THA/008/79/WP/5
REPORT ON THE FIRST TRAINING COURSE ON
FRESHWATER PRAWN CULTURE FOR EXTENSION WORKERS
FRESHWATER PRAWN CULTURE FOR EXTENSION WORKERS
|
THA/008/79/WP/5 REPORT ON THE FIRST TRAINING COURSE ON FRESHWATER PRAWN CULTURE FOR EXTENSION WORKERS |
by
S. Singholka and H.R. Rabanal
National Freshwater Prawn Research and Training Centre
Freshwater Fisheries Division, Department of Fisheries
Ministry of Agriculture and Cooperatives
(FAO/UNDP/THA/75/008)
Bangpakong, Chachoengsao
Thailand, 1979
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3. Dates and duration of training
5.1 Hatchery and nursery
5.2 Site selection, design and management of
hatcheries and grow-out ponds
8. Briefing lectures and practical demonstration
The freshwater prawn hatchery by S. Suwannatous
Collection, selection and prophylatic treatment of prawn broodstock by S. Suwannatous
Preparation of water supply system for freshwater prawn hatchery by C. Sukapunt
Preparation of prawn larval feed by S. Suwannatous
Feeding of prawn larvae by S. Suwannatous
Decapsulation of brine shrimp (Artemia salina) cyst by A. Tunsutapanich
Management of brine shrimp (Artemia salina) as food supply in freshwater prawn hatchery by J. Vos
Preparation of brine shrimp as larval food in prawn hatchery and nursery by J. Vos
Preparation of screens in prawn hatchery tanks by S. Intrapichet
Nursery work for freshwater prawns by A. Tunsutapanich
Transportation of prawn juveniles by V. Suksucheep
Site selection and design of prawn grow-out ponds by S. Singholka
Management of grow-out ponds for prawn by P. Vorasayan
Relationship of pond waters to their suitability for fish culture (A translation from H.S. Swingle)
Questionnaire for evaluation of the course
ANNEXES
Annex A - Schedule of First National Training Course on Prawn Culture for Extension Workers
REPORT ON THE FIRST TRAINING COURSE ON FRESHWATER PRAWN
CULTURE FOR FISHERIES EXTENSION WORKERS
by
Somsuk Singholka* and H.R. Rabanal**
Within recent years, interest in freshwater prawn (Macrobrachium) culture has greatly increased in Thailand. As an item of food, a cash crop, and a potential export, it is a product of high economic value. Rural folks, crop farmers and coastal fishermen are very interested in prawn farming. Some 200-ha prawn farms producing about 50 tons per year and small-scale hatcheries are now in existence in the country.
There is great need to develop a corps of extension workers that could fill the need of the interested farmers and fishermen in this work. The handful of government workers who are now available in various fishery stations are too few to adequately assist this industry.
The National Freshwater Prawn Research and Training Centre of the Department of Fisheries, Ministry of Agriculture and Cooperatives, located in Bangpakong, Chachoengsao was established in 1975 and started operations in 1976. To augment the work of this national project, the United Nations Development Programme (UNDP) through the Food and Agriculture Organization (FAO) started giving assistance to this Centre in 1978. Training is an important aspect of this assistance. Study fellowships, practical study/ tours and local group training have been scheduled.
The first local group training for government extension workers was held at the Bangpakong Centre on 15–29 November 1978. The following is a report of that training.
Mainly at the National Centre in Bangpakong, Chachoengsao province, and also to private farms within one- to two-day travel distance from the Centre.
15–29 November 1978 (15 days)
The detailed schedule for this training course, which was carried out, is summarized in ANNEX A.
Site selection
Accessibility, market, labour, etc.
Design
Layout of grow-out ponds
Management
Since interest on prawn culture is now nationwide, participants for this training course had to be selected from the provinces or stations where the services of an extensionist in this field were most needed. Sixteen participants from 14 provincial fishery services or stations and two from the Department of Fisheries Extension Unit took the course (ANNEX B). The national project training staff are also listed (ANNEX B).
Participation to this training were supported by this Programme (THA/75/008). These included travel from and return to duty station, hotel accommodations, training facilities at Centre, instruction material and instructors.
The training staff contributed briefing lectures and where appropriate these were followed by practical demonstration and were supplemented by field trips and practical work to private prawn farms in communities within travel distance from the Bangpakong Centre.
The following section gives the papers and demonstrations provided in this course.
by
H.R. Rabanal
1. INTRODUCTION
The importance of the fresh/brackishwater prawn (Macrobrachium) fishery in the whole world and particularly in the Indo-Pacific region has been recognized and is a growing industry in the region. So far, no attempt has been made to put together what is known about the fishery of this group and particularly the giant prawn Macrobrachium rosenbergii which is common in the Indo-Pacific area. The discovery of S.W. Ling while on an FAO assignment in Malaysia, on how to hatch this species under controlled conditions is a milestone in this work. While there are many other species of the Sub-Order Caridea, Family Palaemonidae, Macrobrachium rosenbergii appears to be the largest and the most desired of the known species from this group. Another species generally smaller in size, Macrobrachium malcolmsonii has also been reported in the works from India and Bangladesh. Other species of Palaemonidae which are generally smaller in size have also been reported in many areas in the region.
While on assignment as Regional Fish Culturist, this writer was able to travel in many countries of the Indo-Pacific Region and had the opportunity to examine papers on this group. The following paper is an attempt to summarize information that had been gathered.
It is generally agreed that a prawn fishery of economic magnitude exists in many areas in the various countries of the Indo-Pacific Region. The major river systems of these countries are invariably populated by a native population of these species. This is true in Indonesia all the way from Sumatra, in the west of Irian Jaya in the eastern extremity of the country and also in Thailand, Khmer Republic, Vietnam, Malaysia and the Philippines. The species is also reported with exploitable fishery in India, Sri Lanka, Bangladesh and Burma. Except in a few cases, the magnitude of fishery in these areas have not been assessed. Likewise, the existing trade within national boundaries as well as externally have not been evaluated.
2. OBSERVATIONS IN THE VARIOUS COUNTRIES
While the species is known to be indigenous in many countries in the region, its introduction to other countries within or outside the region where it has not been previously reported has also been undertaken. Macrobrachium rosenbergii is a warm water species but recently, experimental introduction has also been made in a number of temperate countries.
2.1 Australia
Great interest on this species has been generated by commercial fish culturists and there has been an increased number of enquiries received at the FAO Regional Office on the sources of stock and methods of culture from this country. It is possible that its introduction might have been made if it has not yet been done at the present moment specially in the northern part of the country. The writer is not aware of any indigenous stock in this country.
2.2 Bangladesh
This country is characterized by a network of river systems which is the natural environment for Macrobrachium. Two economic species M. rosenbergii and M. malcolmsonii have been reported. Their existence as a fishery is well known in the country and they are exploited in many estuarine areas. In recent years, however, water pollution and water development projects such as flood control, irrigation, hydro-electric power development, etc. are reported to have affected the natural fishery of these species in some of the areas where they exist. For example, M. rosenbergii is known to support an important fishery in the Dakatia river. A regulator construction which will be made across this river immediately below the Kamta Khal will eliminate the existing prawn fishery from the areas upstream from the regulator and may cause serious damage to the prawn fishery downstream because of the expected reversal of flow in that protion of the stream.
There is no reported estimate of the magnitude of this fishery.
2.3 China
Juveniles of Macrobrachium rosenbergii were introduced from Bangkok, Thailand to Taiwan, China in 1970. Experiments on propagation of the stock that survived in introduction were successful at the Tungkang Marine Laboratory and a fairly large production of juveniles was achieved. Since large acreage of suitable areas for freshwater farms are available for prawn farming, the raising of Macrobrachium rosenbergii have good prospects of development in this island. Pilot trials are now being conducted.
