LIST OF PARTICIPANTS

APPENDIX I

THE SECOND NATIONAL COORDINATORS' MEETING
OF
REGIONAL SEAFARMING DEVELOPMENT AND DEMONSTRATION PROJECT
20–23 SEPTEMBER 1988, SINGAPORE

LIST OF PARTICIPANTS

MESSAGES

APPENDIX II

WELCOME SPEECH

Chen Foo Yan

When one meets old friends and makes new ones, it is always a pleasure; it is more so when one meets them in a place that is close to his heart and welcomes them to an occasion that is of great interest to each one.

On behalf of the FAO and UNDP I am very pleased to welcome you to the clean and green city of Singapore, and, once again, to the National Coordinators' Meeting of the Regional Seafarming Development Project. As you all know this is our second meeting and it also signals the start of the second year of our operations. Among others we shall assess the progress we have made in the first year. But in this brief welcome remarks, I should like to note with pride, and with gratitude to all of you, the strides we have made towards achieving the Project objectives in this short span of time.

You have made regional collective action along the principle of TCDC a real and concrete activity. The four training courses that we have implemented so far shows that it is not impossible — as doubting critics may have warned — to collaborate in organizing and implementing highly practical courses for technicians and farmers coming from different countries. We have proven on four occasions that it can be done and with success.

The training component of the project, particularly the courses, was not intended to prove only that TCDC can work. They are a means to transfer technologies among our countries rapidly and cost-effectively. I know you are familiar with our strategy of trying to achieve immediate impact on production by quickly introducing and demonstrating the viability of known and better technologies and production systems. The objective of this move is to convince our leaders of the important contribution of aquaculture — in our case coastal aquaculture — to the national economy, in other words that it pays for a country to invest more in aquaculture development. In the process we buy time for us and for our research and development workers to widen and firm up the technological base for its further development.

In the very first year of our project we have made the initial inroad into the consciousness and favourable notice of our national leaderships. Technically, we have successfully taken the first step of introducing technology that will put into production or make more productive the vast and as yet hardly tapped coastal areas of our countries. But there are more tasks ahead and they are just as critical. For instance, even this early we should already begin to take control and provide direction to the growth of the seafarming sector before it finds itself meeting or creating a lot of national problems. I specificially refer to the project activity of developing a management system for the orderly and rational growth of the seafarming industry. We are going to discuss at length the kind and extent of work we have to do to develop an effective mangement system for our respective countries. I have no doubt of the success of this next endeavour. The cooperation and enthusiasm that each of you has put into the initial activities, such as the training component, will carry us through. And our having harmonized the activities of the Seafarming Project with that of NACA has in large measure helped in getting us this far. The backstopping being provided by the NACA coordinating unit and, in many instances, the network centres, has facilitated the work and maximized the use of manpower and financial resources. This in turn has enabled us to implement more training activities to benefit more workers in more countries.

The collaboration of other regional and national projects has largely contributed to a wider participation in the Project, particularly in training. I wish to thank the respective coordinators and staff of the ASEAN Small Scale Coastal Fisheries Development Project, and the Indonesian Seafarming Project, and the Bay of Bengal Programme for their part in the organization, conduct or sponsorship of participants to the training activities and for their continuing interest in all the other activities of the Project. I would also like to put on record our deep appreciation of the efforts of the staff of your respective centres that have implemented or will be implementing the training activities.

Finally, I wish to thank, this time on behalf of the Project, the leadership and staff of the Primary Production Department for making, on short notice, the arrangements for this Meeting. I must apologize to you for giving such a very short notice knowing fully well you have many other duties and responsibilities.

In closing I would like to point your attention to our schedule, particularly to the fact that this Second National Coordinators' Meeting coincides with the final activities in the ongoing Netcage Finfish Culture which is also being implemented by the Station. This is intended to give you the opportunity to witness first hand the various learning activities that your technicians and farmers are undertaking. You will also participate in the seminar conducted by the trainees — an interesting feature of all the training courses, previous and coming — which is to present and discuss in class the status of the commodity or production system they are being trained for. This has been a very fruitful exercise; you will note that from the country status reports, the Project has compiled useful information that can serve many development purposes. It also serves as a well-directed occasion for exchange of experiences among the participants. I am sure that your presence in their programme and interest in their activity will give them encouragement and inspiration to do more and better work. While the training equips them with the skills and tools, it is the leaders like you who have to give the motivation. Joining them in a final training exercise and participating in a joint farewell activity is a small but momentous way of sharing each others' thoughts of the work needed to achieve our common objectives and the responsibilities required of each one.

As they will look forward to your guidance, I also wish to say that as chief technical adviser of this project I also look forward to your guidance.

Again, welcome to Singapore and to this Second Meeting of the National Coordinators of the Seafarming Development Project.

APPENDIX III

SPEECH

W. Chan

It is my pleasure to attend this Second Meeting of National Coordinators of the Seafarming Project. You will recall that I was with you during your first meeting. That had been a successful one which led to a very productive first year. I am sure that this second meeting will be more of a success now that you have had a year's experience to enrich your knowledge and capabilities and further refine your strategies.

I should like to thank you for inviting me to your meeting and to extend, on behalf of the Fisheries Department of the FAO, our congratulations to you for having had a good year and to assure you of our continuing interest and support. I should like to tell you that we have been keeping abreast of your activities and are pleased with the progress you have so far done. Personally, I am proud to be involved in this project.

The potentials of seafarming are now very well recognised by many of our colleagues in development as well as our national leaders. For one, everyone knows that the potential area is great and, as colleagues from China have pointed out, while the expansion of aquaculture on land has met or will soon meet its limits, the coastal areas are hardly tapped. Indeed, in the Yellow Sea area, production from coastal aquaculture is nearly as high as that from capture fishery. It is obvious that to achieve such level of parity or expansion, we must bring in the technology. On your first year you have largely done the job of introducing known technologies into your national systems for immediate application in production. Your next job is to see that your countries are equipped with the measures needed to direct and manage the orderly development of coastal aquaculture. Along with doing more extensive research to further improve known technology as well as to develop new technologies is the equally vital job of managing the development of the industry. I am aware that you have made the first steps necessary to develop a management system; you have been compiling for comparison and eventual synthesis the fishery and aquaculture rules and regulations of your respective countries; you have started work on developing site selection criteria for various coastal aquaculture species; and I know you will soon conduct a training-workshop on Geographic Information System, which is a very essential requisite to the development of a regional seafarming resource atlas and establishment of national seafarming management development systems.

The work ahead is not easy. There is a lot to do yet. But I share your chief technical adviser's optimism and confidence in your capability to achieve the objectives of the Project.

I wish to end by reiterating the best wishes and assurance of continued assistance of the Fisheries Department of the FAO.

APPENDIX IV

OPENING ADDRESS

Dr. Ngiam Tong Tau

On behalf of the Primary Production Department of the Ministry of National Development of Singapore, I would like to extend my warmest welcome to you to the Second National Coordinators' Meeting on Regional Seafarming and Development Project. It is indeed our pleasure that the Network of Aquaculture Centres in Asia (NACA) decided to hold this meeting here in Singapore.

Though Singapore is not an agricultural country and our fisheries sector is small, we see in TCDC projects a means of promoting technical cooperation in the region. For this reason, Singapore supports and participates in the UNDP/FAO Regional Seafarming and Development Project. Marine aquaculture has been an area of great interest to us and we have been actively involved in the development of techniques on floating fish netcage and mussel raft cultures in our coastal waters. To date we have a total of 70 such farms, producing some 1,800 m tons of aquaculture produce annually. In a small way and when the opportunity arises, we try to share our experience so as to encourage development of seafarming in the region.

You may be aware that we are conducting a 3-week training course on Marine Finfish Netcage Culture at our Marine Aquaculture Station at Changi. This course is conducted in collaboration with UNDP/FAO Regional Seafarming and Development Project and ASEAN/UNDP/FAO Regional Small-scale Coastal Fisheries Development Project. I am told that the participants of the course are faring well, and that they will be meeting with you tomorrow to make presentations on some aspects of seafarming activities in their countries.

It is through interactions arising from meetings such as this and through training courses that we can all learn from each others' experiences on seafarming activities. I therefore wish all of you a productive and fruitful meeting, and a happy stay in Singapore. It now gives me great pleasure to declare the Second National Coordinators' Meeting on Regional Seafarming and Development Project open.

Thank you.

