[Appendix M4]
1 PROPOSAL CONTENT AND EVALUATION CRITERIA
Importance and Significance of the Work
This proposal is one of eight research plans comprising the initial research programme of the Brackishwater Station (BS) of the Fisheries Research Institute (FRI). These proposals have been prepared within the overall framework of the original Five Year Research Plan envisaged for the BS, but additionally take into account the present lack of experimental and laboratory facilities due to the delay in acquiring the selected site in Paikgacha. The proposed work should be conducted in the field using existing FRI staff who have already been assigned to the BS plus additional staff specifically recruited for the BS.
Since some access to laboratory facilities will be necessary, it is recommended that, until such time that construction of the BS is completed and it becomes fully operational, project staff will be based at the FRI headquarters at Mymensingh under the supervision of the CSO appointed for the BS.
The proposed three year study on the limnology of brackishwater ponds to determine the impact of salinity changes on the availability of nutrients and dissolved oxygen during the culture season should commence as soon as the necessary project staff are available.
Fisheries production in Bangladesh is extremely important to the economy. Although the capture and culture fisheries contribute about 2.9 % of the GDP and 9 % of foreign exchange earnings, fisheries products account for 6 % of the total per capita protein intake and about 80 % of the per capita animal protein intake. The estimated total fisheries production in Bangladesh during 1983–84 was 751,000 t. The production from inland waters was about 577,000 t (77 %), of which 118,400 (21 %) was contributed by aquaculture. In recent years fisheries production has declined from about 822,000 t in 1974–75, whilst daily per capita fish consumption has fallen from 33 g in 1963–64 to 21 g in 1983–84 (a decrease of 36 %).
Even if per capita fish consumption is to be maintained at the current level, fisheries production will need to be increased to 1,100,000 t by the year 2005 in order to keep pace with the projected population growth. If daily per capita fish consumption is to reach 38 g (recommended by the Institute of Nutrition and Food Science) then production will have to be increased to 1,900,000 t. This reperesents an increase of about 150 % above present fisheries production levels. The Government of Bangladesh has therefore introduced an ambitious fisheries development programme in the Third Five Year Plan, to increase production from both inland and saline waters for both domestic consumption and for export (Rahman, 1986; Anon, 1985d).
The Brackishwater Station (BS) is being established by the Fisheries Research Institute to conduct research into the cultivation of brackishwater species to help meet both domestic and export requirements (Anon, 1986e, 1986g, 1987a, 1987b, 1987c; Karim, 1986a; Farmer, 1988; Muir, 1989). At the present time brackishwater aquaculture is virtually limited to shrimps of the genera Macrobrachium and Penaeus. Penaeid shrimps (mostly Penaeus monodon) currently provide an increasing source of foreign currency through exports to the USA, Europe and particularly Japan.
Brackishwater aquaculture production for local consumption is minimal. Smaller, commercially less important penaeid shrimps (Metapenaeus brevicornis and Metapenaeus monoceros) and some Macrobrachium rosenbergii are consumed locally. Small quantities of mullet (Mugil spp) are also produced as a by-product or secondary crop in some shrimp ponds.
Shrimp culture in Bangladesh started to develop in the early 1970s. At that time there was little local demand and the price of shrimp was consequently very low. The potential of farmed shrimp as a hard currency earner was quickly realised by the private sector, and within 10 years more than 26,000 ha of shrimp ponds were under cultivation. During this period the shrimp farming industry received little or no support from the Bangladesh Government. Only since 1980 with the introduction of the Second Five Year Plan (1980–85) has brackishwater aquaculture been given official recognition by the Government.
The Directorate of Fisheries has estimated that by the beginning of 1986 more than 115,000 ha had been turned over to shrimp farming activities in the whole of Bangladesh. Shrimp farming takes place in the districts of Satkhira, Khulna, Bagerhat, Barisal, Patuakhali, Bhola, Chittagong and Cox's Bazar. The two most important areas lie in the Khulna-Satkhira area to the north of the Sundarbans (ca 90,000 ha) and in the vicinity of Cox's Bazar (ca 24,000 ha). According to the Third Five Year Plan (1985–90) shrimp production is expected to increase from 9,000 t in 1984–85 to 34,000 t by 1989–90.
