Seaweed Farming

Seaweed cultivation has been practiced in patches in the state of Tamil Nadu since past few decades. The local fisherfolk have a hard time in making profits from this cultivation due to lack of markets and modernized techniques.

Addressing the growing importance of the culture, the Finance Minister in the budget speech on Monday  announced that five major fishing harbours will see substantial investments for modernisation and development.

“To start with, five major fishing harbours — Kochi, Chennai, Visakhapatnam, Paradip and Petuaghat — will be developed as hubs of economic activity,” she said. “We will also develop inland fishing harbours and fish-landing centres along the banks of rivers and waterways,” she added.

Seaweeds are fast-growing algae. They utilise energy from sunlight, and take up nutrients and carbon dioxide from the seawater. Scientists suggest seaweed could help fight climate change and offset carbon emissions.

The main food species grown by aquaculture in Japan, China and Korea include GelidiumPterocladiaPorphyra, and Laminaria. Seaweed farming has frequently been developed as an alternative to improve economic conditions and to reduce fishing pressure and overexploited fisheries. Seaweeds have been harvested throughout the world as a food source as well as an export commodity for production of agar and carrageenan products. They are widely used in the food industry, for their gelling, thickening, and stabilizing properties. Their main application is in dairy and meat products, due to their strong binding to food proteins.

Most farmed seaweed is consumed in food, but extracts are used in a wide variety of products. Whether it is toothpaste, cosmetics, medicines or pet food, these often contain hydrocolloids derived from seaweed, which have gelling or thickening properties.

And more products are coming with the usage of seaweeds, with other firms working on textiles and plastic alternatives, including biodegradable packaging, water capsules, and drinking straws.

The best part about this practise is not just the production of carrageenans or biostimulants, but the ecosystem it creates for the coastal community. They can help farmers reduce the use of chemical fertilisers by 25-30 per cent. When paired with organic farming, they can improve the yield by 15-20 per cent.  further, in the advent of a crop undergoing stress, through a delayed monsoon, for instance, the chances of survival or revival using biostimulants are much higher.

The most prevalent method of growing seaweed in open waters is Single Rope Floating Raft (SRFR) method. It involves the building of bamboo rafts and spreading them out in the sea. The fisherfolk take four bamboo logs and tie them to make a frame or a raft, using strings and small pieces of seaweed. When the rafts are ready, they are floated on the sea. Once seaweed grows on them, in about 45 days or so, they are harvested, and the raft is replanted.

There are also numerous environmental benefits of promoting seaweed cultivation. Seaweed farming helps to preserve coral reefs by increasing diversity where the algae and seaweed have been introduced, and it also provides an added niche for local species of fish and invertebrates. Farming may be beneficial by increasing the production of herbivorous fishes and shellfish in the area.

Seaweed culture can also be used to capture, absorb, and eventually incorporate excessive nutrients into living tissue. “Nutrient bioextraction” is the preferred term for bioremediation involving cultured plants and animals. Nutrient bioextraction (also called bioharvesting) is the practice of farming and harvesting shellfish and seaweed to remove nitrogen and other nutrients from natural water bodies.

There has been considerable attention to how large-scale seaweed cultivation in the open ocean can act as a form of carbon sequestration to mitigate climate change. A number of academic studies have demonstrated that nearshore seaweed forests constitute a source of blue carbon, as seaweed detritus is carried by wave currents into the middle and deep ocean thereby sequestering carbon.

It has therefore been suggested that growing seaweeds at scale can have a significant impact on climate change. According to one study, covering 9% of the world’s oceans with kelp forests “could produce sufficient biomethane to replace all of today’s needs in fossil fuel energy, while removing 53 billion tons of CO2 per year from the atmosphere, restoring pre-industrial levels”.

As well as climate change mitigation, seaweed farming may be an initial step towards adapting to inevitable environmental constraints that may arise as a result of climate change in the near future. These include essential shoreline protection through the dissipation of wave energy, especially important to mangrove coasts. Carbon dioxyde intake would lower pH locally which will be highly beneficial to calcifiers like crustaceans or in preventing the irreversibility of coral bleaching. Finally, seaweed farming would provide a strong oxygen input to coastal waters, thus countering the effects of ocean deoxygenation through the rising ocean temperature .


Source- BBC world, the Hindu, the better India

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