Central Marine Fisheries Research Institute
In India, Gulf of Mannar, Gulf of Kuteh, Palk Bay, Lakshadweep and Bay islands are the important areas having considerable natural resources along the 6 100 km long coast line of the country.
About 680 species of seaweeds belonging to the groups Chlorophyta, Phaeophyta, Rhodophyta and Cyanophyta occur naturally in varying degrees of abundance in shallow bays, lagoons and coastal areas which offer suitable substrata for their growth and propagation.
Apart from their utility as a source of food, food derivatives, vitamins, proteins, etc., seaweeds provide the raw material for many agar and algin-based industries. The exploitation of carrageenophytes such as species of Hypnea, Acanthophora, Laurencia, etc. has yet to make a beginning in the country as these are available in sizeable quantities.
In view of the constant demand for the seaweeds, research programmes on seaweed resources and their culture were taken up by the Central Marine Fisheries Research Institute, and Central Salt and Marine Chemicals Research Institute at Mandapam at their Regional and Field Centre, respectively, and various other research organizations belonging to the State Fisheries Departments/Universities. As regards sea-weed farming, experiments were mainly carried out on species of Ulva, Gelidiella acerosa, Gracilaria edulis, Gracilaria corticata, Gelidiopsis variabilis, Gelidium pusillum, Hypnea musiformis, Acanthophora spicifera, Hormophysa triquetra, Cystoseira sp. and species of Sargassum.
The experiments were mainly conducted by the method of vegetative propagation. Some trials were made with spores as well. An appraisal of different techniques adopted were as follows:
1.1 Culture of Gelidiella acerosa
Bhanderi (1974) cultured the apical region of the Gelidiella acerosa by inserting these fragments in a string and suspended in a seawater aquarium at Port Okha, Gujarat. He observed a linear growth of 0.01 cm/day and an increase of 0.01 g/day in weight. Krishnamurthy et al. (1975) conducted some experiments with 2 cm fragments of G. acerosa in a lagoon on the southern side of Krusadi Island. After four months, the fragments grew to full sized plants of about 10 cm in length with seven to eight branches.
In the same area Subbaramaiah et al. (1975) carried out experiments on 2 cm length fragments of G. acerosa fastened to a nylon string at fixed intervals and the seeded string was wound round a rope kept submerged in coastal waters. The maximum growth attained was 6.6 cm and the rate of production was 3.13 g/m/month (wet). The total production of seaweed was 421 g/m (wet) in a year.
Experimental field cultivation of G. acerosa using submerged coral stones as the sub-strata was done at Ervadi (Patel et al., 1979). An annual yield of 115.83 g/m2/day (dry) on overall basis was obtained which was 33 times over the seed material. Patel et al. (1980) reported a maximum yield of 122 g/m2 (dry) in one of their six monthly harvests made in January 1979 from the field cultivation of G. acerosa at Ervadi.
1.2 Culture of Gracilaria edulis
Raju and Thomas (1971) cultured Gracilaria edulis by long line rope method in a sandy lagoon in Krusadi Island. Fragments of 1 cm and 2.5–3 cm length were used for planting and they grew to a length of 35–40 cm in about five months period. Three harvests were made at the end of 5, 8 and 10-1/2 months and the total harvest during the year was about 3.5 kg per 1 m length of rope.
Krishnamurty et al. (1975) carried out cultivation of G. edulis in a lagoon in the Krusadi Island. Fragments of 2.5 cm length were introduced in the twists of the ropes which were tied to bamboo poles planted to the sea bottom. In about five months period, the plants attained a length of 30 cm and the average weight of plant was about 300 g. A total of three harvests were made in a period of 10 months.
1.3 Culture of other red algae
Bhanderi (1974b) recorded a linear increase of 0.02 cm/day and an increase of 0.07 g/day in weight in his culture experiments on Gracilaria corticata in seawater aquarium. In experiment with Gelidiopsis variabilis, he obtained a linear increase of 0.12 cm/day with an increase in weight of 0.04 g/day.
Mairh and Sreenivasa Rao (1978) cultured Gelidium pusillum in the laboratory under free floating conditions and using nutrient enricher and obtained maximum fresh weight and full size within three to four months. Rama Rao and Subbaramaiah (1980) cultured Hypnea musciformis and obtained four fold increase in 25 days.
Thivy (1964) conducted culture experiments in ponds at Porbandar by attaching small plants of Sargassum cinctum, S. vulgare and S. wightii to coir nets with the help of tape. The plants grew to a height of 15–52 cm for an initial 5–10 cm length within 40 days.
Bhanderi and Trivedi (1977) made an attempt to study the possibility of culturing Hormophysa triquetra by vegetative propagation in an aquarium. The fragments gained seven times (fresh weight) over the initial weight at a rate of 0.333 g/day.
2. SEAWEED CULTURE EXPERIMENTS AT CENTRAL MARINE FISHERIES RESEARCH INSTITUTE (CMFRI)
The Central Marine Fisheries Research Institute at its Regional Centre at Mandapam conducted culture experiments especially with Gracilaria edulis and Gelidiella acerosa. In seawater aquaria Gracilaria corticata (Umamaheswara Rao, 1973) was cultured which showed an increase in length from 1.8 to 5.5 cm in 90 days. Experiments with Gracilaria edulis in 0.5 m2 coir nets yielded very good results. The average height of the plants varied from 14 to 16 cm at the end of two months and the fragments gained a weight of 213 and 257 g, respectively. Experiments conducted in 4 × 2 m size coir rope nets yielded 4.4 kg (fresh weight) of seaweed per square meter in 80 days (Umamaheswara Rao, 1974a).
The culture experiments were conducted by introducing fragments of the seaweed into the twists of the coir ropes which in some cases were fabricated in the form of nets of different sizes which in turn were tied to wooden poles fixed in the coastal waters.
Experiments conducted in the submerged floating condition (Chennubhotla et al., 1978) proved to be more beneficial than that at subtidal level.
The cultivation was attempted at slightly deeper water, i.e. 3–4 m depth on HDP rope nets to avoid intensity of sedimentation and grazing by fish. The yield obtained was about four times the initial weight after 70 days. Chennubhotla et al. (1977c) cultured G. acerosa by tieing small fragments along with substratum (coral piece) to the coir ropes in the net. One frame was introduced with 0.9 kg and the other with 1 kg seed material. A yield of 2.5 and 3 kg were obtained, respectively after 76 days.
Experiments conducted by keeping the G. acerosa seeded coral stones kept in cages were introduced in 2 to 4 meters depth. The growth of the seaweed was found to be very luxuriant.
The culture was attempted by fastening fragments of G. acerosa to coral stones with the help of iron nails, reached harvestable size after five months and 1 kg of seed material yielded 3.1 kg of full grown plants.
Fragments of Sargassum wightii obtained from the basal portion of plants with holdfast were inserted in the twists of the coir ropes and cultured in inshore waters of Gulf of Mannar at 1 m depth in mid-water level. An average growth of 15.5 cm was recorded from an average initial length of 7.7 cm within 60 days (Chennubhotla et al. 1976, unpublished).
Cultivation of Acanthophora spicifera was carried out on 2 HDP rope nets in 60 × 30 m sized ponds which are connected through a feeder canal to the sea. An average yield of 22.615 kg (wet weight) was obtained after 45 days from the two nets which was found to be 3.6 times the initial seed material. The remnants were allowed to grow for the second harvest which was made after 35 days. An average yield of 14.4 kg was obtained in the second harvest (Chennubhotla et al, unpublished).
Experiments on Ulva lactuca, pre-treated with ascorbic acid were cultured in the sea-water of different salinities in the laboratory. It was observed that the trials with 18 percent salinity boosted up the production to eight times in 92 days (Chennubhotla et al, unpublished).
2.1 Culture of spores
The number of spores produced by an alga is enormous. In nature only a small number of spores grow to mature plants since viability, settlement and development of these spores are controlled by hydrobiological factors such as water movement, tidal exposure, water temperature, competition for space and predators or grazing organisms. When the spores are raised into germlings on suitable substrata in the laboratory or nursery and then transplanted to the field, a high rate of germlings grow to harvestable size plants. Some work in this direction of culturing the spores of economically important seaweeds was carried out in recent years.
Subbaramaiah et al. (1967) cultured germlings of Ulva lactuca. The germlings were kept growing in attached or in a free floating condition in petridishes containing sterile sea-water which was changed once a week. In two months time the germlings differentiated into cylindrical plants with 2–3 branches arising from the basal cells. The floating plants were found to be longer (1.25–1.7 m) and produced branches while the attached ones were shorter (0.75–0.83 m).
The effect of different culture media on growth and sporulation of laboratory raised germlings of Ulva fasciata was given by Oza and Sreenivasa Rao, (1977). Kale and Krishnamurty (1967) studied the effect of plain seawater, Erdschreiber seawater and artificial seawater medium (modified ASP-6) on the growth of germlings of Ulva lactuca var rigida.
Mairh and Krishnamurty (1968) observed 100 percent germination of spores of Cystoseira and subsequently 94 percent of their survival. The germlings survived and grew to young and healthy plants under experimental conditions. Chauhan and Krishnamurty (1967) cultured the oospores of Sargassum swartzii in petridishes lined with filter paper. They developed into germlings and some of them grew for a period of five weeks. Experiments were also conducted using different substrata such as coral pieces, shells, granite stones, nylon threads and rough stones. Some of the oospores attached to the substrata developed into healthy germlings while a large number did not survive. Continuous illumination of the culture experiments with a light intensity of 600–800 lux, 23–26°C temperature and circulation of a thin stream of filtered sea-water were found favourable for healthy growth of germlings. Chauhan (1972) observed the survival of germlings in Sargassum swartzii for about six months under the controlled laboratory conditions. Of the eight different substrata used, the concrete blocks, bricks and filter paper were found to be good substrata as they retained 84.55 percent, 78.42 percent and 62 percent of the germlings, respectively. The filtered seawater and enriched seawater were found to be most suitable culture media for the growth of germlings. The use of media like ASP-6 and ASP-12 did not give good growth of germlings. Continuous illumination was found to be more beneficial than 18 hours photoperiod.
Raju and Venugopal (1971) made an attempt to allow the oospores of Sargassum plagiophyllum to settle on a concrete substratum with a view to find out the time required for the appearance and growth. The concrete cylinders were lowered in Sargassum beds. Observations revealed that the appearance of Sargassum germlings on the cylinder took 10 months and another eight months to grow to maturity. Observations after one year revealed that there were a number of new plants which had germinated from the spores within the year and some had regenerated from persisting holdfasts. There appear to be potentiality for regeneration for a third year in a few plants. Umamaheswara Rao and Kaliaperumal (1976) maintained the oospores of Sargassum wightii in a medium of seawater enriched with agar and found that 47.6 percent of germlings were in healthy condition at the end of 60 days. Krishnamurthy et al. (1969) raised the germlings of Gracilaria edulis and G. corticata on a nylon fabric from carpospores under laboratory conditions. They were transferred to the sea. After four months, young plants appeared and they took another four months to attain maturity and develop reproductive structures.
Chennubhotla et al. 1977 (unpublished) conducted laboratory culture experiments on the viability, germination growth of germlings of Turbinaria ornata and Gracilaria edulis under controlled temperature of 18±2 and light intensity of 4 K lux. The spores of T. ornata were found to be viable even after a period of two months, but growth of germlings was not satisfactory. Carpospores of G. edulis were allowed to germinate and parenchymatous stage of development was noticed.
It is understood that UNDP/BOBP Programme at Madras has embarked on culture of seaweeds by tetraspores in Mandapam-Vedalai area. This may throw light on the aspect of spore culture in the natural environment.
2.2 Environmental factors in relation to seaweed culture
In the Central Marine Fisheries Research Institute, the culture experiments were conducted in different seasons of the years from 1976 to 1985 continuously. Although there were variations with respect to the quantity of seed material introduced, the yield rate showed fluctuations during certain seasons. In order to understand these variations, relevant environmental data were collected from the inshore waters where culture operations were carried out.