2.4 Hawaii, U.S.A.
Macrobrachium rosenbergii was introduced into the state of Hawaii some years back. Work on this species has been going on at the Anuenue Fisheries Research Center of the State of Hawaii's Fish and Game Division. The work has been quite successful and presently the Laboratory is the centre for international training and modernization of the prawn culture industry. Credit should be given to T. Fujimura and his associates who have done extensive studies in this field.
Likewise, it should be noted that some private farms have started to be established in this state.
2.5 India
As in Bangladesh, two major species of Macrobrachium, M. rosenbergii and M. malcolmsonii are reported to have commercial importance in many estuarine areas of India. In the State of Kerala, it is estimated that 10 000 metric tons of shrimps mainly species of the Family Penaeidae are harvested annually. Small amount of this harvest consists of prawns of the species Macrobrachium rosenbergii. With the construction of water development works in many estuarine areas, it is expected that the natural fishery of Macrobrachium will decline and culture of the species will be required.
M. malcolmsonii is an important fishery in East Godavari district in Andhra Pradesh state. The biology of this species has been studied and it was found that it is essentially an inhabitant of flowing waters such as rivers and estuarine areas. Like Macrobrachium rosenbergii it requires brackishwater for spawning and nursing of the post-larval stages. In the Andhra Pradesh state, a managed fishery of this species occurs when juveniles brought into flooded ponds during the monsoon season grow into marketable sizes when the water recedes after the monsoon. This species also occurs in many other river systems in India such as the river Mahanadi, in Chilka Lake, the waters of the river Krishna and its tributaries, as well as in the Hooghly estuary system. These river systems usually account for heavy production of juveniles during certain periods of the year which may open up the possibilities of supplying stock for rearing purposes. This species has simple feeding habits utilizing organic matter and detritus as food which simplifies the requirements for feeding. The natural habitat of this species which requires flowing water has to be overcome as culture has to be done in stagnant impoundments. As the fishery of this group is very widely spread, there are not available and consolidated data on the magnitude of the fishery at present.
2.6 Indonesia
Of the countries in the region, Indonesia perhaps has the most extensive natural fishery for the giant freshwater prawn. Macrobrachium rosenbergii has been reported to occur in Irian Jaya, Java, Kalimantan and in Sumatra islands. Undoubtedly, it may also be present in the other provinces and islands of the country. A valuable fishery of commercial importance is being exploited in South Sumatra. In Irian Jaya, it is known to occur in the extensive swampland areas in south coast of the province. However, there has been no actual evaluation of the magnitude of the resource.
In Java, it is reported that the known grounds have been affected by pollution and public development works. An attempt on the culture of this species, however, is in the programme of the Directorate General of Fisheries. Studies on the biology of Macrobrachium are being conducted at the Inland Fisheries Research Institute at Pasar Minggu, Jakarta while experimental culture has been set up in Ngracec fishery station in Central Java. Hatchery work for this species are also being undertaken at the FAO/UNDP Jepara Shrimp and Milkfish Culture Research and Training Project to supply stocks for the Ngracec rearing ponds and neighbouring areas.
A preliminary study was made on the Macrobrachium fishery in Sumatra through a consultant in inland fisheries, to the FAO/UNDP Land and Water Resources Development of Southeast Sumatra project. It was found during the survey of the five million-hectare project area, that at least one million hectares of the project site are under water either in part or throughout the year. Of these 100 000 hectares, are tidal brackishwater swamplands. A number of fishery resources including Macrobrachium rosenbergii are extensively exploited from these waters. The largest harvest for finfish takes place when the water recedes during the dry season or during the period from June to September. In the case of the giant freshwater prawn, however, the height of harvest occurs during the start of the first rains of the rainy season, in October through May. At this time, great numbers are said to float downstream in the form of “prawn rafts”, from the Palembang area in the Musi, Upang and Telang rivers and their connecting channels. This species is commercially important in Sungai Saleh and in Sungai Bawang below the Menggala area and are also believed to be abundant in the lower portions of other streams trailing the eastern swamps of South Sumatra and Lampung provinces.
During this period of abundance, the prawns are caught by the use of the following methods:
bamboo barriers set up in the streams as the water recede,
small movable bamboo traps baited with cassava,
cast nets operated over baited areas, and
small hooks or short light lines operated from small boats.
Individual fisherman in the area gather their catch, consume the small ones and keep the rest alive for regular collectors that visit the fishing sites to buy the selected sizes of the catch. There is a good demand for giant freshwater prawn, both in the local and foreign markets. The foreign demand has resulted in the establishment of three new processing plants in the Palembang area. The choice prawns are frozen and shipped to Singapore, Hong Kong, Japan and also to the markets in Europe and North America. This has resulted in the radical increase in the local price for prawns.
The fishery for prawn has a number of problems. There is a growing danger of the effects of aquatic pollution in the areas. There is also the destructive changes brought about by barrier dams, dredging and other man-made developments. There are no regulations to conserve the fishery and the catch has been observed to be on the decline and its composition is changing to smaller sizes.
The possibilities of extensive culture of this species has been suggested and in the project site of the assisted agricultural project, the Kenten area close to Palembang was pointed out as a possible place where this type of aquaculture study could be started.
As the data on the salt water shrimps are normally mixed with that of freshwater prawns, either for local consumption or for export, the quantity actually contributed by the freshwater prawn fishery has not been clearly evaluated. For purposes of formulating a sound national programme, statistics on the level of the fishery as well as that of other species will be needed.
2.7 Japan
Recently, Macrobrachium rosenbergii was introduced in Japan for experimental purposes. Experiments on the biology under laboratory conditions are now being conducted at the Tokyo University of Fisheries. No published reports of these studies has so far been noted by the writer.
2.8 Khmer Republic
A large segment of the lower stretches of the Mekong river system is a natural habitat of Macrobrachium species, particularly Macrobrachium rosenbergii. This country enjoys a strategic position with regards to this fishery and good amount of the natural catch from the Mekong system is normally available in the local market. Under present circumstances, this fishery is perhaps under-exploited and there is no known attempts or trials to culture it in this country. While the amount is consequential, there is no available estimate of the magnitude of what is harvested from year to year.
2.9 Malaysia
Malaysia is the site of the first successful spawning of Macrobrachium rosenbergii under controlled conditions through an FAO/UNDP project conducted in 1959–1962. It is here that S.W. Ling discovered that the species would require brackishwater to spawn and develop its post larvae. After this the refinements of the methods of spawning were conducted in many other areas and countries, with success. From this developed method, the Fisheries Research Institute at Penang has been hatching Macrobrachium for trial stocking in the fishery stations of the Government as well as in the ponds of private cooperators. A hatchery with improved construction has recently been constructed in this Institute and hatchery work on this species is now providing stock for aquaculture trials in this country. It has been noted that some of the natural river systems in the country also abound with this species, but there is no available data of the harvest from these natural waters. It is apparent that due to environmental changes which may affect the existence of this species in natural freshwaters, hatchery work and culture experiments will have to continue to maintain future supply of this resource.
2.10 Palau
Off in Micronesia in the Pacific in Palau of the West Carolina Islands, it is reported that there is an indigenous population of Macrobrachium rosenbergii. However, additional stocks for inter-breeding work were introduced from Hawaii from strain previously obtained from Malaysia. The stock were reared in ponds and tanks while capture of local strain were made from the Ngermeskong river and its tributaries. Studies on this species in Palau are continuing.
