Bangladesh is a riverine country possessing a vast offshore water area in the Bay of Bengal along the southern region. Both inland and offshore waters of Bangladesh retain a good potentiality of prawn fisheries. Prawn is one of the favourite foodstuffs to the people of Bangladesh. They usually take it as food in freshly cooked form, sundried or smoked. Culture of marine prawn in coastal dikes, canals and ponds have already become a traditional profession to the people of the coastal areas. Some people also practice the culture of freshwater prawn through the utilization of wild fries in the ponds, paddy-fields, borrowpits, etc. Yields are typically low, i.e. 150–400 lb/acre/year (168–448 kg/ha/ year), but the operations are profitable due to minimal establishment and management costs.
Till date, 17 species of marine shrimps, 9 species of freshwater prawns and 3 species of brackishwater prawns have been reported from Bangladesh waters. The marine species are Penaeus monodon, P. indicus, P. semisulcatus, P. merguiensis, P. penicillatus, P. orientalis, Metapenaeus monoceros, M. brevicornis, M. affinis, M. spinulatus, M. lysianassa, Parapenaeopsis sculptilis, P. hardwickii, P. coromandalica, P. uncta, Solenocera subnuda and S. melantho. The freshwater prawns include Macrobrachium rosenbergii, M. malcolmsonii, M. villosimanus, M. dayanus, M. mirabilis, M. lamarrei,M. dolichodactylus, M. rudis and M. birmanicus birmanicus. Two species of brackishwater prawns were previously reported from Bangladesh waters. These are Palaemon styliferus and Palaemon tenuipes. In addition, one brackishwater species of the genus Palaemon, i.e. Palaemon karnafuliensis has recently been reported as new to the prawn fauna of the world. The specific name of this species was derived from the type locality.
In spite of the presence of potential prawn fishery in both inland and marine waters of Bangladesh, much emphasis has been given on the exploration and exploitation of marine shrimps since long. Rich shrimp fishing grounds in the Bay of Bengal off Bangladesh have been located, efficient management programs have been taken up for the production of marine shrimps, and their export to the countries like U.S.A. and Japan has already been organized. Annual shrimp exports to the United States exceeded 11 million pounds (4 989 490 kg) in the year 1976–1977. But the freshwater prawn fishery still remained at research stage. That is to say, the commercial production of freshwater prawn in the controlled scientific environment is still awaited.
It is not far ago that inland waters of Bangladesh retained very rich stock of prawns. But nowadays, construction of dams and regulators all over the country, increase of shipping and dredging functionaries and coastal pollutants have caused an adverse effect on the natural habitats of freshwater prawn. Moreover, construction of embankments as a part of irrigation and flood control project of the country has blocked the routes of many migratory freshwater and marine prawns and thereby their spawning grounds have been eliminated. All these factors have resulted a serious decline of freshwater prawn population in Bangladesh.
Happily, some development projects in order to increase the inland fishery resources have already been initiated. The biggest hatchery complex occupying 60 acre (24 ha) area of land has preliminarily produced 10 million fry of major carp and Chinese carp in the present year. In this hatchery campus, some demonstration ponds have been built to enlighten the people for culturing the giant freshwater prawn, Macrobrachium rosenbergii. A hatchery for culturing M. rosenbergii is going to be constructed by the Government in collaboration with the World Bank. Feasible site for the purpose has been selected along the sea coast at the port city of Chittagong. The location is very near to an estuary that falls into the Bay of Bengal and is about 12 miles (19.3 km) away from the main city.
Macrobrachium rosenbergii has a very wide distribution in Bangladesh occurring almost in every district, particularly, most abundant in the southern districts. It is caught in large numbers during the months of September -February in the upstream freshwater areas and during June - August in the estuarine areas. Fishing gears generally used to catch the freshwater and brackishwater prawns are cast net, push net, drag net, purse net, beach seine, jags, traps and hooks.
It is hoped that the present prawn production in Bangladesh could be substantially increased through the establishment of the proposed Macrobrachium hatchery, in order to increase animal protein foods for the people, rural income and foreign exchange earnings. Also, the development of a prawn hatchery and the year round availability of prawn fry would permit: (1) improved pond management through control of stocking densities and species composition; (2) elimination of seasonal supply fluctuations through control of the timing of pond production cycles; and possibly (3) restoration of various wild stocks through stocking programme in selected natural waters.
