OCEAN'S BOUNTY: V. Krishnamurthy, algologist (right) with a seaweed farmer at Mandapam camp in Ramnad district of Tamil Nadu. — Photo: M. J. Prabu

MARINE ALGAE, commonly called seaweeds (Kadal passi in Tamil), are used in industrial and agricultural sectors.

Seaweeds are rich in vitamins and minerals and are consumed as food in various parts of the world. They grow almost like weeds in the coastal areas extending over vast stretches under water.

Abundant growth

In India, seaweeds have been found to grow abundantly in the southern coastal regions, especially in the Gulf of Mannar and Palk Bay. More than 100 species of seaweeds have been found growing in this area.

Of these, the red alga Kappaphycus is found to be ideally suited for cultivation by the coastal fishermen of Mandapam, Pamban and Thangachimadam areas of Ramanathapuram District in Tamil Nadu, according to Prof. V. Krishnamurthy, Director, Krishnamurthy Institute of Algology, Chennai.

Kappaphycus yields a substance called carrageenan, which is used in the manufacture of several food products, drugs and cosmetics. Another red alga called Gracilaria is used as raw material for the production of agar, a substance similar to carrageenan.

Loss of natural habitat

At present, industries producing agar collect algae from the wild. "By continuously collecting the wild species, the natural growth gets destroyed. To prevent this loss, fishermen's groups have been encouraged to cultivate these red algae," said Prof. Krishnamurthy.

Growing these red algae would benefit the industries, which can have a continuous supply of raw material, fetch good economic returns for the farmers and at the same time save the natural growth from being destroyed, he explained.

Growing seaweeds is an ideal vocation for the womenfolk of the fishermen community. The fishermen can also take it up as an alternative means of income when they do not venture out for fishing.

At present there are two private companies, which have entered into a buy back agreement with the farmers for marketing their produce.

Maintaining seed stock

These companies give the seedlings and the infrastructure for growing the seaweeds. After the first harvest, farmers have to retain a part of the harvested seaweeds for future seed stock.

The most common method of cultivating these seaweeds is by using the floating raft method, according to Prof. Krishnamurthy.

For making the raft, four bamboo poles of about 3 metres length are made to form a square using a rope.

Nylon wires are tied across the poles in straight lines. The bottom of the raft is covered by a fishing net. The net at the bottom prevents fishes from eating the algae.

Seaweed seedlings are then tied to the nylon wires and the raft is anchored to the sea bottom and allowed to float in the water.

In some cases, plastic drums or floats are tied to the raft to keep it afloat.

Fishermen dip the raft inside the water and splash water on the seedlings every alternate day to clear the dirt and foreign organisms accumulated on the seedlings. Absence of tides in this area ensures that the rafts are not washed away or tossed about.

"In one year about six harvests can be made and from one raft about 90 kgs of seaweeds can be harvested," he said.

Harvesting schedule

The harvested produce is then dried in the sun and sold. When planted in summer, the first harvest can be done in about 60 days and during winter, in about 45 days.

The dried produce is sold at the rate of Rs. 8.50 per kg and if fresh, it is sold at 85 paise.

Seaweed cultivation, apart from providing alternative income to the fishermen, also earns foreign exchange and opens up new vistas for entrepreneurs to invest in this enterprise, according to him.

For more information, readers can contact Prof. V. Krishnamurthy at No.9, Lady Madhavan I Cross street, Mahalingapuram, Chennai 600 034, phone: (044) 2817 1134, email: krishalg@yahoo.com

Printer friendly page  
Send this article to Friends by E-Mail