Seaweed farming

People grow seaweed in the ocean.

Some farmers tie tiny plants to ropes. The seaweed grows on these lines.

We use seaweed for many things. It can be food for us. It can also be in skin creams. Seaweed helps the planet too. It can take in bad air.

This helps keep our world healthy.

Seaweed farming is the way people grow and harvest seaweed.

Some farmers gather it from natural beds in the sea. Other farmers control the whole life cycle of the crop. They use different ways to grow it. Some tie tiny seedlings to lines in shallow water. Others use long lines that float in deeper water.

Seaweed is very useful. People eat many kinds after they process them. Some types make agar, which is a jelly-like substance. Others make carrageenan, which is a gelling agent. These help make food and medicines. Seaweed is also used in skin creams and fuels.

Farming seaweed helps the earth. It can take in carbon from the air. This can help slow climate change. In Indonesia, seaweed farming employs about one million people. In Tanzania, most seaweed farmers are women. This work provides important money for their country. Farming can also give homes to many sea animals. However, farmers must be careful not to harm seagrass or mangroves while they work.

Seaweed farming is the practice of growing and harvesting seaweed in the ocean.

This work is very important for many people around the world. It helps improve economic conditions for coastal communities. It can also help reduce the pressure on fishing. Some seaweed types are grown for food. Others are used to make special ingredients like agar or carrageenan. Carrageenan is a gelling agent used in many products. Agar is another useful substance made from seaweed.

Seaweed is different from plants like mangroves or seagrass. It is a type of photosynthetic algae that does not have flowers.

Farmers use several different ways to grow these crops. In the Philippines, early guides suggested growing seaweed in shallow water. Farmers might tie seedlings to thin lines. These lines are often strung between stakes in the seabed. This is called an off-bottom method. Other farmers use long-line cultivation in deeper water. These floating lines are anchored to the bottom of the sea. This method is very common in North Sulawesi, Indonesia.

In some places, farming is done with a lot of manual labor. Scientists are even looking at using robots to help in deeper waters.

People have used seaweed for a very long time. Human use of seaweed goes back to the Neolithic period. In Japan, seaweed farming began as early as 1670 in Tokyo Bay. Farmers there used to throw bamboo branches into shallow water. They waited for seaweed spores to collect on the branches. Later, they moved the branches to river estuaries to help them grow. In the 1940s, Japanese farmers improved this by using synthetic nets. This change helped to double how much they could produce.

Today, seaweed farming is a huge global industry. In 2022, China was the largest producer at 58.62 percent. Indonesia was the second largest at 28.6 percent. South Korea and the Philippines also produce a lot. The global market for seaweed extracts was worth $16.5 billion in 2023. In Indonesia, seaweed farming employs about one million people. In Tanzania, 90 percent of the seaweed farmers are women. This industry provides a very important source of money for them.

Seaweed farming can also help protect our planet. It is a carbon negative crop. This means it can help fight climate change by taking carbon from the water.

Some seaweed, like giant kelp, grows very fast. It can even grow as much as a day's worth of length in one day. Seaweed farms can also create homes for many marine animals. This helps increase biodiversity in the ocean. However, farmers must be careful. They should not cut down mangroves or damage seagrass to make their farms. Doing so could hurt the water quality and the local environment.

Seaweed farming, also known as kelp farming, is the practice of cultivating and harvesting various types of seaweed.

Unlike land plants, seaweeds are photosynthetic algal organisms that do not produce flowers. This distinguishes them from other marine plants like mangroves or seagrasses. This industry is vital for global economies and environmental health. It provides food, industrial ingredients, and potential solutions for climate change.

Farmers use different methods to manage the seaweed life cycle. In the Philippines, an "off-bottom" method is common in shallow water. Farmers tie seedlings to monofilament lines, which are then strung between stakes in the substrate. In deeper waters, farmers use long-line cultivation. These floating lines are anchored to the ocean floor.

In North Sulawesi, Indonesia, these anchored long-lines are widely used for species like Saccharina and Gracilaria. While much of this work is currently low-technology and labor-intensive, researchers are exploring the use of Remotely Operated Vehicles (ROVs). These robots could install helical anchors to expand farming into unprotected, deeper waters.

Different seaweed species are grown for very specific purposes. The seven most cultivated taxa include Eucheuma spp., Kappaphycus alvarezii, Gracilaria spp., Saccharina japonica, Undaria pinnatifida, Pyropia spp., and Sargassum fusiforme. Species like Eucheuma and Kappaphycus alvarezii are highly valued for producing carrageenan, a gelling agent. Gracilaria is farmed specifically for agar. Other varieties are harvested for direct human consumption after limited processing.

This variety of use drives a massive global market. In 2023, the global seaweed extract market was valued at $16.5 billion.

History shows that humans have interacted with seaweed since the Neolithic period. Seaweed farming began in Tokyo Bay, Japan, as early as 1670. Early Japanese farmers would throw bamboo branches into shallow, muddy water. They waited for seaweed spores to collect on these branches before moving them to river estuaries. In the 1940s, Japanese farmers improved production by using synthetic nets tied to bamboo poles. This innovation effectively doubled their output. Later, in the 1950s, commercial cultivation of sea grapes (Caulerpa lentillifera) was pioneered in Cebu, Philippines.

The economic impact of seaweed is significant across many nations. As of 2022, China led global production at 58.62%, followed by Indonesia at 28.6%. South Korea and the Philippines also maintain large shares of the market. In Indonesia, seaweed farming accounts for 40% of the national fisheries output and employs roughly one million people. In Tanzania, the industry is a major source of foreign currency. Notably, 90% of seaweed farmers in Tanzania are women.

In Japan, the annual production of nori alone reaches US$2 billion.

Seaweed farming also plays a critical role in climate change mitigation. It is considered a carbon negative crop because it absorbs carbon dioxide. Commercially harvested seaweeds remove about 0.7 million tonnes of carbon from the sea every year. Some species, like the giant kelp (Macrocystis pyrifera), grow incredibly fast. It can grow as much as a day's worth of length in a single day. Some studies suggest that if 9% of the world's oceans were covered in kelp, it could remove 53 billion tons of CO2 per year. This process is part of "blue carbon" sequestration, where seaweed detritus moves to the deep ocean.

However, farmers must manage ecological risks to ensure sustainability. If farmers cut down mangroves to use as stakes, they can reduce water quality and biodiversity. Farming on top of seagrass meadows can also cause environmental damage. There is also a biosecurity risk regarding the introduction of invasive species. Because of this, regions like the UK and British Columbia only allow native seaweed varieties. When managed well, however, seaweed farms can provide habitat for marine life and help protect coral reefs. They can even assist in nutrient bioextraction, which removes excess nitrogen from the water.