution.
So the building blocks differWe match them to what packaging needs
- Heat resistance
- Grease resistance
- Formability
- Viscosity
- Transparency
- Flexibility
Herbarium specimens: Natural History Museum London, New York Botanical Garden and Museum of New Zealand Te Papa Tongarewa (CC BY 4.0), Smithsonian National Museum of Natural History and Yale Peabody Museum (CC0). Cut out from the original scans.
- Laminaria hyperborea, Natural History Museum, London (Data Portal), nhmuk-BM001216109, CC BY 4.0
- Laminaria digitata, Natural History Museum, London (Data Portal), nhmuk-BM001213350, CC BY 4.0
- Alaria esculenta, Natural History Museum, London (Data Portal), nhmuk-BM001004231, CC BY 4.0
- Alaria tenuifolia, New York Botanical Garden, William & Lynda Steere Herbarium, ny-02224237, CC BY 4.0
- Fucus distichus, New York Botanical Garden, William & Lynda Steere Herbarium, ny-02335160, CC BY 4.0
- Fucus vesiculosus, Natural History Museum, London (Data Portal), nhmuk-BM001033710, CC BY 4.0
- Nereocystis luetkeana, New York Botanical Garden, William & Lynda Steere Herbarium, ny-02257969, CC BY 4.0
- Halidrys siliquosa, Natural History Museum, London (Data Portal), nhmuk-BM001199794, CC BY 4.0
- Plocamium cartilagineum, Museum of New Zealand Te Papa Tongarewa, nmnz-A033783, CC BY 4.0
- Delesseria sanguinea, Smithsonian NMNH, US National Herbarium (Botany), us-US233800, CC0 1.0
- Delesseria sanguinea, Natural History Museum, London (Data Portal), nhmuk-BM000772039, CC BY 4.0
- Delesseria sanguinea, Yale Peabody Museum, Botany, ypm-YU.096223, CC0 1.0
- Ptilota densa, Smithsonian NMNH, US National Herbarium (Botany), us-US93948, CC0 1.0
- Ptilota densa, Yale Peabody Museum, Botany, ypm-YU.094378, CC0 1.0
- Chondrus crispus, New York Botanical Garden, William & Lynda Steere Herbarium, ny-02335158, CC BY 4.0
- Gracilaria vermiculophylla, New York Botanical Garden, William & Lynda Steere Herbarium, ny-02335051, CC BY 4.0
- Palmaria palmata, Smithsonian NMNH, US National Herbarium (Botany), us-US233605, CC0 1.0
- Porphyra purpurea, Smithsonian NMNH, US National Herbarium (Botany), us-US234019, CC0 1.0
- Porphyra purpurea, Yale Peabody Museum, Botany, ypm-YU.087375, CC0 1.0
- Ulva rigida, New York Botanical Garden, William & Lynda Steere Herbarium, ny-03909749, CC BY 4.0
- Codium fragile, Museum of New Zealand Te Papa Tongarewa, nmnz-A034961, CC BY 4.0
- Codium fragile, New York Botanical Garden, William & Lynda Steere Herbarium, ny-02335159, CC BY 4.0
- Cladophora glomerata, New York Botanical Garden, William & Lynda Steere Herbarium, ny-02137524, CC BY 4.0
- Cladophora vagabunda, Smithsonian NMNH, US National Herbarium (Botany), us-US227012, CC0 1.0
- Bryopsis pennata, Smithsonian NMNH, US National Herbarium (Botany), us-US232856, CC0 1.0
04 · How it grows
+60 cma day, for giant kelp
at peak season
at peak season
One of the fastest growing organisms on the planet, and one of its most renewable resources.
Since you opened this page, a kelp at peak growth has grown
0.00 mm
A land crop needs
Seaweed needs- FreshwaterIrrigation, in a world short of water0 L
- FertiliserSynthetic nitrogen, phosphorus and potash0 kg
- LandArable land that could grow food0 ha
- PesticideSprayed through the season0
Built into the crop, not a practice we have to enforce. That is what lets seaweed scale without creating a second problem on land.
05 · Four ways to source
Four routes, all already at scale
Seaweed grows on almost every coastline. Each geography, species and scale has a route that works best, and the four complement each other.
Farming
Growing seaweed on lines at sea.
- Offers
- Biodiversity gains, community income, scalability
- Watch
- Cost, few species domesticated so far
- Best practice
- Native species, genetic diversity, multi-trophic farms
Beach cast
Collecting what the sea washes ashore.
