Coastal Aquaculture and Mariculture (2+1)

Unit 1 - Shore based aquaculture and mariculture

1.2.8. Seaweeds
Aquatic plants are a major production component of mariculture in the Asia-Pacific region. About 13.5 million tonnes of aquatic plants were produced in 2003. China is the largest producer, producing just less than 10 million tonnes. The dominant cultured species is Japanese kelp (Laminaria japonica).

There are around 200 species of seaweed used worldwide, of which around ten species are intensively cultivated, including the brown algae L. japonica and Undaria pinnatifida, the red algae Porphyra, Eucheuma, Kappaphycus and Gracilaria, and the green algae Monostrema and Enteromorpha.

Seaweeds are grown for
Direct consumption, either as food or for medicinal purposes; production of the commercially valuable polysaccharides alginate and carrageenan; used as fertilizers; and feed for other aquaculture commodities, such as abalone and sea urchins.

Production technology
Because cultured seaweeds reproduce vegetatively, seed stock is obtained from cuttings. Grow-out is undertaken using natural substrates, long-lines, rafts, nets, ponds or tanks.
Production technology for seaweeds is inexpensive and requires only simple equipment. For this reason, seaweed culture is often undertaken in relatively undeveloped areas where infrastructure may limit the development of other aquaculture commodities, for example in Pacific Island atolls. Existing technologies rely on tying individual plants to lines and are time-consuming and limit production.
Selective breeding for specific traits has been undertaken in China to improve productivity, increase iodine content and increase thermal tolerance to better meet market demands. More recently, modern genetic manipulation techniques have been used to improve temperature tolerance, increase agar or carrageenan content and increase growth rates. Improved growth and environmental tolerance of cultured strains are generally regarded as priorities for improving production and value of cultured seaweeds in the future.
Seaweed aquaculture is well suited for small-scale, household-level business operations run by people living in rural coastal communities. Seaweed fisheries are traditionally the domain of women in many Pacific Island countries, so it is a natural progression for women to be involved in seaweed farming