AGENDA AND LIST OF DOCUMENTS

APPENDIX V

AGENDA

1. Procedural Matters

1.1 Opening of the Meeting
1.2 Election of Chairman
1.3 Adoption of Agenda and Arrangement for the Meeting

2. Presentation of Progress Report on Project Activities

3. Presentation of Country Reports by National Coordinators

4. Demonstration and Training Courses of Seafarming Systems

5. Management System for Seafarming Development

5.1 Seafarming Resources Atlas
5.2 Seafarming Site Selection Criteria for Each Culture
5.3 Technical Requirements for Formulating Seafarming Rules and Regulations
5.4 Strategies for Coordinating with Common Users of the Sea

6. Seafarming Information Exchange

7. Women Concerns in Aquaculture/Seafarming Activities

8. Other Matters

9. Date and Venue of the Third NCM

10. Adoption of the Report

APPENDIX VI

LIST OF DOCUMENTS

COUNTRY REPORT: CHINA

APPENDIX VII

SUPPLEMENTARY INFORMATION ON
SEAFARMING IN CHINA

Chen Jiaxin

In several international meetings and conferences on aquaculture, the information and data on seafarming in China have been reported, such as in the “Present Status and Trend of Seafarming in China” (1st NCM, October 1987) by Tong Jin Wen and “Status and Future Perspective of Mariculture in China” (7th IPFC Working Party of Aquaculture Experts, August 1988) by Chen Jiaxin. On the other hand, there is a lot of special reports and publications, including “Mussel Culture Methods”, edited by Mr Luo Yousheng, “Shrimp Culture” by Wang Ke Xing, “Breeding of Laminaria Seedling” by Miao Guoyong and Chen Jiaxin and “Porphyra culture” by Zhang Youji, etc. These papers detail the main species cultured in China. In this report, therefore, only the seafarming situation and problems that occurred in 1987 as well as the point of view and policy about seafarming made by the Chinese Government are presented.

In January 1988, during the National Working Group Meeting of Fisheries, the director of the Bureau of Aquatic Products, Mr. Tu Fongjing, proclaimed that the total fish and fisheries products in 1987 in China reached 9,530,000 MT exceeding the target of the Seventh Five-Year (1986–1990) Plan three years in advance. Of these products, marine landing was 4,380,000 MT, mariculture 1,100,000 MT and freshwater fish 4,070,000 MT. The figures illustrate that the mariculture products increased very rapidly in 1987, for example, the total culture area and products of shrimp culture was 130,000 ha and 153,000 MT, respectively. An unprecedented surge in scallop and abalone culture occurred in Liaoning and Shandong provinces. The culture area for abalone in Liaoning reached about 470 ha and the scallop culture area in Shandong also about 470 ha. More than 40,000 MT of scallop was produced last year, nearly 1.5 times more than in 1986.

In order to satisfy the market for high quality finfish, the culture areas for grouper, red sea bream, black sea bream and sea bass have increased to more than 2,000 ha and the number of cages for marine finfish to about 10,000. Mussel, Oyster, Gracilaria, Undaria, Porphyra crab and clam cultivation have also gained rapid expansion. Although the culture area and production of Laminaria have been going down, the yield per unit area has been increasing in most phycoculture farms.

In sum, culture fisheries gained 15 per cent in species and 21 per cent in production. This is the result of a combination of new fishery price policy and advanced culture techniques adopted by the Chinese government.

To ensure the steady increase in mariculture production, the Government has adopted a three-point measure:

1. To combine the technical advantages of fisheries research institutes and higher education establishments with the economic advantages of advanced towns, villages and large and medium sized enterprises in exploiting the natural fisheries potentials. The purpose is to set up enterprise groups covering different businesses, departments, districts and ownership systems.

2. To encourage scientists, researchers and technicians working in fisheries research institutes to contract, rent or operate fisheries development agencies and business entities, or to set up private ones. This scheme allows them to take up concurrent posts or use their spare time to offer technical consultancy and services which allows them to earn more income. A new streamlined system of scientific research, production and business complementation is coming into being.

3. To strengthen research on the weak points or areas that have the greatest influence on the development of fisheries. The national fisheries development plan expects the amount of fish and fisheries products to be doubled by the year 2000. Of this, 90 per cent will come from aquaculture. In view of this goal, the supply of feeds for finfish and shrimp will be the most serious constraint. Thus, the government has been supporting and encouraging relevant units to strengthen their research and development on finfish and shrimp food. Meanwhile Chinese fisheries must bring the advantages of fishery itself into full play, combining fisheries with agriculture, animal husbandry and other commodities to exploit new resources and simultaneously develop cultivation/enhancement, collection and processing that would take advantage of both traditional experiences and modern scientific techniques in keeping with the Chinese characteristics of solving problems.

National standards for finfish/shrimp feeds have been drawn up to gradually improve feeds. The establishment of a feed quality control system will make feed formulations more scientific, quality standardised, products serialised and application normalised.

At present, there are three difficult problems that influence the development and expansion of seafarming production in China:

1. The supply of finfish fingerlings do not meet demand.

2. Shortage of high quality finfish/shrimp feeds. The lack of animal protein resources has especially seriously hindered the development of formulated feeds.

3. As the level of seafarming management is rather low, techniques such as pond design, water quality control, feeding and prevention of disease need to be improved. Take shrimp culture; for example, the excessive speed in the expansion of the shrimp culture has caused some serious irrationalities in the shrimp industry. For one thing the culture techniques have not been popularised. And, nationwide, the general result is a low yield single crop of low quality but produced at a high cost.

In conclusion, we consider that seafarming in China has a strong base and huge potentials. Apart from taking advantage of our own manpower and resources, it is important for us to make closer ties and cooperation with other countries to further expedite the development of seafarming.

Criteria on the Site Selection for Culture of Porphyra and Laminaria in China

Porphyra

1. Sea bed

Except rocky bottom, grounds and any other bottom substances, such as mud, clay and sand, etc suitable for fixing pine poles or concrete blocks, can be selected as cultural sites.

2. Limitations of site

Until now, the floating raft method has not been adopted for the culture of Porphyra in China so that culture sites are limited to intertidal areas. The higher limit cannot exceed the line of low tide, the lower limit is near the line of low ebb. The exposure time to the air is about 2–5 hours every day during the lowest ebb. The site near the lower limit is submerged for 3–4 days during low ebb.

The site has an influence on the number of seedling, growth and quality of Porphyra thallus. The fact is that the number of seedlings is much more in higher sites than in lower ones, while the growth of thallus is very poor. On the other hand, the thallus grows fairly well in a lower site, while growth of miscellaneous seaweeds is luxuriant on the same floating rack with Porphyra; management of collection becomes difficult.

3. Nutrition

According to nitrogen level, cultural sites are classified into three types:

1. fertile : 200 mgN/m³

2. medium fertile : around 100 mgN/m³

3. sterile : 50 mgN/m³

4. Current velocity

The current velocity plays a very important role in the exchange of gas, supplement of nutrient substances and adjustment of water temperature, etc.

To get good results, a faster current is needed in sterile area.

The criteria for current velocities are:

1. in fertile area : 10 cm/sec

2. in medium area : 20 cm/sec

3. in sterile area : 30 cm/sec

Laminaria

Laminaria is the most important commercial seaweed in China. It has been traditionally cultured along the maritime provinces, from Liaoning to Fujian. Recently the cultural method using floating raft has been introduced. The advantage of this method of farming Laminaria is that some environmental factors can be controlled so that the criteria for site selection are not quite strict. These are as follows:

1. Sea bed : mud, clay and sand

2. Water depth : > 5 m

3. Nutrition 15 mgN/m³ [no need to fertilize] 5 mgN/m³ [need to fertilize]

4. Water temperature

The water temperature range suitable for growth of Laminaria sporophytes is 0–18°C. The optimum temperature is 5–10°C. Water temperature determines the growth period of kelp. As a result, grounds are chosen where optimum temperature lasts longer [see the table below].

COUNTRY REPORT: D.P.R. OF KOREA

APPENDIX VIII

PROGRESS OF SEAFARMING ACTIVITIES, RESEARCH
AND DEVELOPMENT IN D.P.R. OF KOREA

D.P.R. of Korea is situated in the northwest section of the Pacific Ocean and has advantageous natural, geographical and oceanographic conditions. The Government of D.P.R. of Korea, realizing there is not much arable land, has taken various steps to develop seafarming as an important measure to increase national income.

Recently the Government paid more attention to the seafarming development investing large amount to it. Target is to develop 100,000 hectares of seafarming land and produce 8 million tons of seafarming products with the nationwide movement.

Last year the seafarming culture area was increased by two times and the number of state enterprises and co-operative farms by three to four times.

The Government adopted a policy of intensive artificial farming, hatchery, and seeding on a large scale by building seed production facilities in many areas. This measure is intended to protect natural resources. Therefore seafarming in D.P.R. of Korea is developing on a firm technical basis.