- Offers
- No pollution, low cost, uses biomass that would rot
- Watch
- Seasonality, sand, beach ecology
- Best practice
- Quotas and ecological monitoring
Blooms
Clearing mass growths such as Sargassum.
- Offers
- Removes a nuisance biomass, lowest cost potential
- Watch
- Heavy metals, sand, variability
- Best practice
- Verify contaminants before use
Where seaweed already happens
Tap a regionFarmingWildBeach castBlooms
Farming
East Asia
China, Korea, JapanBy far the largest producer. Kelp, nori and wakame are grown on ropes at sea, at a scale no other region matches. China alone grows more than half of the world's seaweed (FAO).
Farming
South East Asia
Indonesia, Philippines, MalaysiaWarm-water red seaweeds farmed on lines in shallow lagoons, mostly by smallholder families. Indonesia is the world's second-largest producer.
Farming
South Asia
India, Sri LankaAn emerging region. Red seaweed farming is growing along India's southern coast from a small base.
Wild harvesting
West Europe
Norway, France, Ireland, ScotlandMostly wild kelp and wrack, harvested under quotas, and home to much of the world's extraction know-how. Seaweed farms are starting up.
Wild and beach cast
West South America
Chile, PeruOne of the world's largest sources of wild brown kelp, much of it collected from beaches and rocky shores by artisanal harvesters.
Blooms
Caribbean
From the Gulf of Mexico to West AfricaSargassum washes up on these coasts every year. Today it is a clean-up cost. We see a resource.
Region photos: Global seaweed industry analysis deck. Production shares: FAO.
97%of the world's seaweed was farmed in 2020 (FAO)
Wild 3%
06 · Scale
Is there enough seaweed in the world?
The world's ocean, as squares of equal area1,517
0.066% of the ocean is one of them1
That one squarewould grow enough seaweed to replace every single-use plastic with Notpla
Seaweed does not suit every use, so this is not a claim we make. It shows how far seaweed can scale without touching land.
And extraction?
The world already makes 55,000 tonnes of brown seaweed extract a year, mostly for pharma, food, fertiliser and cosmetics. At our current inclusion rate, that would coat
568 billionfood trays a year
18,000trays every second
≈ 70trays a year for every person on Earth
<1%of our main supplier's capacity is what Notpla uses today
So neither feedstock nor extraction is the constraint. The next opportunity is dedicated packaging-grade extraction, which does not exist yet and would make seaweed coatings cheaper and more fit for purpose.
07 · Sargassum
A nuisance that could replace plastic
Sargassum is a brown seaweed that floats in open water. Since 2011 it has bloomed across the tropical Atlantic every year, fed by fertiliser runoff that rivers carry from farmland to the sea.
Sargassum belt, schematic, after USF satellite observations. Swipe the map to see West Africa.
Record biomass, 202537.5M tmeasured by satellite, and expected to keep growing
Belt length, 20255,500 mimore than twice the width of the continental United States
Countries affected30+from the Caribbean to West Africa
Clean-up cost, Caribbean$120M+a year, before any lost tourism
What it does
Left unchecked, it smothers coastal habitats and strips the water of oxygen as it rots, which kills marine life. It closes beaches and drives tourists away.
Why it is an opportunity
Coastal communities and hotels already pay to have it cleared, so the biomass carries a negative cost. We have validated that Sargassum extracts make performance coatings for food packaging, and we are working with partners across the value chain to scale its extraction.
08 · Carbon
Where the carbon goes
Seaweed is about 30% carbon by dry weight, pulled from CO₂ in seawater. Close to a tonne of CO₂ is fixed per tonne grown. Fixing is not the same as storing, so here is where it goes.
- 01 · Fixed
Taken up from seawater as it grows
Seaweed turns CO₂ dissolved in the sea into its own tissue.
- 02 · Harvested
Part becomes product
The canopy is cut. The fraction we use goes into the coating on a takeaway box.
- 03 · Released
Back to the air at end of life
When the packaging is composted, that carbon returns to the air. It is biogenic carbon from today’s cycle, unlike the fossil carbon in plastic.
- 04 · Grazed
The ocean takes the first bite
Fish help themselves before anything is harvested, so part of the carbon feeds the marine food web.
- 05 · Exported
Fragments sink, and some stays down
Currents and waves break pieces off. They sink and become sediment, and a portion is stored long term.
