POTENTIAL FOR EUCHEUMA “COTTONII” SEAWEED
FARMING IN THE KINGDOM OF TONGA
Field Document No.18
| POTENTIAL FOR EUCHEUMA “COTTONII” SEAWEED
FARMING IN THE KINGDOM OF TONGA |
| TABLE OF CONTENTS |
by
DAVID LUXTON
Seaweed Specialist
1999
SOUTH PACIFIC AQUACULTURE DEVELOPMENT PROJECT (PHASE II) FOOD AND AGRICULTURE ORGANISATION OF THE UNITED NATIONS (GCP/RAS/116/JPN)
Suva, Fiji
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PREFACE
The History of Cottonii in the Kingdom of Tonga
HA'APAI GROUP (population 8350)
NIUATOPUTAPU (population 1160)
SEAWEED DEVELOPMENT PROGRAMME - FARMING
Financial Return of Cottonii Growing at the Farm Level
Farm Inputs per Module - Capital costs for 30-line module
SEAWEED DEVELOPMENT PROGRAMME - TRADING
PROPOSED TECHNICAL ASSISTANCE PROGRAMME
1. Vava'u Group
2. Size class distribution of rabbitfish in February
3. Size class distribution of two rabbitfish species
4. Utungake Island: Vava'u Group
5. Floating long-line farming method
6. Areas suitable for floating long-line farming trials
7. Lifuka Group: Ha'apai Islands
8. Recommended farming areas on Tongatapu
9. Recommended off-bottom farming method
10. Niuatoputapu Island
11. FOB prices for Indonesian cottonii seaweed
The detailed results from earlier attempts to develop a cottonii farming industry in the Kingdom of Tonga strongly suggest that there is no potential for this activity in the northern island groups of Vava'u and Ha'apai.
In Vava'u further trials by Fisheries Division using the hanging long-line method of farming are recommended. This method is untried in Tonga, and may solve the problem of the seasonal destruction of farm stocks by juvenile rabbit fish, which previously prohibited any significant commercial farming. Trial results should also be used to determine the economics of long-line farming in Vava'u.
The west coasts of Ha'apai islands are generally considered too wave-exposed to justify any new long-line farming trials. Further trials with the off-bottom constant-depth method are possible in the Lifuka Group, but rabbit fish grazing is predicted to be a significant problem.
A Fisheries Division farming trial using the off-bottom method is recommended for Niuatoputapu Island in the far north. The impact of herbivorous fish is unknown on this island, and it may be considerably less than that in Vava'u and Ha'apai.
The long-term survival and growth of cottonii in the Tongatapu lagoon indicates that there may be potential for a small export industry based on production from the coastal villages in the Nukuleka to Navutoka region, at the entrance to the lagoon. Commercially viable farming on Tongatapu can only properly be assessed by starting some family-owned and operated farms, and monitoring yields and financial returns for effort. The motivation of people to engage in farming is difficult to predict. However, a conservative farmer price of T$ 0.38 per kg. is recommended, based on estimated trading costs and current world market export prices. Data is presented which indicates that this price would provide an attractive cash income opportunity to some rural households, provided commercial growth rates were consistently obtained from off-bottom farms on Tongatapu.
To promote and assist with the start-up of commercial farms on Tongatapu it is recommended that the Government submit aid-donor proposals for a six-month input from a cottonii production expert.
Seaweed mariculture, the managed cultivation of marine plants, has been established in the eastern world for over 400 years and is associated with the use of cultivated species for food. In the western world seaweed extracts, known as phycocolloids, are used in processed foods, cosmetics, and pharmaceutical products. As new applications for seaweed extracts have developed, the demand for certain species has initiated the recent mariculture of carrageenan-bearing seaweed.
The supply of red seaweed for carrageenan manufacture was dominated until the early 1970s by the wild crop harvesting of species on the Atlantic coasts of Europe and North America. Wild Eucheuma species were also harvested from Indonesia, but the supply was limited due to over-exploitation. After ten years of research the commercial ocean farming of Eucheuma was established in the Southern Philippines in 1973, and the technology has subsequently been transferred to Indonesia, Malaysia, Tanzania, and several Pacific Island countries. The Republic of Kiribati was one of the first countries to receive farmed Eucheuma introduced from the Philippines twenty years ago, in 1977.
The principal species farmed in the Philippines today is Kappaphycus alvarezii var. tambalang, previously named as Eucheuma alvarezii, and also previously referred to as Eucheuma striatum. However, in seaweed trade this commodity is referred to as cottonii seaweed, and the trade name ‘cottonii’ is adopted in this report. The farming of a second species, Eucheuma denticulatum, followed the success of cottonii production from the Philippines. This species is known in seaweed trade as spinosum. Carrageenan is the commercial name given to the hydrocolloid extract from cottonii, spinosum, and several other seaweeds of the class Rhodophyceae. Carrageenan has numerous applications, the most important being the formation of water soluble gels.
Today the carrageenan industry consumes more than 130,000 MT of seaweed per annum, and 85% of this requirement comes from farm production in the Philippines, Indonesia and Zanzibar. Philippines production of cottonii is in excess of 80,000 MT per year. The continuing success and growth of the carrageenan industry is largely due to the development of cottonii and spinosum farming. In the Philippines it is estimated that more than 70,000 fisherfolk are directly involved in farming cottonii.
Farming cottonii seaweed has now been established as a successful industry for twenty-five years in South East Asia. The fact that prices for this commodity have never been stable has led to cyclic fluctuations in world production. At times supply has exceeded demand, and at other times demand has been higher than supply. Overall the industry has shown good sustained growth, and it is predicted to continue growing at an average rate of between 5% and 8% per annum.