Market Demand and Economic importance
The local demand for fish is likely to approach 1.9 million t yr-1 by the year 2005. Some of this demand will have to be met by increasing the production from existing inland waters through the introduction of improved husbandry and water management practices, however, other sources of fish will need to be sought. Bangladesh has about 2,500,000 ha of coastal tidal lands, of which about 2,167,000 ha may be be suitable for aquaculture. There is therefore an enormous potential for increasing fish production through brackishwater aquaculture. So far these coastal tidal lands contribute very little to the domestic consumption of fish, although they are already an important and increasing source of foreign exchange through farmed shrimp exports.
The local demand for farmed shrimp in Bangladesh is poor since very few Bangladeshis eat shellfish. However, the international market is extremely important and a major source of hard currency for Bangladesh. It has been projected that the export value of shrimp will have increased from about US$ 57 million in 1984–85 to around US$ 225 million in 1989–90. Most of the shrimp produced in Bangladesh is exported to Japan. Recent export prices for shrimp shipped to Japan are shown in Table 1.
Less emphasis has been placed on the freshwater shrimp market by shrimp processing and exporting companies. This may be a reflection of the preference for marine shrimp in Japan, which is currently the main market for Bangladeshi shrimps. There are increasing market opportunities for both freshwater and brackishwater shrimp in Europe, whilst the US market can still absorb additional imports of high quality brackishwater species (Rackowe et al, 1983).
Table 1. Shrimp export prices (C & F Tokyo) January 1989.
| International market size (tails lb-1) | Equivalent harvest size (whole shrimp kg-1) | Price (US$ kg-1) |
| 4–6 | 10 | 24.23 |
| 6–8 | 12 | 24.23 |
| 8–12 | 15 | 23.61 |
| 13–15 | 20 | 17.16 |
| 16–20 | 27 | 13.21 |
| 21–25 | 35 | 11.54 |
| 26–30 | 45 | 10.30 |
| 31–40 | 53 | 8.53 |
| 41–50 | 65 | 7.02 |
| 51–60 | 80 | 5.98 |
| 61–70 | 95 | 4.78 |
| 71–90 | 115 | 4.16 |
Most shrimp farms in Bangladesh are operated on a very extensive basis, relying on natural productivity and little or no management. Current production levels generally lie within the range of <50 kg ha-1 yr-1 to >300 kg ha-1 yr-1, although the majority of shrimp farms are operating towards the lower end of the scale. A few enterprising farmers are claiming production levels of 900 kg ha-1 yr-1 or more.
In the long term there is enormous potential to increase the total production of shrimp in Bangladesh. This can be achieved in two ways: first by encouraging the introduction of more intensive shrimp farming methods whereby average production could be increased to >600 kg ha-1 yr-1 (Table 2), and secondly by developing freshwater shrimp farming which has the potential of being even more important economically than brackishwater shrimp farming.
Much of the area currently used for brackishwater shrimp production in the vicinity of Khulna and Satkhira, could be utilised for the production of both brackishwater shrimp during the dry season and freshwater shrimp during the rainy season. The latest estimate (1986) of the area under shrimp production is 115,000. This leaves enormous potential for increasing not only brackishwater and freshwater shrimp production for export, but also brackishwater fish production for local consumption.
It is, however, essential that the importance of the Sundarbans to both the capture and culture fisheries is fully appreciated and that these forests are should not be cleared for the construction of fish and shrimp ponds. This issue if the subject of another closely related research proposal that has been prepared for the BS:
Impact of Aquaculture on the Mangrove Environment: code no O-04.
Table 2. Characteristics of different levels of intensification of brackishwater shrimp farming. [In practice, the distinction between categories is artificial. A continuum exists between the lowest and highest levels of production.]
| Parameter | Extensive | Semi-intensive | Intensive |
| Feed | natural only | natural plus supplementary feed | formulated feed (complete diet) |
| Water supply | tidal | tidal or pumped | pumped |
| Aeration | none | none | paddles or blowers |
| Stocking density (ha-1) | 1,000–10,000 | 10,000–50,000 | 50,000–200,000 |
| Tambak area (ha) | 2.0–15.0 | 1.0–4.0 | 0.1–1.0 |
| Yield (kg ha-1 yr-1) | 100–500 | 600–4,000 | 5,000–15,000 |
| Unit cost (US$ ha-1)* | 1,000–2,000 | 3,000–5,000 | 8,000–12,000 |
| Gross income (US$ ha-1) | 1,000–5,000 | 6,000–40,000 | 50,000–150,000 |
* Approximate construction cost for a bare site.
