Seaweed Mariculture: Scope and
Venkatesh R Thakur, Bhakti Peje
The marine ecosystem is one of the richest ecosystems among all.
Marine algae, commonly known as seaweeds are one of the major
potential living as well renewable resources of the oceans. Seaweed
resources available around the world include more than 1000 species,
from which only a hundred species are being commercially used.
Seaweeds are mainly utilized in phycocolloid industries, but many
edible types of seaweed are rich in proteins, vitamins, minerals and
trace metals. In the past few decades, the research in the marine
areas has yielded vast knowledge on seaweed utilization. The major
utilization of the seaweeds is in phycocolloid industries, for
extraction of agar (Gelidiella, Gracilaria), alginate (kelps,
Sargassum), and carrageenan (Eucheuma, Chondrus, Hypnea).
Apart from this, other uses such as fertilizer, non-conventional
source of energy, bioactive compounds, etc.
The increasing demand of the raw material required for phycocolloid
production such as agar, alginate and carrageenans leads to only one
direction and that is large scale cultivation of these species. In
many places, so far the natural harvest used to be the source. The
cultivation of seaweeds involving several protocols such as seeding,
site selection, laying out nets in the field etc.
Seaweeds are an untapped source of income from the seas, which has
been ignored. In India, with the advent of Kappaphycus
cultivation along the Tamilnadu coast, some awareness has been
created. However, the local communities, though little importance is
known traditionally, remain oblivious to this treasure in their
seaweed production and trade
Currently there are 42 countries in the world with reports of
commercial seaweed activity. China holds first rank in seaweed
production, with Laminaria sp. accounting for most of its
production, followed by North Korea, South Korea, Japan, Philippines,
Chile, Norway, Indonesia, USA and India. These top ten countries
contribute about 95% of the world's commercial seaweed volume. About
90% seaweed production comes from culture based practices. The most
cultivated seaweed is the kelp Laminaria japonica, which alone
accounts for over 60% of the total cultured seaweed production while
Porphyra, Kappaphycus, Undaria, Eucheuma and
Gracilaria make up most of the rest to a total of 99%. The
most valuable crop is the red alga Nori (Porphyra species,
mainly Porphyra yezzoensis), used as food in Japan, China and
According to FAO, between 1981 and 2000, world production of aquatic
plants increased from 3.2 million tons to nearly 10.1 million tons
(wet weight), upholding US $6 billion world trade in 2000, compared
to US $ 250 million trade in 1990. The contribution of cultured
seaweeds is 15% of total global aquaculture volume (45,715,559 tons)
or nearly 5% of total volume of world fisheries production
(141,798,778 tons) for 2000. The seaweeds that are most exploited for
culture are the brown algae with 4,906,280 tons (71% of total
production) followed by the red algae (1,927,917 tons) and a small
amount of green algae (33,700 tons). East and South-East Asian
countries contribute almost 99% cultured production, with half of the
production (3 million tons) supplied by China. Most output is used
domestically for food, but there is a growing international trade.
The Porphyra cultivation in Japan is the biggest seaweed
industry, with a turnover of more than US $1.8 billion per annum.
Total EU imports of seaweed in 2001 amounted to 61,000 metric tons
with the Philippines, Chile and Indonesia as the biggest suppliers.
Significant quantities of Eucheuma are exported by the Philippines,
Tanzania and Indonesia to USA, Denmark and Japan. The Seaweeds are
macrophytic algae, a primitive type of plants lacking true roots,
stems and leaves. Most seaweeds belong to one of three divisions -
the Chlorophyta (green algae), the Phaeophyta (brown algae) and the
Rhodophyta (red algae). There are about 900 species of green seaweed,
4000 red species and 1500 brown species found in nature1. The
greatest variety of red seaweeds is found in subtropical and tropical
waters, while brown seaweeds are more common in cooler, temperate
Some 221 species of seaweed are utilized commercially. Of these,
about 145 species are used for food and 110 species for phycocolloid
production (eg. agar). Seaweed has been a staple food in Japan and
China for a very long time. The green seaweeds Enteromorpha, Ulva,
Caulerpa and Codium are utilized exclusively as a source of food.
These are often eaten as fresh salads or cooked as vegetables along
with rice. Porphyra (Nori), Laminaria (Kombu) and Undaria (Wakame)
are used for making fish and meat dishes as well as soups and
accompaniments. Agar-agar, agarose and carrageenan are commercially
extracted from red seaweeds and find extensive use in many
The greatest use of agar is in association with food preparation and
in the pharmaceutical industry as a laxative or as an outer cover of
capsules. With the advent of modern molecular biology and genetic
engineering, agar gums producing an 'agarose' factor are used
extensively in electrophoresis in most laboratories around the world.