2.11 Philippines
Like the other countries of the Indo-Pacific Region, a number of species of Palaemonidae including Macrobrachium rosenbergii occur in the Philippines. Report of the general occurrence of prawns in the waters of the country are reported in the paper of Escritor (1975) contributed to an international conference on this species. It is worthwhile pointing out that in addition to the giant freshwater prawn, there are other species, some of which compose an economic fishery occurring in many inland waters of the country. Cowles (1914), Estampador (1937) and Guerrero, et al (1975) listed the following:
| Palaemon1 carcinus2 | P. orientalis |
| P. sundaicus | P. latidactylus |
| P. lanceifrons | P. grandimanus |
| P. lanceifrons var montalbanensis | P. philippinensis |
| P. lar | P. latimanus |
| P. jaroensis | P. idae |
| P. lepidactylus | P. lanchesteri |
1 It is apparent that the genus Palaemon is synonymousto Macrobrachium of present usage.
2 From Cowles' description P. carcinus is apparentlyMacrobrachium rosenbergii.
The culture of M. rosenbergii in the Philippines has not been started except for a few preliminary trials as reported (Escritor, Guerrero, et al, and Rivera). However, the advent of aquatic pollution and water resources development works which can adversely modify the natural environment for this fishery underscores the need for culture and hatchery work in the country. There is no data available to show the magnitude of the natural fishery at present.
2.12 Singapore
There is no report showing the existence of a fishery for Macrobrachium in Singapore but the experiments on the culture of this economic and highly priced species is being undertaken in the stations of the Primary Production Department of this country and some results have been obtained on the techniques of rearing and feeding these species under confinement. Given the space and facilities, this country can hatch and raise the giant freshwater prawn under controlled conditions.
2.13 Thailand
Macrobrachium rosenbergii constitutes an important fishery in Thailand. During the period from 1965–1973, the annual production of this and related species fluctuated from 2 900 to 4 000 metric tons valued at Baht1 150 to 300 million (based on wholesale price of Baht 60 per kg and retail price of Baht 70–80 per kg). This production is far from adequate to supply even only the local demand and there is good prospect for exportation. The production, however, has been showing a gradual decline during recent years.
The fishery for the giant prawn is confined to a number of sea- connected rivers, lakes and estuaries in the country. These include Songkhla Lake, Chao Phraya River, Mae Klong River, Thajeen River, Tanee River and several other sizable freshwater areas with connection to the sea. The fishery for this resource at Chao Phraya and Mae Klong rivers are practically gone due to pollution, silting and man-made changes in these rivers. At Songkhla Lake, studies at the Songkhla Marine Fisheries Station showed that the catch per unit effort by cast net fishermen has declined significantly from 500 grams to 150 grams per hour and is still declining.
Macrobrachium in the remote rural areas where it is available is used as an important source of protein food but as the catch has greatly declined, this source is gradually being lost. It has also provided work and source of income to the population along the catching areas. In urban areas, it is a priced food item and if caught in good quantities it can be exported abroad as a good source of foreign exchange. Though no detailed survey has been made, it is known to be exported to Malaysia, Hong Kong, Singapore, Japan, U.S.A., Italy and France.
Although the technology for the pond culture of Macrobrachium is already known in the country from pilot experiments by government stations as well as trials by private pond owners, the industry is still very limited so that the production of this species from culture is still negligible. Also, there are still innumerable problems to be solved to make its culture a profitable industry. The kinds and amounts of economical feed for the stock will need study and the supply of prawn seedlings from government and private hatcheries will have to be increased to fill the need for stocking natural waters, where found needed, and for culture.
In the meantime, other events are taking place in the natural environment of this species which may seriously endanger the fishery. Pollution from newly established industries and from growing population centres threaten to reduce greatly if not completely decimate the natural fishery of this species in certain areas. Over-fishing due to increased number of fishermen and improved efficiency of gear is also an added factor leading to rapid depletion of the giant prawn fishery
2.14 Vietnam
As in Khmer Republic, the Macrobrachium resources of Vietnam come mainly from the Mekong river system and its tributaries. The fishery is therefore extensive and has high potentials for development. The hatchery work for this species and its culture as are presently being initiated by the Mekong Committee of ESCAP* are good innovations in this field. The writer is not aware of any available statistics on the magnitude of the fishery in Vietnam at present.
4. SUMMARY AND RECOMMENDATIONS
4.1 It is recognized that there is in existence a worldwide (but particularly in the Indo-Pacific Region) fishery for the fresh/brackish prawn (Macrobrachium). One species, M. rosenbergii is known to be commercially important in national as well as international markets.
4.2 Present knowledge of this fishery is mainly qualitative. There is therefore an urgent need to quantify the status and potential of the fishery upon which to base the formulation of rational national as well as regional development programmes for this resource.
4.3 Despite the fact that the importance of this fishery was realized only recently, it is noted that aquatic pollution and water resources development works in many natural grounds of this resource are adversely affecting the fishery. Appropriate and immediate action will be needed to prevent large-scale destruction of this valuable fishery.
4.4 One of the worthwhile innovations that can lead to the maintenance and increase of the fishery is through the propagation of stocking material (hatcheries) and through culture. National and regional support for this work will be required.
4.5 To put the fishery on a firm foundation and particularly for the growing aquaculture development of this resource, extensive research to solve the technical problems of the industry and training of technologists and technicians for this work will be needed. Among others, it is suggested that future lines of research should emphasize on feeds and feeding, prevention of mortality and control of diseases, genetic selection and hybridization, culture intensification techniques, design of culture systems, and maintenance of water quality.
* Economic and Social Commission for Asia and the Pacific.
5. LIST OF REFERENCES
Beard, T.W., 1972 A preliminary report on the growth and survival of Macrobrachium resenbergii de Man, Penaeus aztecus Ives, P. indicus H. Milne- Edwards and P. Monodon Fabricius in laboratory recirculation systems. ICES Benthos Comm., C.M. 1972/K:26, 10p. (mimeo)
Bhrahmanondha, P. and S. Sahavacharin, 1970 Certain biological notes from experiments in culturing the giant freshwater prawn Macrobrachium rosenbergii de Man at Songkhla Marine Fisheries Station. Songkhla Mar. Fish. Sta., Div. Res. Invest., Dept. Fish., 33p.
Bhrahmanondha, P. and S. Sahavacharin, 1971 Results of experimental culture of giant freshwater prawn larvae (Macrobrachium rosenbenbergii de Man) at Songkhla Marine Fisheries Station, Songkhla Mar. Fish. Sta., Div. Res. Invest., Dept. Fish., Contrib. (2): 27p.
Cowles, R.P., 1914 Palaemons of the Philippine Islands. Philpp. J. Sci., 9 (D, 4). 319–403
Department of Fisheries, 1973 Fisheries record of Thailand. Statistics Sect. Dept. Fish., 13p.
East-West Center, 1973 Building prawn farming systems: A professional development report of the East-West Food Institute, 5p.
Escritor, G.L., 1975 Status of the giant prawn resources of the Philippines. Contrib. Internat. Conf. Prawn Farm., Vung Tau, Vietnam, 1975: 16p.
Estampador, E.P., 1973 A checklist of Philippine crustacean decapods. Philipp. J. Sci., 62(4): 465–559
Forster, J.R.M. and J.F. Wickins, 1972 Prawn culture in the United Kingdom: Its status and potential. Minist. Agric. Fish. Food, Lab. Leaflet (27) N.S.: 32p.
Fujimura, T. and H. Okamoto, 1970 Notes on progress made in developing a mass culturing technique for Macrobrachium rosenbergii in Hawaii. IPFC/C70/SYM 53: 17p.
Goerge, A.T. and M.J. Sebastian, 1970 The prawn fisheries of Kerala backwaters problems and prospects with special reference to aquaculture. IPFC/C70/SYM 20: 5p.
Guerrero III, R.D., L.A. Guerrero and J.H. Grover, 1975 Notes on the culture of freshwater shrimps in central Luzon. Contrib. Internat. Conf. Prawn Farm., Vung Tau, Vietnam, 1975: 7p.
Inland Fisheries Division, Department of Fisheries, Bangkok, Thailand, 1974 A report on giant freshwater prawn, Macrobrachium rosenbergii de Man, in Thailand: Its distribution and abundance. Inl. Fish. Div., Dept. Fish. (13): 24p.
Larimore, R.W., 1973 Report on fisheries of project on land and water resources development in Southeastern Sumatra. UNDP/SF Proj. No. 182/ INS/18: iv + 42p.