The average values of each environmental parameters such as surface temperature, salinity, O2 and nutrients during each culture operation were compared in relation to biomass increase and duration of culture period (Table 1). It was observed that no single environmental parameter could be pinpointed as responsible for variation in production. At best it could be inferred that a complexity of environmental factors operating in a dynamic inshore area may be responsible for seasonal variation in the yield of seaweeds. The Gulf of Mannar and Palk Bay experience contrasting seasonal changes ' in wind velocity and direction and wave action. The solar radiation in the region, rainfall, transport of inorganic and organic material into the region are some of the factors Other than those observed parameters.
2.3 Survey of seaweed resources
The surveys conducted in various maritime states of India have revealed that the resources of seaweeds along the coasts can be put around 1 lakh tonnes. The break-up figures are as follows:
|Stn.No.||Area||Annual yield in tonnes (fresh weight)||References|
|I||Tamil Nadu||22 044||Subbaramaiah et al. (1979a)|
|II||Gujarat||20 000||Chauhan and Krishnamurty. (1968)|
Bhanderi and Trivedi (1975)
Sreenivasa Rao et al. (1964)
Chauhan and Mairh (1978)
|III||Maharashtra||20 000||Untawale et al. (1979)|
|IV||Lakshadweep Islands||8 000||Subbaramaiah et al. (1979b)|
|V||Goa||2 000||Dhargalkar (1981)|
|VI||Kerala||1 000||Chennubhotla et al. (1987)|
|VII||Unexplored areas||27 000|
The seaweeds along the Indian coast are mainly harvested by small- as well as large-scale industrialists by engaging divers. Seaweed collection is an occupation by itself and offers employment to rural population. There are a number of agents who deal directly with the collection and supply of seaweeds to the industries. The methods of collection of seaweeds are very crude at present and hence extension work is very essential to educate the people in collection and management of the natural beds in a judicious way.
3. ECONOMICS OF SEAWEED CULTURE
In view of the importance of marine algae as a source of food, fodder fertilizer and . pharmaceutical compounds, augmentation of this resource by different methods has to be undertaken. The economics worked out by the Central Marine Fisheries Research Institute indicate that at least a minimum of Rs 500/- per month accrues to the farmer by taking up cultivation in one hectare area.
Culture experiments conducted in the inshore coastal waters from 1972 to 1986 in Gulf of Mannar and in Palk Bay have revealed that on the culture frames the agarophyte Gracilaria edulis reaches the maximum length (harvestable size) within three months while in nature it takes 4 to 5 months time.
These studies have further indicated that the minimum period for the seed material to reach harvestable size is two months for G. edulis and that the length of the algae at the time of harvest would be 20 to 25 cm. The suitable period for carrying out the culture operations are October to April in Gulf of Mannar and May to September in Palk Bay.
Harvesting is done by hand picking or by cutting the crop with sickles leaving the basal portions to the net for regeneration. One kilogram of seed material of G. edulis yields an average of 3 kg/m2 of net after 60 days of growth. In one-ha area of nets (i.e. 1000 nets) 30 tonnes of fresh G. edulis could be harvested. Based on the above studies, the economics of culture of G. edulis has been worked out for a hectare area and details are given below.
For the cultivation of G. edulis in one-ha area, 1 000 coir nets of 5 × 2 m size are used. Two thousand casuarina poles of 1.5 m height and 10 000 kg for fresh seed material (for initial introduction) are required. The cost of 2 000 casuarina poles is Rs 6 000/-(approximately) and the cost of 1 000 coir rope nets is Rs 33 000/- including charges for fabrication. The seed material will be collected for the initial introduction from the natural beds and from the cultured crop for the subsequent seeding. Wages for seeding harvesting and maintenance of the farm for four persons at the rate of Rs 10/- per day for 360 days work out to Rs 14 400/-. The total expenditure for one year would be Rs 54 000/- including a miscellaneous expenditure of Rs 600/-. The estimated cost is arrived at on the assumption that a minimum of four harvests could be made in a year. A total of 120 tonnes (fresh weight) of crop could be obtained from the four harvests in a year when the yield is 3 kg/m2. If the seaweed is dried (75 percent moisture) and marketed at a rate of Rs 2 000/- per tonne, the net profit would be Rs 6 000/-for one year.
If the harvested seaweed is dried and converted as agar, the profits will be around Rs 100 000.
At Mandapam, the culture frames were often the target of attack by certain fishes like Siganus javus and S. canaliculatus. The crabs, Thalamita crenata and T. integra caused extensive damage to growing parts of the seaweeds by merely clipping them with their Chelipeds as they crawl about amongst the seaweed (James el al., 1980). The problem of predators can be solved to a great extent by enclosing the cultivation area with latticed fence or a net of a suitable mesh size.
3.2 Effects of hormones on the seaweed growth
Studies on this aspect are very limited. Oza (1971) has found that low concentrations of IAA progressively stimulated the growth of Gracilaria corticata while higher concentrations were found to be lethal. Raju (1971) conducted experiments on the effect of hormones and fertilizers on the photo-synthetic carbon assimilation in Ulva fasciata, Sargassum sp. and Gracilaria corticata. The photosynthetic uptake of C14 was found to be maximum in G. corticata followed by U. fasciata treated with gibberrellic acid. In Sargassum maximum effect on photosynthetic C14 assimilation was observed in plant supplied with ammonium sulphate. Tewari (1975) found that Chlorflurenol in hormonal range increased the fresh weight and the number of proliferations. But the elongation growth was found to be inhibited. Chauhan and Joshi (1979) reported that Indole-3-acetic acid at the concentration of 105 proved a stimulant on the growth of Sargassum swartzii germlings than the other concentrations tried. The 10-3 to 10-6 M concentration of gibberettic acid helped in increasing the length of pseudophylls of the sporelings.
4. CONCLUSIONS AND RECOMMENDATIONS
4.1 Attempts have to be made to simplify the seaweed culture technology so as to reduce the cost of production and to make the technology economically viable.
4.2 The seaweed farmer and his family members or some families jointly have to undertake on cooperative basis, the cultivation of seaweeds and extract agar.
4.3 The cultivation of seaweeds is beset with problems such as grazing by fish in the sea and hence some times the yield in the crop and thereby the production may come down from the expected level. Hence, some attempt should be made to find out the methods of controlling the grazing of the crop by fishes and other predators.
4.4 In order to enable the fishermen or landless labour to undertake the seaweed cultivation, the government or some funding agencies may offer credit facilities with subsidies under the programmes such as IRDP, DPAP, etc. which will be of immense use to them.
4.5 Use of hormones and fertilizers must be tried in the culture fields or the seed material may be pre-treated with hormones.
4.6 Evolving of hybrid varieties of sea weeds by genetical methods may be given due consideration.
4.7 Transplantation of commercially important exotic species like Eucheuma and Caulerpa lentillifera will be attempted in Indian waters in suitable locations.
Bhanderi, P.P. 1974 Culture of the agar yielding seaweeds on ropes from Gujarat.J. mar. biol. Ass. India. 16(3): 847–848.
Bhanderi. P.P. and Y.A. Trivedi. 1975 Seaweed resources of Hanumandandi reef and Numani reef near Okha Port.Indian J. mar. Sci., 4(1): 97–99.
Bhanderi, P.P. and Y.A. Trivedi. 1977 Rope culture of algin yielding seaweed Hormophysa triquetra (Linnaeus) Ku Bot. Mar., 20(3).
Chauhan,V.D.and V. Krishnamurthy. 1967 Observations on the output of oospores, their liberation, viability and germination in Sargassum swartzii (Turn.) C.Ag. Proc. Semi. Sea Salt and Plants, CSMCRI, Bhavanagar, pp. 197–201.
Chauhan, V.D. and V. Krishnamurthy. 1967 An estimate of algin bearing seaweeds in the Gulf of Kutch. Curr. Sci. 37. 648.
Chauhan, V.D. and H.V. Joshi. 1979 Effect of Indole-3-acetic acid and gibberellic acid on the early growth of Sargassum.Proc. Int. Seaweed Symp. Marine Algae of the Indian Ocean Region. CSMCRI,Bhavanagar, India p. 23 (Abstract).
Chauhan, V.D. and O.P. Mairh. 1978 Report on the survey of marine algae resources of Sourashtra coast. Salt. Res. India,14(2): 21–41.
Chennubhotla, V.S.K., N. Kaliaperumal and S. Kalimuthu. 1978 Culture of Gracilaria edulis in the inshore waters of Gulf of Mannar (Mandapam) Indian J. Fish.25 (1 and 2). 228–229.
Chennubhotla, V.S.K., S. Kalimuthu, M. Najmuddin and M. Selvaraj. 1977 Field culture of Gelidiella acerosa in the inshore waters of Gulf of Mannar, Supplement to Jour. Phycos. 13.
Chennubhotla, V.S.K., S. Kalimuthu and M. Selvaraj. 1986 Seaweed culture: Its feasibility and industrial utilization.Proc. Symp. Coastal Aquaculture, 4: 1206–1209.
Chennubhotla, V.S.K., B.S. Ramachandrudu, P. Kaladharan and S.K.Dharmaraja. 1987 Seaweed resources of Kerala coast. Seminar on Fisheries Research and Development in Kerala, Trivandrum.
Dhargalkar, V.K. 1981 Studies on marine algae of the Goa coast. Ph. D. Thesis,Bombay University, Bombay. 186 pp.
James, P.S.B.R., V.S.K. Chennubhotla and J.X. Rodrigo. 1980 Studies on the fauna associated with the cultured seaweed Gracilaria edulis. Proc. Symp. Coastal Aquaculture, MBAI, Cochin.
Kale, S.R. and V. Krishnamurthy. 1967 Effect of different media on the germlings of Ulva lactuca var rigida. Phycos, 6 (1 and 2): 32–35.
Krishnamurthy, V., P.V. Raju and R. Venugopal. 1969 An aberrant life history in Gracilaria edulis. J.Ag. Curr. Sci. 38(14): 343–344.
Krishnamurthy, V., P.V. Raju and P.C. Thomas. 1975 On augmenting seaweed resources of India. J. mar. biol. Ass. India.17(2): 151–155.
Mairh, O.P. and V. Krishnamurthy. 1968 Culture studies on Gelidium pusillum (Stack). La Jollis. Bot. Mar., 21(3): 169–174.
Oza, R.M. 1971 Effect of IAA on the growth of fragments of Gracilaria corticata. Seaweed Res. Util., 1: 48–49.
Oza, R.M. and P. Sreenivasa Rao. 1977 Effect of different culture media on growth and sporulation of laboratory raised germlings of Ulva fasciata sellis. Bot. Mar. 20(7): 427–431.
Patel, J.B., B.V. Gopal, V.R. Nagulan, K. Subbaramaiah and P.C. Thomas. 1979 Experimental field cultivation of Gelidiella acerosa at Ervadi, India. Proc.Int. Symp. Marine Algae of the Indian Ocean Region. CSMCRI, Bhavanagar, pp. 24–25 (Abstract).
Patel, J.B., B.V. Gopal, V.R. Nagulan, K. Subbaramaiah and P.C. Thomas. 1980 Experimental field cultivation of Gelidiella acerosa at Ervadi. Symp.Coastal Aquaculture. Marine Biol. Ass India. Cochin, pp. 189 (Abstract).
Raju, P.V. 1971 The effect of its situ application of growth hormones and fertilizers on photosynthetic C14 incorporation in some marine algae. Bot. Mar. 14(2): 129–131.
Raju, P.V. and P.C. Thomas. 1971 Experimental field cultivation of Gracilaria edulis (Gmel.) Silva. Bot. Mar. 14(2): 71–75.
Raju, P.V. and R. Venugopal. 1971 Appearance and growth of Sargassum plagiophyllum (Mart.) C.Ag. on a fresh substratum. Bot. Mar. 14(1): 36–38
Sreenivasa Rao, P., E.R.R. Iyengar and F. Thivy. 1964 Survey of algin bearing seaweeds at Adatra reef, Okha. Curr.Sci. 33: 464–465.