Main commercial species for intensive farming include oyster, laver, scallop, mussel, prawn and rainbow-trout. Flounder, sea-cucumber and abalone are developed by semi-artificial cultivation. The seeds are hatched and released in large quantity. The thrust of seafarming is to increase productivity per unit area and make effective use of the bottom of coastal farms.

The social requirement of producing seafarming products with less materials and labour is also an important consideration.

Research

The Government has given lots of attention to seafarming. It is investing much into its development with science and technology as the means to increase seafarming products rapidly.

The Government has formed the management system of scientific organizations while increasing their number and rationally placing them in strategic locations.

With the intensification and expansion of aquaculture, research to prevent aging of the farms and to enable the use of the space and water column available in a farm is being held. The stress is on developing mixed farming techniques to prevent aging or deterioration of farms by the excrement of, for instance, mussels.

Research has helped increase output per hectare to over 400 mt by utilizing a mixed farming method in which mussel and sea tangle are cultivated in the upper part of the sea and seacucumber and flounder in the bottom.

As seedling is one of the important inputs and a vital factor in improving production, research is trying to modernize the breeding method of undaria and sea tangle. Lately, researches have developed the technique of cultivating sea-tangle sprout in high temperature (it is traditionally cultivated in low temperature) and in high humidity.

To breed improved species, research has been done on the mono-development technique of Undaria, Laminaria, longipedalis and other seaweeds. Also, research is going on in breeding species that are resistant to low or high temperatures. Other R & D projects are on mechanization of hard and labour-consuming work, protection from typhoon, and utilization of rural materials.

To increase the population of flounder and seacucumber, a new method was discovered: releasing young shells 5–7 days after fecundation instead of the previous practice of releasing them after metamorphosis stage.

Overall, the combination of favourable policy and intensive application of research results has ensured that enough seafarming products are supplied to the people and satisfy domestic demands.

Selection criteria for the more commonly farmed species

In D.P.R. of Korea, the criteria for seafarming species are regulated on the basis of industrial experience in various places. These were developed by authorized scientists, technicians and experts.

Technical criteria

• Depth of water 1–5 m within 8 km area from the cost

• Places where wave does not destroy the facilities

• Places where there are no big changes in the bottom quality by the influence of river and streams.

• Good bottom quality (not rock) bed

• Places free from sewage flow and away from a sea-route

Biological aspect

• Laminaria and Undaria
  They grow well in places where other seaweeds, including ulvaceae, grow.

• Laminaria cichorioides
  It grows well in places where Laminaria japonica and Undaria pinatifida grow, namely, lime bed and lichen-bed.

• Porphyra tenera
  The places where Undaria grows and seacucumber and abalone live.

• Gracilaria lichenoides
  It grows where multi-season seaweed grows

• Crassostrea gigas
  It grows well where seacucumber and other shells such as short-necked clam live.

• Scallop
  It grows well where Undaria pinatifida and Laminaria japonica grow.

• Abalone
  It grows well where Laminaria grows.

COUNTRY REPORT: INDIA

APPENDIX IX

CURRENT STATUS AND TREND OF SEAFARMING ACTIVITIES IN INDIA

P.S.B.R. James

Seafarming, in the modern sense, is relatively new to India, although certain age-old practices of semi-farming of fish and prawn in saline coastal areas, such as paddy-cum-prawn culture in Kerala and ‘bheri’ culture in West Bengal, continue to this date. It has been estimated that about 25,000 ha of such saline areas which are under this practice produce about 10,000 mt of fish and prawns per annum. Starting from 1915, seafarming of finfish, especially mullets and milkfish, has been attempted at several centres in Tamil Nadu and Kerala with varying results, but it did not lead to establishment of a viable seafarming industry in the country.

Research and development in mariculture was renewed in the early seventies and, since then, several achievements have been made. The Central Marine Fisheries Research Institute under the Indian Council of Agricultural Research has played a pioneering role in this programme with a major effort in research, education and extension education in Mariculture. Other ICAR Institutes and programmes such as the Central Institute of Fisheries Education and All-India Coordinated Research Project in Brackishwater Fish Farming, national laboratories such as the National Institute of Oceanography and Agricultural Universities under their Fisheries Colleges have also made significant contributions in specific areas of seafarming. The Ministry of Agriculture is implementing schemes in brackishwater farming in different States starting from the Sixth Five-Year Plan. The Marine Products Export Development Authority of the Ministry of Commerce is implementing development and extension programmes in shrimp farming and shrimp hatchery in several States.

Shrimp farming is the only seafarming activity in India. It has been taken up on a commercial scale by the private sector with technical and some financial assistance from government agencies. For other species, commercial farming activity is yet to be taken up.

Culture of molluscs which have a high production potential, has received considerable attention. Oyster farming techniques have been developed for Crassostrea madrasensis in Tuticorin. The technology is adaptable for other areas and species. Open-sea culture techniques for the green mussel (Perna viridis) and brown mussel (Perna indica) have been developed at Calicut and Vizhinjam, respectively. Some work has been done in Goa. Green mussel culture in a saltwater lagoon near Madras had given encouraging results. Cockle (Anadara granosa) farming has given consistent results in Kakinada Bay. Technology for cultural pearl production in Pinctada fucata has been developed and good quality cultured pearls with a gross production rate of 60 per cent has been developed. In the case of oyster and mussel, Lab-to-Land transfer of technology was done for the benefit of fishermen. However, this could not be followed up. The major constraint has been the lack of an internal market for the produce as consumption of these foods is highly localised. Pilot-scale programmes are being taken up for overcoming the present obstacles, exploring market potential and establishing economic viability.

Hatchery techniques for producing spat of pearl and edible oyster have been successfully developed and an experimental shellfish hatchery has been established at CMFRI. The hatchery is capable of producing yearly about 4 million seeds each of pearl oyster and edible oyster. Non-availability of seed would not be a constraint for future programme.

Seaweed collection from natural beds and utilization in the production of agar-agar and algin is practiced at several centres in the country. Since natural production in the exploited beds has been declining due to indiscriminate exploitation culture techniques have been sought to be developed to increase production. Vegetative farming technique has been adopted for Gracilaria edulis at Mandapam with some amount of success. Work on other species and spore production techniques is in progress. An experimental transfer of technology programme on seaweed culture has shown that it can be profitable only if production of raw material is integrated with production of final product of agar.

Finfish culture has been experimented upon at several centres in different ecosystems. The candidate species have been invariably local species of mullets and milkfish. Some work has been done with Sillago sihama and Siganus spp. Experiments have been conducted in the ponds at Mandapam, Madras and Tuticorin, pen culture in the lagoon at Mandapam, polythene-lined ponds dug on the sandy beach at Calicut, cage culture at Mandapam and salt-pan culture at Tuticorin. Some experimental work has also been done in Mangalore, Kakinada and Sunderbans. Estimated production rates have ranged widely from a few kg to about 1.5 t/ha/year in monoculture/polyculture of the species mentioned above. The stocking rates, pond sizes, feeding etc. have varied. On the whole, much remains to be done in standardising the finfish culture technology for seafarming.

The UNDP/FAO/ICAR Centre of Advanced Studies in Mariculture was established at the Central Marine Fisheries Research Institute, Cochin in 1970 for providing post-graduate education and research in mariculture leading to Master's and Doctoral degrees. 49 students have taken M.Sc. degree with two batches currently in the course. Out of 50 Senior Research Fellows admitted to doctoral programme, 6 have taken their degrees and others are in various stages of awaiting results. The programme, on completion of UNDP/FAO assistance in 1986, is being continued as a Post-Graduate Programme in Mariculture at CMFRI.

The CMFRI has strong research programmes in mariculture for prawns, molluscs, finfishes and seaweeds. Production technologies have been aimed at reducing cost of production, utilisation of local resources and competence at farmers' level to manage the programme. The environmental aspects have received due consideration. Multidisciplinary programmes in physiology, nutrition, pathology and genetics have been strengthened. Compounded feeds for larval stages and adult prawns have been developed and evaluated.

Development of seafarming as a production activity has not made much headway in India, except for shrimp farming which is catching up. For many of the technologies, economic viability has not been established. Pilot-scale projects are being considered for this purpose.

Brief write-ups on the current status of R & D in prawn farming, hatchery production of prawn seed, oyster culture, pearl culture, mussel culture, shellfish (mollusc) hatchery technology and seaweed culture are given in the pages following.

Prawn Farming

Candidate Species

A number of species of prawns native to Indian waters are eminently suited for culturing in coastal waters by virtue of their large size, fast growth rate and euryhalinity. The most important are Penaeus monodon, P. indicus, P. merguiensis, P. penicillatus, P. semisulacatus, P. japonicus and P. latisulcatus. Some species of the genus Metapenaeus, such as M. Kutchensis are also found to grow well in the traditional culture systems in the country. But due to their smaller size they fetch a low market price and hence are not generally preferred for scientific farming.