Liao, I.C., N.H. Chao and L.S. Hsieh, 1973 Preliminary report of the experiments on the propagation of the giant freshwater prawn, Macrobrachium rosenbergii, in Taiwan. J. Fish. Soc. Taiwan, 2(2): 48p.
Ling, S.W., 1962 Studies on the rearing of larvae and juveniles and culturing of adults of Macrobrachium rosenbergii (de Man). IPFC Curr. Aff. Bull. (35): 11p.
Ling, S.W., 1967 The general biology and development of Macrobrachium rosenbergii (de Man). FAO World Sci., Conf. Biol. Cult. Shrimps Prawns, FR: BSCP/67/E/30: 18p.
Ling, S.W., 1968 A brief working bibliography on shrimp culture with particular reference to Macrobrachium spp. IPFC Occas. Pap. 68/1: 4p.
Ling, S.W., 1973 The South China Sea fisheries: Aquaculture development. UNDP/FAO South China Sea Fish. Dev. Coord. Progr., SCS/DEV/73/5: vii + 51
Rabanal, H.R., 1973 Report on travel in connection with the South China Sea Fisheries Development and Coordinating Programme to Southeast Asia (from 23 July–30 August 1973). FAO/RAFE Trav. Rep., 25p. (mimeo)
Rabanal, H.R., 1974 Adviser's assignment report: Bangladesh. UNDP/FAO, 16p. (mimeo)
Rabanal, H.R., 1974 Adviser's assignment report: Sri Lanka. UNDP/FAO, 10p. (mimeo)
Rabanal, H.R., 1974 Adviser's assignment report: Irian Jaya, Indonesia. SCS/TR/74/4: 10p. (mimeo)
Rajyalakshmi, T., 1974 The freshwater prawn Macrobrachium malcolmsonii for use in pond culture. Seafood Exp. J., March 1974: 25–31
Ridenhour, R.L. and B. Indrambarya, 1974 Observations and recommendations concerning the fisheries within certain irrigation-flood control project areas in Bangladesh. Consultant's Report: 13p. (mimeo)
Rivera E.D., 1975 Brief note on the preliminary culture of Macrobrachium rosenbergii in the Philippines. Contrib. Internat. Conf. Prawn Farm., Vung Tau, Vietnam, 1975: 3p.
Soehardi, 1972 Freshwater fish culture in Indonesia. Direct.-Gen. Fish., Minist. Agric., 13p. (mimeo)
Wickins, J.P. and T.W. Beard, 1974 Observations on the breeding and growth of the giant freshwater prawn, Macrobrachium rosenbergii (de Man) in the laboratory. Aquacult. 3 (1974): 159–174
Wong, N. and H. Deese, 1974 Macrobrachium project. Micron, Maricult, Dem. Cent. Newsl. P-2–6
by
S. Suwannatous
ABSTRACT
The subject was introduced by statement that prawn hatchery is useful to supply stock for aquaculture and present technology has been developed in this field.
In selecting prawn hatchery, availability of good quality fresh and salt water, accessibility and availability of electric power should be considered.
OUTLINE
1. INTRODUCTION
2. SITE SELECTION
2.1 Quality of fresh water
2.2 Quality of sea water
2.3 Accessibility
2.4 Electricity
3. EQUIPMENT
3.1 Tanks
3.1.1 Salt water tank
3.1.2 Fresh water tank
3.1.3 Green water tank
3.1.4 Hatchery tank
3.2 Air blowers
3.3 Air pipes
3.4 Screen
3.5 Salinometer
3.6 Others
4. PREPARATION OF WATER
4.1 Water quality
4.4.1 pH
4.4.2 Salinity
4.2 Preparing green water
4.2.1 Mixed water
5. SELECTION OF GRAVID FEMALE
5.1 From natural sources
5.2 From ponds
6. METHODS OF FEEDING LARVAE
6.1 Stocking gravid female in hatchery tank
6.2 Rearing larvae
6.3 Preparation of larval food
6.3.1 Fresh fish
6.3.2 Brine shrimp
6.3.3 Others
6.4 Methods of feeding
6.4.1 Feeding in 1–7 days
6.4.2 Feeding in 7–20 days
6.4.3 Feeding of juveniles
6.5 Cleaning tank
6.6 Changing water
6.7 Lowering salinity
7 OTHER PROBLEMS (mortality when young, stocking rate of larvae in hatchery tanks, etc.)
by
S. Suwannatous
ABSTRACT
First, the water for the selected gravid females should be prepared in advance taking into consideration proper water level (50 cm) and salinity (6–9 ppt).
Gravid females may be selected from stock obtained from natural waters or those raised in ponds. The former are generally larger (approaching 100 g), the latter smaller (about 50 g). The usual prophylactic treatment for breeders consists of immersion in 5 ppm copper sulfate for one hour or 15 ppm formalin for one hour.
OUTLINE
1. PREPARATION OF WATER FOR GRAVID FEMALE
1.1 Water level (hatchery tank) 50 cm
1.2 Salinity (6–9 ppt)
2. SELECTION OF GRAVID FEMALE
2.1 From natural waters, 100 g
2.2 From rearing ponds, 50 g
3. TREATMENT BEFORE STOCKING IN HATCHING TANK
3.1 5 ppm copper sulfate per one hour
3.2 15 ppm formalin per one hour
3.3 Concentration
by
C. Sukapunt
ABSTRACT
First, water wuality is an important consideration. Salinity, pH and dissolved oxygen were discussed to be of primary importance.
The source of water and their preparation were described in detail. Three types of water used in hatchery - salt water, fresh water and green water were discussed. Preparation of green water including salinity of water used, amount and kind of fish to stock, feeding of stocked fish, and duration of the usefulness of prepared green water were explained.
The instruments used to measure salinity which is a very important quality for hatchery water were enumerated and their uses explained.
OUTLINE
1. WATER QUALITY
1.1 Salinity
1.2 pH
1.3 Dissolved O2
2. SOURCE OF WATER AND PREPARATION
2.1 Salt water
2.2 Fresh water
2.3 Green water
2.3.1 Salinity
2.3.2 Stocking rate of Tilapia for preparing green water
2.3.3 Feeding of fish
2.3.4 Duration in use of green water after preparation
3. MEASUREMENT OF SALINITY
3.1 Refractometer
3.2 Chemical
3.3 Hydrometer
by
S. Suwannatous
ABSTRACT
The importance of using proper food that is properly prepared was emphasized. Prepared fish flesh, chicken egg or live food like Daphnia, etc. may be used. Some problems encountered in the use of each type were mentioned. The facilities used and preparation of the food were described.
OUTLINE
1. OBJECTIVE
2. TYPE OF FOOD
2.1 Fish
2.2 Egg
2.3 Daphnia
2.4 Constraints (overdose cause pollution, live food, etc. and may carry
disease like protozoan, etc.)
3. SIZE OF FOOD
4. APPARATUS - SCREEN, KNIFE, ETC.
5. HOW TO PREPARE LARVAL FOOD
by
S. Suwannatous
ABSTRACT
Detailed description on feeding of prawn larvae was given. This starts with feeding larvae of 1–7 days old followed by feeding larvae 5–20 days and finally feeding of the juveniles. Under these stages, the type of food, size of food particles should be considered.
Daytime and night time feeding were considered. Usually prepared fish flesh are used for day feeding while live food like rotifer, brine shrimp, etc. are used at night. The juveniles that has just molted from the last larval stage is delicate and requires special feeding. Fresh fish flesh may be used initially and later chicken broiler starter feed can be given.