Subbaramaiah, K., K. Rama Rao. M.R.P. Nair, C.V.S. Krishnamurthy and M. Paramasivam. 1979a Marine algal resources of Tamil Nadu. Proc. Int. Symp. Marine Algae of the Indian Ocean Region. CSMCRI, Bhavanagar, India, p. 14.
Subbaramaiah, K., K. Rama Rao and M.R.P. Nair. 1979b Marine algal resources of Lakshadweep. Proc. Int. Symp. Marine Algae of the Indian Ocean Region. CSMCRI,Bhavanagar, India. pp. 6–7 (Abstract).
Tewari, A. 1975 The effect of morphaction on the vegetative growth of Gelidiella acerosa. Phycos. 14(1 and 2): 125–128.
Thivy, F. 1984 Marine algal cultivation. Salt. Res. Ind. 1: 23–28.
Umamaheswara Rao, M. 1973 The seaweed potential of the seas around India. Proc. Symp. on Living Resources of the Seas Around India (1968). pp. 687–692.
Umamaheswara Rao, M. 1974 On the cultivation of Gracilaria edulis in the nearshore areas around Mandapam. Curr. Sci. 43(20): 660–661.
Umamaheswara Rao, M. and N. Kaliaperumal. 1976 Some observations on the liberation and viability of oospores in Sargassum wightii (Greville) J.Ag. Indian J. Fish.,23(1 and 2): 232–235.
Table 1. Data on seaweed production and related environmental factors in Gulf of Mannar and Palk Bay, Southeast Coast of India
|Mean values of hydrological data|
|Year||No. of days of culture operation||Initial weight to seed material|
|Final weight (kg)||Average gain of seed|
|Gulf of Mannar||30||1.00||4.30||0.1100||27.7||32.79||4.65||0.45||0.53||8.25||8.2|
|Gulf of Mannar||88||34.||162.17||1.4565||27.3||30.31||4.38||1.55||0.15||0.73||8.13|
|Gulf of Mannar|
|Gulf of Mannar||60||2.4||7.50||0.0850||27.3||30.00||4.95||7.9|
|Gulf of Mannar||55||1.80||9.50||0.1400||29.3||29.72||5.51||0.12||0.44||60.00||7.4|
Staff, Marine Fisheries Production
Jakarta Fisheries Service
J1. Medan Merdeka Selatan No. 8–9
Block G, 21st Floor, Jakarta, Indonesia
Kepulavan Seribu lies north of Jakarta. Most of the coastal waters in Kepulavan Seribu is suitable for seaweed culture, e.g., Pari Island, Laneang Island, Panggang Island, etc. There are many species of seaweeds which have economic value that can be cultivated such as Eucheuma, Gracilaria, Gelidium and Hypnea. But most of the market demand preferred on Eucheuma mainly. The other species are under research by Department of Agriculture.
In Kepulavan Seribu, seaweed culture is not the source of the main income but only a secondary activity to fill spare time. So, the production is still low and not managed as a business.
We began culturing Eucheuma cottonii since October 1986 using seedlings from Bali.
There are two culture methods in Kepulavan Seribu:
Kepulavan Seribu has a high potential for producing seaweed but at the moment only about 1.5 ha have been planted to Eucheuma cottonii. -
The Eucheuma cottonii production in Jakarta is still low till January 1988, the wet production is only 300 mt. We hope in the long run seaweed culture will be projected as tradeable goods to fulfill the demand of international market. On the other hand, it means increasing fishfarmer's income.
The most important problems in seaweed marketing is the very low market price compared with the production cost. The farming site is too far from Jakarta. The other problem is the collector does not buy the Eucheuma product on a regular basis. To overcome these problems the government advised the farmers to join in cooperatives. The collector/exporter must buy the Eucheuma product from the cooperative.
On April 1988 the exporter in Jakarta exported about 20 mt dried product from the Kepulavan Seribu to Hong Kong.
Since seaweed is tradeable commodity and source of foreign currency, it is reasonable that the government of Indonesia pushing up seaweed production by applying new methods and technology.
Staff, Marine Resources Section
Dinas Perikanan, J1. Patimura No. 77
Denpasar, Bali, Indonesia
Bali Province has a coastline of about 470 km. It consists of several islands, namely: Nusa Penida, Nusa Lembongan, Nusa Ceningan, Nusa Dua, Pulau Serangan and Pulau Menjangan. Most of the coastal areas in Bali Island are characterized by growing reefs, particularly by sandy bottoms which gradually slopes toward the sea.
The production of Eucheuma culture in Bali Province is about 73 899.40 mt. These production has been produced from an area of 179.1 hectares and has come from three different places namely:
|a)||Badung||5 070.00 mt|
|c)||Klungkung||68 790.00 mt|
|73 899.40 mt|
Most of the seaweed production from Bali Province were mainly marketed to the other districts especially in Java (Surabaya and Jakarta), with the exception of Eucheuma which are generally marketed for export to other countries.
The problems of the Eucheuma culture in Bali Province are as follows:
The plants are grazed by small fishes and are affected by heavily rainfall in the culture site.
Eucheuma plants are being disturbed by different species of seaweeds such as Ulva species which cause the main branches of the plant break down.
1 Reported by Mr. Jung Jin-Tae, Staff, National Fisheries Research and Development Agency, Republic of Korea.
1.1 Geographic characteristic of Korean coast
The surrounding waters of Korean peninsula has special environmental characteristics according to the eastern, western and southern coasts.
The first, is the eastern coast characterized by a sudden drop in water depth, the surf is strong, many submerged rocks/reefs, and the coastline is monotonous without irregular curves; the current is more influenced by the Liman cold current than the Tsushima warm current; seaweed culture of this area is possible to place long line rope structure for sea mustard and sea tangle.
The second, the southern coast, is characterized by severe curved coastline as fiord, and there are many islands including many inlet bays. The current is influenced strongly with Tsushima warm current. The rising and falling tidal wave as well as moderate water depth is adequate to place various cultural structure such as hanging, long line rope and bamboo raft type. There are many species of cultural organisms. Therefore, this coastal area has become the center of culture in Korea, and almost all of the major seaweed culture such as sea mustard and laver is centered on this area.
The third, the western coast, is characterized with many isles including complicated coastline, though this phenomena is relatively smaller than the southern coast. There is a long stretched shallow water with a broad tidal land. The high tidal wave of ebb and flow is well known worldwide. Consequently, the laver culture has been practiced since long ago, and floating net culture system of laver is now under extension. Koreans enjoyed seaweed as daily food from ancient time, and could do seaweed culture easily owing to such rich marine environmental benefaction.
1.2 The sea current and water masses
There are correlation between the sea currents of Korean adjacent sea and that of Pacific Ocean especially the current of Korean waters is mainly influenced by Tsushima warm current which is the branch stream of Kuroshio current originating from eastern Philippines and is flowing upwards to the western Pacific through the eastern China Sea. Therefore, the characteristic of currents and water masses in accordance with the three sides of Korean waters is characterized as follows: (a) in the southern coast, the Kuroshio current forms the West Sea (Yellow Sea) warm current flowing into the western sea through the southern part of Jeju Island; (b) in the eastern coast, the Tsushima current forms the Korean east sea warm current, and this is faced with the Liman cold current, the North Korea cold current flowing downwards with lowered temperature by cold weather and thawed ice during winter; and (c) in the western coast, the Yellow Sea warm current flowing in through western Jeju Island as the branch stream of Tsushima current flowing upwards to the northwestern coast of China during April to August. The strength of , this current is relatively weak comparing to the China coastal line waters flowing downward by forming cold current. Consequently, the two kinds of currents are forming a reflux in the central part of Yellow Sea, and Yellow Sea bottom cold current is going downward as a result (Figure 1).
Figure 1. Sea current of Korean coastal area
1.3 The distribution of water temperature in surrounding waters of Korea
The seasonal variation of sea surface temperature in Korean waters ranges from 5 to 27°C in general (Figure 2). The sea surface temperature (SST) in Korean waters depends not only on incoming radiation but also on heat advections by winds and ocean current as mentioned above. The heat advection by the Asian monsoon decreases the mean SST and increases the annual range of SST, while the heat advection by warm currents such as Tsushima current and the Yellow Sea current increases the mean SST and decreases the annual range of SST. Also, it is shown that the higher mean SST and smaller range of SST in the East Sea (the sea of Japan) than in the West Sea (the Yellow Sea) resulted mainly from the fact that the heat advection into the East Sea by the Tsushima current is more pronounced than that into the West Sea by the Yellow Sea warm current. On the other hand, the maximum SST in the neighbouring sea of Korea occurs between mid-August and early September (Figure 3).
1.4 The distribution of seaweed (algae)
The algae distributed in Korean coastal area is predominant in the temperate zone flora (this flora occupied over 70 percent of the total amount of algae). In accordance with the different coasts the situation of flora is classified as follows:
Figure 2. Monthly variation of SST according to the major cultural areas
Figure 3. Mean oceanographic chart of the adjacent sea of Korea (SST)
1.4.1 East coast
Although there are predominant family of northern seaweed flora than any other coast resulting from the influence of cold current, it is shown that the central part of the eastern coast is also distributed with the family of temperate zone flora nearing about 70 percent among total seaweed flora.
1.4.2 West coast
Although the distribution of the family of temperate zone flora reaches about 71 percent among total seaweed flora and is poor in the northern flora, owing to the weak cold current as the special tidal land is broad, the algae is distributed only to the surrounding coast of isles so the flora of seaweed is poor.
1.4.3 South coast
The family of temperate zone flora occupies about 70 percent among total seaweed flora, and there are many large and small islands as well as severe curved coastline in the geographical condition. Many, subtropical temperate zone algae is distributed in the coast of Jeju island. It is general characteristic in Korean coast belonging to the temperate zone that the algae after reaching highest growth during spring (from March to May) is declining during summer.
Now, the algae showing abundant distribution in Korean coast in accordance with life cycle are as follows:
The annual plants (in common name) Laver, sea mustard, green laver, the family of Gulf weeds and others.
The perennial plants (in common name) Hijiki, Irish moss (Rock moss, carrag-heen), seaweed cava, tangle (kelp), agar, seaweed tenella, Zostera marina (scientific name), and others.
1.5 Major culturing seaweed
Here, the major algae being cultured now in Korea are as follows:
1.5.1 Laver (Porphyra spp.)
This is the major algae cultured as well as sea mustard, and the history of culture is the oldest one. The culture area stretches from southern coast to the eastern coast, and the center of culture is located in Wando, Shinan, Hadong, etc. in southern coast and Seochon, Anmyundo, etc. in western coast (Figure 4).
1.5.2 Sea mustard (Undaria pinatifida)
This is one of the most cultured alga and is distributed all along the coastal areas. There are abundant, good quality Undaria in the eastern coast growing in natural state. The technique of artificial seeding was introduced in Korea in 1962 and the production amounted to 300 thousand tons in 1986; the center of culture area is Wando in the southern coast and Ilgwang, Kijang in neighbouring Pusan (Figure 4).
1.5.3 Sea tangle (Laminaria)
This is generated abundantly in the north eastern coast going upward to latitude of 38° parallel line. The culture of this species is practised a little in the east southern coast.
1.5.4 Hijiki (Hijikia)
Although this is found almost all over the Korean coast, the culture of this species is practised only in Jeju island including Wando of southern coast.
1.5.5 Agar (Gelidium spp.)
Although the Gelidiaceae is found all over the Korean coast, the production of this alga is from natural algae collection until now. But recently, because the price of raw material as agar products is high, the culture of Gelidium amansii is under experiment in southern coast.
1.6 The status of shallow sea culture in Korea (Figure 5)
Korea has shown rapid progress in marine cultural fisheries from the late 1960's. Although the total amount of maricultural production attained 19 thousand tons, only 4.1 percent was part of the total Korean fisheries production in 1962. The production of 947 thousand tons in 1982 has shown about 50 percent increase compared to that in 1962 and which occupied 25.9 percent of total Korean fisheries production (Table 1 and Figure 6). On the other hand, the development of culture areas which reached about 100 thousand hectares in 1986 showed occupying about 55 percent in total possible maricultural area that is estimated about 183 thousand hectares. This maricultural fishery has made such a rapid progress due to great influence by decreased fisheries resources in offshore and curtailment in deep-sea fishing that resulted from 200 miles economic zone by the coastal states along with increased demand of sea food as a provisions nowadays. Consequently, the extension service in mariculture with supply of artificial seeding in governmental basis as well as the activation of license system in private cultivation area has acted effectively to the rapid progress of mariculture in Korea.