Natural Distribution and Production

These prawn species have a distinct pattern of distribution along the Indian coast. P. monodon forms an important component of the trawl net catch in Andhra Pradesh, Orissa and West Bengal while it occurs as stray catch along the other coastal States. P. indicus is an important species in the prawn catches of Tamil Nadu, Andhra Pradesh and Kerala, while the banana prawn, P. merguiensis is more common in Orissa on the east coast and in North Karnataka and South Maharashtra on the west coast. P. penicillatus which is very similar to the banana prawn is common in north Maharashtra and Gujarat on the west coast and in West Bengal on the east coast. P. semisulcatus, the “Pink flower” prawn, dominates the prawn fishery in the Palk Bay region and in the Gulf of Kutch region where sea grass and seaweed beds are present. The other two species P. japonicus and P. latisulcatus occur in small number all along the Indian coast. Among the species belonging to the genus Metapenaeus, M. monoceros is the dominant species on the east coast, M. dobsoni is important on the south west coast. M. ensis is common only in West Bengal. M. brevicornis has a patchy distribution occurring in the Sunderbans, Kakinada region, Bombay and Gujarat. M. kutchensis is found only in Gujarat.

Seed Availability and Collection Techniques

Surveys to study the seasonal availability of prawn seed in the coastal regions of Kerala, Karnataka, Tamilnadu and in selected centres in Andhra Pradesh have been carried out by CMFRI. Under the All-India Coordinated Project on Brackishwater Fish Farming, the States of West Bengal, Orissa, Andhra Pradesh, Kerala, Tamilnadu and Goa have also conducted prawn seed surveys for assessing the availability of seed resources for culture purposes. These surveys have revealed that prawn seed are available in the creeks, estuaries and low-lying coastal swamps during the post-monsoon period in large numbers. They are usually collected with the help of drag nets made of velon screen, in shooting nets which filter the tides or in triangular push nets. Trade in prawn seed has become a way of earning additional income to fisherman families in West Bengal, Orissa and Andhra Pradesh where seed of P. monodon is available in plenty in brackishwater areas.

In India we now have commercial prawn hatcheries in the State sector in Kerala and Maharashtra at Azhikode and Bara-Pokaran, respectively. In the private sector a prawn hatchery has been established at Muttukadu near Madras. The MPEDA has started constructing large commercial hatcheries in Orissa and Andhra Pradesh with foreign collaboration. The CMFRI has developed an indigenous low-cost technology for hatchery production of prawn seed suitable for Indian conditions, utilising locally available raw materials and equipment.

Farming Techniques

Traditional methods. In Kerala the method of trapping and growing the naturally available prawn seed in the low-lying paddy fields in the coastal regions during the post and pre-monsoon periods have been traditionally practiced for generations. During the monsoon when the backwaters turn fresh due to the heavy rains, one crop of a salt resistant variety of paddy is grown in these fields. After the paddy is harvested the fields are leased out to prawn farmers from November-April when the salinity is too high for paddy cultivation. The paddy stalks are not removed completely; they are allowed to decay in the water and form detritus. The decomposing stalks also provide a substratum for the growth of pennate diatoms, stalked ciliates, rotifers, nematodes and harpacticoid copepods on which the prawns feed. At high tide the brackishwater, rich in the seed of penaeid prawns and fish, is let into the fields through the sluice. At low tide, a bamboo screen is kept in the sluice and the water is allowed to flow out. This is done everyday throughout the culture period to stock the fields with naturally occurring seed of prawns. The prawn postlarvae that enter the field settle down and grow rapidly, feeding on the rich food available there. Fishing with sluice nets begins only towards the end of December. It is done during nights for 6–7 days around the new and full moon phases when the tidal amplitudes are high, with the help of conical sluice nets. At the end of lease period, the fields are fished out completely. Then the fields are handed over to the owners. There are about 7100 ha of such fields in Kerala. The prawn catch is chiefly made up of the small sized Metapenaeus dobsoni (60–80 per cent) and M. monoceros (5–15 per cent) while the larger Penaeus indicus forms only 15–35 per cent of the catch. This traditional type of prawn filtration was introduced in the paddy fields of coastal Karnataka in 1970–71. Now about 1800 ha are used for this purpose.

The large brackishwater “bheris” of West Bengal in the Sunderbans (about 20,000 ha) have been traditionally used for growing fish and prawns by trapping the prawn and fish seed that enter these enclosures during the high tides. These deep enclosures are not suitable for growing a monsoon crop of paddy and are exclusively used for growing fish and prawns. The more elevated areas bordering these “bheris” are used for paddy cultivation during the monsoon season and for fish and prawn production. Species constituting the catch are P. monodon, P. indicus, Metapenaeus brevicornis, M. monoceros, Palaemon styliferus, and P. tenuipes among prawns, and mullets, milkfish and Lates calcarifer among the fishes.

Improved methods. In recent years, organizations like the CMFRI, CIFRI, CIFE, MPEDA, the Agriculture University of Kerala and the State Fisheries Departments of Tamilnadu, Andhra Pradesh, Orissa, Kerala and Goa have been conducting experiments in marine and brackishwater tidal ponds on the monoculture of P. indicus and P. monodon and the polyculture of these species along with mullets, milkfish and pearl spot. The production rates have been highly variable depending on the ecological conditions in the pond, the duration of culture period, the species stocked and the stocking density. The salient points that emerge from these researches are:

1. It is better to culture prawns for not more than 3 months. Keeping the prawns longer in the ponds leads to stunting of growth and mortality from diseases.

2. The grow-out ponds should be stocked with juvenile prawns at least 25–30 mm in size to get good survival rates. When postlarvae are stocked directly into the ponds mortality is high.

3. A nursery phase is necessary. The postlarvae from natural sources or hatcheries should be grown for about 20–30 days in especially prepared nurseries free of predators, before they are ready for stocking in grow-out ponds. It is more economical to have the nursery as part of the grow-out facility rather than as an adjacent to the hatchery.

4. The brackishwater ponds on the west coast are generally more productive and hence can support a greater stocking rate than the ponds on the east coast. However the problem of acidic soils is more common on the west coast.

5. The presence of a small population of milkfish in the prawn ponds appears to be beneficial as they check the undue growth of algae in the ponds.

6. In monoculture of prawns a stocking density of 30,000–50,000 juveniles/ha in the case of P. indicus and 10,000–20,000/ha in the case of P. monodon depending on the natural productivity of the area, is recommended for semi-intensive prawn culture with minimal supplementary feeding. Higher stocking densities lead to stunted growth and poor survival.

7. Under favourable culture conditions a harvest of 600 kg/ha of P. indicus can be obtained in a culture period of 60–75 days. In the case of P. monodon 500 kg/ha can be obtained in 80–100 days.

8. The presence of the fast breeding Tilapia in the ponds retards the growth of the prawns as they compete with the prawns for food.

Apart from these efforts experiments have also been done on pen culture and cage culture of prawns by the BOBP at Killai and the Tamilnadu State Fisheries Department at Madras. Encouraging results have been obtained at Killai although maintenance of the barrier nets in pen culture is posing some problems. The culturing of P. indiscus and P. monodon in velon-net cages installed in the Kovalam backwaters near Madras was successful but expensive.

In the last two years enterprising farmers in Andhra Pradesh have developed pump-fed farms to culture P. monodon in a very profitable manner. Instead of depending on the tides for water management in the ponds, the farmers have installed pump sets to lift the water from the creeks into the pond system. The pumped water is filtered through large filter bags before being distributed to the ponds. A similar system is being followed in the salt pan areas at Tuticorin where pump-fed ponds have been constructed for culturing P. indicus. Supplementary feeding with clam meat, trash fish etc. in addition to manuring the ponds with organic and inorganic fertilizers is done to accelerate growth of prawns.

Growth of Prawns in Ponds

Under favourable conditions P. indicus seed 20 mm in TL grows to an average size of 130 m (17 g) in 60 days of culture, after which it is advisable to harvest them. In the case of P. monodon, seed 42 mm in size, grew to a marketable size of 170 mm (33 g) in 80 days.

Best growth is obtained during the low salinity period when the pond salinity ranges from 10–25 ppt. When the salinity exceeds 35 ppt, growth is retarded in all species, especially P. monodon. Similarly a temperature range of 26–30°C is ideal for prawn growth. Higher temperature leads to deterioration in water quality in the ponds.

Harvest Techniques

In the traditional culture fields the prawns are harvested by conical sluice nets (in Kerala) or in bamboo traps kept near the sluices (West Bengal) making use of the high tidal amplitude during the new moon and full moon phases. Cast nets, drag nets and hand picking are also employed to capture the prawns. Total harvest is not possible by these methods in ponds that cannot be drained fully. But in pump-fed ponds where the water can be fully drained by gravity, the prawns accumulate in trenches or catching pits from where they are easily harvested.