Brackishwater aquaculture has become increasingly important throughout the tropics and sub-tropics, especially in the cultivation of penaeid shrimp for export to Japan, North America and Europe. Both brackishwater and freshwater shrimp farming are still major growth industries in many parts of Asia, Africa and Latin America (Rackowe et al, 1983) and represents an extremely valuable element in the economy of many developing countries as a major source of foreign exchange.
Penaeid shrimps are found thoughout the tropics and sub-tropics in coastal and estuarine waters. The life cycle of most penaeid shrimps follows the same general pattern. The adults spawn off shore and each female can produce up to 500,000 eggs. The minute eggs hatch very quickly after being released directly into the water. The planktonic larvae pass through a number of distinct stages (up to six naulius stages, three protozoea stages and three mysis stages) before metamorphosis. The late larval stages and postlarvae migrate towards the coast seeking less saline conditions in estuarine and mangrove areas before settling on the bottom. The post larvae grow rapidly as a result of the enormous biological productivity in these coastal ecosystems.
After spending one to two months living in these rich nursery grounds the young shrimps gradually migrate away from the coast where they eventually mature and spawn to complete the life cycle. Widespread destruction of coastal mangroves throughout the tropics and sub-tropics has led to substantial decreases in the landings of shrimp fisheries in affected areas, and shortages of shrimp fry for stocking shrimp farms.
Freshwater shrimps (Macrobrachium spp) are found throughout the tropics and sub-tropics in most inland freshwater areas including lakes, rivers, swamps, irrigation ditches, canals and ponds, as well as in estuarine areas. Most species require brackishwater during the initial stages of their life cycle, although a few species are able to complete their life cycle in inland saline and freshwater lakes. Some species prefer clear riverine conditions, whilst others (including Macrobrachium rosenbergii) are found in extremely turbid conditions.
Most Macrobrachium spp display a reversal of the migration pattern common to most penaeid shrimp. As the adult shrimps reach sexual maturity they migrate downstream into more saline conditions (≤12 ‰). As is the case amongst all the Palaemonidae the eggs are carried on the pleopods unlike penaeid shrimps. Macrobrachium spp normally produce only 5,000–100,000 eggs. The eggs hatch under brackishwater conditions and the larvae take several weeks to pass through 8–11 distinct larval stages before completing their metamorphosis.
The postlarvae begin to migrate upstream into freshwater conditions one to two weeks after metamorphosis and are soon able to swim and crawl against rapidly flowing currents. They are able to climb vertical surfaces and cross land provided that there is abundant moisture available (New & Singholka, 1985).
Water quality management of shrimp ponds is vitally important for two basic but related reasons. First it provides the means and the opportunity for farmers to maintain optimum environmental conditions within their ponds, so that the growth and survival of shrimp can be maximised (Spotte, 1979; Muir & Roberts, 1982; Sakaranarayanan et al, 1982). Secondly, the maintenance of good water quality will eliminate most of the disease and disease-related problems which are likely to be encountered by shrimp farmers (Wedemeyer et al, 1976; Tareen & Farmer, 1983). Sound pond design can also make an important contribution to the maintenance of water quality (Cruz, 1983).
Probably the two most important water quality parameters which need to be taken into account are the levels of dissolved oxygen and ammonia. The solubility of oxygen in water is related to water temperature and salinity. As both water temperature and salinity increase, so the solubility of oxygen in water is reduced. This relationship is summarised in section 6 ANNEXE (Table 6). Most active aquatic organisms (including shrimp) require dissolved oxygen saturation levels of not less than 75%. Within the range of temperatures likely to be encountered in brackishwater shrimp ponds in the tropics, this is equivalent to a dissolved oxygen concentration of about 4 mg 1-1. Reduced oxygen levels lead to depressed growth rates, increased risk of disease and eventually total mortality.
Dissolved oxygen concentrations can be controlled through increased water exchange and in the case of highly intensive systems, aration provided by paddles or air blowers. The stocking density and size of the shrimps will have a direct effect on dissolved oxygen levels through increased oxygen consumption (Rajayalakshmi et al, 1981; Madenjian et al, 1987).