Figure 4. A map showing major seaweed aquaculture areas
|Figure 5. Yield of total shallow sea cultural products, (1986)||Figure 6. Yield of total fisheries products (1986)|
1.7 The status of seaweed culture in Korea
The major seaweeds cultivated in Korea are laver, sea mustard, kelp including hijiki and green laver which is now under extension stage (Figure 7). In Table 2, it is shown that the culture of laver has been under continuous increase, and sea mustard under stagnation without fluctuation, but the kelp under decreasing state from 1980 to 1986 in accordance with the areas. It has shown that the amount of products in laver and sea mustard, the highest amount of which recorded in 1986 have been varied with relative high amplitude through the years. The important problems faced from now on is that: How to keep stable production by preventing natural disaster in marine environment along with how to minimize fluctuation in production by strengthening the regulation concerning the license of private cultural area. Consequently, as shown in Table 3, the two species occupy an important position in Korean seaweed culture.
Table 1. Annual yield of aquacultural products in Korea
|(unit: thousand tons)|
|Total fisheries product||470||935||2 410||2 812||2 644||2 793||2 910||3 103||3 660|
|Total cultural product*||18||119||541||701||596||644||678||788||947|
*Total cultural product = Total marine cultural product
Figure 7. Yield of total cultivated seaweed products, (1986)
2. CULTURE OF PORPHYRA SPP. IN KOREA
2.1 Development of cultural technique
The original cultural method of laver reportedly began in 1623 on Kwangyang Bay (adjacent to the estuary of Sumjin river) in central southern coast of Korea and this was preceded 50 years than Japan. The original cultural method is now obsolete and extinct (except Kwangyang Bay); Korea was involved in placing bundles of leafless branches of bamboo, or other trees at or just above the mean water level located well away from brackishwater during September to October. Since then, this was improved as a fixed semi-floating type that was made of split bamboo rattan and fixed with pole on either or both sides in the 1630's on Wando island of Jeonnam Province (in accordance with this principle, movable type fixed with pole on both sides to place split bamboo rattan in parallel with the sea surface was improved by Japan). But it was later in 1962 that artificial production of monospore and culture of conchocelis filament was practised in Korea. Owing to this technical development, the technique of nursery nets storage and floating net cultural system was introduced in Japan, and free living conchocelis culture method was dispersed during 1970's. As a result, annual laver production was attained over 23 × 108 sheets of dried products from 1979 (Figure 8). Since 1980 the annual production has been kept over 30 × 108 sheets, and over 62 × 108 sheets of dried laver was produced in 1986 while annual production of 1987 decreased to 34 × 108 sheets resulting from bad condition in marine environment. Consequently, it has shown that the harvest of cultivated laver depends greatly on the influence of the marine environment condition in Korea until now.
Table 2. The annual cultivated area (licensed) of seaweed in Korea
|Total cultivated||19 156||46 670||78 573||85 561||83 825||88 465||89 557||96 885||101 189|
|Total seaweed cultivated||5 316||17 016||28 584||35 369||37 275||43 578||47 661||51 547||54 008|
|Total laver cultivated||730||13 459||20 593||25 144||27 256||33 355||37 953||42 011||44 451|
|Total sea mustard cultivated||271||2 960||7 590||9 445||9 253||9 530||9 116||8 944||9 009|
|Total sea kelp cultivated||-||-||237||291||241||125||32||50||50|
Table 3. The annual yield of seaweed products according to major cultural species
|Total shallow sea||18 106||147 221||540 564||701 065||596 316||643 798||628 321||787 571||946 965|
|Total seaweed||6 054||48 818||527 880||383 063||314 535||347 227||383 661||377 461||524 117|
|Total laver||4 247||34 801||56 274||80 490||79 784||87 963||136 484||109 819||143 369|
|Total sea mustard||804||11 103||196 147||294 622||225 045||237 128||230 188||256 436||346 434|
|Total sea kelp||-||-||940||1 963||3 987||11 606||7 927||11 796||9 445|
2.2 Characters of laver
There are about 10 kinds of species cultivated in Korea. Among them: P. tenera, Kjellman and P. yezoensis are more important cultural species than others.
a) Phylum: Rhodophyta
b) Size and shape
Length of fully grown frond of P. yezoensis varying from 15 to 36 cm, and that of P. tenera from 17 to 35 cm, sometimes up to 1 m.
Fronds very dark purple.
d) Life cycle (Figure 9)
Figure 8. The annual yield of laver since 1962 (Dried products)
Life cycles of both species are the same. The algae germinate from spores released from conchocelis filaments (sporophyte) from September to November and appear as small germlings of 1 mm in length from mid to late October, when the water temperature drops to 22°C. The germlings grow rapidly to fronds (gametophyte) 15 to 20 cm long, or more, by mid to late November and flourish during winter in waters of 3 to 8°C. In April, fronds of the algae wither and disappear by May when the water temperature rises to 14°C.
Germlings of 150 μ to 1 mm in length form a large number of neutral spores during the period between late September and early November. These neutral spores also germinate and grow into fronds. When germlings grow into fronds of 3 to 5 cm in length in November, sexual reproductive organs are formed on the fronds. These organs continue to release fertilized carpospores until the fronds disappear in May. Released carpospores attach to shells on the sea bed to germinate and become conchocelis filaments. Conchocelis filaments bore into the shell and grow in the pearl layer of the shell to form colonies of 1 cm in diameter by August to September when they start -to release spores called conchospores.
Generally speaking, the characteristic of laver in the life cycle and ecology differ from almost all of the agricultural cultivated species in the side of carrying out accessory reproduction by asexual spores given off by the young thalli. The growing of laver into fronds is a result of repeating complicated process of life cycle such as: (1) carphospore ﺣ (2) conchocelis rosa ﺣ (3) conchospore (monospore) ﺣ (4) germling (young thalli)⇌ (5) neutral spore (monospore) ﺣ (6) fronds of thalli. The process between (4) and (5) differ from any other cultivating species, that is, germling germinated from carposhore form neutral spore, in return, this neutral spore germinate germling. After repeating this process many times, germling grows into fronds of thalli.
6, Germination of Carpospore;
7, Discharge of Monospore;
9, Leafy thali (Gametophyte);
Figure 9. Life cycle of laver
e) The process of laver culture (Figure 10)
2.3 Cultural technique in genera
2.3.1 Culture of conchocelis filaments
This is carried out by placing oyster shells either loose or stung on wires, in indoor tanks in the early spring and adding chopped thalli. The conchocelis plants are then cultured in the tank until the artificial seeding of conchospores begins in October.
a) Culture by oyster shell
This starts from collecting the thalli during December to mid-January. The thalli is cold stored until March to April before conchocelis culture begins, thalli is dried in dark place until the moisture contents are about 20–30 percent. The conchocelis culture begins with inputting carpospore solution into the oyster shells, and the method of inputting carpospore solution is either by hanging the stringed oyster shells into the concrete tank perpendicularly, or by placing the shells loosely into the plastic container filled with sea water (Figures 11 and 12).
(i) Preparation of carpospore solution
Put the cold stored thalli into the container filled with sea water (10 g dried thalli per 1 liter of sea water) The thalli which release carpospore after two to six hours had elapsed, show change of water color. The carpospore solution prepared is put into the culture tank filled with sea water, and the carpospore bore into the shells after one week elapsed and grow into conchocelis filaments.
Figure 11. Artificial seeding in container
Figure 12. The method of sting wires on the shells
Monthly process of conchocelis culture after inputting carpospore solution is shown below.
|Month||Process||Water temperature control|
|From February to March||Attaching of carpospore solution into oyster shell||From 10 to 15°C|
|From mid-march to April||Growing of conchocelis filaments||From 16 to 24°C|
|From May to June||-do-||Forming the sporangium From 18 to 25°C|
|From July to August||-do-||Proliferation of sporangium (carpospore being liberated) control under 28°C|
|September||Maturing of conchocelis filaments|
Monospore collection with conchocelis bearing shells
b) Culture of free living conchocelis
This method was introduced in 1975 for the first time in Korea and over 30 percent of total culturists now in Korea is adopting this method. This method is to grow the nurtured free living conchocelis filaments, after planting it into the oyster shell in May until it may be used in monospore collection.
But recently, it was found out that the free living conchocelis release spore by forming carposporangium without substrate and monospore collection by free living conchocelis without substrate has been possible.
2.3.2 Artificial seeding of conchospore
This is to collect either the monospore (conchospore) released from conchocelis filaments, or neutral spore germinated from germling (young plant). The method is divided into: (1) natural spore collection with nets in the sea which is practised in timely season; and (2) artificial collection of spore in the sea or in the tank with oyster shells bearing matured conchocelis.
a) Natural spore collection in the sea with nets
This is to set up culture nets to the seashore in the fall to collect released conchospore in natural state when water temperature is about 22°C. Whatever collecting device is used, catching of monospores is best when the water temperature is 22 to 23°C. After a storm is considered to be a particularly good time as are in the second to fourth days, after the first or fifteenth of each lunar month. The western coast of Korea is not concerned with the lunar month where it is practised everyday in the morning during the period.
b) Artificial seeding of conchospores in the sea
This is carried out by placing conchocelis-bearing oyster shell cultured in indoor tank, beneath the spore collecting nets which is spread horizontally in the sea with supporting pole, and the nets and conchocelis bearing shells are kept as is for the seeding period of three days.
c) Artificial seeding of conchospore in concrete water tank
This is to place the mature conchocelis-bearing oyster shells on the bottom of concrete tank, and conchospores released from the conchocelis filaments attached to the twine of the nets dipped into the tank. The release and attachment of spores is induced by stirring the water in the tank. Nets are of the same quality as those used in the sea, and it is set one upon another up to 30 to 50 layers in thickness. The laver net are knitted with twigs of palm, etc. and the stretched mesh size of the net is 30 cm, the length is 18 m, and the width is about 1.5 m. There are several methods for seeding the spores into the nets. The device is classified as follows: (a) rotary type (Figure 13); (b) vertical movement type (balance type); (c) running water type (belt conveyor type); and (d) bubbling type, etc.
Figure 13. Porphyra seed collector in indoor tank (rotary type)
2.3.3 Correlation between timely artificial seeding and growing of laver
At the start of September, every culturist is careful of practising timely spore collection along with placing the nursery nets in the sea. Generally, there is poor annual harvest when sea water temperature drops with the coming fall. Meanwhile, in the late reduction of sea water temperature, artificial seeding was also late along with placing of nursery nets and showed rich annual harvest. After all annual harvest is correlated with timely seeding (spore collection) along with placing culture nets in the cultivation grounds. Harvesting of grown laver usually begins in November, and takes about 40 to 60 days from the start of growing to harvest time. Therefore, after 40 days had elapsed the amount of thalli in the cultivation grounds reaches its peak, and the growing rate of thalli is suddenly fast. If the water temperature is lowered fast, the artificial seeding and placing of the nursery nets in the sea is hastened. Consequently, the amounts of thalli reached its peak rapidly. If the growing rate of thalli is fast as much as the nutritive salts in sea water is demanded the higher discharge of waste material from the thalli is shown. If the growing rate is slowly decreasing or there is stagnation and the sea water temperature tends to be more upward with the result of stratosphere phenomena without convection of current, the supply of nutritive salts will be slow along with the elimination of waste material discharged from the thalli. A decreased harvest in cultivation grounds will be shown. In addition, if the wind and rainfall is less, the stronger the effect will be. Also, when the laver become activated in photosynthesis under the water temperature of 15 to 16°C, the demand of nutrient salts become highest in this time than any other season. Meanwhile, the peak time in growing rate of thalli coincides with the optimum water temperature of 15 to 16°C, and also the convection of current is weakened at that time. As a result, the thalli's growth is impaired with the imbalance between the demand and supply of the nutrient salts. Such a phenomena causes disease and the laver finished its life cycle.
a) Optimum sea water temperature in artificial seeding at the sea.