Upside not yet claimed in LCAs
Our claim today is the displacement of fossil-carbon plastic. The carbon that sinks and stays down is extra upside that life-cycle assessments do not count yet. The science on how much is durably stored is still settling, so we put no number on it.
09 · FAQ · Heavy metals
Why heavy metals do not carry through
No seaweed is toxic in itself, but seaweeds absorb minerals from seawater very efficiently. That can include heavy metals if they are present, so they are checked at every step.
- 01Clean water, tested biomassThe seaweed is regularly analysed. Heavy metals are low in the clean waters it comes from.
- 02Stripped during extractionA pretreatment strips the metals from the biomass. They leave with the discarded liquid.
- 03Tested against the specificationWe buy food-grade extracts from manufacturers who also supply pharma. Every batch is tested, and every shipment carries a certificate of analysis.
10 · How we buy
Supplier visit, China
A partnership to unlock impact
We know our suppliers and go and see them. Then we buy against ten principles that reward the best practice in the industry.
One holistic view of a supplier
Ten principles around one crop
Seaweed needs nothing put in, and gives back to the sea and the people who grow it. The principles hold suppliers to all four sides of that at once.
- Biodiversity upliftRestorative seaweed farms and kelp forests can support more marine life than the open water around them, depending on siting and design. Our partners need to show the data.Regular biodiversity monitoring against historical site data
- Regenerative practicesWe want to turn aquaculture from a historically extractive industry into a restorative one, without affecting the genetic diversity, structure or long-term volume of seaweed forests.Harvesting within local quotas, with full transparency
- Biosecurity protocolsOperators must be rigorous in preventing disease and the settlement of invasive species and pests, with regular monitoring and risk assessment.A documented strategy against diseases, pests and invasive species
- Pollution and wasteOur products reduce plastic waste. We do not want suppliers creating excess waste or pollution to make them.Plans in place to prevent pollution and reduce waste
- Energy efficiencyWe want to minimise the footprint of our products, so we push suppliers towards green energy and less fossil fuel.Energy records shared, with a plan to cut fossil fuel use
- Agricultural land useSeaweed is not tied to food or feed crops, and we want to keep it that way, with no food-versus-packaging trade-offs as it scales.No conflict with agricultural land use
- Social impactOur supply chain must strengthen the communities it serves and never be exploitative. Local stakeholders are engaged at every step.Legal requirements met, with no serious negative social impact
- Labour practicesEveryone in the industry should have safe, fair and non-discriminatory working conditions.Employment records in line with ILO standards
- Chemical usageSeaweed needs no inputs to grow, so we limit synthetic chemicals across the rest of the supply chain too.Chemical records kept, with a plan to reduce synthetic chemicals
- Water qualityWater is a key input in extraction. Local water quality must never be compromised. Seaweed improves water quality, and so should we.Water monitoring, and compliance with local regulations
11 · Shaping the industry
From our supply chain to the whole industry
- NowOur own Buying Principles
As the first on the market, we use our buying power to reward producers with the best practices.
- NextA coalition of willing partners
Building a coalition of organisations that buy on shared principles.
- In the futureAn independent certification
A body such as the UN or WWF creates a scheme for everyone, as FSC did for wood and paper.
Our work beyond Notpla so far
- Developed the Notpla Standard and Buying Principles from existing certifications and standards
- Connected ASC-MSC with the Global Seaweed Coalition
- Advocated at the UN Global Seaweed Initiative in Geneva for better certification
- Helped make the ASC-MSC seaweed standard more accessible to producers
- Contributed to removing royalty fees for seaweed extract producers
- Invited by the UN to take a leadership role in advancing this work
12 · Our Seaweed Advisory Network
Supported by seaweed experts across the world and industries
Nine advisers we work with regularly, across seaweed extracts, science, market intelligence and policy.
Extracts and processing
Nesha ZalesnyIMR HydrocolloidsPartner at IMR. 20+ years as a food scientist in hydrocolloids and market intelligence.
Frédéric FaureAlgilityPresident and CEO. 20+ years in seaweed extracts. Former CEO of Algaia, ex-Cargill.
David MackieMarine BiopolymersSeaweed biorefining and extraction expert with 20+ years of experience.
Science
Dr Alan CritchleyVerschuren CentreResearch fellow in applied phycology. 250+ seaweed papers, former VP Research at Acadian Seaplants.