Nitrogen in the form of nitrates, nitrites and urea can make an important contribution to the productivity of shrimp ponds. These nutrients are utilised by phytoplankton, benthic algae and higher plants growing within and around the periphery of shrimp ponds. Nitrogen may be deliberately provided by the shrimp farmer in the form of (animal dung and agricultural urea), but usually is the result of excretion by the shrimps and through the activities of nitrifying bacteria. Excreted nitrate and nitrite normally cause no problem since the levels are usually well below the tolerance of the species being cultured, however, ammonia is extremely toxic especially in conditions of high pH.
Ammonia dissolved in water is present both as dissociated ammonium ions and free undissociated ammonia. The dissociation relationship is provided in section 6 ANNEXE (Table 7). Free ammonia is many times more toxic to aquatic organisms than ammonium ions, and since most aquaculture species require neutral or alkaline water, there is always a risk that high ammonia levels can occur. The effect of nitrogen levels and ammonia in particular has been the subject of intense research (Gerhardt, 1980; Mevel & Chambroux, 1981; Moriarty, 1986; Rajamani, 1982; Sohier & Bianchi, 1983; Spotte; 1979; Wedemeyer et al, 1976).
Plankton blooms in shrimp ponds, particularly of blue-green algae (Cyanophyseae) and dynoflagellates (Dynophyceae) can also have a serious effect on shrimps (Avault, 1979; Lightner, 1982).
Acid sulphate soils caused by the oxidation of pyrite horizons exposed during the construction of ponds and water channels can have a drastic effect on water quality, although methods for eliminating or at least mitigating this problem have been developed (Brinkman & Singh, 1982; Simpson & Pedini, 1985; Yunker & Scura, 1985).
In view of the enormous potential for the development of both freshwater and brackishwater shrimp farming in Bangladesh, it is very important that basic scientific data on both freshwater and brackishwater shrimp should be obtained in order to exploit the full potential of these resources.
Current Status of Shrimp Culture in Bangladesh
As has already been described, there is currently very little brackishwater aquaculture in Bangladesh in relation to the potential for future development. Virtually all brackishwater production at the present time is directed towards the farming of brackishwater penaeid shrimp.
Most shrimp farming has developed within polders created by the Bangladesh Water Development Board (BWDB) in low-lying coastal flood plains. These activities have been started without the consent of the BWDB, and one of the major concerns has been the creation of unauthorised sluice gates or channels through the perimeter dykes of the polders. Only those areas that are low enough to permit inundation of the land by at least 0.5 m of water at spring tides have generally been used for shrimp farming.
Only two species are deliberately stocked in ponds: Penaeus monodon and Macrobrachium rosenbergii. Of these P monodon is by far the more important. Other species of penaeid shrimps are also cultivated, through the accidental introduction of their fry when the ponds are filled or water exchange takes place. These include: Penaeus indicus, Penaeus merguiensis, Metapenaeus monoceros and Metapenaeus brevicornis.
Shrimp farming in Bangladesh relies entirely on the supply of wild fry for stocking purposes. It has been estimated that 1–3 billion fry of P monodon were harvested in 1985. The main collection centres are Satkhira, Khulna, Bagerhat and Cox's Bazar. At present, most fry collection for P monodon is conducted within the rivers and creeks of the coastal flood plain. It has been suggested that there may be a huge unexploited resource within the Sundarbans.
Collection of shrimp fry is carried out using either a fixed bagnet (behundi jal) which relies on tidal streams in small rivers and creeks to carry postlarval shrimp into the codend, or alternatively triangular (or less frequently rectangular) nets which are pushed or pulled along the bed of the river or creek. In Cox's Bazar shrimp fry collection is also carried out along the beach. In the Khulna-Satkhira area the peak season for shrimp fry is February-May, whilst at Cox's Bazar it is April-June.
Shrimp fry collectors transfer their catches to earthenware bowls which are then carried back to the villages where the fry are sorted and counted by children using white enamelled plates. This undoubtedly results in a very large wastage of fry of both penaeid shrimps and other commercially important species including fish. The shrimp fry then pass through a chain of middlemen before reaching the shrimp farmers, during which the fry are usually transported in 20–30 1 aluminium vessels using every conceivable form of transport. Shrimp fry mortality is believed to be very high, due to extreme water temperature and salinity fluctuations, low dissolved oxygen levels, and even the use of table salt in the mistaken belief that this will provide the correct salinity for the fry.