When the monospore collection is carried out in the sea by placing conchocelis-bearing shells beneath the collecting nets, the most important factor to decide the period is the sea water temperature. Although the conchospore filaments release spore from 26°C in water temperature, it is done well under 24°C. In the releasing of spore from germling (young plant), this temperature has no problem in considering the attaching diatom, etc. on the nets. However, the; optimum water temperature is 22.5°C in general. If the nursery net is placed over 23 °C in order to harvest thalli as soon as possible, the result will fail in collecting spores or the attached green laver, diatoms, etc. and will result to poor harvest.
b) A comparison between harvest and marine environment
As mentioned above, harvest is correlated with marine environment such as water temperature, light, specific gravity of water, sea current, - and the condition of rainfall, etc. (Table 4). Disease of laver is occurring frequently during November to December with the result of long stagnation of high water temperature. Such a disease occurs in ebb tide when stagnation of sea current, warm temperature along with no wind continue temporarily.
2.3.4 Germinating of conchospores and growth of germling
The laver nets seeded with conchospores in the sea or in the tank are spread in the sea with the cultural structure to await spore germination. To increase the passage of sea currents on the surface of nets twines, only up to five nets are stacked upon each other for germination. The nets are set at a level which keeps the net exposed to air for about four hours a day to get rid of undesirable algae. About 15 to 20 days after seeding, the germling of laver become visible on the nets. The germling grows to 2–3 cm in length after 40–50 days after seeding and the nets are ready for use as nursery nets. The density of germlings is several hundreds per cm of net twine. The nets are either placed in the sea for cultivation, or stored in freezer for use in later months.
2.3.5 Growing of laver plants
The growing season of laver fronds lasts from November to early April. Cultivation ground should be located in the sea with as much nutrient salts and sea Water movement as possible. Waves and wind are desirable to secure rapid water exchange as long as the cultural structure is not destroyed. The nursery net of which the germling grows to 2–3 cm in length is spread in the surface layer of the sea horizontally to grow the laver fronds.
Table 4. Analysis of harvest in comparison with marine environment during October 1–December 31
|Year||Production*||Duration of water temperature(22–24°C)||Stagnation of water temperature(14–15°C)||Storm days||Rainfall|
|1986||63 × 108 sheets||52 days||Nov. 12–Nov. 16||17 times||12 times|
|(5 days)||(49 days)||(81 mm)|
|1987||35 × 108 sheets||66 days||Nov. 16–Dec. 29||7 times||4 times|
|(19 days)||(11 days)||(14 mm)|
*Production: Total national yield of dried laver (1 sheet = 24–30 g)
Source: District: Central southern coast of Korea (Wando)
2.4 The structure for growing laver
There are many types of man-made structures for growing laver such as old fashioned type of placing only bamboo bundles or any other trees at or just above the mean water level, now obsolete and extinct except at the estuary of Sumjin river, to floating net culture system fixed with anchor, developed lately. But the major type now in use is classified as movable type with pole and floating net culture system. The structure which was used from the old days in Korea and is used until now is classified as follows.
* 'Hong' means the cultural structure of laver
2.5 Any other technical problems
2.5.1 Developing floating net culture system for an effective use of cultivation grounds
The laver is cultivated in shallow sea by placing the man-made structure with culture nets and the net9 should be exposed to air two times a day. This is necessary to stop disease and keeps stable growth of laver with good color, and control the fertilization of diatoms, green lavers when the fronds grew in some estimated length. It is helpful to cultivate without exposure to spur the growth of algae plants. The floating net culture system aiming at fast growth of laver was developed in Japan and was introduced in 1972 in Korea. But the practical use of this floating net culture system was begun from 1981. According to fisheries regulation, the floating net culture system is distinguished from any other man-made structure in water depth. It is designated to be placed under 10 m water depth. Any other structure such as movable, floating but fixed with pole type is designed under 7 m in water depth. After all, the difference between floating net culture system and other structure fixed with pole type is only 3 m gap in water depth. If the floating net culture system increase, we are faced with problems that not only the shallow cultivation ground under 10 m in water depth will become narrow if it is occupied with floating net culture system but also, it will be difficult to observe the intervals of placing the structure over 500 m, and will bring up the problem of high intensive culture. Finally, in order to develop the cultivation ground more effectively, it is necessary to develop the floating net culture system by correcting the fisheries regulation concerning the depth in which the floating net culture system is designated now “under 10 m” and to place the structure “under 20 m” in water depth in the future.
2.5.2 Utilizing cold-stored nursery nets and extending the cultivation period
When sea water temperature rise at night in the cultivation ground, the algae take physiological injury, and in case of severe injury, the thalli falls out from the nets. But if such phenomena of rising in sea water temperature occur during early mid-November, it is necessary that the nursery nets be stored in freezer. Generally, the nursery net germinated in autumn can be stored in a freezer for one to two months for cultivation in later months. Nursery nets attached germling of 1–3 cm in length withdrawn from cultivation ground, follows dehydration with air drying in dark place or (dehydrated in centrifugal) to reduce the moisture content to 30–40 percent, and be stored in -20°C freezer (usually stored until early December, this is called cold-stored nursery nets). In December when the oceanographic condition becomes favourable, the nursery net is placed on cultivation area, and the germlings of 1–3 cm in length begins growth again. Owing to the artificial seeding developed, it is faster to place laver nets on the cultivation area. As a result, harvest of grown laver begins from early November. The thalli to be annuated declines in quality with the curtailment of cultivation period and shows various diseases. Yet, many culturists now in Korea has not been equipped with freezer for cold storage of nursery nets except some industrialized culturists. Finally, they are faced with the problem of how to supply the cold storage system of nursery nets effectively for small-scale fisheries.
2.5.3 Arrangement of cultivation grounds and high intensive cultivation
The standard of placing cultural structure in cultivation grounds is regulated now in Korea by the law of the Ministry of Agriculture, Forest and Fisheries, to keep the ratio between the area of covering culture nets and licensed cultivation ground to be 20–25 percent in case of floating net culture system, and 20–30 percent in case of any other culture structures (Figure 14). Under this law regulating the standard of placing culture structure in cultivation ground, it is not designated specially to the difference between the floating net culture system which could be placed offshore and any other structure fixed with pole type which could be placed only on seashore. Therefore, the problem is that the floating net culture system which is expanded from now on will cover almost all of the offshore cultivation ground. The cultivation ground of estuaries/shore will be disturbed by sea current. Consequently, in order to keep laver from disease resulting from the sea current disturbance, it, is necessary to lower the standard ratio of placing culture structure in cultivation ground. In case of floating net culture system, the ratio which is now 20–25 percent (covering culture nets area/licensed cultivation area) is to be 10–15 percent in general, and in case of any other structures the ratio of 20–15 percent, in general to be 20 percent on the offshore, and to be 15 percent on the estuaries/shore.
(1) placing pine trees/bamboo bundle; (2) bamboo culture, movable type fixed with pole; (3) net culture, movable type fixed with pole; and (4) floating net culture system (ladder type)
Figure 14. Development of laver cultural structure
2.6 Harvesting and processing
Harvesting of grown laver fronds usually begins from early November to April in Korea. This is done either by hand picking or with machine such as vacuum cleaner like a machine attached with a rotating knife or other type of machine attached with long rotating knife (the length of knife is about 1.2 m fitting to the breadth of cultural nets), over which the net is being moved and the laver is picked up (Figure 15). But until now in Korea, harvest is done almost all by hand picking. After thinning the density of laver by harvesting, the smaller fronds left on the nets flourish again. Thus, laver is usually harvested five times from each net until growth declines and the net is then replaced by a new nursery net which has been kept in low temperature storage in case harvest is finished in early December. In some parts of the southern coast such as Kohung Peninsular of Jeonnam Province, harvesting is done possibly nearly 10 times from each net by developing the floating net culture system cultivated with “upset net culture method” to expose the floating net reversely sometimes.
The harvested frond is processed into dried laver sheets by the culturists themselves or by the processors equipped with machine. Many culturists now in Korea consign to the processor. The mechanical drying is expensive, 800–1 000 wons per bundle of dried product, but the basic cost is about 400–500 wons per bundle, and the entire process is automized by machine. The manufacturing process begins with washing the laver fronds in sea water, followed by chopping the washed laver into small pieces (10–15 mm in square), and stirring in fresh water to make a laver suspension (about 1 kg of laver pieces are placed in 20 liters sea water and stirred). The resulting suspension is spread within a small rectangular wooden frame placed upon a screen mat made of fine stems of bamboo, reed, or synthetic design sticks. The wet sheet of laver formed on the screen is dried in nature or hot air chamber (40 + 1°C) and then peeled off the screen (the sheet formed thus weighs 2.5 to 3.0 g). The sheet of dried laver are folded in half (sometimes not folded) and packaged together for marketing.
One 1.8 7times; 40 square meter culture net produce an average of 7 500 sheets of laver (50–200 sheets), or 20 kg of dried laver product per net. If it is estimated that one fourth of intensive cultivation is covered by laver net, this amounts to 100 nets/ha producing a total of 20 000 kg of dried products during six to eight months growing season.
The standard size of one sheet of dried laver product is 21 cm long, 19 cm breadth, and one sheet weighs average from 2.4 to 3.0 g, and one bundle is equal to 10 piles which consists of 10 sheets, so one bundle equals to 100 sheets. The yield of dried product is 600–800 g per 10 kg of wet raw material (harvested laver).
In accordance with Fisheries Statistics in 1986, the production ratio showed 2.08 kg of laver (wet base) per m2 of culture net and this was compared with Japan of which was calculated 3.17 kg/m2 of culture net.
Almost all of the processed laver is now consumed in domestic market. There are some differences in marketing routes according to the districts. The marketing routes now in Korea is shown in the following figure (Figure 16). As shown in the figure, either the producers/culturists themselves deal with wholesale/retail dealers directly, or is dealt through the consignment of Local Fisheries Cooperative Association (LFCA). However, over 90 percent of culturists are processing dried products by the processor equipped with machine, and about 10 percent of culturists are processing laver by sun dry method until now.
Figure 15. Harvesting of laver, upper; hand picking, under; mechanic harvest
Figure 16. The marketing routes of laver
The consumer's price is about 3 to 5 thousand wons per bundle.
The harvesting of laver frond begins from November and finishes from March to early April, therefore, the dried product is necessary to be stored for a long time. In case the moisture content of the product after processing is about 10–12 percent, it should be dried again so that the moisture content would be 5 percent before storage. The moisture content of over 10 percent brings about changes in color, taste, etc. for long time storage of over two months.
Dried laver is usually sold as a set of 10 sheets packaged, and this weighs approximately 24–30 g and is called pile.
2.8 The problem of laver industry in Korea
Recently, the laver culture industry of Korea has shown remarkable increase in production due to the technical development such as artificial seeding, supplies of culture nets' made of synthetic fibers, floating net culture system including improved culture species (such as P. tenera Kjellman form, Tamatsuensis mura, and P. yezoensis). Almost all of the products are consumed in domestic market. Yet, the production is unstable annually because of variation in marine environment along with deficiency in cold storage system for the storage of nursery nets. On the other hand, expanding of culture areas with culture nets placed has given increase in production, and consequently, the change in processing from manual harvest to sun drying to mechanical harvest and mechanical drying. Therefore, expenditure for purchasing of mechanics as well as equipments inputting into the cultural structure enhanced inevitably the cost of final products. But in the side of customer, the price is keeping 3 000 to 4 000 wons per bundle or 12 000 wons/kg of dried products. The processor is also faced with the problem of “how to make the consumer's price stable and how to lower the basic cost without damage to the culturist through the development of various products as low cost”.