Philippines accounts for nearly 80% of the world's total Eucheuma
cottonii production of 1,300,000 tons, roughly 35% of which is traded
in dried form. It supply 14% of the world's total raw seaweed
production and holds first rank as producers of semi-refined
carrageenan, contributing close to 60% of the world market.
resources of India
Seaweeds grow abundantly along the Tamil Nadu and Gujarat coasts and
around Lakshadweep and Andaman and Nicobar islands. There are also
rich seaweed beds around Mumbai, Ratnagiri, Goa, Karwar, Varkala,
Vizhinjam and Pulicat in Tamil Nadu and Chilka in Orissa. Out of
approximately 700 species of marine algae found in both inter-tidal
and deep water regions of the Indian coast, nearly 60 species are
commercially important. Agar yielding red seaweeds such as Gelidiella
acerosa and Gracilaria sp. Are collected throughout the year while
algin yielding brown algae such as Sargassum and Turbinaria are
collected seasonally from August to anuary on Southern coast.
A standing crop of 16,000 tons of Sargassum and Turbinaria has been
reported from Indian waters. The surveys carried out by Central Salt
and Marine and Chemical Research Institute (CSMCRI), Central Marine
Fisheries Research Institute (CMFRI) and other research organizations
have revealed vast seaweed resources along the coastal belts of South
India. On the West Coast, especially in the state of Gujarat,
abundant seaweed resources are present on the intertidal and subtidal
regions. These resourceshave great potential for the development of
seaweed-based industries in India.
Large-scale seaweed mariculture is carried out only in Asia, where
there is a high demand for seaweed products and burgeoning
populations to create market growth. Cultivation of seaweeds in Asia
is a relatively low-technology business in that the whole, attached
plants are placed in the sea and there is a high labor content in the
operation. Except for the large kelp harvesters of Southern
California and Baja California or in Philippines and Taiwan Province
of China, most seaweed are grown or harvested from wild stocks using
manual techniques. The demand from the phycocolloid industry of India
is great but the present production from natural habitats is very low
and insufficient to cater to the needs of the local industry.
This gap between the demand and supply can be bridged through
mariculture practices for seaweeds by cultivating the useful species
on a commercial scale. Continuous supply, improved yield and quality
as well as conservation of natural seaweeds beds are some of the
important advantages of seaweed mariculture. Laminaria Brown Japan
Kombu China Hai Dai Japan Nori / Amanori / Hoshinori China Zicai
Korea Kim Porphyra Red UK (Wales) Purple laver / Laver bread Undaria
stipes Japan Wakame Undaria pinnatifida Brown China Quindai cai
Scotland Dulse Ireland Dillisk Rhodymenia palmate Palmaria palmate
Red Iceland Sol Chondrus crispus Red Europe Irish Moss / Carraghean
Asparogopsis taxiformis Red Hawaii Limu kohu Misc. sp. - Hawaii Limu.
1. The major problems in the seaweed industry include
overexploitation leading to a scarcity of raw material, poor quality
raw material, labor shortages during the paddy harvesting and
transplanting season, lack of technology to improve processed product
quality, and a lack of information on new and alternative sources of
2. Despite the great number of sheltered bays and lagoons suitable
for mariculture, no large-scale attempts to grow seaweed have been
made in India so far.
3. Efforts are needed to increase production through improving
harvesting techniques, removal of competing species, creation of
artificial habitats and seeding of cleared areas. As the technology
for reliable methods for the cultivation of different commercially
important seedstocks and their improvement has either already been
developed or presently being in research, it needs to be disseminated
effectively to the target community.
4. Extensive surveys need to be conducted to identify suitable sites
for large-scale seaweed culture. There is great potential for the
agarophyte cultivation because of its low availability from the wild
stock due to over-exploitation.
5. Many edible seaweed species are available on the Indian coast;
attempts should be made to develop products suitable for the Indian
palate and to popularize the same amongst the public.
6. With regard to pharmaceutical substances, heparin analogues
(heparinoids) that are inhibitory to thrombin activities have been
reported from Chlorophyta of Indian coasts; this and many other
important types of seaweed are available on Indian coast that can be
utilized for production of many important pharmaceutical products
through extraction of bioactive compounds.
7. Attention should also be given towards developing hybrid species
with superior growth and nutritional characteristics, as the same has
been proved successful in countries like Japan.
8. Rather opting for high-volume, low-value seaweeds, culture of
highvalue seaweeds should be aimed for, as part of integrated coastal
and national development programmes.
9. Seaweed polyculture in association with molluscs and fishes seems
to have good prospects to increase harvest and profits.
10. Pond and canal culture of seaweeds (e.g. Gracilaria) in shrimp
farming areas can help to treat effluent water.
11. The problem of eutrophication of culture ponds due to overfeeding
and excreta released by fish/shrimp can be tackled by culturing
seaweeds in such ponds. Out of estimated around US $3 billion global
phycocolloid and biochemical business, India's share is meager.
12. We can surely grab a bigger part in this lucrative business with
sincere efforts towards large-scale cultivation of commercially
important species and processing.
13. To facilitate this, more technologically sophisticated extraction
plants with easy access to markets and marketing.
Dawes C. J. (1981) Marine Botany. John Wiley & Sons, New York.
Chapman V. J. (1970) Seaweed and their uses. Second edition, Methuen
& Co. Ltd., London.
FAO (2002) Status of world fisheries and aquaculture. Food and
Agricultural Organization of United Nations, Rome, Italy.
Kaliaperumal N. (1992) Seaweed culture. In:
Handbook of Aquafarming.
Seafood — Fish — Crustacea
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