Production Rates

Under experimental conditions the best production rate for P. indicus was 600 kg/ha/crop 55 days duration and for P. monodon it was 515 kg/ha/crop 80 days. Under commercial conditions the farmers culturing P. monodon in Andhra Pradesh are said to harvest 600–700 kg/ha/crop of 7–8 month duration. In the salt pan areas at Tuticorin a commercial venture has successfully produced 1200–1600 kg/ha in 7.5 months growing period. The longer duration is due to the high salinity (38–48 ppt) obtaining in the ponds in this region.

From these results it is reasonable to say that a production of 3 tons per ha per year is well within the reach of entrepreneurs who take up prawn culture seriously.

Economic Data

The salt pan owner at Tuticorin who undertook the successful culture of P. indicus reported above sold 2930 kg of prawns produced from 2.75 ha of ponds for Rs. 100,537/-. This works out to an income of Rs. 36,558/ha/7 months. The cost of fixing sluice pipes and the recurring expenditure such as wages for watchman, cost of supplementary feed, fertilizers, fuel and energy, preparation of ponds, harvesting, marketing and miscellaneous expenditure come to 50–60 per cent of the income. The capital expenditure involved in the construction works and installation of pump sets, etc., can be recovered in 4 crops at the rate of 25 per cent of the profit.

There is a ready market for cultured prawns in India. The buyers buy ex-farm.

Extension Needs

The ICAR has two KVKs — one at Kakdeep and one at Narakkal for training local farmers in prawn culture. The TTC attached to CMFRI conducts regular training courses in prawn farming for State Government officials and extension personnel. The MPEDA also conducts 3-month training courses for farmers actually engaged in prawn farming. The MPEDA has a prawn farming wing engaged in developmental and extension work in the field of prawn culture in three maritime States.

All the maritime State Fisheries Departments also have taken a keen interest in promoting prawn farming in their respective States, the most active States being Orissa, Andhra Pradesh and West Bengal. Orissa has established Brackishwater Fish Farmers Development Agencies (BFDA) which are doing very active work to popularise prawn culture in the areas around the Chilka Lake. The other maritime States are also planning to start BFDAs.

Hatchery Production of Penaeid Prawn Seed

Induced Maturation and Spawning

Penaeid prawns mature and spawn only in the sea, although the juveniles are found in brackishwater environments. Prawns may attain adult size in brackishwater ponds but the females never become mature although the males may attain full sexual maturity. Hence, for hatchery work the spawners have to be collected from the sea. Since this is expensive and uncertain, efforts have been made to induce the prawns to mature and spawn in captivity. Intensive work in this area of research at the Narakkal Prawn Culture Laboratory (NPCL) of the CMFRI resulted in the development of a reliable method of inducing the Indian white prawn P. indicus to mature and spawn in captivity.

Immature large sized females prawns collected from the grow-out are subjected to unilateral eyestalk ablation using an electrocautery apparatus. They are then introduced into a 10-ton capacity circular maturation pool filled with seawater, along with unabated mature males in the ratio of 1 male to 3 females.

The pool is fitted with a sub-gravel biological filter through which the seawater is recirculated by airlift pumps. The nitrifying bacteria which grow on the gravel pieces oxidise the toxic ammonia secreted by the prawns into harmless nitrates. The resultant lowering of pH of the seawater is compensated for by daily addition of slaked lime or sodium carbonate to the water and the pH is maintained at 8.0–8.2. The prawns are fed ad libitum with clam meat. Under these conditions about 80 per cent of the eye ablated females develop into mature spawners within 3–5 days time. The mature females are removed from the maturation pool and kept individually in 200 litre capacity seawater tanks where they spawn viable eggs which hatch out into nauplii. The nauplii are transferred to the hatchery for further rearing.

The above technique has been successfully used to mature and spawn P. indicus, P. monodon, P. semisulcatus, P. japonicus, Metapenaeus monoceros, and M. affinis. P. monodon may take a longer time (5–20 days) to mature in captivity. It is also very sensitive to handling and other environmental stresses. P. indicus has been made to mature and spawn even without eyestalk ablation, by regulating the pH of the maturation pool at 8.2. But while ablated prawns 140 mm in size mature within 3–5 days, it takes a longer time (5–10 days) for the unabated prawns to mature and the females should be larger than 160 mm in total length.

The technique of induced maturation developed by the CMFRI is simple; the infrastructure needed is minimal and can be constructed at low cost. It is suited for Indian conditions.

Artificial Insemination

Another major breakthrough in the field of induced breeding of prawns is the development of the technique for artificial insemination of prawns at the NPCL of the CMFRI. Using this technique P. indicus and P. monodon have been made to spawn eggs that had a hatching rate of 90–95 per cent, i.e. almost similar to normal spawning. This has opened new vistas in selective breeding and genetic manipulation of cultivable prawns species.

Larval/Post-Larval Rearing

The CMFRI has developed a modular type of hatchery. The modules consist of 2-ton capacity rearing tanks made of fibre glass, concrete or plastic material. By increasing the number of tanks the capacity of the hatchery can be increased to the desired degree. Tanks larger than 2 tons are difficult to manage. The rearing tanks are kept in a glass roofed shed. Settled seawater (30–34 ppt salinity) filtered through a 50 micron-mesh nylon bolting silk is used for larvae rearing. The density of larvae in the tanks is 75 nauplii per litre of water. The protozoa and mysis stages are fed exclusively on a mixed culture of diatoms. The cultures are grown in one ton capacity white fibreglass tanks by fertilizing raw seawater with nitrates, phosphates and silicates. When exposed to sunlight, a diatom bloom dominated by Chaetoceros spp. develops within 24 hours. The diatom culture is pumped into the rearing tanks for feeding the larvae; the volume of diatom culture added is regulated to maintain a cell count of above 20,000 diatom cells per ml of water. Well-fed larvae swim about actively, trailing a long faecal pellet. The sediments are removed and ⅓-½ the volume of water is exchanged every day. Up to the mysis-3 stage the larvae are filter feeders and are fed only with diatom cultures. When they metamorphose into the first post-larval stage (PL 1) they become carnivorous and so a particulate feed developed at the NPCL is added to feed the post-larvae. The feed is compounded from locally available raw materials such as Squilla, prawn head waste, groundnut oil cake, tapioca and fish meal. The particle size is around 250 microns to start with and the size is gradually increased as the postlarvae grow older. A survival rate of 50 per cent is obtained from nauplius to the PL 5 stage, when the hatchery phase ends.

Nursery Rearing

After the PL 5 stage the post-larvae are grown in nurseries which could be concrete tanks or large plastic pools with a capacity of 10 tonnes of water. The density of post-larvae in the nurseries is reduced to about 15 per litre of water to reduce mortality due to cannibalism. The same particulate feed is given to the postlarvae in the nurseries; only the particle size is increased as they grow. The PL 20 can be stocked in grow-out ponds.

The hatchery techniques developed by the CMFRI eliminates the use of pure cultures of phytoplankton and Artemia nauplii to feed the larvae. The technique has drastically reduced the production costs by developing inexpensive mixed diatom cultures and particulate feeds. Apart from reducing the cost of production this technology has greatly simplified the procedures so that even farmers can take up this work after a little training.

This hatchery technique has been successfully used by the CMFRI for producing the seed of P. indicus, P. monodon, P. semisulcatus, P. japonicus and P. latisulcatus. Every year about 2 million seeds of P. indicus are distributed to the farmers, free of cost, from the NPCL.

Extension

Officers from the Fisheries Departments of the Maritime States of India have been trained at the NPCL during 1985 and 1986 in the hatchery production of prawn seed. A practical manual on hatchery techniques has been published by the CMFRI.

Recognising the significance of the hatchery technology developed by the CMFRI to the Indian context, the State Fisheries Departments of Kerala and Andhra Pradesh have initiated action to set up prawn hatcheries in their respective States with technical guidance from the CMFRI and financial assistance from the MPEDA.

The MPEDA is also setting up prawn hatcheries in Kerala, Orissa and Andhra Pradesh by importing foreign technology from U.K., France and Hawaii.

Oyster Culture

Oysters of the genera Crassostrea and Saccostrea are found all along the Indian coast. Crassostrea madrasensis (Preston) is widely distributed and, therefore, it was chosen as the candidate species for farming.