3. CULTURE OF UNDARIA PINATIFIDA IN KOREA
3.1 Development of culture technique
Sea mustard, brown algae belonging to the genus Undaria is a cold water algae occurring widely in temperate zone, for the whole life cycle, a temperature of 10 to 20°C is suitable. The ecological condition of this algae is restricted in estuaries and other brackishwater region which typically occurs in open sea situation with inflow of water from rivers influence greatly the growth of this algae. This algae grows all along the Korean coast except at higher latitude over 40°C parallel in western coast.
It has been an important foodstuff along with laver from old days in Korea. What is more, it is cheaper than laver and has become a necessary food for soup cooking especially for a pregnant woman.
The history of culture by artificial seeding lately from 1963 in Korea and the culture method before then was extremely primitive. Inputting stone only at suitable depth for attachment of young plants or weeding algae competing with sea mustard for existence is done by brushing the rock or reef for the attached fertilized eggs from spermatozoa on the substrate during late fall of every year. From 1967, cultivation by floating rope type method was developed. The culture product reached over 100 thousand tons (wet) annually from 1970 especially in 1974, the amount of culture product was 180 thousand tons (Figure 7). With the decreased consumer's price resulting from over production as compared to the domestic demand, the production decreased. But owing to the exportation to Japan with blanched-salted products that developed from 1975, the culture production has began to increase again. Now, the annual yield of culture product is being kept on about 200–300 thousand tons. On the other hand, natural harvest which was 28 thousand tons in 1972 (the production ratio between natural harvest was 28:29 in 1972), decreased under 6 thousand tons per annum which is harvested only in the eastern coast. Now cultivation of sea mustard is occupying over 60 percent among total yields of seaweed culture and the major culture areas center on Wando of Jeonnam district and Kijang, Ilgwang near Pusan of Korean southern coast which produce over 80 percent among total yields of sea mustard in Korea.
3.2 Characteristics of sea mustard, Undaria pinatifida
There are three kinds of species; Undaria pinatifida (Harvey), Suringar, U. undarioides (Yendo) Okamura and U. peterseniana (Kjellman) Okamura. Of these species, U. pinatifida is the most widely distributed and favoured for consumption.
a) Phylum: Pheophyta
b) Size and shape
Maximum 1–2 mm in thallus length, grows larger in east than south.
Fresh fronds is dark brown to greenish brown but when cooked (boiled) the color is turning brighter to brownish green to green.
d) Life cycle and ecology
Undaria pinatifida is an annual plant which grows on rocks and reefs at a depth of 1 to 15 m in places facing the open sea or near open seas influenced by warm ocean currents. When the 10 days average of water temperature rises above 14°C in April in the southern part of Korea, the discharge of zoospores begins from the sporangium formed on sporophylls at the base of the fronds. The discharge of zoospores continues until the temperature reaches 23°C peaking at 17 to 22°C.
Figure 17. The annual yield of sea mustard (wet basis)
The discharged zoospores are 9 μ in length and locomotive with flagella. They drift in the sea with the water current, adhering to any substrate they contact by chance. Zoo-spores germinate on the substrate and grow to gametophytes at water temperatures up to 24 °C. They stop growing at temperature higher than 24 °C and form resting gametophytes with thicker cell walls to tolerate the high temperature (Figure 18).
Gametophytes are microscopically small bodies which perform sexual reproduction when mature at water temperatures of around 20°C in October. Spermatozoas discharged into the sea from the male gametophyte fertilized eggs formed on the female gametophyte. The fertilized eggs germinate into sporophytes which grow well at temperatures lower than 17°C. Sporophytes grow fast in winter to form large edible fronds. In the spring, the sporophytes form sporangium on sporophylls at the base of frond to perform a sexual reproduction to produce gametophytes. Having discharged zoo-spores, sporophytes wither and thus, finish the year long life of the plant.
(1) Zoospore; (2, 3, 4) Germination; (5, 6) Gametophyte (male); (7, 8, 9) Gametophyte (female); (10) Fertilized oosphere; (11) Sporephyte; (12) Plumule; (13) Sporophyte; (a) Oogonium; (b) Oosphere; (c) Spermatozoid; (d) Rhizoid; (e) Sporophyll.
Figure 18. Life cycle of Undaria
e) Process of culture
3.3 Culture technique
The life history of Undaria pinatifida, as of other brown algae is rather complex and involves an alternation of generations between sexual and asexual form. The asexual form or sporophyte is the obvious macroscopic plant of which the fronds of the main thallus are used as food.
The sporophyte phase grows during the winter months when the temperature is between 10 and 15°C. The cultivation of Undaria begins with collecting sporophyll, which was left on the culture structure for use of spore sowing after finishing harvest of plant (sporophyte) from December to May.
In nature during winter months, the sporophyte develops asexual zoospore and these are released from sporophyll in spring and early summer when the water temperature rises above 14°C. After a brief planktonic life, the zoospore settle and adhere to a solid surface (stone, shells, etc.) and germinate to produce the macroscopic sexual plant, the gametophyte.
Germination of zoospore and growth of the gametophyte occurs between water temperature 15 and 20°C.
3.3.1 Artificial spore production (spore sowing)
In order to do spore sowing, first of all, the mature sporophytes (the plants) are brought into the laboratory and placed in concrete/plastic tanks. Into these tanks are placed rectangular plastic/wooden frames (generally 40 × 50 cm2) around which is wrapped 90 cm of approximately 1.6 m/m diameter braided cotton strings (frame with strings for collection of zoospore) (Figure 19).
Figure 19. Spore collector for Undaria culture
The zoospores are released from the plant and attach to the strings in late spring or early summer; the gametophytes ultimately the young sporophytes develop on the strings during the summer and early fall.
In carrying out artificial sowing the useful method is as follows: after drying the sporophylls collected in culture area in dark place for one to several hours, place them into the tank filled with sea water. Then the sporophylls start discharging zoospores within 5 minutes which lasts about 20 to 30 minutes. Now, take out the sporophylls in the tank. After 30 minutes have elapsed from the start of inputting it into the tank, place the spore collector (the plastic/wooden frame wrapped with string to collect the zoo-spore) into the tank. After 30 minutes have elapsed the spore collector is taken out from the tank (being the strings of spore collector are attached with zoospore in full) and are transferred to sea water or cultural tank for culture of gametophyte germlings.
The suitable amount of sporophylls used in spore sowing is about 3 kg (wet basis) per 1 km of string length or is estimated 10 individuals per 200 meter in length of strings.
The sea water in the tanks should be controlled to keep the water temperature under 20°C and specific gravity over 1.020.
3.3.2 Culture of gametophyte germling
There are two methods to culture germlings: one is to culture them in the sea by hanging spore collector from a raft; and the other is to culture them in indoor concrete tanks (the suitable capacity of the culture tank is to fill 1 ton of sea water, and the strings of the spore collector is about 300 meters in length); the culture of gametophyte germlings starts by putting the spore collector into the tanks. In Korea, the culture of germlings is carried out in indoor concrete tanks. The spore collectors with attached zoospores are hung vertically in the tank where zoospores germinate on the strings of the spore collector.
In this germling culture, the water temperature, light and water flow should be controlled according to the growing stages carefully and also, in some cases nutrient salts such as sodium nitrate and sodium phosphate are added to the water to stimulate the growth of germlings. Gametophyte ' enter a resting stage over 25 °C in summer. During the resting stage, germlings are kept in still water and the temperature should be controlled under 28°C. Over that temperature the germling is easy to be killed and also it is very important to control the light in accordance with the water temperature (in southern part of Korea the sea water temperature upwards over 25°C in August, and the growth of gametophyte continues until early August, and from mid-August the gametophyte begins resting. In case of this, supply of nutrient salt is necessary). When the water temperature drops below 23°C in autumn, the gametophyte can resume their growth, and the light conditions of waters tanks are increased to 2 000–4 000 lux. Gametophyte matures at water temperature of 20°C and sexual reproduction takes place. When fertilized eggs germinate as sporophytes, lighting is increased over 5 000 lux, and the exchange of water and addition of nutrient salts are effective to accelerate the growth of sporophytes.
If the growth of sporophytes is not efficient, tank water should be cooled to 20°C, or spore collectors should be hung in the sea.
Conditions of water temperature and light in accordance with the growing stages is shown (see table below).
3.3.3 Floating culture of Undaria sporophytes
In September or November, the sporophytes grow to 100 to 1 000 μ in size, attach the strings of the spore collector and are ready for further culture in the sea. Thus, floating culture of Undaria has begun in autumn, from September to November when the water temperature drops below 20°C. The culture ground should be located where temperature is below 15°C since the Undaria grows well at water temperature below 15°C and the specific gravity should be above 1.025.
Before the main culture of the sporophyte (young thalli) by floating rope culture system, the spore collector is hung to the main rope of culture structure for about two weeks until the young thalli grows to 0.5–1 cm in length. After that, strings covered with young thalli (sporophytes) of Undaria are wound around the main or branch line of the floating rope type culture structure placed in the sea.
Undaria fronds are harvested from a boat with a knife in cultivation ground from December to May. There are some differences in harvest period between the east southern part and the central southern part, in accordance with the oceanographic condition of water temperature and sea currents (Figure 20). Generally, the central part of southern coast finish in April, but the east southern part continues until end of May. Nowadays, the disease of thalli by the appearance of Harpacticoida has given great problems in cultural area especially from March. The damage resulting from the Harpacticoida reached over 20 percent decrease in total annual harvest in recent years.
|Growing stage||Water temperature||Light||Month|
Sporophylls form sporangium
|not concerned with special temperature||April–July|
Sporangium discharge zoospore
|14 to 22°C|
(opt. 17 to 20°C)
Zoospore germinate gametophyte, growing of gametophyte
|17 to 20°C|
(growth stop at 23°C)
|2 000–6 000 lux||May–July|
|Resting of gametophyte||25 to 30°C||500 lux||July–August|
Maturing of gametotophyte and germination of germling
|drops under 20°C||1 000 lux||September–October|
|Growing of germling||17 to 10°C|
Growing fronds of thallus
|13 to 5°C|
Figure 20. Harvesting of Undaria pinatifida
3.4 The floating culture system of Undaria pinatifida
In the cultivation of Undaria, the culture method now in Korea mainly consists of the floating rope type or hanging rope type.
The main lines of the culture structure are 1 to 3 cm in diameter and 70 to 80 m long; in case of long line rope type, it is composed of synthetic fibers (or strong rubber for continuous use) which are kept afloat and are fixed at suitable intervals in the sea with anchors.
In the floating rope method, branch lines are hung from the main lines. The strings covered with young thalli (sporophytes) of Undaria are either wound around the main or branches lines or cut into short pieces, several centimeters long and inserted between the strands of main or branch lines (Figure 21). The method of winding around the main line is popular. The water depth at which the main line should be set 1 to 5 m below the surface. The depth from the sea surface should be controlled from 1 to 4 m in accordance with the growing stages.
(a) Horizontal single rope (side view)
(b) Horizontal single rope
(c) Horizontal double rope
(d) Rectangular assembling rope
(e) Suspending horizontal single rope
(f) Single rope hanging
Figure 21. Floating culture method of Undaria
Grown fronds in market size in cultivation ground is harvested by cutting the strips nearing the sporophyll with knife on boat and the harvest is only through hand picking. Meanwhile, natural grown Undaria is harvested by diving which is practised now in Korea only in the eastern coast of Kangwon province. After harvesting, Undaria is processed as sun dried product, blanched-salted product, or cut type product, etc. General processing type practised now in Korea are as follows:
a) Sun dried product
The fronds of sea mustard rewashed with fresh sea water after harvesting and they are cut into two similar halves by removing the midrib or cut into small size by removing the end part of thalli and are dried in the sun or in a hot air dryer. The yield from raw material (fronds) is about 10 percent.
b) Blanched-salted product
Raw material fronds are heated soon after harvest at 90–98°C for about 40–60 seconds and cooled quickly with water. Then the fronds now vivid green, are mixed with salt in a ratio of 3:10 (w/w) in a machine. They are preserved in a tank for one to two days, then packed in a bag to remove excess water. The product is stored in a cold room at -10°C for sale. This product is a major commercial form of Undaria at present and much of them is exported to Japan.
c) Cut products
The blanched-salted product is desalted by washing with fresh water, centrifuged to remove excess water, then cut mechanically into small pieces and dried in a rotary type of flow-through drier. These cut fronds are stored into uniform sizes by sieving any faded fronds (if present) which are removed and then appropriate amounts are packed in a bag of plastic film for sale. But now the processing of this type is treated easily with hand by fishermen themselves, that is, to be sun dried after desalting the blanched-salted product (used as raw material without storage or packing in the plastic bag), except industrialized processing company.