(COUNTRY REPORT OF BURMA)
Production of M. rosenbergii in Burma is from capture fishery. The People's Pearl and Fishery Corporation organized collecting centres at various towns in the delta region. The prawns collected also consist of Metapenaeus and Palaemon species. It was found that a quarter of the total prawns landed were M. rosenbergii.
For the period 1979 (April) to 1980 (March), total yield for M. rosenbergii was 178 202 tons. From the monthly production record, the prime period appeared to be from September to January (late monsoon).
From random samples taken in 1977 and 1978, the mean weight was 60 and 90 g for males and 40 to 60 g for females, respectively.
In general, the fishermen use four types of gear techniques and traps in prawn fishing, which are as follows:
Traps
1. GEAR TECHNIQUES AND OTHER CAPTURE METHODS
1.1 Coconut longline
This method is used in shallow water. The bamboo poles are placed near the bank. The poles are 3–4 meters apart from one another and interconnected by long fishing line. On the fishing line, the secondary line with a hook at the terminal are attached. The secondary lines are aparted 35 cm.
In this long line gear technique, the coconut is used as bait. The prawn is caught with large chela locked on the hook. This method is used for fishing the large size prawn.
1.2 Bain win (bamboo screen)
In the method, the main apparatus is bamboo stick screen. The net is made of bamboo sticks woven to about 5 mm apart and they are connected side by size with ropes. The highest of the net is approximately 1 × 3 meters.
During low tide, in shallow rivers, the bamboo nets are placed and supported by bamboo poles. With the incoming tide the prawn and fishes enter the area between the screen and flooded river bank. When the tide recedes, the prawn and fishes are trapped in bain win (bamboo screen).
1.3 Bushing
This method is based on providing food and artificial shelter for prawn.
First, the fisherman might broadcast any food particles in shallow waters and placing bushes, so as to attract the prawns. About 4–6 hours after bushing, the bushes are lifted and by using scoop net underneath the prawns can be collected.
1.4 Traps
Traps are made of bamboo stick screens with the size 20 × 30 cm (height × diameter. Basically, these operate the same as other traps, having an entrance with a locking device.
Food (ricebran mixed with clay and made into a ball) is used as bait and placed in a trap. The trap is usually left in the water for about 6 hours.
A skilled fisherman can operate up to 100 traps per day. In one trap up to 5 prawns can be caught.
1.5 Culture
There is practically no development yet in the field of prawn culture. Some work has been conducted in hatching Macrobrachium in aquaria in laboratory experiments where the results are still poor. There are no attempts yet to culture the giant prawn in ponds by rearing frys collected from natural resources.
COUNTRY REPORT OF INDONESIA1
1. INTRODUCTION
The economically important species of shrimps and prawns produced from marine, brackishwater as well as freshwater open water capture culture in Indonesia are as follows: Penaeus monodon, P. indicus, Metapenaeus sp., and giant freshwater prawn (Macrobrachium rosenbergii).
Shrimp and prawn production in Indonesia has been increasing since 1971. The production of 46 800 mt in 1977 has attained 129 000 mt in 1979 with an average increase of about 30% per year. Concomitant with the production increase, the export volume has been increasing as well, i.e. from 2 461 mt (valued at US$718 000) in 1968 to 30 000 mt (valued at US$155 600 000) in 1978.
In Indonesia, freshwater prawn (M. rosenbergii) has been captured since time immemorial. However, the prawn has been considered important only since 1971 when the export of frozen prawn was started.
The prawn are mostly collected from open water (rivers, swamps and lakes) in source areas such as: Aceh, North Sumatra, Riau, Jambi, South Sumatra, Lampung, southern part of West and Central Java and Kalimantan.
To collect the prawn, the fishermen usually use: bamboo traps with bait, bamboo screen or fence, cash net, hook and line, floats and skimming net and long line.