OUTLINE
1. FEEDING LARVAE IN FIRST WEEKS
1.1 1–7 days
1.2 After 7th day
1.3 Feeding the juveniles just after transformation from larvae
2. FEEDING AT DAYTIME
2.1 Fresh fish
2.2 Other organisms
3. FEEDING AT NIGHT TIME
3.1 Artemia
3.2 Other organisms - rotifer, etc.
4. FEEDING OF JUVENILES THAT HAVE JUST CHANGED FROM LARVAE
4.1 Fresh fish
4.2 Chicken pellet (broiler starter)
5. PERIOD FOR GIVING FOOD
5.1 1–7th day
5.2 5–20th day
5.3 Period after larvae changed to juveniles
by
A. Tunsutapanich
ABSTRACT
The reason for decapsulation was explained. The various apparatus and chemicals and their uses were described. The method was explained and demonstration was made. An explanation on how the method operates was given.
OUTLINE
1. INTRODUCTION
2. PURPOSE
3. APPARATUS AND CHEMICAL
3.1 Balance
3.2 Thermometer
3.3 Bucket
3.4 Air pump
3.5 Filter
3.6 Ice
3.7 Ca hypochlorite
3.8 CaO
3.9 Na thiosulphate
3.10 Salt
4. THE METHODS OF DECAPSULATION
5. HOW METHOD WORKS
by
J. Vos
ABSTRACT
Commercial Artemia cysts presently available in the world market come from Argentina, Australia, Brazil, Canada and the United States. The San Francisco Bay Brand and Living World Brands are known in the trade.
Prices of Artemia cysts are high (range from $30–80/kg). There was no reliable criterion for quality, previously. However, recently, hatching efficiency (HE) can be used as a good basis. This is based on weight of cyst to produce 1 million nauplii.
Storage of cysts is done in vacuum cans. When kept dry or in brine, the cyst remain in good condition. Humidity will affect quality.
To economize on the use of Artemia the following initiatives can be undertaken.
Nauplii production in water of low salinity;
Production of Artemia adults in raceways using cheap local feed like ricebran and using adult and pre-adult Artemia as food for cultured species of various stages; and
Inoculation in natural salt ponds to produce cysts or adults.
1. PURCHASE OF CYSTS
1.1 Different strains
Only recently many different strains or races of Artemia salina came on the market. Apart from the San Francisco Strain (San Francisco Bay Brand and Living World), following countries among others also produce cysts on a commercial basis: Canada, Brazil, Argentina, Australia.
1.2 Prices and quality
Prices as well as quality vary very much from one strain to another. And very often high prices do not correspond with high quality. Even within one brand quality can be changing a lot depending on the time the cysts were harvested. Thus, when cysts are bought, one can never be sure of the good quality, the company who sells the cysts, is claiming.
Fortunately, recently an easy method for quality control has been worked out. This method uses a new criterion, i.e. hatching efficiency.
Hatching efficiency (HE) = x gram product needed to produce one million of nauplii
This HE is not the same as the hatching percentage (HP) criterion, the different brands are still using.
Hatching percentage (HP) = % of cysts which will hatch to nauplii.
However, since the product contains not only cysts but also dirt, sand, and empty cyst shells, the criterion HP can be a misleading one. A good brand has a HE between 3–5 grams (3–5 g product needed for 1 106 nauplii).
1.3 Storage
Once a specific brand is chosen and purchased, the cysts have to be stored. Almost all companies are selling cysts packed in vacuum cans. These cans should be kept out of the sunlight to prevent too high temperatures. As long as a can is not opened, the viability and HE of the cysts is guaranteed. However, once a can is opened, the HE might decrease in a period of several days. This is due to high humidity, which hydrates the cysts. To prevent this quality decrease, the cysts remaining in the can, can either be kept in perfectly dry conditions (Sillicagel or CaCl2) or submerged in brine 300 ppt salinity).
2. METHODS TO ECONOMIZE ON THE PURCHASE OF CYSTS
Since the commercial Artemia cysts are expensive (US$40–80/kg), this expense can be a major part of the budget of the hatchery. Therefore methods to lower this expense should be considered.
2.1 Cyst production in local salt ponds
In the past all commercial cysts were obtained from natural Artemia populations living in salt lakes with high salinity. However, Artemia can be inoculated in existing salt ponds which do not have a natural Artemia population. In the site selection, following criterions should be carefully checked:
High continuous salinity (more than 100 ppt) for at least 2–3 months per year. This is in order to prevent the presence of predators in the ponds, such as fish: Tilapia and goby.
Minimal depth of 40 cm to prevent high water temperatures (lower than 33°C).
High productivity of the water to guarantee a good food availability for Artemia. Mangrove areas are very well suited.
If inoculated in the right way and place, cysts will be produced as long as the salinity can be maintained at a high level. Such inoculations have been performed successfully giving minimum production results of 10 kg/ha/3 months.
2.2 Nauplii production
Adults may also directly produce nauplii ovoviviparously in low salinities. The economic feasibility of this possibility is presently under study.
2.3 Adult production
Nauplii can be grown to larvae and adults of different sizes, which are also an excellent food. Starting from 10 grams of cysts and using ricebran as food, about 500 grams wet weight of adult Artemia can be cultured in 14 days in a 500-liter tank. Since ricebran is a very cheap product, this means providing nutrition results in good economy. Up to now, the feasibility of using adults as food, has been proven for crabs, fish and shrimps, but not yet for Macrobrachium. Sub-adults, on the other hand, were successfully used in feeding Macrobrachium.
by
J. Vos
ABSTRACT
Brachionous, Moina and Artemia are mentioned as useful live food organisms of hatchery-raised prawns. The advantages and characteristics of the brine shrimp as larval food were cited - its cysts can be stored, easily hatched, and with high food value.
Brief description of the biology of Artemia was given including optimal environment for its life, oviparous and ovoviviparous reproduction, life cycle and feeding habits.
The scheme on how to use Artemia in aquaculture was diagrammed especially as it applies to prawn hatchery. Production of cysts, decapsulation and hatching were briefly described.
1. LIVE FOOD
To feed prawn larvae up to the juvenile stage, live and/or inert food must be given. Inert feed should be administered in small quantities to make sure that all of it is consumed after each feeding period. If too much feed is given at a time, sedimentation of the feed particles will follow, contaminating the culturing water.
Live food on the other hand, has the advantage that it can be given in bigger quantities (no sedimentation) and therefore it can cover longer nonfeeding periods. Different types of animal live food exist. The most important are Brachionous, Moina and Artemia. Among these Artemia salina, the brine shrimp is most often used.
2. ARTEMIA
Artemia has indeed many interesting characteristics for use as live food in aquaculture:
The “eggs” occur in a dry dormant state (cysts) and can be stored for many years. Appropriately packed, they can be sent all over the world.
From the cysts, live larvae, i.e. nauplii are easily and quickly obtained by putting them in seawater (hatching). Thus, no separate culturing tanks are needed to obtain large quantities of live food.
The nauplii survive and remain active in water of different salinities. Even when put in freshwater, mortality only occurs after 2–3 hours.
The nauplii have a very high protein content (up to 40%), which makes them an excellent food. Freshly hatched nauplii (Instar I - first larval stage) have a higher nutritional value than 2 or 3 days old nauplii.
3. BIOLOGY OF ARTEMIA
3.1 Growth
In optimal conditions (35 ppt salinity and 28°C), Artemia reaches the adult size after 7–10 days. When adult they measure about 1 cm.
3.2 Reproduction
Two modes of reproduction exist:
Oviparous: The fertilized egg (embryo) is surrounded by a brown shell. This cyst is very resistant to drying, high temperature, direct sunlight, etc. The cysts which are deposited by the female are hydrated. These cysts will only hatch and give free swimming nauplii when they are first dehydrated, and afterwards hydrated again.
Ovoviviparous: The fertilized eggs are not surrounded by a shell and hatch into nauplii in the female body itself (broodpouch). Thus, in the ovoviviparous reproduction mode the female produces directly free swimming nauplii.
The mode of reproduction is controlled by environmental factors such as dissolved oxygen and type of food. Each 5–6 days a female can produce an offspring of 50–200, either nauplii or cysts.
