Seaweeds in the World Today


Seaweed farming as we think of it today was virtually non-existent prior to the 20th century. Aside from a few extensive crop enhancementImproving the quality and yield of crops through various methods. strategies being used in Japan and basic ideas for seaweed raft culture in China, commercial seaweed cultivation was all but a pipe dream.

Enter Dr. C. K. Tseng and his team of researchers at the Chinese Institute of Oceanology in 1950. Using basic and applied research on seaweed cultivation– including breedingThe act of controlling the mating of animals. and seedingThe act of producing or planting seeds. seaweeds in a nursery setting– Tseng and his team developed a systematic vision of a highly productive seaweed industry in China. Fueled by demand for high quality food and raw materials for the chemical industry, the Chinese seaweed industry expanded rapidly during the 1960s, 70s, and 80s, to form the first and largest commercial seaweed aquaculture industry in the world. To this day, China continues to boast the largest farmed seaweed industry globally, producing over 50% of the world’s seaweed supply.

Following Tseng’s early innovations, significant research and development continued to launch the commercialization of new species and farming techniques. Notably, the work of Kathleen Drew-Baker– a pioneering female scientist whose research on the lifecycle of nori in the 1950’s allowed for breakthrough advances in the cultivation of this highly valuable species. To this day, Drew-Baker is still celebrated in Japan each year on April 14th as the “Mother of the Sea” for her discoveries on seaweed.

Image credit: 365 Women in Botany

How much seaweed is being farmed in the top producing countries?

tooltip text

1. China

20.8 million metric tons (2022)

3. South Korea

1.8 million metric tons (2022)

5. Japan

0.4 million metric tons (2022)

2. Indonesia

9.6 million metric tons (2022)

4. Philippines

1.5 million metric tons (2022)

East and Southeast Asian nations are the top producers of seaweed in the world. China alone produces more than 50% of seaweed– nearly all using aquaculture. 

A few important questions to ask ourselves about the development of seaweed aquaculture are:

  1. What seaweeds are people farming?
  2. How are people farming seaweed?
  3. What are people doing with farmed seaweed when it comes out of the water? 

What seaweeds do people farm?

The variety of seaweeds that people farm in any given location is based first and foremost on the environment. What is the local water temperature? What native species of seaweed inhabit the area? Is the water calm or rough? Depending on a combination of these ecological and environmental factors, different locations are suited to growing certain species of seaweed rather than others.

Prominent Global Seaweed Species and Their Growing Conditions


Grows in deeper waters up to 10 meters with currents between 0.2 and 1 m/s. Prefers water temperature between 2 and 20 degrees Celcius.


Image credit:


Grows in shallow, sheltered environments with little to no current. Prefers warm water temeratures of 15 to 30 degrees Celcius. Can tolerate high salinity (up to 50 ppt). 


Image credit: Seaweed Insights


Grows in sheltered sites with varied depths. Prefers cold water temperatures below 10 degrees Celcius.


Image credit:


Grows in shallower water with moderate water exchange. Prefer warm water temperatures of 27 to 30 degrees Celcius.


Image credit: ORRAA

So in response to our first question, what seaweeds are people farming?, the answer varies by location. In China, the top species of farmed seaweed is Saccharina japonica, a cold-water variety of brown kelp commonly known as Kombu. Meanwhile, in the tropical waters of Indonesia, the top aquacultured seaweeds are the Eucheumatoids, which include the taxa Eucheuma and Kappaphycus, are warm-water, red algae commonly known as sea moss. Both Saccharina japonica and the Eucheumatoids grace the list of top globally produced algaes, taking first and second slot respectively.

Table credit: FAO SOFIA

However, as neither of these species are native to the North Atlantic, we do not farm them here in Maine. Instead, the top species of cultivated seaweed along the northeastern coast of the United States is the native brown kelp Saccharina latissima, widely known as sugar kelpBrown algae, found in the north Atlantic, north Pacific, and Arctic Oceans and is commonly farmed in these areas.. This cold-water species is closely related to Saccharina japonica (Kombu) and can be used in many of the same dishes. Another species farmed along the coast of Maine is Alaria esculenta– or winged kelpBrown algae that is grown and traditionally eaten in the North Atlantic in Northern Europe.. Winged kelp is a brown algae species that serves as the Atlantic equivalent of wakame (the Pacific version is Undaria pinnatifida). Wakame is most commonly used in Asian style soups and salads.

Sugar kelp

Saccharina latissima, the most commonly farmed seaweed species in Maine. Sugar kelp grows in cold temperatures (10 to 15 degrees Celcius) and can reach up to several meters in length.


Image credit: Maine Coast Sea Vegetables

Winged kelp

Alaria esculenta, another species farmed in Maine. Winged kelp grows in cold temperatures (10 to 15 degrees Celcius, preferably at the lower end of the range) and can reach two to three meters long.