Natural Distribution/Production

Extensive natural beds of C. madrasensis are located along the stretches of backwater, estuarine and coastal regions of Tamil Nadu, Andhra Pradesh, Orissa, Kerala and Karnataka. Of particular mention are the extensive beds in Pulicat Lake in Madras, Adyar estuary, most of the tidal creeks in the south-east coast of India. Along the Kerala coast abundant oyster settlement is found in Ashtamudi Lake, Chaliyar, Nileshwar and Manjeshwar regions. In Karnataka oyster settlement is found in Karwar and in Mulki estuary.

While oyster resources are moderate large-scale traditional exploitation to raise the status of oyster landings to that of an established fishery does not exist. Oyster fishing is mainly subsistence. As such precise information on the production of oysters is not available. In very recent years there is a change in this trend with oyster gatherers exploiting grown oysters as a source of income.

Seed Availability and Collection Techniques

Oyster spats are collected from natural beds by placing suitable cultch material like lime-coated tiles at the appropriate time during the oyster spawning season. Large-scale spat collection has been demonstrated at Tuticorin using lime-coated tiles as spat collectors in the shallow coastal stretches and tidal creeks in the vicinity of natural oyster beds. The number of spat collected per m² of surface area of cultch was high (316/m²) in the shallow bay area, and 77/m² in the tidal inlets. The cultch laid over the natural beds also gave good results (92/m²).

Various spat collectors, apart from lime coated tiles like oyster shells, mussel shells, sized asbestos sheets, velon' screen net, P.V.C. pipes and polythene linear sheets can be used for spat collection.

Tiles: The semicylindrical tiles are given lime coating twice and 50 of these are kept in each rectangular tray and placed on the rack. Although maximum of 120 spat can be collected from a single tile, the average settlement per tiles was 33.5. After settlement, the spat are allowed to grow undisturbed to 15–20 mm size on the tiles itself. Thereafter they are scraped and transferred to growing trays.

Rens: Another method successfully tried in recent years at Tuticorin is the ‘ren’ collection. Oyster shells are made into strings by a 1.5 m long G.I. wire. About 95–100 rens are laid horizontally for spat collection. Average settlement was 7/shell.

Although oysters spawn throughout the year. The peak season for large-scale spat collection at Tuticorin is April-May and August-September. This season slightly differed from one area to another.

Farming Techniques

The method of rearing oysters depends upon the type of spat collectors used.

Rack method. The spat set on tiles after attaining 15–20 mm size are scraped and transferred to box-type cages of 40 × 40 × 10 cm and hung from a rack. The rack is constructed by erecting six poles (2.4 m in length) 2 meters apart. Long horizontal poles are tied across these poles at the top at a height of 1.8 m. From the horizontal poles, the cages or strings are suspended.

Oyster grown to 50 mm size of bigger are transferred to the rearing trays of size 90 × 60 × 15 mm. 20 such trays are kept on a rack. Rack for this purpose is constructed in shallow oyster farm site. Six casuarina poles of 2.4 m length with 5–6 cm dia. are driven to the bottom of the oyster farm site 2 m apart. Another set of six such poles are driven 2 m apart, but parallel to the first row. These two rows are connected by 2 long cross poles supported by the strength of this wooden frame work. Eight poles each 5.5–6.5 m long are placed horizontally securely tied by coir rope to the cross poles. This structure serves as the platform for keeping the rearing trays.

Ren. In the case of ren-collected spat, the shells with spat set on them are removed and restrung. Nylon rope (3 mm dia.) of 1.5 m length is strung with 4 or 5 spat settled shells with an interspace of 15–20 cm between each shell. These strings are suspended from the rack to allow the spat to grow in the water column.

Growth and Market Size/Duration/Season

C. madrasensis attains 36 mm in 2 months after spat fall. At 4 months the mean size is 52 mm, at 8 months the size is 60 mm and at the end of first year the average growth recorded is 84 mm. The wet flesh weight of the oyster is 8–10 per cent of the whole weight, which is about 90–100 g.

Harvesting Techniques

Since the oysters are individually cultured in trays, the trays are transported in plastic dinghy to purification tanks after completing cleaning process. The cleaned oysters are kept for 12 hrs in purification tanks where filtered sea water is filled to a height of 70 cm. Later the oysters are kept for an hour in sea water purified by treating with 3 ppm chlorine. At the end the oysters are again washed with filtered sea water and heat-treated for easy shucking. Shucking is done manually. After washing, the shucked meat is sold. Large quantities of meat are quick frozen and supplied to Integrated Fisheries Project, Cochin where the meat is smoked and canned or canned in brine.

Production Rates

Production per rack containing 4000 oysters, at the end of one year, has been observed to be 425 kg (shell on) indicating a production capability of 119 t/ha. In the case of ren culture method, the total yield works out at 5.0 t/ha. Although the production rate in the latter case is less than the rack system, it is to be noted that the cost involved is very cheap compared to the first method. In the initial stage of the experiments 4 or 5 shells are strung together and suspended. It is possible to increase the number of shells in the string which in turn can result in increased production. At present spat settlement in the hatchery is mainly effected on shells for facilitating adoption of ren culture method.

Economic Data

Economic evaluation of oyster culture by rack and tray method in 0.25 ha shows that, with the sale of meat at Rs. 37/kg, the produce will fetch Rs. 91,575/- with net income of Rs. 28,121/- about 30 per cent return on the investment. Attempts are being made to bring down the cost of production by the string and stake method.

Extension Needs

People do not go much for oyster mainly because of lack of information regarding the nutritive value of oyster meat. Traditional local markets are restricted. Extensive extension work is necessary to popularise the oyster meat. Training of personnel in oyster culture work is essential. Extension, training, marketing, processing, product diversification and quality control are some of the needs which will help to establish the oyster culture industry better. The C.M.F.R. Institute gives a training course in oyster culture.

Pearl Culture

Candidate Species

Although six species of pearl oysters, viz. Pinctada fucata (Gould), P. margaritifera (Lin.), P. chemnitzii (Philippi), P. sugillata (Reeve), P. anomioides (Reeve) and P. atropurpurea (Dunker) occur in the Indian waters, only P. fucata, which is genetically capable of producing nacre of high quality, has been found to produce pearls of gem quality. Attempts to produce pearls in P. sugillata, P. anomioides and P. atropurpurea with graft tissue either from the same species or from P. fucata did not give satisfactory results.

Natural Distribution

The pearl oysters are distributed in the Gulf of Manner on ‘paars’ at depths ranging from 12–25 m and on ‘khaddas’ in the intertidal regions of the Gulf of Kutch. In the Gulf of Mannar, there are over 65 pearl oyster beds, extending from Kanyakumari to Rameswaram. They are located at varying depths. These beds are grouped into the northern, central and southern divisions, of which the central division (off Tuticorin) is the most productive. The pearl fisheries are irregular and intermittent and there are more ‘barren’ than productive years.

Seed Availability and Collection Techniques

The production of pearl oysters in the natural beds is subject to wide fluctuation. The unproductive spells are far more numerous than the productive periods. From the year 1663 to 1961, only thirty-eight pearl fisheries were conducted in the beds of the Gulf of Mannar. The recent survey of the beds during 1975 to 1986 has given 3-2164 oysters per diving hour. during the year 1971–1973, 3.2 oysters per hectare had been collected from the ‘khaddas’ of the Gulf of Kutch.

Collection of pearl oysters in the Gulf of Mannar is by diving up to a depth of 20 m. SCUBA-diving facilitates to cover wider areas and thereby good collection when compared to skin-diving. In the Gulf of Kutch, fishery is conducted on days of good ebb tides. Oysters are picked up hand from the intertidal flats.

Spat collection from the natural beds has not been successful so far. It may be due to the open condition of the natural beds. Some spatfall inside the basins of Tuticorin and Vizhinjam Harbours, where experimental mother oyster culture has been done, has been noted. But the composition of the P. fucata is very low and hence this method cannot be depended on to get oyster seed.

Recently, hatchery production of pearl oyster seed has proved to be successful and by this method an assured supply of oysters for pearl culture can be made possible.

Farming Techniques

Sheltered bays, protected from wind and wave but with replenishment of water and planktonic food offer a good site for farming the pearl oysters. The mother oysters are cultured in rafts. A raft of the size 6m × 5m is found to be convenient for handling. Unit raft system has been adopted using single rafts with independent moorings. The frame of the raft is of teak logs lashed with ropes and floated with four buoys and moored by two anchors, each weighing about 40 kg connecting them to the raft by 12 mm anchor chains. To achieve more buoyancy and durability of floats, FRP coated styrofoam floats have been used. This kind of raft is well suited for the bays and coastal waters where sea conditions do not get rough.

Rearing of pearl oysters is done in nylon twine meshed cages by suspending them at appropriate depths from rafts. Each box-cage measures 40 cm × 40 cm × 15 cm. This is good for general mother oyster culture. To follow the history and performance of individual oyster, frame-nets are useful. All the materials used are given anticorrosive treatment with a suitable paint.