3.3 Feeding
Artemia is an obligatory non-selective filter feeder. Thus, it removes all particles from the water, i.e. mono-cellular algae, detritus bacteria, plant material, smaller than 60 microns. However, Artemia cannot feed on sedimented food.
4. USE OF ARTEMIA
In aquaculture Artemia can be used as an excellent food in different foods (scheme):
4.1 Nauplii
Cysts can be hatched to nauplii.
4.2 Decapsulated cysts (DC)
Cysts can be removed of their shell by a decapsulation process. The decapsulated cysts, although not actively swimming, can be used as an excellent direct food. DC even have a higher food content than nauplii.
4.3 Nauplii from decapsulated cysts
DC can be hatched to free swimming nauplii the same way as capsulated cysts.
4.4 Sub-adults and adults
Nauplii can be cultured into bigger larvae and adults of different sizes. Adults have a protein content of 60% of their dry weight and are therefore even a better food than nauplii (40% content). Used as food, adults can be administered either live, frozen or dried.
5. HATCHING
Cysts (decapsulated as well as capsulated) can be hatched to nauplii. The cysts are put in sea water (not more than 35 ppt). Strong aeration at the bottom of the hatching tank is used to keep all the cysts in suspension (no sedimentation). Even under optimal aeration-circulation conditions, a maximum density of 10 g per liter should not be surpassed. The hatching must be carried out in the shade, but not in the dark. After a specific time period, depending on the temperature (optimal: 28°C) and the Artemia strain used, the cysts will hatch in free-swimming nauplii. In case no decapsulation was performed previously, the empty cyst shells have to be removed from the nauplii. Hereafter, the nauplii can be sieved off (hatching water contaminates the culture) and administered to the prawns.
6. DECAPSULATION
During the decapsulation process, the outer cyst shell is dissolved, leaving the embryo only covered by the embryonic membrane. Since the membrane is transparent, the colour of DC is bright orange versus brown for capsulated cysts. Although during the decapsulation Ca(OCl2), calcium hypochloride or bleaching powder is used in a high concentration, the viability or hatching efficiency of the cysts is not decreased. Decapsulated cysts can either be used as a direct food or be hatched into nauplii. The use of DC in hatcheries has many advantages compared to capsulated cysts.
No more separation of the empty cyst shells after hatching.
No more contamination of the cultures since the embryos have been sterilized.
DC can be easily stored in brine (300 ppt salinity) without changing the hatching efficiency.
For many Artemia strains the hatching efficiency is improved after decapsulation.
by
S. Intrapichet
ABSTRACT
The need for screens was explained. Various types used for screens in prawn hatcheries were shown such as synthetic cloth and stainless metal screens. The characteristics and advantages of each were given. Preparation and installation of the screens were explained and practiced.
OUTLINE
1. OBJECTIVES
2. TYPE OF SCREENS
2.1 Synthetic cloth
2.2 Stainless steel
2.3 Mesh sizes screens (30–50 meshes/cm)
2.4 Constraints (deterioration of synthetics)
3. APPARATUS (PIPE 3", ETC.)
4. HOW TO PREPARE SCREENS
by
A. Tunsutapanich
ABSTRACT
Preparation of nursery concrete tanks should be undertaken before stocking prawn larvae or juveniles. The necessary installations of air pipe line, shelter in tanks and shading were also explained. The usual stocking rate in nursery tanks is 2 000 juveniles per square meter, 1 m deep. Care of juveniles, particularly feeding, cleaning of tanks and change of water during culture were explained and demonstrated. Duration of culture considering various factors was explained supplemented by actual practical work.
OUTLINE
1. PREPARATION OF NURSERY TANK
1.1 Air pipe line
1.2 Installation of shelter in tank
1.3 Nursery tank cover
2. STOCKING RATE 2000/m2 (1 m deep)
3. CARE OF JUVENILES
3.1 Food
3.2 Method of feeding
3.3 Cleaning nursery tanks
3.4 Change of water
4. DURATION OF CULTURE IN NURSERIES
by
V. Suksucheep
ABSTRACT
As prawn hatcheries are managed separately from grow-out ponds and from natural waters that need stocking, transport of juveniles to stocking area will be necessary. The various apparatus used and how they are used were described and demonstrated. The equipment for monitoring water quality were also cited. Preparation before transport, carrying rate of containers in relation to distance and time were discussed. Other additional care needed during transport were also enumerated.
OUTLINE
1. OBJECTIVES
2. APPARATUS
2.1 Box
2.2 Plastic bag
2.3 Rubber bag
2.4 Pure oxygen
2.5 Electric fan
2.6 Ice
2.7 Bucket
2.8 Thermometer
3. WATER PREPARATION
4. DISTANCE
5. CARRYING CAPACITY OF PLASTIC BAG
6. TRANSPORTING WITH OPEN BAG
7. CARE DURING TRANSPORT
by
S. Singholka
ABSTRACT
Background information on location of suitable land for prawn culture sites within Thailand was discussed. The major considerations are: quality of soil, availability and quality of water supply, accessibility, and availability of area for expansion. The characteristics of suitable water from river, underground or open canals were described.
On design, discussions were made on the types of ponds and relative sizes, sizes of dikes and their correct slope, design of water inlet and outlet. Prevention of dike erosion and renovation of old ponds for prawn culture were also explained.
OUTLINE
1. HOW TO SELECT LAND FOR SITE
1.1 Geography - location
1.2 Quality of soil
1.3 Water supply
1.3.1 Water from river
1.3.2 Water from seepage
1.3.3 Water from canal
1.3.4 Artesian wells
1.4 Accessibility
1.5 Area for expansion
1.6 Other considerations
2. DESIGN
2.1 Size and type of ponds
2.2 Size of dikes and shape
2.3 Water inlet
2.4 Water outlet
2.5 Preventing erosion of dikes
3. RENOVATION OF OLD PONDS
by
P. Vorasayan
ABSTRACT
First, the transport of juveniles from hatcheries to rearing pond areas was described. On arrival at site, proper stocking procedure using proper stocking rates should be used. Food and feeding, change of water, periodic sampling, protection from predators such as through improvised shelters were described. The growth rate should be checked periodically and at appropriate periods selective harvesting need to be done. The production and survival rates should be evaluated on cropping. Harvested crops were often subjected to premarket processing (icing, boiling) or sold fresh. Culture problems such as pollution (poor quality) and predators were explained.
OUTLINE
1. FEEDING JUVENILES IN EARTH PONDS
2. FEEDING JUVENILES IN DITCH PONDS
3. PREPARATION OF EARTH POND
4. TRANSPORTATION OF JUVENILES
5. STOCKING METHOD
6. STOCKING RATE
7. REARING JUVENILES IN GROW-OUT PONDS
8. FOOD AND FEEDING
9. CHANGE OF WATER
10. SAMPLING
11. PROTECTION FROM PREDATORS
12. SHELTER
13. GROWTH RATE
14. DURATION TILL MARKETABLE
15. SELECTIVE HARVESTING
16. PRODUCTION AND SURVIVAL RATE
17. PRE-MARKET PROCESSING
18. CULTURE PROBLEMS
18.1 Pollution
18.2 Predators
Translated from H.S. Swingle
Agricultural Experiment Station, Alabama Polytechnic Institute2
Auburn, Alabama, U.S.A.
Thousands of measurements of the pH of waters are made annually throughout the world, and buried in files or in the interior of manuscripts because too often there is nothing that can be done with the information. Part of this information is actually worthless because of its isolated nature or the manner in which pH was measured. The use of colorimetric methods cannot be depended upon to give accurate results on a wide variety of waters. Universal colorimetric indicators and pH papers give only general approximations that may vary 1 to 3 units from the true pH. Reliable measurements are best obtained by use of electrometric glass electrodes or similar equipment.