The prawn production in 1977 has reached 2 759 mt. In 1976, the total quantity of the prawn collected and processed for export from Sumatra, Java, Kalimantan and Sulawesi was about 1 697 mt.
Although shrimp and prawn production in Indonesia to a greater extent or more than 70 percent obtained by collecting from marine and other open waters the potential for culture is high. These are due to the acceptable and favorable climate, the availability of the fry/juveniles throughout the country, and presence of large potential areas for farming development. There are now ongoing some shrimp and prawn hatcheries and those innovations to the development of shrimp and prawn culture in Indonesia.
2. MACROBRACHIUM CULTIVATION IN INDONESIA
In Indonesia the production of giant freshwater prawn (Macrobrachium rosenbergii) by way of culturing in ponds was not fully practiced until 1976.
Prior to the establishment of some government hatcheries in Java some fish farmers have been trying to cultivate the prawn in freshwater ponds by using juveniles which were collected from natural waters, although with unsatisfactory results due to some problems encountered.
To supply the fry or juveniles of prawn, seven hatcheries of Macrobrachium rosenbergii have been established in some areas, one in the Brackishwater Aquaculture Development Centre at Jepara (Central Java), one in sub-station of Inland Fisheries Research Institute at Pasar Minggu (Jakarta), two in East Java Province (at Prigi and Probolinggo), one in Central Java (Adiredja and Cilacap), one in West Java Province (Pangandaran) and one is small scale hatchery at the Freshwater Aquaculture Development Centre at Sukabumi (West Java).
In 1976 a plan was made by the Directorate General of Fisheries to cultivate the prawn in freshwater ponds covering a total area of 100 ha in 5 districts in Central Java. In the meantime, a limited number of fry/juveniles were supplied from the Brackishwater Aquaculture Development Centre, Jepara and were distributed through some freshwater hatcheries in Central Java.
Furthermore, since 1976 there were also established in some of the Provincial Fisheries Development Units test ponds for Macrobrachium culture such as in Riau, South Sumatra, Lampung, Kalimantan, West Java, Central Java, and East Java provinces by using juveniles produced from hatcheries or collected from natural waters. Prawn farming was conducted as monoculture or polyculture system mixed with certain species, like the silver carp (Hypophthalmichthes molitrix), Java carp (Puntius javanicus), and Osteochilus hasselti, with supplementary feeding.
Some problems which have been encountered with this prawn farming were reported, particularly from test ponds as well as private ponds in Java. These include among others problems associated with the lack of juvenile supply both quantitatively and qualitatively, pests, predators such as wild fish, water mouse or otter-like animal, high acidity of the soil and water, and lack of feed.
There are few Macrobrachium species in Malaysia which are indigenous in natural waters. They are found in the rivers, reservoirs, natural and artificial lakes, swamps, paddy fields and irrigation canals. Among the Macrobrachium species found in Malaysia, Macrobrachium rosenbergii is the most important when fishery and farming are concerned. The other species are too small and the taste is not good.
Macrobrachium rosenbergii is fished using gears such as cast nets, bamboo traps, etc. At present their population is declining rapidly. This is not due to the fishing activities, but due to dam construction, water pollution, etc. This pollution is due to following reasons:
Domestic waste discharge, etc.
This rapid decline in population has to be considered. We can not depend on their production only from the natural source. They are suitable for culture in freshwater ponds and there is high demand for it. So the farming of this particular species becomes necessary.
The government encourages fish farmers to grow them in ponds. They are given subsidy to construct the pond. The greatest problem for the farmers is to find the seed. To overcome this problem we have a hatchery to produce juveniles and juveniles are supplied free including the transport.
More ponds have been constructed and at present the demand of seed supply has increased rapidly. Our juvenile production is very much lower than the demand, although we also have a few commercial hatcheries. The farmers have to wait for a long time to get the supply. To overcome this problem more hatcheries have to be constructed. Now four government hatcheries and two big scale commercial hatcheries are under construction. Research also have been carried out to improve the production technique and minimize the production cost.
At present we are using only the green water technique developed in Hawaii and clear water technique is under experimentation. When all of these hatcheries are completed and successfully operated, we hope our seed problem can be settled or reduced and we will be able to extend the farming system to enhance the increased production of Macrobrachium.