The Undaria harvested by fisherman follows the marketing chain as shown in Figure 22. In reference, the price of cultivated Undaria is 10 thousand wons per 100 kg after harvesting. Now a small amount is sun dried by culturists/fishermen themselves and is marketed to consumer through wholesale/retail dealers in domestic market. Only the blanched-salted product made of good quality fronds are exported to Japan. Generally, this product for export finishes in March because of good quality in fronds of thalli and the price of raw material (harvested fronds), which is used on this product kept on about 120 thousand wons per 100 kg after harvest last year. The standard of this product is regulated as to the moisture content which is under 63 percent, the midrib should be removed thoroughly and the contents of salts from 25 to 40 percent. The yield of the product from the raw material is about 40 percent. The products for export are packed in wooden boxes and the unit of package is 15 kg per box. Consequently, the other products made by culturists/fishermen/processors are sold to domestic market through the marketing channel as shown in Figure 22. However, the cooking method is simple, that is almost all of them are cooked for soup.
3.7 The problems of Undaria industry
Undaria is the most productive shallow sea culture species in Korea. Although the total production reached 350 thousand tons in 1986 with developed culture technique, the income of culturist decreased in general, owing to the stagnation in price. Also, disease caused by the Harpacticoida in cultivation area resulting from intensive cultivation is now a serious problem. The damage led to an estimated decreased harvest of about 20 percent of the total possible production in 1987. What is more, the reason why this gives a serious damage to Undaria culture is that the disease of the fronds by this microorganism mainly occurs in March when the harvest of good quality fronds reaches the peak. There is no special counter measure to keep the fronds from this damage. The only preventive measures are: (1) controlling culture process thoroughly from spore sowing to the growing stage according to the growth of thalli; (2) preventing the intensive cultivation (controlling the intervals of culture structure between the main ropes of which is now 2–3 m to be 3–5 m; and (3) keeping marine environment from pollution, etc. On the other hand, as the processed products of Undaria is only consumed for soup so the price between producer and consumer is limited domestically. Consequently, in order to increase the consumption in the domestic market a higher grade product should be developed in participation with the industry such as instant foods as Undaria tea, powdered product, seasoned product, fish pasted product, Undaria noodle, etc.
Figure 22. The marketing route of Undaria
Arman Shah Ambo Dalli
Fisheries Assistant, Fisheries Department Sabah
Menara Khidmat, Tingkat 8, Jalan Belta
88000 Kota Kinabalu, Sabah
Sabah and Sarawak are two states in East Malaysia which have a potential of producing seaweeds. There are several seaweed species found growing on reefs in Semporna area, south of Sabah and in Banggi Island of the South China Sea in Kudat area, north of Sabah. The major seaweed species found are namely: Sargassum, Eucheuma, Caulerpa, Gracilaria, Hypnea, Padina and Hydroclathrus.
2. EUCHEUMA FARMING
Eucheuma culture was developed in Semporna area which has a greater number of coastal inhabitants. It was started in May 1986 which was done by the Fisheries Department Personnel and four fishermen with their families involved. The aim of the Fisheries Department is to farm Eucheuma as a source of seed stock and to attract the fishermen to involve themselves in farming in order to increase their income. As for the information gathered, there was no actual data collected.
3. SITE SELECTION AND PRODUCTION
An estimate of about 1.5 hectares of suitable site was planted with Eucheuma striatum for the initial seedlings which consisted of 30 000 plants with an average weight of 250–300 grams per plant. The farmers were able to plant four hectares in October 1987. There were six families who started to culture Eucheuma. The total number of fishermen involved in planting Eucheuma at present are 10 families which cover an area of 10 hectares. This does not include the Fisheries Department Eucheuma farm.
The production of Eucheuma in 1987 amounted to 400 metric tons wet weight. Some were consumed as food and others were exported as dried material. The total Eucheuma production as reported does not include the wild stock harvested by the fishermen and as far as I know there was no record available.
4. METHODS OF CULTURING SEAWEEDS
Two methods of farming were employed namely:
4.1 Semi-raft method
Semi-raft method is applied only in the lagoon area where the depth of the water is between 10–20 feet deep and the width is about 200–500 ft. Pegged stakes are placed on opposite sides of the lagoon with floats tied to the monoline at a depth of 3 ft from water surface.
4.2 Bottom method
This method is also called stake and nylon line method. It is cheaper compared to the other method for it is made up of two stakes and a monofilament nylon No. 200 lbs and 15 meters long. Stakes are pegged one meter apart from each other and 15 meters long. A 15-meter nylon line can be planted with 40–50 plants with a distance of 30 cm from each plant.
5. PROBLEMS ENCOUNTERED
When the culturing started, we encountered some problems as follows:
5.1 Fish predators that graze on the plants. The fish was identified as Siganus sp.
5.3 Environmental factors such as salinity, light and temperature, water movement and water depth which affects the growth rate of the Eucheuma and other seaweed species
5.4 Marketing. Since seaweed farming is still being developed in our country marketing of the product is also a major problem to the East Malaysian seaweed farmers.
In the future, more efforts in research on other seaweed species should be carried out by the Fisheries Department.
Rizalina M. Legasto
Supervising Fishery Extension Specialist II
Fisheries Extension Division
Bureau of Fisheries and Aquatic Resources
Arcadia Bldg., 860 Quezon Avenue
Quezon City, Metro Manila
The Philippines is blessed with abundant aquatic resources which provide food and livelihood to many Filipinos. Seaweeds are one of these resources which are found in lagoons and reef areas all over the country. The country is one of the few in the world which has pioneered the farming of these plants in substantial quantities.
Seaweeds are good sources of colloidal material which are used as gelling agents, emulsifer, food stabilizers, pharmaceutical, cosmetic and industrial products. It also constitute an important food item, fertilizer and animal feed.
In 1966, seaweeds was the only negligible item of the country's economy. Export at that time amounted to only 800 mt. But with the development of seaweed farming in 1973 foreign revenues had increased to almost fifty times. Since then what was considered a minor sea product is now generating 466 732 486 (32.2 thousand mt) for the country and now the third fishery export of the Philippines.
2. EXISTING SEAWEED RESOURCES
Production of seaweeds in the Philippines is dependent on harvest of natural stocks except for Caulerpa and Eucheuma which are produced through mariculture. Limited information are available on other commercially important seaweed such as Gelidium, Sargassum, etc.
Among the different seaweeds found in the country, Eucheuma dominates the industry. Eucheuma alvarezii (cottonii type) and E. denticulatum (= spinosum type) as “gozo” are the species commercially cultivated in the country. Eucheuma, a red alga is an important source of raw material for carrageenin, a colloidal substance used as gelling agent, stabilizer or emulsifier in food, cosmetics and other products. Gracilaria or “gulamang dagat” are raw materials for agar which are used for food, pharmaceuticals and culture media for research laboratories.
Gracilaria is harvested in Manila Bay and provides income to coastal communities in Bataan and Cavite. Unfornately, it is of inferior quality due to pollution surrounding these areas. Gathering of Gracilaria is also undertaken in Buguey, Cayagan and sold at 2.00/kg. These are marketed in Manila and gathering is undertaken only as secondary to farming.
Sargassum, a brown seaweed containing alginate is known as “samo”. It can also be used as food and in pharmaceuticals. Sargassum industry developed in Misamis Oriental in 1978. This seaweed grows abundantly in shallow coastal waters in the country. It is used as insect repellant and feed supplement for poultry and livestock. Harvesting is by hand picking during . the months of January–June.
Caulerpa known as “lato” or “ar-arosep” is utilized as vegetable salad and sold both in the foreign and local markets. About 400 hectares of ponds are utilized in Caulerpa farming in Mactan, Cebu. Retail price in Metro Manila markets range from 20–22/kg.
Hydroclathrus or “balbalolong” is used mainly as a food item in Pangasinan and sold at 80.00/can.
Other species such as Codium (pokpoklo), Porphyra (garnet), Digenea simplex (bodo-bodo) and Gelidium are also utilized in the country but very little information is available on their usage and production.
3. SEAWEED EXPORT
Seaweeds exported to other countries come in dried and treated form; fresh or salted or as seaweed meal powder. Eucheuma produced through farming are sold in the international market in treated (chips) semi-refined and refined forms. A portion of the local produce of Gracilaria and Gelidiella are processed into crude agar which are sold in the local market in the form of dried agar bars.
A small amount of Caulerpa is sent to Japan in dehydrated (or salted) form. Sargassum is processed in Central Visayas and exported to Japan. A significant amount of Gracilaria and Gelidiella are exported while the rest is locally produced into agar bars for food. Production of Codium and Porphyra are dependent on natural stocks and are consumed locally.
Major bulk of dried seaweeds goes to Denmark. Japan is the biggest importer of salted seaweeds and seaweed meal. The total export of seaweeds of the Philippines increased from 16 890 tons in 1982 to 32 293 tons in 1986. The breakdown of this export product in kgs, value and destination is shown in Table 1. Seaweed is the third largest export item of marine product of the Philippines.
4. CULTIVATION AND POST HARVEST PROCESSING
The present farming of Eucheuma utilizes the monoline or bottom and floating methods.
Seaweed farms range from 2 500–5 000 sq m. There are about 100 seaweed farms in Bohol province and an estimate of 3 000 farms in Tawi-Tawi, Sulu in Mindanao. It has been reported that there are approximately 2 500 ha of Eucheuma farms in the Tawai-Tawi and Sulu areas (Smith, 1987). Farmers use 10 m nylon lines. Seaweed cuttings weighing about 150–200 g are attached to these lines with the use of plastic straw. These are suspended and attached to wooden stakes. The distances between lines is at least one meter. Seaweed farming manuals are available from the ASEAN/UNDP/FAO Project based in Manila.
In the floating raft method, the monolines are attached to a rectangular bamboo raft.
The best months for growing are from November to July with March to May as peak growth months.
Harvesting is undertaken after 45 days. The harvested seaweed is sun dried for three to four days.
One kilogram of dry seaweeds require 6–9 kg of fresh seaweeds.