Many of the pH measurements published convey no information to the reader because the conditions under which the measurements were made are not stated. For example, the pH of a soft water may be 6.5 at daybreak, and 9.5 in the late afternoon if the sun is shining and a heavy growth of phytoplankton or underwater weeds has removed most of the available CO2. Thus, pH of 9.5 may indicate alkali water, soft water or hard water, depending upon the conditions under which it was measured. For interpretation by others, the time of day, the amount of light, the amount of underwater vegetation, the depth at which the sample was taken, and the classification of the water should all be included in published information dealing with the pH of pond waters. For greatest usefulness, pH readings should be made periodically from just before sunrise until sunset.
The pH of pond waters, however, is in general useful information in questionable waters because it will indicate those that lie in the desirable range for fish culture, those that are too acid or too alkaline for good production, those that are toxic to fishes, and those in which fishes may live but be unable to reproduce. If the measurements are made before daybreak, pH will indicate approximately the class to which freshwaters belong. Unfortunately information upon the relationship of pH to various fishes is fragmentary, and it is necessary to generalize from information on a few species (Figure 1).
pH of Water Toxic to Pondfishes
Waters with pH from 5.4 to 3.6 are reported toxic to various species of pondfishes. The acid danger point for common carp is reported from 4.8 (Schaeperclaus, 1933) to 5.4 (California Water Pollution Control Board, 1952). For pondfish in general, however, the acid death point in natural waters may be accepted as pH 4.0 (Ellis et al., 1946).
1 Proc. 9th Pacific Sci. Congr. 10 (1961)
The alkaline danger point is reported as 9.0 for carp by Schaeperclaus (1933), but in American ponds no deaths of carp were observed in ponds with pH as high as 10.0. Ohle is quoted (Mortimer, 1954) as reporting the upper toxic limit for carp as 10.8. However, all authorities agree that practically all pondfishes die when the pH reaches 11.0, and this may be taken as the alkaline death point for pondfishes.
Rapid change in pH also may cause death at values that a species can tolerate if the change is gradual (California Water Pollution Control Board, 1954).
pH of Waters Most Desirable for Pondfish Production
Waters ranging in pH from 6.5 to 9.0 before daybreak are generally regarded as most desirable for pondfish production. Waters in this range are capable of giving highest production if the level of fertility is adequate. Waters with pH 6 to 6.5 may also give excellent results following fertilization if the acidity is due to carbon dioxide. However in this case, the pH shifts to above 7.0 during the daytime period as free CO2 and HCO3- are utilized in photosynthesis.
Fig. 1. Relationship of pH of pond waters to their suitability for fish culture
Effect of pH on Production
Acid waters with pH 4.8 to 6.0 give low production even when not toxic to fish. In experiments at this Station, waters with pH 4.5 to 5.5 in mid-afternoon yielded excellent growth of phytoplankton following fertilization, but yielded practically no zooplankton or bottom organisms. As a result, bluegills made practically no growth. In waters 5.5 to 6.0 in mid-afternoon, chironomid larvae were produced sparingly, and bluegill growth was very slow.
In waters with pH 9.5 to 10.5 before daybreak, production is also very low. In this case, low production appears due to unavailability of carbondioxide for photosynthesis. Phytoplankton are able to utilize free CO2 and bicarbonates, but are not able to use CO2 in the form of carbonates. At pH 9.5, almost no carbon dioxide occurs as the bicarbonate and above pH 10.0 it is all in the carbonate form. In such ponds following fertilization, phytoplankton growth occurred only at the surface of the water where CO2 from the air was available (Swingle, 1947). Rooted aquatic plants were able to grow in these waters indicating that they were able to utilize carbonates.
pH and the Classification of Freshwaters
The pH of natural waters indicate in general the classification to which they belong. Natural soft waters range in pH from 3.0 to 7.2 if readings are taken before daybreak. Certain of these waters containing heavy growths of phytoplankton or underwater higher plants may, during the photosynthetic period, increase in pH to 9.5 (Swingle, 1947) or even to 10.0 (Smith, 1952) as the available CO2 is exhausted. Wide fluctuation in pH during this period indicates soft waters.
Hard waters range in pH from 7.5 to slightly above 8.5, both before daybreak and during the photosynthetic period. The buffering action of calcium and magnesium bicarbonates reduces fluctuations in pH.
Alkali waters range in pH from 9.5 to approximately 11.0. These waters occur principally in dry-land areas, with high alkalinity principally due to sodium and potassium carbonates.
pH and the Liming of Ponds
Waters more acid than pH 6.5 may in general be corrected for use in fish culture by liming. Schaeperclaus (1933) does not believe that liming will correct waters more acid than pH 4. However, Smith (1952) reported apparently successful results from liming ponds with pH as low as 3.0.
In tests conducted by this Station at a hatchery that had an acid water supply (pH 5.0), the addition of just sufficient lime to correct the acidity of the water failed to materially increase fish production. Following applications of calcium carbonate to water in these hatchery ponds, the pH rose above 7.0. However, it was found that the pH of the bottom soils remained at 4.4 and no bottom organisms were being produced. Production of bluegills increased only after the bottom soils were limed to correct this acid condition. From observations in a number of ponds, it appears that if the bottom soils are more acid than pH 5.5, they must be limed before high fish production is possible.
Pond waters and pond bottom soils should normally be limed using finely ground calcium carbonate (limestone) or a mixture of calcium and magnesium carbonates (dolomite). This results in tying up the free CO2 in the form of bicarbonate which is still available to phytoplankton for photosynthesis:
CaCO3 + CO2 + H2O → Ca (HCO3)2
If the pH of the water is less than 4.5, this indicates the presence of strong acids, and calcium hydroxide Ca (OH)2 also known as hydrated lime, should be used. However, it should not be used in amounts greater than that necessary to increase the pH to approximately 6.0 to 6.5. This will result in leaving at least part of the CO2 in available form. The use of excess calcium hydroxide results in tying up all the CO2 as the unavailable carbonate:
Ca(OH)2 + CO2 → CaCO3 + H2O
Smith (1952) used a combination of calcium hydroxide and calcium carbonate in neutralizing acid bog ponds (pH 3 to 4).
Calcium oxide (CaO) and calcium hydroxide are occasionally used to kill parasites on pond bottoms after draining. Both of these materials can cause such high pH (11 or higher) in water that they kill fish.
Consequently, they are best applied to the damp pond bottom and the pond should not be refilled for about 2 weeks, or until these materials are transformed into carbonates by CO2 from the air:
CaO + H2O + CO2→CaCO3 + H2O.
Ca(OH)2 + CO2→CaCO3 + H2O.
The amounts of lime required to correct acid waters can be determined by titration. The amount required to correct acid soils varies with the soil type. Schaeperclaus (1933) suggests for loamy sand soils 1 500 kilos CaO per hectare for soils with pH 4, and 1 000 kilos for soils with pH 5. Where finely ground limestone (CaCO3) is used, practical experience has shown that soils of pH 5 require approximately 2 000 kilos per hectare and those with pH 4.0 require from 4 000 to 6 000 kilos.
Where pond waters before daybreak are more alkaline than pH 6.5 and bottom soils are more alkaline than pH 6.0, no liming is needed and additional lime may reduce production (Swingle, 1947).
Relation of pH of Waters to Fertilization
Waters more acid than pH 5.5 should not be fertilized until after they are corrected by liming. In acid waters, it is desirable to use non-acid forming fertilizers. The source of nitrogen should be preferably sodium nitrate or calcium nitrate. These tend to make waters less acid because phytoplankton utilize the nitrate radical, and the cations largely remain in the water to neutralize acidity.
Waters with pH 10 or more should not be fertilized because there is insufficient available CO2 to give high production. In waters with pH 8.5 to 9.5 before sunrise, acid-forming fertilizers should be used. The source of nitrogen should be preferably ammonium sulfate. This tends to make waters more acid because phytoplankton utilize the ammonium ion and the sulfate ion remains in the water to reduce the alkalinity.