The price of P monodon fry in the Khulna-Satkhira area has risen dramatically from about Tk 40–50 in 1980 to Tk 400–600 per thousand (postlarvae of ca 15 mm total length) in 1988. The price of shrimp fry is much lower in the vicinity of Cox's Bazar being only Tk 40–100 per thousand for fry of a similar size.
Macrobrachium fry (postlarvae and juveniles) are collected in the Khulna region for stocking freshwater or low salinity brackishwater shrimp farms. There are no estimates available on the number of fry collected annually. Fry are available in the Khulna area from April onwards with the peak demand occurring in July. The price of Macrobrachium fry in the Satkhira area in 1986 was Tk 500–1,000 per thousand (25–50 mm total length), although at Paikgacha prices were only half this figure. Hatchery reared Macrobrachium fry produced in Cox's Bazar were being sold in 1988 for Tk 440 per thousand (15–20 mm total length).
In the Khulna-Satkhira area the shrimp farming pattern, often in rotation with agriculture, reflects the ambient seasonal salinity fluctuations in response to the monsoon:
January-July [high salinity season]:
August-December [low salinity season]:
In the Cox's Bazar area this pattern may be reversed due to the generally higher ambient salinities. Therefore some farmers produce salt during the the dry season and brackishwater shrimp during the rainy season.
Most of the shrimp farming is carried out within larged dyked areas (polders or ghers). Transplanted aman rice can be grown from August-December, when water and soil salinities are low. Agricultural crop production from January to July is difficult due to the shortage of freshwater and increased salinities in the soil. Acid sulphate soils may also present special problems in some areas.
Before the recent and rapid growth of shrimp farming, the land used to be left fallow during the dry season and used instead for grazing cattle and water buffalo. Animal dung remaining on the land, if not collected for fuel, would help to increase the production of aman rice in the following rainy season. The loss of grazing has resulted in very serious conflicts in land use in some areas.
Until recently all shrimp farmers, either individually or in groups, have leased land within BWDB polders. In some cases the land has been seized from the rightful leaseholders by force. The BWDB perimeter dykes are deliberately breached and wooden sluice gates or reinforced concrete culverts installed before repairing the dykes. The ponds, which may extend up to 500 acres (200 ha) or more, are usually allowed to remain dry during January after havesting the rice. The stubble is left in place. The ponds are then flooded during spring tides.
Since the early 1980s the Government of Bangladesh has played an active rôle in improving the level of shrimp farming husbandry and technology. Screens to prevent the entry of predators and competitors have become much more widespread, in combination with the selective stocking of fry. Simple nursery production methods have been introduced in some cases through the construction of a shallow nursery pond within the confines of each growout pond. Pond preparation, liming, fertilisation, pest control, nursery production, supplementary feeding and water management have only started to be introduced during the last five years, and even now are employed in only a few areas.
Recently P monodon production has been increased by the more enterprising farmers from <50 kg ha-1 yr-1 to >300 kg ha-1 yr-1. In the case of the Allah-Wala shrimp farm at Cox's Bazar, production of up to 900 kg ha-1 yr-1 was claimed during 1988.
There are plenty of signs that shrimp production levels in Bangladesh will continue to rise as a result of the gradual introduction of more intensive practices. At the present time, however, most farms are operated on an extensive basis, with relatively few examples of semi-intensive production.
A major constraint to the future growth of both freshwater and brackishwater shrimp farming in Bangladesh is likely to be the current lack of awareness and expertise in basic animal husbandry and water quality management. Insufficient attention is currently being paid to the needs of the shrimp, especially in terms of pond and water quality management. As yet no thorough studies have been made of the limnology of shrimp ponds in order to determine the shortcoimings of current management practices and how these might be improved in order to increase production yields.
Previous Research in Bangladesh
Some research on the development of brackishwater shrimp cultivation has already been completed at Chittagong University (sponsored by BARC) and the Directorate of Fisheries.
Chittagong University:
Directorate of Fisheries:
Shrimp culture demonstration project at Satkhira: demonstration of improved culture techniques; provision of practical training for fishery officers, identification of the socio-economic support required to assist small scale shrimp farmers. [FAO/BOBP.]