Dr Emily KostasUniversity College LondonLecturer in sustainable biorefining of seaweed, UKRI Future Leaders Fellow.
Dr Mélanie CueffGlobal Seaweed CoalitionScientific Officer of the Global Seaweed Coalition and research engineer at CNRS.
Markets and policy
Steven HermansPhyconomyFounder of Phyconomy, which tracks data on the global seaweed industry.
Peter GreenHatch BlueRegenerative projects adviser. Author of The Paxtier Report, a seaweed market newsletter.
Vincent DoumeizelUN Global CompactSenior Adviser on Ocean and Food, co-founder of the Global Seaweed Coalition, author of The Seaweed Revolution.
13 · The literature
Do your own due diligence
Check it for yourself. These are the best independent sources on seaweed, from leading international organisations. Each covers a different question, so start with the one closest to yours.
World Bank · Aug 2023Global Seaweed: New and Emerging Markets Report
- Ten emerging seaweed markets worth up to $11.8bn by 2030
- Investment gaps, and jobs for women in coastal communities
EU Commission · Nov 2022Towards a Strong and Sustainable EU Algae Sector
- Governance and licensing for algae farming
- Research gaps and public awareness in Europe
FAO · 2018The Global Status of Seaweed Production, Trade and Utilization
- How much seaweed is farmed and harvested, by country
- Trade flows, extracts and processing technology
United Nations · Jun 2026The Third World Ocean Assessment
- State of the global ocean, with a chapter on macroalgae
- Climate, pollution and disease pressures on marine life
Go deeper
Questions we often get
Do you source seaweed from the UK?+
50,000people worked in Scotland's kelp industry around 1800, burning seaweed for glass and soap makers.
Not today. The UK resource is rich, but there is no way to turn it into the extracts our products use. The UK has no seaweed extraction plants: Scotland had them, but the industry declined from the 1970s and they have since closed. Shipping fresh seaweed to France, Norway or Spain to be extracted would make no sense on sustainability grounds.
New farms have opened in recent years, mostly supplying high-end restaurants. Industrial uses need far more scale and automation. Licensing is slow, and a seaweed farm licence takes around twice as long as one to drill for oil and gas. We hope local demand grows enough to bring the industry back.
Is a seaweed farm good for biodiversity?+
A seaweed line is habitat. Peer-reviewed work finds seaweed and shellfish farms associated with more wild marine life around them, through structured habitat, food and better recruitment (Theuerkauf et al., Reviews in Aquaculture, 2022).
The size of that effect depends on siting and farm design. That is why we ask partners for site-level monitoring data rather than accepting the claim in general.
Are there heavy metals in seaweed extracts?+
Seaweeds absorb minerals from seawater, which can include heavy metals where they are present. The biomass comes from clean waters and is tested, extraction strips the metals out, and every batch of extract is tested against the international food-additive limits: arsenic no more than 3 mg/kg and lead no more than 5 mg/kg. How it works.
Does seaweed for packaging compete with seaweed for food?+
No. We buy extracts from the same industry that already supplies food, pharma and cosmetics, and today we use less than 1% of our main supplier's capacity. On land, seaweed takes nothing from food crops at all.
Does harvesting wild seaweed harm the ecosystem?+
It can if it is done badly. Good practice is enforced quotas, grid rotation, cutting only mature plants and leaving the seabed undisturbed. Our Buying Principles require harvesting within local quotas, with full transparency on the harvesting strategy.
Is Notpla packaging carbon negative?+
We do not claim that. Our carbon claim today is the displacement of fossil-carbon plastic. Seaweed fixes carbon as it grows and some of it sinks and is stored, but the science on how much stays down is still settling, so we treat it as upside.
Can Sargassum be used safely?+
Bloom seaweed has to be checked for contaminants such as heavy metals before use. We have validated that Sargassum extracts make performance coatings for food packaging, and the same specification limits apply to any extract we buy.
Is there a sustainability certification for seaweed?+
Not one that fits industrial seaweed well yet. ASC-MSC has a seaweed standard, and we have worked with them and the Global Seaweed Coalition to make it more accessible to producers. Until a scheme matures, we buy against our own Buying Principles.
Why not grow the seaweed yourselves?+
We did not need to. More than 40 million tonnes are already grown every year, and processed by an industry with decades of know-how. We work with it to make a packaging grade of seaweed extract.
Notpla · Seaweed, explainedIllustrations made with Magnific