SUMMARY
The relationships of pH of pond waters to their suitability for pondfish culture are summarized in Figure 1.
The pH of a pond water may be an indicator of the type of water, its suitability for fish culture, its toxicity to fish, its potential productivity, its response to liming and its response to fertilization.
The acid death point for pondfishes is pH 4.0 and the alkaline death point pH 11.0.
Waters ranging from 6.5 to 9.0 before daybreak are most suitable for pondfish culture.
Waters with pH 4.8 to 6.0 and from 9.5 to 10.5 produce low yields of fish.
Natural soft waters range in pH before daybreak from 3.0 to 7.2; hard water from 7.5 to 8.5 and alkali waters from 9.5 to 11.0.
Production in acid waters, from pH 3.0 to 6.5, may be improved by liming the water; high production, however, can only be achieved by also liming acid bottom soils.
BIBLIOGRAPHY
California Water Pollution Control Board. 1952 Water quality criteria. California State Water Pollution Control Board Publication 3: 315–319
California Water Pollution Control Board. 1954 Water quality criteria. California State Water Pollution Control Board Publication 3, Appendum No. 1: 99–100
Ellis, M.M., Westfall, B.A. and Marion D. Ellis. 1946 Determination of water quality. U.S. Dept. Int. Fish and Wildlife Service Res. Rept. 9: 42–45
Mortimer, C.H. Fertilizers in fish ponds. 1954 British Colonial Office Publication 5: 11–15
Schaeperclaus, Wilhelm. Textbook of pond culture. 1933 Translation by F. Hund. U.S. Dept. Int. Fish and Wildlife Service Fishery Leaflet 311: 50–53
Smith, Roland F. 1952 Neutralization experiments in certain acid ponds in New Jersey. Natl. Lime Assn. 50: 89–96
Swingle, H.S. 1947 Experiments on pond fertilization. Ala. Poly. Inst. Agr. Exp. Sta. Bul. 264: 34p.
Bangpakong, Chachoengsao, Thailand
15–29 November 1978
SCHEDULE
| 15 November, Wednesday | |
| A.M. | Opening excercises at the National Inland Fisheries Institute, Bangkhen, Bangkok |
| 0900–1000 | Opening remarks and general briefing by Mr. Ariya Sidthimunka |
| 1000–1100 | General report on Macrobrachium fishery with emphasis on the state of this resource in the Indo-Pacific Region by Dr. H. R. Rabanal |
| P.M. | Travel to Chonburi and check-in at Eastern Hotel Advance of daily subsistence allowance issued to participants |
| 16 November, Thursday | |
| A.M. | General briefing on Chachoengsao Fishery Station by Mr. Somsuk Singholka |
| Briefing on principles of Macrobrachium hatchery by Mr. Sombhong Suwannatous | |
| P.M. | Briefing on Macrobrachium hatchery (continued) |
| Practicum-preparation of hatchery tanks demonstration by Messrs. Chamnan Sukapunt and Prasit Phuhoung | |
| 17 November, Friday | |
| A.M. | Preparation of water supply for hatchery - briefing and practicum by Mr. Chamnan Sukapunt |
| Collection of broodstock and prophylaxis from diseases, briefing and practicum by Mr. Sombhong Suwannatous | |
| P.M. | Culture of Artemia, briefing and demonstration by Mr. Mr. Jan Vos |
| Nursery work for Macrobrachium - briefing and practicum by Messrs. Anand Tunsutapanich and Virojana Suksucheep | |
| 18 November, Saturday | |
| A.M. | Preparation of larval food - briefing and practicum by Mr. Sombhut Intrapichet |
| Feeding of larvae - briefing and practicum by Mr. Sombhong Suwannatous | |
| 18 November, Saturday | |
| P.M. | Preparation of screens - practicum led by Messrs. Sombhut Intrapichet and Suksit Chalaypote |
| Preparation and cleaning of hatchery tanks - practicum led by Messrs. Chamnan Sukapunt and Prasit Phuhoung | |
| 19 November, Sunday | |
| Holiday | |
| 20 November, Monday | |
| A.M. | Management of larval tanks - practicum led by Messrs. Sombhut Intrapichet and Suksit Chalaypote |
| P.M. | Decapsulation of Artemia - briefing and practicum by Mr. Anand Tunsutapanich |
| 21 November, Tuesday | |
| A.M. | Selection of site and pond design of grow-out ponds by Mr. Somsuk Singholka |
| Open discussion on site selection and pond design of grow-out ponds led by Messrs. Somsuk Singholka and Paiboon Vorasayan | |
| P.M. | Management of grow-out ponds - briefing by Mr. Paiboon Vorasayan |
| Discussion on pond management - participating - Messrs. Somsuk Singholka, Paiboon Vorasayan, Prasit Phuhoung, Suksit Chalaypote and Virojana Suksucheep | |
| 22 November, Wednesday | |
| A.M. | Preparation and transporting juveniles from hatchery nursery tanks to prawn farms - practicum led by Mr. Virojana Suksucheep |
| P.M. | Stocking of juveniles in prawn farm. Field trip to a Chachoengsao farm and practicum led by staff of Extension Section of the Station. |
| 23 November, Thursday | |
| A.M. | Field trip to Ayudhaya province to make practical observations to different prawn farms led by staff of Extension Section of Station |
| P.M. | Proceed to Suphanburi province and overnight stop at Suphanburi - Staff of Extension Section coordinating. |
| 24 November, Friday | |
| Whole day | Extensive survey of several prawn farms in Suphanburi province, including practicum lead by Extension Section staff. Overnight at Suphanburi |
| 25 November, Saturday | |
| A.M. | Proceed to Pathomthani province and field survey and practicum in private prawn farms lead by Extension Section staff |
| P.M. | Return to Chonburi province to headquarters hotel at Chonburi |
| 26 November, Sunday | |
| A.M. | Start preparation of report by participants at Hotel |
| P.M. | Visit to prawn farm at Chonburi and stopover at Pathaya Beach |
| 27 November, Monday | |
| Whole day Completion of report and open discussions by staff and participants | |
| 28 November, Tuesday | |
| A.M. | Evaluation of training course, submission of report and final discussions |
| P.M. | Closing exercises |
| 29 November, Wednesday | |
| Participants return to respective Stations | |
Bangpakong, Chachoengsao, Thailand
15–29 November 1978
LIST OF PARTICIPANTS
| Name | Province/Office | |
| 1. | Mr. Kreitanun Boontaum | Chiengmai Fishery Station |
| 2. | Mr. Rean Siriwong | Payao Fishery Station |
| 3. | Mr. Chann Suthanukul | Pitsanukloke Province |
| 4. | Mr. Chirdchoo Rangmorya | Nakornsawan Fishery Station |
| 5. | Mr. Narongritti Pusadee | Chainat Fishery Station |
| 6. | Mr. Chanyoot Nearpardits | Ayudhaya Province |
| 7. | Mr. Somkaun Mahanarm | Khonkhaen Fishery Station |
| 8. | Mr. Vinit Nakornpun | Ubonrajthani Fishery Station |
| 9. | Mr. Supawit Sukhasem | Pathomthani Province |
| 10. | Mr. Anake Tongpitak | Chonburi Province |
| 11. | Mr. Peerasak Pisutnijakarn | Samutprakarn Province |
| 12. | Mr. Chareon Sahaisook | Chanthaburi Province |
| 13. | Mr. Prasarn Chanamporn | Samutsongkram Province |
| 14. | Mr. Vinai Supol | Suphanburi Province |
| 15. | Mr. Narong Boonmeelarp | Bangkok (Extension Unit, DOF) |
| 16. | Mr. Somsakdi Luanprida | Bangkok (Extension Unit, DOF) |
TRAINING STAFF
A. National Staff
B. FAO/UNDP
Mr. Jan Vos, Associate Expert, THA/75/008
* Present position - Deputy Director-General, Department of Fisheries.