Image credit: Seaweed Solutions

Skinny kelp

Saccharina angustissima, a sub-species of sugar kelp (Saccharina latissima) is farmed in Maine and shares similar growing characteristics to sugar kelp. Skinny kelp grows in cold temperatures (10 to 15 degrees Celcius) and can reach several meters in length.


Image credit: Atlantic Sea Farms

How are people farming seaweed?

Knowing what seaweeds people are growing brings us to our next question, how are people farming seaweed? Again, the answer here is going to depend; across the world, a variety of cultivation methods exist for diverse seaweeds which include short and bushy red algae, long and lasagna-like brown algae, and fine, lettuce-y green algae– just to name a few! 

Each of the species in these categories has its own environmental needs for growth and reproduction, so it’s not surprising that people have developed various seaweed cultivation methods. From flow-through seawater tanks on land to grow red seaweeds in California to floating rafts with nets full of Nori in Japan to experimental off-shore long-lines for kelp in the Faroe Islands, there are many options for seaweed aquaculture. 

Explore different farm equipment based on seaweed species

Seaweed Insights is a great resource where you can learn about global seaweed farming, including how farms are designed based on the species of interest. This website focuses on the five most farmed seaweed varieties globablly. Although the aquaculture methods discussed here are not necessarily in the United States, they can still be valuable to people exploring the idea of farming seaweed in Maine. 

A video (1:58) about nori production in Japan from seed to sushi. Video Credit: Yamamotoyama. Available on YouTube:

In Maine, farmed sugar kelp and winged kelp begin their lives in a seaweed nurseryPlace that produces seaweed seed to help support the seaweed aquaculture industry.. Seaweed nurseries are land-based facilities where kelp is grown from its microscopic stage to a heartier, juvenile stage in tank systems with seawater, light, and nutrients. Once the juvenile kelp is a few millimeters long, farmers transfer the kelp to the ocean where they use long-linesType of aquaculture system where the cultured species is suspended in the water column from a floating line that is anchored to the seafloor at the ends. to grow the kelp to harvest size.

A video (3:24) featuring Maine seaweed farmers who work with the company Atlantic Sea Farms. Video Credit: Atlantic Sea Farms. Available on YouTube:

Seaweed’s uses in the world today

So now that we have an idea of what seaweeds people farm and how they cultivate it, we are left with one final question: what are people doing with farmed seaweed when it comes out of the water? And the answer, of course, depends: macroalgae are a diverse group of organisms with different chemical properties depending on species, time of collection, geographic region of growth, and various other environmental conditions. This array of chemical properties make seaweeds useful for a number of commercial purposes, including: 

  1. Human food and food additives
  2. Agricultural fertilizers
  3. Animal feed
  4. Cosmetics
  5. Pharmaceuticals
  6. Nutrient bioremediation

In the previous section we covered the nutritional benefits of eating seaweed, but did you know that you’ve probably been consuming seaweed in more ways than just traditional foods like sushi and seaweed salad? Common extracts like carrageenanA substance extracted from red and purple seaweeds that is used as a thickening agent., agarA gelatinous substance obtained from various kinds of red seaweed and used in biological culture media and as a thickener for food., and alginateCompound found in brown algae; used as a thinkener, binder or lubricant.are gathered from seaweeds and used as texture stabilizers in a number of foods. For example, lots of dairy products like ice cream, yogurt, and chocolate milk contain seaweed extracts to help maintain their creamy textures. Many baby food formulas even have seaweed extracts!

Apart from being used in foods, these seaweed extracts (known as phycocolloidsA gum-like substance that is made from seaweed.) are also used as stabilizers in cosmetic products like skin lotion, shampoo, and make-up, and pharmaceutical products like toothpaste and medications.

Beyond these applications, seaweed is being explored for its potential uses as a substitute for petroleum-based products including plastic and fuel. Maine-based companies are even interested in utilizing seaweed as replacements for PFASLarge complex group of synthetic chemicals that have been used in consumer products since the 1950's and are not easily biodegradable.-containing food packaging and synthetic twines used in the seaweed cultivation process.

A video (8:36) about producing plastic subsitutes from seaweed-based materials. Video Credit: Business Insider. Available on YouTube:

With so many commercial uses for seaweed in the world today, it is an exciting time to be involved in the rapidly expanding American seaweed industry. Here in Maine, we are the proud home of the first seaweed farm in the United States and the largest volume of seaweed production– farmed and wild harvested– in the country. Maine seaweed companies are at the heart of aquaculture innovation, devising new ideas for everything from growing new species of seaweed in nurseries to creating novel, value-added food products for emerging markets.

Maine Coast Sea Vegetables

Maine seaweed products from the wild harvested seaweed company Maine Coast Sea Vegetables ranging from whole dried seaweed blades to Kelp Krunch bars.

Atlantic Sea Farms

Maine seaweed products from the largest farmed seaweed company in the state, Atlantic Sea Farms, ranging from Ready-to-Eat Kelp to Sea Veggie Burgers.

Nautical Farms

Products from the farmed seaweed company Nautical Farms in Downeast Maine who grow, process, and market their own kelp.