Table 1. Export of seaweeds, 1982–1986
|Year||Dried/Treated||Fresh||Salted||Kelp meal powder||Total|
|1982||16 073 947||82 418 082||173 890||2 172 649||_||_||532 008||456 749||16 779 845||85 047 480|
|1983||15 594 056||108 332 508||149 331||2 559 185||1005||22 155||910 075||1 058 680||16 654 467||111 972 528|
|1984||10 255 505||81 238 046||400||6 300||-||-||634 250||1 019 692||10 890 155||82 264 038|
|1985||23 749 056||364 474 804||803 358||15 796 444||131 183||791 736||4 124 626||8 691 137||28 808 223||389 744 121|
|1986||29 182 896||455 572 060||166 145||3 186 057||77 470||388 148||2 866 393||7 587 221||32 292 904||466 733 486|
|1982||Fresh||173 890||2 172 649||USA||1 783 815||19 468 271|
|Treated||654 475||6 037 468||Spain||1 658 340||6 089 624|
|Dried||15 419 472||76 380 614||Denmark||6 687 101||17 473 431|
|Kelp meal||532 008||456 749||France||2 874 500||6 945 260|
|Japan||1 538 596||6 460 127|
|Total||16 779 845||85 047 480|
|1983||Fresh||149 331||2 559 185||France||3 155 360||10 109 068|
|Treated||633 026||15 157 992||USA||2 374 789||18 594 731|
|Dried||14 961 030||93 174 516||Denmark||5 705 225||22 883 123|
|Salted||1 005||22 155||Japan||1 859 835||7 375 255|
|Kelp meal||910 975||1 058 680||England||1 004 550||35 624 853|
|Total||16 654 467||111 972 528|
|1984||Fresh||400||6 300||Denmark||3 360 317||28 716 904|
|Dried||10 217 505||80 023 546||France||1 528 050||4 924 947|
|Treated||38 000||1 214 500||Hong Kong||1 272 706||4 046 005|
|Kelp meal||634 250||1 019 692||Japan||631 750||918 752|
|Total||10 890 155||82 264 038|
|1985||Dried/treated||23 749 056||364 474 804||Denmark||9 887 301||99 084 429|
|Fresh||803 358||15 796 444||Japan||5 379 808||49 146 789|
|Salted||131 183||791 736||France||4 088 043||32 085 938|
|Kelp meal||4 124 626||8 691 173||USA||2 261 883||30 806 381|
|United Kingdom||2 299 947||101 327. 651|
|Total||28 808 223||389 744 121|
|1986||Dried/treated||29 182 896||455 572 060||Denmark||12 532 440||108 739 116|
|Fresh||166 145||3 186 057||France||4 145 698||35 138 008|
|Salted||77 470||388 148||USA||3 646 455||55 890|
|Kelp meal||2 866 393||7 587 221||United Kingdom||2 550 156||128 412 659|
|Japan||3 998 661||50 970 009|
|Total||32 292 904||466 733 486|
Research Officer, Ministry of Agriculture
Animal Husbandry and Fisheries
Beijing, People's Republic of China
In China, the seaweed with commercial importance are mainly Laminaria, Undaria, Porphyra, Gelidium, Gracilaria, Eucheuma and Macrocystis.
Laminaria is the most important economic seaweed in China. Mariculture of Laminaria on artificial floating rafts started in 1952 and the production increased steadily until 1980 when the highest yield of 252 907 tons of the dry product was produced. In recent years, the cultivation area and total yield of Laminaria declined because the culture of shellfish developed so quickly that the farmers prefer cultivating shellfish to Laminaria. Annual yield of Laminaria keeps over 200 000 tons.
Undaria is cultivated by the same raft method as the Laminaria and is often mix-planted with the latter on the same floating raft in Qingdao and Dalian. The annual production keeps only a few thousand tons. It is usually used for feeding abalone and some are exported to Japan. Porphyra is mainly cultivated in Jiangsu, Zhejiang and Fujian province. It is used for food and extraction of agar. Gracilaria and Eucheuma are mainly cultivated in Guangdong province also used for extracting phycocolloid.
Now let me introduce the productive procedure of Laminaria. The culture of other brown algae such as Undaria and Macrosystis are almost similar to Laminaria.
The productive procedure of Laminaria include mainly four steps: (1) culture of Laminaria sporelings; (2) cultivation of sporelings in the sea and transplantation; (3) cultivating methods of Laminaria; and (4) harvesting and processing.
1.1 Culture of Laminaria sporelings
The first is collecting zoospores onto the seeding cords. To do this, Laminaria fronds with mature sporangial sori are subjected to partial drying in the air and then placed in a small container with seawater. The liberated zoospores will soon attach themselves to the substratum, the seeding cords. The gametophytes and early sporophytes are cultured in water of 8–10°C in glass-house for three months. After that the juvenile sporophytes can reach 2–3 cm long.
1.2 Cultivation of sporelings in the sea and transplantation
When the water temperature has already dropped to about 20°C, we can remove sporeling cords to the sea from glass-house and hang them on the floating raft. In a month or so the sporelings will have grown to juveniles of 10–15 cm long or more. These juvenile sporophytes have to be brought to the transplanting room and placed in tanks filled with seawater. Since they grow on the cords so thickly, they have to be thinned. The best way in our experience is to remove them from the original sporeling cord and insert them in the twists of the kelp ropes, generally, with about 30 juveniles to each rope of 2 m.
1.3 Cultivating methods of Laminaria
There are two basic floating raft kelp cultivation methods. One is hanging kelp rope (also called single-raft) cultivation method. Another is horizontal kelp rope (also called double-raft) cultivation method. The floating-raft, floating line is about 60 m long floated at the surface by buoys generally made of glass or plastics and anchored terminally by anchoring lines to wooden pegs driven into the sea bottom. Each kelp rope has about 30 kelps twisted in it and is about 2 m in length. In the single-raft method, the kelp ropes are hung down from floating line and weighted down by a small piece of stone. In the double-raft method, the end of two kelp ropes are linked or tied together, the other ends are tied to floating lines, respectively. The hanging kelp rope method has the advantage of better water movement but has the defect of uneven growth of the kelps. The horizontal kelp rope method has the benefit of more even growth of the kelp. However, it has the defect of being more resistant to water motion. Generally speaking, the single-raft method is better adapted to comparatively clearer water regions and the double-raft method to turbid regions with lower water transparency such as the Zhejing coast.
2. HARVESTING AND PROCESSING
Harvesting takes place when the fronds are mature. The time for harvesting is important to kelp farmers. Since the Laminaria is sold in the market on the basis of dry weight, and since the wet weight to dry weight ratio changes from month to month, the criterion for selecting harvest time should take into consideration the highest per unit area production rate plus the lowest wet-to-dry ratio.
Table 1 shows the results of an experiment conducted on the quantity and quality of the production on kelp drop at different dates.
From the table, it is readily seen that mid to late June is the best time for harvesting. It is, therefore, recommended harvesting begins in mid-June and continue until late June or early July in North China. In harvesting the Laminaria, the kelp ropes are detached from the floating line and collected in small boats, many of which are retowed in a long line by a motor boat. When the boats reach the wharf or shore, Laminaria are transported to land and dried under the sun.
Table 1. Production quality and quantity per kelp rose at different dates
|Harvest time month/day||Production in wet weight|
|Production in dry weight|
|Wet weight dry weight ratio|
3. UTILIZATION AND MARKETING OF LAMINARIA
Most of the Laminaria japonica produced in China is used for food. Besides its role as a “health” vegetable in China, Laminaria is also important as raw material to be processed for its algin, mannitol and iodine content in a special programme for the comprehensive utilization of Laminaria. Recently, the kelp produced in China has also been employed in the processing of synthetic feed use in mariculture. Formerly, the kelp was sold in the market only in the crude dried form, but recently small package of shredded and seasoned forms with different flavours have appeared in the market and are very well accepted by the people.
Fishery Biologist/Seaweed Team Leader
National Institute of Coastal Aquaculture
Ministry of Agriculture and Cooperatives
Rajadamnern Avenue, Bangkok, Thailand
Thailand exports dry seaweed (approximately 20 to 200 tonnes), most of which are of the genus Gracilaria, which can be processed to agar. At the present time, Thailand has no agar processing industries and therefore, agar has been imported (around 200 to 300 tonnes/yr valued at 50 to 100 million baht). The major producing areas are the southern region of Songkhla Lake and the shallow mud-flats in Pattani Bay. Production is mostly from natural beds. Two methods of culture are practiced: pond culture with a production of approximately 6 442.5 kg/ha/yr; and polyculture in seabass (Lates calcarifer Bloch) cage with a production of approximately 100 kg/cage/yr (1 cage = 10 × m2). Mostly dry seaweed is exported to Malaysia.
Thailand exports seaweed at quantities ranging approximately between 20 to 200 tonnes/yr (dry weight) valued at 4 to 10 million baht (HAI, 1986). Most of the seaweed exported are of the genus Gracilaria. Major export markets are Japan, West Germany, Hong Kong and Malaysia. In view of this and due to the absence of processing plants, Thailand has been importing agar at quantities ranging between 200 to 300 tonnes/yr at a value of 50 to 100 million baht. Some of the production is utilized and consumed in Thailand, but the bulk is exported; in 1984 seaweed exports totalled around 8.4 tonnes valued at 1.5 million baht (HAI, 1986).
Gracilaria species are found in shallow mudflat areas. They can propagate by sexual and asexual reproduction. They can be eaten in fresh form or dried for export (Plate 1). At present, eight endemic agarophytes are found in Thailand, four species belonging to the genus Gracilaria and four to Polycavernosa, G. tenuistipitata var. liui, G. firma, G. irregularis, G. salicornia, P. fisheri, P. changii, P. fastigiata and P. percurrens (Abbott, LA. 1987). The major producing areas are the southern region of Songkhla Lake and the shallow mudflats in Pattani Bay (Figures 1, 2 and 3).
2. CULTURE TECHNIQUES
Thailand does not produce large quantities of seaweed. Harvest is mostly from natural beds. The Department of Fisheries is conducting research and investigating the feasibility of mass propagation of a number of seaweed species especially Gracilaria sp. (Sirikul and Singthaweesak, 1987; Tachanaravong et. al., 1987).
The culture methods practiced in Thailand are as follows:
2.1 Long line
Raffia and polyethylene lines were used as materials for the long line culture method in an experimental culture farm; the results obtained were not satisfactory (Plate 2).
2.2 Pond culture
Farmers collect young Gracilaria sp. from natural grounds and transfer them to earthen pond with a water level of around 0.5–1.0 m (Plate 3). The exchange of water depends on the tide. The average production level obtained in 1985 was 1 030 kg/rai/yr (1 rai = 1 600 m2) (Tookwinas et. al, 1987).
2.3 Polyculture in seabass cages
Seabass (Lates calcarifer Bloch) farmers harvest Gracilaria that naturally collects and grows on the cages. They grow on the polyethylene net and on the bottom of cages. Production levels range between 50–100 kg/100 m2/yr.
Figure 1. Map of Thailand
Figure2. Songkhla lake bathymetry, 1984
Figure 3. Pattani Bay showing the natural beds of Gracilaria sp. (shaded area)
An export market for dried, wild harvested Gracilaria has developed in southern Thailand; this has been unreported. Exact quantities leaving Thailand for Malaysia are unknown but are estimated to range from 30 to 50 tonnes annually at a value (first sale) of 1.8–3.0 million baht in 1987. The major producing areas are the southern regions of Songkhla Lake and the shallow mudflats in Pattani Bay. Price was in the range of 30 to 90 baht per kg. The market appears to be fairly limited and highly seasonal with nearly all the trade occurring during the Muslim fasting month of Ramadan.
4.1 Farmers who harvest from natural beds normally collect the whole of the Graci laria shoot or with the substrate (live shell) and dry them. This practice causes considerable damage to the natural stocks of Gracilaria. They must be harvested by cutting, leaving around 5 to 10 cm of the Gracilaria shoot. The live shell must be brought back to the sea.
4.2 There are no commercial or industrial-scale agar manufacturing facilities in Thailand so the price of Gracilaria is not stable.
Plate 1. Dry Gracilaria sp.
Plate 2. Gracilaria seedlings on long line, Songkhla lake
Plate 3. Pond culture of Gracilaria sp., Pattani Bay
Abbott, LA. 1987 Some species of Gracilaria and Polycavernosa from Thailand. Paper report, 26 pp.
Hawaiian Agronomics International, Inc., (HAI). 1986 Progress Report for the Agriculture Technology Transfer Project: Seaweed production and processing subproject. Department of Fisheries, Ministry of Agriculture and Cooperatives, Bangkok.
Sirikul, B. and W. Singthaweesak. 1987 Experiments on seaweed Gracilaria sp. culture in Chanthaburi province. Meeting Report for the Agriculture Technology Transfer Project: Seaweed production and processing subproject,13–14 Aug. 1987, NIFI. Kasetsart University, Bangkok.
Tachanaravong, S., V. Wattanakul and S. Junyampim. 1987 Experiment on culture of Gracilaria sp. in the outer part of Songkhla Lake, 1987. Meeting Report for the Agriculture Technology Transfer Project: Seaweed production and processing subproject,13–14 Aug. 1987, NIFI. KasetsartUniversity, Bangkok.
Tookwinas, S., S. Tachanaravong and S. Jaesoe. 1986 Traditional Gracilaria culture at Pattani Bay. Thai Fisheries Gazette,Vol. 39, No. 2, p. 145–150.