1. INTRODUCTION
The following report is a country experience for submission by every participant from eight Asian countries to the Training in Food and Cash Crop Production for Countries in Asia and the Pacific: Prawn Farming Course held in Jepara, Indonesia from 5 October to 15 November 1980. Appropriately, the subject matter in this country experience report must deal with the participants' experience or any topic relevant to Macrobrachium hatchery/culture, this being the core of the aforecited training course.
Thus, this report from Philippine participants cover the status of Macrobrachium fishery and technical feasibility of potential areas proposed for fishpond.
2. STATUS OF MACROBRACHIUM FISHERY
The Philippines which is an archipelago of 7 100 islands is endowed with considerably numerous rivers, lakes, streams, creeks, swamps and estuaries which by common knowledge could be natural habitats of Macrobrachium because majority of Macrobrachium species are biologically known to inhabit freshwater and estuarine areas. This particular species has not as yet attracted the attention of fish farmers as much as they do for Penaeid shrimps, milkfish, carp, tilapia and other fish species. Except for the capture production from the wild made by subsistence rice/fish farmers, Macrobrachium would not be able to reach consumers. Because of this, the quantity is insignificant.
Very recently, however, when Macrobrachium hatchery/farming has successfully attained occupational status in few Asian countries like Thailand and Indonesia, other countries in Asia have been reminded to look once more into their freshwater resources towards developing and promoting Macrobrachium as a supplement to Penaeid shrimps in supplying animal protein for their populace. The Philippines, has started a few experiments on the cage culture of Macrobrachium rosenbergii in Laguna de Bay, the largest lake in the Philippines and which at certain times of the year is encroached by low saline water. These experiments are still ongoing.
What then is the prospect for Macrobrachium aquaculture production? Be it hatchery or pond farming, Macrobrachium has a bright prospect in the Philippines. As earlier mentioned, the Philippines is an archipelago. It being so, the Philippines has several potential areas for Macrobrachium hatchery. Likewise, potential freshwater areas for pond farming are vast. What seems to be absent at the outset is the appropriate technology and trained manpower to apply it. Obviously, therefore, for the Philippines, this training in Macrobrachium in Jepara is very important.
3. TECHNICAL FEASIBILITY OF POTENTIAL AREAS PROPOSED FOR FISHPOND
Potential fishpond areas in the Philippines are generally swampy, marshy or estuarine and unless located within private property are ports of public domain.
The government with the private sector as partner in the development of these public domain for aquaculture production has established a procedural system of granting fishpond lease agreements for these fishpond areas before any interested person/corporation can develop them. One of these procedures takes care of the following:
Suitability of site for fishpond purposes - water supply, soil, elevation, topography, watershed, flood, climatic conditions, fry or fingerling supply, supply of skilled labor, marketing (inputs and outputs).
Development program and cost-fishpond layout, construction materials, supplies and cost, duration of development, equipment.
Production programmes and cost - species, system of culture, number of croppings per year, projected production and value.
Managerial aspects - technical capability of applicant to undertake construction and management of proposed fishpond project, availability of skilled labor needed in the operation and maintenance of the proposed project, salaries and wages, sharing system, type of management.
Marketing aspects - accessibility to sources of inputs, market outlet(s) identified.
1. GENERAL INTRODUCTION
Sri Lanka is a continental island surrounded by the Indian Ocean. There are extensive back water bodies and also marshy low lying areas which could be easily converted into highly productive brackishwater areas suitable for culture of prawns and finfishes.
The finfishes and prawns contribute to a very high percentage of the protein content of our food, in Sri Lanka and it is also important as a foreign exchange earner. So far we had naturally occurring prawn resources from brackishwater areas and from inland freshwater bodies. During the past few years, it is suspected that we have reached our “maximum sustainable yield” and in the present prawn fishery has been subjected to “overexploitation.” This has resulted in a marked decline in the commercial catch. On the other hand the demand for the prawns have been consistently increasing in the local market as well as in the export market. To overcome this situation the necessity has become necessary to start intensive programmes to enhance the production of prawns.