The first of the public sector shrimp farming activities in Bangladesh was the Bay of Bengal Programme (BOBP) shrimp farm at Satkhira. This semi-intensive demonstration and research unit has recently been taken over by the Gramin Bank and is now known as the Satkhira Shrimp Farm.
Very little by way of practical research results is available from these various projects.
Present Status of Research in Bangladesh
Research on shrimp culture is currently being undertaken or alternatively being planned by the Fisheries Research Institute, the Directorate of Fisheries and Chittagong University. In most cases this work has only started recently and few research results are available. Some of this work is sponsored by BARC, whilst the rest is supported by ADB, FAO/UNDP and the World Bank. The various projects are summarised below:
Fisheries Research Institute:
Establishment of the Brackishwater Station (formerly designated the Brackishwater Fisheries Research Station) at Paikgacha. Part of the World Bank Second Agricultural Research Project. [WB/FAO/UNDP.]
Directorate of Fisheries:
Chittagong University:
Studies on growth and quality of shrimp and mullet with supplementary feeds (1986 onwards).
The largest of the Government shrimp farming projects is the IDA Shrimp Culture Project which is being adminstered by the Directorate of Fisheries. The Project comprises two parts: one near Khulna and another south of Cox's Bazar. The budget for the entire project is 117 crore Taka (US$ 36.5 million). The six year Project (1985/86 to 1990/91) involves the development of 3,500 acres (1,405 ha) of shrimp-cum-paddy farming in the Khulna area, most of which will be leased to individual farmers as 10 acre (4 ha) ponds. This part of the Project will also operate a demonstration farm and a hatchery, and provide an extension service for the leaseholders and other local farmers.
The second part of the IDA Shrimp Culture Project based at Cox's Bazar will comprise a penaeid shrimp hatchery and 5,000 acres (2,000 ha) of shrimp ponds at Rampura within an existing polder with a perimeter of 39 miles (62 km). Single 10 acre (4 ha) ponds will be leased to individual shrimp farmers. A further 12,000 acres (4,900 ha) have been earmarked for subsequent development by the private sector. In the long term it is planned to establish a total of nine private hatcheries. A 22 acre (9 ha) demonstration farm and training centre will be built soon on a site already selected at Teknaf.
The ADB shrimp farming project at Rampura, also near Cox's Bazar, comprises a 50 acre (20 ha) demonstration shrimp farm for penaeid shrimps and a further 1,715 acres (700 ha) for private farmers. The concept is the same as for the IDA project in that single 11 acre (4 ha) ponds will be leased to 115 individual shrimp farmers. The demonstration farm comprises 13 growout ponds of 13.4 ha each and four smaller nursery ponds.
As soon as the Brackishwater Station of the Fisheries Research Institute has been constructed and becomes fully operational, the FRI will play an increasingly important national rôle in the development of the shrimp farming industry.
The overall purpose of this research project is to correlate the changes in salinity in both shrimp ponds over an entire culture season, with nutrient availability, dissolved oxygen concentration, and shrimp production yield. The project will include the monitoring of selected freshwater and brackishwater shrimp ponds in the general Khulna-Satkhira area north of the Sundarbans and in the vicinity of Cox's Bazar.
Selection of Sites
Objective: To select a number of brackishwater and freshwater shrimp ponds for subsequent monitoring, which represent the full range of current management practices in Bangladesh from the most extensive to the most intensive.
Routine Water Sampling
Objective: To determine the major water quality characteristics of both freshwater and brackishwater shrimp ponds during a complete culture season in relation to nutrient availability, dissolved oxygen concentration, and shrimp production yield.
Soil Sampling
Objective: To determine the physical characteristics of the soil in the bottom of both freshwater and brackishwater shrimp ponds in terms of nutrient availability, both before and after each culture season.
Report Preparation
Objective: To prepare a final report consisting of a description of the work undertaken during the course of the project, the methodology, the results, their subsequent analysis and interpretation, and the formulation of effective water management practices to maximise the production of shrimp.
Project Management
Objective: To provide overall technical and administrative control of the research project, co-ordination with other projects, other sections of FRI and other Government agencies, and the preparation of concise quarterly progress reports covering both research and administrative issues.