Nucleus Implantation Technique

From among the lot, the donor oysters are selected. The pallial mantle is cut from the donor and made into small pieces and kept as graft tissues for transplantation. Healthy oysters with spent or just developing gonads are conditioned with the chemical methol. To produce free, spherical cultured pearls, spherical shell-bead nuclei are used.

The ventral portion of the gonad is the best site for nucleus implantation to produce spherical pearls. After cutting an opening sub-epithelially from the base of the foot to the gonad, the graft tissue is inserted with a needle followed by the nucleus of the required size.

The seeded oysters are placed in a gently flowing/midly aerated sea water. Frequent change of water is needed till the effect of narcotization wears off. The oysters are returned to the farm after 3–4 days under observation. During the post-operative culture, the density of oyster per cage is kept low. They are suspended in areas of high phytoplankton production and at greater depths than the mother oysters.

Growth and Market Size/Duration/Season

The oysters of the Tuticorin Harbour farm attained lengths of 47, 64.5 and 75 mm at the end of first, second and third years, respectively. The corresponding weights at the ages 1 to 3 years are 8.3, 31.6 and 45.4 respectively.

Oysters of about 20 g have been found to be the ideal size for production of medium size pearls and also for double implantation. The growth of nacre was found to be 0.32 mm in 191 days on nucleus of 3 mm, 0.31 mm on nucleus of 4 mm in 161 days, and 0.26 mm on nucleus of 5.8 mm in 159 days. Higher seawater temperature in the tropics accelerates the growth of oysters and rate of deposition of nacre on the nucleus. Multiple implantation techniques are adopted to enhance the rate of pearl production.

Harvest Techniques

Implantation is generally done in the ventral gonad region to produce free, spherical pearls ranging in diameter from 3–8 mm. Because these oysters are comparatively small (maximum length 80 mm dorsoventrally), they are not suitable for production of half pearls. Some 1–5 pearls can be produced in a single oyster depending on its size. Pearl harvest is done during the period of low temperature taking into account the annual ambient range of temperature. The seeded oysters are taken to the shore and opened for the collection of pearls. Re-used oysters for a second crop of pearls is possible under certain conditions.

Production Rates

A 6m × 5m raft can accommodate 100 cages. Each cage holds 100 oysters of 45–55 mm length. In the experiments on the pearl production, the rate of rejection of nucleus and the overall mortality rate of the seeded oysters were kept within 10 per cent each under favourable conditions. Among the surviving oysters about 60 per cent pearl production rate was obtained.

The quality of pearls produced shows considerable variation. In the experiments conducted, top quality pearls of Grade A (flawless, one flaw, small stains, pink, silver or light cream) formed 30 per cent and Grade B (fairly large flaws, stains, cream colour, irregularities of shape) pearls which can be used in the jewelry contributed another 30 per cent while Grade C (trash pearls and rejects) accounted for 40 per cent.

Economic Data

Available with the joint sector company in India.

Extension

The CMFR Institute has been organising training programmes in pearl culture since 1976. Theoretical and practical trainings on pearl oyster biology, resources, mother oyster culture, pearl oyster surgery, post-operative culture and pearl collection are offered through long-term and short-term courses. The training programme in pearl oyster hatchery, is aimed at helping not only technicians connected with pearl culture but also molluscan aquaculturists in general. Gujarat and Lakshadweep and the Central Agricultural Research Institute in Andamans have taken up R & D programme in pearl culture.

In India, the mainland has almost a straight coastline with shallow inshore waters. Limited areas of the mainland coastal waters may offer suitable sites for pearl culture. Sheltered lagoons and bays of sufficient depth with clear unpolluted water, are available in the oceanic islands of Andamans and Nicobar and Lakshadweep. Moreover, though limited, these islands are reported to have their own pearl oyster resources. Pearl culture in these islands through natural collection and transplantation from mainland will enable establishment of pearl culture in different parts of India.

Molluscs Hatchery Technology

Availability of seed is vital in any farming activity. The successful development of shellfish and molluscs hatchery by CMFR Institute at Tuticorin has solved the problem of seed. The hatchery has the capacity to produce millions of spat of both the oyster Crassostrea madrasensis and the pearl oyster Pinctada fucata. Although experimental success has been achieved in production of green mussel (Perna viridis) seed at Madras and brown mussel (P. indica) seed at Vizhinjam, mass production is yet to be achieved.

Hatchery Building

The shellfish hatchery laboratory at Tuticorin has been constructed to provide maximum light and air. A portion of the roof is fitted with transluscent fibreglass sheets to allow light for indoor culture of larval food. To avoid heat radiation the roof is kept 20 feet high. Glass panelled large windows are provided for free ventilation. Entry of insects and birds is prevented by fixing wire mesh panels to the windows. Adequate supply of freshwater and power has been ensured. The slope of the floor and drainage system keep the hatchery neat and dry. Air-conditioned wet laboratory has also been provided for controlled larval rearing operations as well as brood-stock management.

Water Quality Management

Seawater quality is one of the critical factors in determining the success of hatchery production of seed. Water should be relatively free from pollutants, particularly metallic slats, pesticides, detergents and silt. Water drawn from the sea is collected in a well through 5" PVC pipe by gravitation. This water is pumped (1.5 hp) to the sedimentation tanks (4 × 500 l). It is then filtered through a biological filter which has a layer of river sand at the top, followed by granite pebbles or ½" size and activated charcoal at the bottom. The river sand is periodically replaced for effective filtration. The filtered sea water is stored in a pump (20,000 liters) and lifted to over-head tank (10,000 l) by a 5 h.p. pump and supplied to the hatchery. The seawater used in larval rearing is passed through a series of cartridge filters ranging from 15 um to 2 um and sterilised by U.V. radiation. For spat rearing the water drawn from the overhead tank is directly used.

Aeration System

A 7.5 hp air compressor supplies oil-free air through a PVC pipe. The air is tapped at different points to supply the rearing tanks.

Larval Food Production

Phytoflagellates measuring less than 10 μm are used as larval food. Among those tried, Isochrysis galbana forms the best food for the bivalve larvae. Species of Pavlova, Chromulina and Dicrateria also proved to be good alternate food for them. Stock culture of these species is done in Haufkins flasks (93-5 l) and the culture is maintained at the stationary phase for about 2 months under 400–500 lux illumination. Mass culture is carried out in 20 l glass carboys or in 100 l perspex tanks under 1000–1500 lux. The maximum concentration of cells is attained in mass culture on day 5–6. Walne's medium is used for both stock and mass cultures.

Broodstock Maintenance

Healthy oysters are maintained as broodstock in 50-litre sea water in a fibreglass tank at temperature about 5°C below ambient. They are fed with mixed phytoplankton, mostly Chaetoceros, Skeletonema, Thallassiosira and Nitzschia at 0.81 per oyster per day and 41 per pearl oyster per day. Water is changed every day.

Induced Spawning

Thermal stimulation is employed to induce spawning in the conditioned oysters. Spawning occurs at temperatures 2 to 4°C above the ambient. Alternatively addition of sperm suspension to the medium results in spawning in Crassostrea oysters. In the case of pearl oyster a high percentage of spawning is achieved in 9.0 pH using TRIS buffer and by the injection of 0.2 ml of 0.1 n NH₄OH solution into the adductor muscle. Mechanical stimulation has been employed for mussels such as shaking of ripe mussels, pricking of adductor muscle by a needle and stretching the same by opening the valves.

Larval Rearing

Fertilisation occurs immediately. The fertilised eggs are allowed to develop at the bottom of the vessel where they settle. The supernatant water containing milt is removed gently by siphoning and fresh seawater added. At times, instead of siphoning, the whole medium is sieved carefully through 30 um mesh and the eggs alone are released either to 5 l glass beaker or to 50 l fibreglass tank depending on the concentration of the eggs. The morula stage is reached in 3–4 hours after fertilisation. They congregate at the surface of the vessels and are siphoned out to a fresh vessel. Unfertilised and undeveloped eggs and broken tissues are discarded. Most of the embryos reach straight-hinge stage within 20 hours and swim at the surface of water. Estimation of larval concentration and stocking is done at this stage in 1-ton tank holding 500 l sea water. Further growth of larvae depends on the supply of right type of food and maintenance of water quality. In static larval rearing water is changed once in two days. Feeding is given once in a day. No aeration is provided during larval phase. The optimum water temperature for larval rearing is around 29°C and the salinity 32 /oo. The larvae set as spat between 18 and 20 days after fertilisation. A young edible oyster spat is recognised at the size of 450 um and the pearl oyster spat at 300 um on 24th day.