2. THE DISTRIBUTION OF MACROBRACHIUM ROSENBERGII
The estuaries and lagoons can be divided into four major categories considering various environmental parameters such as sandbar formation at the river mouth, salinity distribution, water flow, turbidity, etc.
| Type | Environment | Distribution of M. rosenbergii |
| Estuaries with mouth open throughout the year | Fast moving, water flow high, salinity low throughout, turbidity high, completely mixed | Distribution evenly in lower reaches as well as in upper reaches |
| Estuaries with mouths which get cut off completely from a sandbar during dry weather period of the month | Slow moving, intermediate water flow, salinity low throughout, turbidity low in dry period, high during wet period | Relative abundance is poor. |
| Estuaries with a mouth which is cut off from the sea due to a sandbar throughout the year | Slow moving freshwater input low, salinity low, turbidity high during wet period, turbidity low during dry period | Relative abundance very low |
| Estuaries with artificially constructed groyne at the mouth to prevent complete closure of the mouth | Medium flow, high salinity during most part of the year, stratified, low turbidity | Limited mainly to upper reaches |
3. PRAWN FISHERY AND COMPOSITION OF CATCH
Prevailing prawn catches in Sri Lanka are from interior freshwater bodies.
As far as the freshwater prawn fishery is concerned, M. rosenbergii contributes more than 85 percent to the total freshwater prawn catch; M. malcomsonii contributes around 8 percent but there is no significant economical acceptability for this species.
4. SEASONAL OCCURRENCE OF PALAEMONIDE LARVAE IN PLANKTONS OF THE LOWER REACHES OF THE ESTUARIES AND ITS RELATION TO SOME HYDROBIOLOGICAL PARAMETERS
In Sri Lanka four seasons can be distinguished according to the prevailing wind systems.
| Season | Direction of wind |
| 1st inter monsoon | More frequency of calms |
| Southwest monsoon | Winds are with predominately westerly component |
| 2nd inter monsoon | More frequency of calms |
| Northeast monsoon | Winds are with predominately easterly components |
These monsoonal periods are closely associated with rains. Normally, inter monsoonal periods are of higher rainfall than the monsoonal seasons. Generally January, February and July, August months are drier. April, May, June and October, November months are relatively wet.
The relative abundance of the palaemonid larvae are high during the months of March, April, July, August and in October and November.
The above periods are characterized by having intermediate rainfall and intermediate salinity when compared to other periods of the year.
5. PRESENT STATUS OF THE MACROBRACHIUM ROSENBERGII FISHERY
It is apparent that there is a gradual decline in the M. rosenbergii catches in the commercial fishery during the last few years. This depletion may be due to following reasons:
The adverse effects of the irrigational bunds and flood protectional bunds. Irrigational bunds are to provide water for paddy cultivation. These gates are closed during dry weather period thus the recruitment of adult males and females to the lower brackish regions for breeding is prevented.
Land bar formation at the river mouth.
Destruction of gravid females.
Overexploitation due to the recent increase in fishery management units.
Non-selective fishing methods.
Destruction of breeding grounds by reclamation.
6. PROGRAMMES UNDER IMPLEMENTATION
Pond culture of P. monodon, P. indicus in brackishwater ponds. Monoculture and polyculture.
To evaluate the effect of urea, tobacco dust, organic fertilizer in pond culture on above species.
Pen culture of Chanos chanos with P. monodon or with M. rosenbergii.
1. MACROBRACHIUM SPECIES IN THAILAND
An investigation of the prawns of the family Palaemonidae which inhabit both estuarine and freshwater of Thailand had been made from 1976 to 1978. There are nine species found. Macrobrachium equidens, M. idae (Heller), M. sintangensis and Palaemon styliferus are estuarine residents, while M. esculentum, M. nipponeuse, M. lanchesteri and M. asperulum are freshwater. The last and the largest species M. rosenbergii inhabits both habitats.
2. HATCHERY PRODUCTION
Currently there are two government funded freshwater prawn hatcheries in Thailand. Post larvae are still produced in the far south at the Songkhla Fisheries Station, mainly for stocking in pens in the 616 750 rai (98 680 ha) brackishwater lake but also in ponds in the surrounding area. In addition to government hatcheries, the number of small or backyard hatcheries has grown to over 30 and there are currently also large commercial hatcheries.