This project has been designed to provide basic data for the future research programme of the BS once the laboratory and experimental facilities are fully operational. The information collected by the project will provide an important data base for the future development of the shrimp farming industry in Bangladesh.
During the first four months the proposed project will be involved in the selection of a number of representative brackishwater and freshwater shrimp ponds for subsequent monitoring over two complete culture seasons. The management practices used in the various ponds will be recorded carefully and the water quality measured on a daily basis. In addition soil samples will be taken from each pond both before and after each culture season for chemical and physical analysis.
Water temperature, salinity, dissolved oxygen concentration, nutrient levels (NO3-, NO2, NH+4, PO43) and pH will be measured on a daily basis in order to determine the relationship between water management practices and the availability of nutrients and dissolved oxygen concentration in response to salinity changes during the culture season.
After a period or 24 months, during which two complete culture seasons will be monitired in both freshwater and brackishwater ponds, in the Khulna-Satkhira and Cox's Bazar areas the data will be analysed and interpreted, in order to formulate effective water management practices to maximise the production of shrimp.
The implementation of this project will additionally provide an excellent opportunity for research and technical staff recruited for the BS to gain useful field experience in survey and research activities prior to the BS becoming fully operational. This should make the process of commissioning the BS and implementing the full research programme a much easier task for the appointed CSO. The project can also be used to provide ad hoc training for technical and support staff during its three years' duration.
The scheduling of the major project activities or tasks is summarised in Table 3. Ideally the project should be timed to coincide with the shrimp production seasons at Cox's Bazar and in the Khulna-Satkhira area. The approximate seasons are as follows:
Khulna-Satkhira Area:
Brackishwater season - January to July
Freshwater season - August to December
Cox's Bazar Area:
Fully saline season - January to July
Brackishwater season - August to December
Table 3. Activity chart (time scale: units of 2 months).
| Activity Months | ||||||||||||||||||
| 02 | 04 | 06 | 08 | 10 | 12 | 14 | 16 | 18 | 20 | 22 | 24 | 26 | 28 | 30 | 32 | 34 | 36 | |
| Year 1 | Year 2 | Year 3 | ||||||||||||||||
| TASKS - | ||||||||||||||||||
| Work plan preparation | - | |||||||||||||||||
| Literature survey | -- | |||||||||||||||||
| Selection of sites | - | -- | - | |||||||||||||||
| Pond management records# | - | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | - | |||||
| Routine water sampling# | - | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | - | |||||
| Soil sampling# | - | - | - | |||||||||||||||
| Analysis | -- | - | -- | |||||||||||||||
| Report preparation | - | - | - | - | - | - | - | - | - | - | -- | -- | ||||||
| DELIVERABLES- | ||||||||||||||||||
| Work plan | * | |||||||||||||||||
| Quarterly reports | * | * | * | * | * | * | * | * | * | * | * | |||||||
| Final report | * | |||||||||||||||||
- Project activity/task.
* Reporting date.
# Timing may require adjustment according to the shrimp culture seasons.
The methodology and procedures to be utilised in this project have been kept as simple as possible in order to permit the completion of the project without the need for the specialised facilities which will eventually becaome available at the BS. There will, however, be some need for laboratory work and it is proposed that this should be undertaken at the FRI Freshwater Station's laboratories at Mymensingh. Since some of the field work will be undertaken in the Cox's Bazar area, it is recommended that the FRI Marine Station at Cox's Bazar should be utilised for the laboratory analysis of water samples from the ponds being monitored in that area.
The project will investigate the relationship between nutrient availability and dissolved oxygen concentration in response to seasonal salinity changes and their effect on shrimp production yields.
At the start of the project the principal investigator should translate the project proposal into a written and detailed work plan which should be approved by the CSO of the BS before the research investigations get underway. This work plan should define the following elements: project objectives; detailed methodology; equipment and consumable requirements; logistic support requirements; areas requiring co-operation or co-ordination with other projects or sections of FRI; staff assignment and manpower requirements, and reporting deadlines. A period of one month has been allowed for the preparation of the work plan.
Before commencing the field work components of the project, a thorough review of the literature should be made. The bibliography appended to this proposal not only includes references for those citations incorporated in the text, but also recommendations for background reading. The FRI Library and Documentation Centre should obtain as many as possible of these references before that start of the project. These should be reviewed and digested by the principal investigator and his scientific staff at the beginning of the project. A period of two months has been allowed for the completion of this task.