Lime coated tiles, oyster shell rens and polythene sheets are found suitable for Crassostrea spat collection. In the case of pearl oysters, the spat are allowed to set on the rearing tank itself and the grown up spat are later collected for further rearing and sea-ranching.

Spat Production

Larval growth and spat production depend on several factors. The larval density and feeding levels are found to play a vital role in the growth and spat settlement. Agitation in the larval rearing medium through areation is found to cause poor growth and settlement. Though spat production is achieved in the hatchery throughout the year, it is low from May to September due to high salinity, high temperature and heavy dust fall during the period. The hatchery at Tuticorin has the capacity to produce about 4 million spat each of pearl oyster and edible oyster in four spawning in a year.

Transplantation

The spat are fed with mixed phytoplankton. At size 3 mm they are transplanted in the farm in a net cage of 0.4 mm mesh. As the spat grow they are transferred to 1.0 mm mesh net cage. The edible oyster spat collected on the oyster shell rens and lime coated tiles are reared in situ in cages in the farm. The spat on the oyster shell grits and those detached from the polythene sheets are reared in meshed cages as ‘cultchless spat’.

Transfer of Technology

The CMFRI conducts training courses in shellfish hatchery technology both for pearl oyster and edible oyster.

Mussel Culture

Candidate Species

The species with great potential for culture in India is the green mussel Perna viridis. The second species with a much smaller potential is the brown mussel P. indica.

Natural Distribution/Production

Perna viridis forms natural beds along the Indian coasts in varying densities. The east coast is relatively poor in mussel resources. On the other hand there is a rich resource on the west coast. The region from Calicut to Cannanore in Kerala is the virtual mussel zone of India, where the fishery is of considerable magnitude. The annual production is estimated at 16,000 tons. The maritime States of Karnataka, Goa and Maharashtra have a sparse distribution of mussels. The annual production in the three States is estimated at 500 tons.

Seed Availability and Collection Technique

The peak spawning season of the green mussel is in August and September. Juvenile mussels are found carpeting all over the intertidal and submerged rocks during October and November, reaching an average density of 6500/m². Collection of seed for the farm is mainly done from the intertidal and submerged rocks. The suitable size for farming is 15–25 mm. Mussels in the farm spawn after 90 days of their transplantation. Seed can also be collected from the farm on spat collectors like frilled nylon and HDP ropes, roofing tiles and also on coir ropes suspended from the rafts at the time of peak spawning.

Farming Techniques

The raft culture or suspended culture technique is followed for farming mussels. Raft culture of Perna viridis in the open sea is done only during October to April and the rafts are beached in the unfavourable season. Raft size is generally 6 × 6 m and is constructed using wooden and bamboo poles lashed together with coir and nylon ropes. It is mounted over 5–6 metal barrels of 200 l capacity, given 2–3 mm thick coating of fibreglass. Iron chain and two anchors, 100 kg each, are used for mooring the rafts in depths 8–10 m in the open sea.

Mussel spat in the natural beds reach a size of 15–25 mm in October/November. The seeds are scraped from the rocks and collected. They are cleaned to remove the adhering mud and epifauna.

Seeding, i.e. attachment of the juvenile mussels to the rope, is the most important aspect in mussel farming. Synthetic or coir ropes of 16–20 mm diameter and 8 m long are used for growing mussels from the rafts. The seeds are placed around the rope at the rate of 600 g/m and secured with knitted cotton cloth of 25 cm width. The seeded length of the rope is 6 m. The seeded ropes are taken to the raft on the same day and suspended from the bamboo poles 60 cm apart with the lower free end about 2 m above the bottom. A standard raft of 6 × 6 m can accommodate 60 ropes. The seeded mussels get attached to the rope within 2–3 days and the cloth cover disintegrates in sea water within about 10 days.

Growth and Market Size

Growth of Perna viridis in the farm is very rapid. Seeds 15–25 mm long weighing 0.3–1.9 g transplanted in November grow to 80.0–88.2 mm weighing 36.4–37.5 g in April, a period of 6 months. The average monthly growth ranges are 11.6–12.9 mm in length and 5.9–7.3 g in weight. The meat yield at the time of harvest in April is about 40 per cent of whole weight.

Harvest Technique

Mussels are harvested when they reach the marketable size of 80–88 mm and a meat yield of 40 per cent or more which is attained during March/April. The mussel ropes are lifted from the raft, taken ashore, washed and depurated.

Production

The production per meter of rope ranges from 10–12.3 kg of clean marketable mussels. Taking a minimum average production of 10 kg/m rope, the production from a standard raft of 6 × 6 m size holding 60 ropes would be 3600 kg of whole mussels or 1 kg of meat.

Economic Data

Mussel farming can be done on unit raft system depending on the scale of operation. Projections based on production from a single raft show that the investment for one raft of 6 × 6 m with working capital for a three-year period would be Rs. 26,000. The revenue from the produce for the same duration would be Rs. 43,000 (Production 10.8 t;price Rs. 4000 t). The profit on a raft for 3 years would be Rs. 17,000.

Extension Needs

Despite the fact that the technology of mussel culture has been developed and some demonstrations have been conducted, there has been no large-scale adoption of the production technology. The major constraints faced are (a) mariculture as a whole is a new venture for the country and therefore there is some hesitation on investment for any work in the sea in the absence of proven economics of the technology; (b) acceptance of mussel as food is low and is restricted to few pockets in the coastal areas; (c) the sea food processing industry has not taken any serious note of the export potential and efforts have so far been lacking for exploring export markets for the Indian mussels.

Seaweed Culture

Candidate Species

Economically important seaweeds such as Gelidiella acerosa, Gracilaria edulis, Sargassum and Turbinaria occur in good quantities along Tamil Nadu and Gujarat coasts. Studies on the biology and growth of seaweeds have shown that many seaweeds including species of Sargassum, Gracilaria and Gelidella acerosa attain their maximum size in Mandapam region in a few months' time. Out of these three, in the natural beds the recuperation and regrowth of Gracilaria edulis was found to be faster than that of the other two species.

In view of the economic importance of the species and faster growth rate, the agarophyte G. edulis has been tested for augmentation by culture practices. In the field culture studies, it had given encouraging results so that it has been selected as candidate species.

Natural Distribution Production

G. edulis is available in the natural beds along Tamil Nadu, Gujarat, Andaman-Nicobar Islands and the Lakshadweep. The resource of this species can be put around 3000 tonnes along the Indian coast.

Studies conducted on the growth of G. edulis in the natural environment have indicated that it would take 4 to 5 months to grow to maximum length while on the culture frame this growth could be attained three months.

Seed Availability and Collection Techniques

The seed material is available in significant quantities in the Gulf of Mannar Islands, Pamban, Rameswaram, Mandapam, etc. and nearly 20900 t (fresh weight) of G. edulis was estimated to be available in the natural beds there. Generally collection of seed material is made by hand-picking in the shallow waters of intertidal and subtidal zones while in deeper areas it is done by skin diving. As soon as the seed material is collected, it is transported to the culture site to be introduced in the culture nets.

Farming Techniques

The seaweed culture farm will have several nets of 5 × 2 m size, fabricated with coir (2.5 cm dia.) or HDP ropes (3 mm dia.). It can be done in saline ponds also of 60 × 30 m size with a sandy loam bottom and free flow of seawater through sluice gate. The culture site must have a minimum depth of 1 m. The seed material after thorough cleaning is cut into 4 to 5 cm long fragments and inserted into the twists of the coir ropes. In the case of HDP rope nets, the seed material is tied at the intersections of the nets with the help of nylon twine (no. 6). The nets are tied to the poles fixed in the inshore waters or in the ponds.

Growth and Market Size/Duration/Season

The minimum period for the seed material to reach harvestable size is 2 months for G. edulis. The length of the alga at the time of harvest is from 20 to 25 cm. The suitable seasons for carrying out the culture operations are October to April in Gulf of Mannar and May to September in Palk Bay.

Production Rate

One kg seed material of G. edulis yields an average of 3 kg/m² of net after 60 days growth. In one ha area with about 1000 nets, 30 tonnes of fresh G. edulis could be harvested.

Economic Data

For the cultivation of G. edulis in one ha, 1000 coir nets of 5 × 2 m size, 2000 casuarina poles 1.5 m long and 10,000 kg of fresh seed material (for initial introduction) are required. The cost of 2000 casuarina poles is Rs. 6000/- and 1000 coir rope nets Rs. 33,000/- including fabrication. The seed material will be collected for the initial introduction from the natural beds and from the cultured crop for subsequent seedings. Wages for seeding, harvesting and maintenance of the farm for 4 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/-.

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 four harvests in a year when the yield is 3 kg/m². If the seaweed is dried (75 per cent 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-agar the profits would be around Rs. 100,000/yr.

COUNTRY REPORT: INDONESIA