The green water technique is used, however, some hatcheries previously using green water do not use anymore. A salinity of 12 ppt is sometimes reduced gradually before and after metamorphosis. This is done with water changes after the first ten larval rearing days varying from 10 to 50 percent daily, depending on the availability of water.
3. GROWING IN POND
Ponds are stocked at 5/m2 to 20/m2. The lower stocking density achieve a greater proportion of market size animals under the management system in use now. Post larvae are usually stocked within two weeks of metamorphosis. Management systems vary but typical, after six months ponds are seined to remove market size animals 10 to 15/kg.
Freshwater prawns are usually grown in earthen ponds where a variety of natural food are stimulated by fertilization, either directly or by feed stuff supplementation. Enquiries are received however as to the possibility of rearing Macrobrachium rosenbergii in concrete ponds. Pelleted diets with three protein levels (15% and 35%), derived from those formulated for a parallel experiment in commercial earthen ponds have been tested in concrete ponds at the government Institute.
Research workers found that growth, production, survival and feed conversion of prawns fed 15%, 25%, 35%, protein diets and broiler starter feeds were not significantly different (p < 0.05). The protein efficiency ratio of the prawns fed 15% protein diet was also not significantly different but appeared better than the other diets.
4. THE ECONOMICAL ANALYSIS OF POND
Culture was done by means of a case study approach. Four farm sizes of 0.48, 1.2, 2.4 and 12.48 ha were selected for the study. Data obtained from individual farm interviews and based on the 1979 production year are given. Analysis revealed that the farm size of 12.48 ha yielded the highest return.
In Vietnam there are three research centres on seawater and brackishwater, freshwater shrimps and prawns. These three centers belong to Ministry of Marine Products.
Research Institute of Marine Products, Haiphong City
Research Institute of Brackishwater and Freshwater Aquaculture, Haiphong City
Sub-Institute of Marine Products - Ho Chi Minh City. Formerly this Sub-Institute was the Freshwater Research Institute at Saigon (from 1973 to 1975)
The Research Institute of Marine Products in Haiphong conducts research on fishing and processing of marine products. In the fishing function, the Institute takes up studies on the biology and reproduction of species of shrimps that are important in the Tonkin Gulf. These include:
P. merguiensis
P. indicus
P. orientalis
P. monodon
P. semisulcatus
P. penicillatus
Metapenaeus affinis
M. ensis
M. intermedius
M. joynesy (venus)
In the Research Institute of Brackishwater and Freshwater Aquaculture, Haiphong City the principal functions are studies on the aquaculturing of seaweed (Gracilaria verucosa) algae, pearl-oyster, Ostrea (Mytilus sp.) and culture brackishwater shrimps, Penaeus merguiensis and P. semilcatus. The Institute was just founded in the beginning of 1975.
The Sub-Committee of Marine Products in Ho Chi Minh City was founded in 1977 which function was to study the culture of brackishwater shrimps. At present, the Sub-Institute only conducts research on the hatchery and culture of freshwater fish, and from mid-1978 the Sub-Institute has begun the culture of brackishwater shrimps: Penaeus indicus and P. merguiensis and Metapenaeus brevicornis and M. ensis in the ponds of fishermen which culture shrimps with an area of about 100 hectares. We only used stock of fry from natural sources with the incoming tide. This work is progressing well. The production of shrimps in 1979 was about 350 to 400 kg/ha/year; this work need to be continued.
And now about Macrobrachium rosenbergii, it is available in South Vietnam. Moreover, also available are M. acanthurus, M. carcinus, and M. lanchestere.
Weather condition in South Vietnam is very good for aquaculture of M. rosenbergii. So in 1974, UN external assistance helped to build a station for research and to produce fry of M. rosenbergii (prawn) and P. indicus (shrimp) in the Vung Tau City. But during years of conflict, that work was stopped. Presently, installations left includes two wells: one well of freshwater and one of seawater. In 1978, there was an attempt to revive the hatchery work through a short time consultancy of three months. This was very short and when the consultant left, the work was stopped.