A minimum of 14 ponds should be selected for detailed limnological investigation throughout a period of two complete culture seasons. The ponds should be chosen to provide the following combination:
At Cox's Bazar two of the ponds selected should be currently operated semi-intensively (eg Allah-Wala Ltd and Beximco), two should be operated very extensively, whilst the remaining two should fall somewhere between the other two pairs. At present there are no truly semi-intensive shrimp farming operations in the Khulna-Satkhira area. Therefore one pair of ponds should be selected at the lowest level of intensification, whilst the second pair should represent the highest level currently being practised. This arrangement should be duplicated for both freshwater and brackishwater shrimps in the Khulna-Satkhira area.
It is essential that the ponds are selected carefully, since the routine sampling will require to co-operation of the shrimp farmer over an extended period. It should not be necessary to provide any incentive for the shrimp farmers since they will in effect be receiving a very personal ‘extension service’ during the field investigations. The results and conclusions of the study should of course be communicated to them at the end of the research project. A period of four months has been allowed for the pond selection and for making all the necessary arrangements with the shrimp farmers concerned.
It will be necessary for the shrimp farmers co-operating in this project to keep very detailed records of their daily activities throughout the two culture seasons. It is recommended that pre-printed diaries are prepared for this purpose, so that the farmers get into the habit of recording all the relevant information on a regular basis. The minimum information required by the project will be:
Daily measurements of the most important water quality parameters will be taken in each of the ponds throughout two complete culture seasons. Nutrient availability will be measured by monitoring nitrogen (nitrate, nitrite and ammonia) and phorphorus (phosphate) levels in the water. Potassium is not normally limiting, especially in brackish and saline waters. Measurements or water samples should be taken where possible half way between the surface and the bottom of the pond. The parameters to be measured will include:
In addition dissolved oxygen concentrations should be measured hourly throughout a period of not less than 24 hours at monthly intervals in each shrimp pond.
Depending on the size of each pond being monitored, several measurements for each parameter at different locations may need to be taken in order ensure that representative samples of the water quality in each pond have been measured.
Water temperature
Water temperatures should be measured by using a standard mercury thermometer capable of being read to 0.1 °C.
Salinity
Salinities should be measured using a temperature compensated salinity refractometer capable of being read to 1.0 ‰.
Dissolved Oxygen Concentration
Dissolved oxygen concentration should be measured using a portable oxygen meter capable of being read to 0.1 mg 1-1. The realtionship between the solubility of oxygen in water in realtion to temperature and salinity is provided in section 6 ANNEXE (Table 6).
pH
pH levels should be measured with a portable pH meter capable of being read to 0.1 pH unit.
Nitrogen
Nitrate, nitrite and ammonia levels should be measured to the nearest 0.1 mg 1-1 using a select ion/pH meter with separate NO3-, NO2-, and NH4+ electrodes, or a suitable spectrophotometer. When monitoring ammonia it is also necessary to measure the pH simultaneously in order to determine the relative dissociation of ammonium ions into free ammonia. Free ammonia is many times more toxic than ammonium ions. The dissociation relationship between ammonia and ammonium ions in response to temperature and pH is provided in section 6 ANNEXE (Table 7).
Phosphorus
Phosphorus (phosphate) levels should be measured to the nearest 0.1 mg 1-1 by titration or preferably by spectrophotometer.
Turbidity
Relative turbidity (light penetration) should be measured using a Secchi disc and the depth at which the disk disappears from sight recorded to the nearest whole centimetre. This will be used as a relative indicator of the density of the phytoplankton population in the ponds. Minimum water quality requirements for both brackishwater and freshwater tropic shrimp are provided in Table 4.
Table 4. Basic water quality requirements for tropical shrimp.
| Parameter | Acceptable limits |
| Water temperature | 25–30 °C |
| Light penetration (Secchi disk) | 25–35 cm |
| pH | 7.0–9.0 |
| Salinity (Penaeus monodon) | 15–25 ‰ |
(Macrobrachium rosenbergii) | ≤ 10–15 ‰ |
| Dissolved oxygen | > 75 % saturation |
| [> 4 mg 1-1] | |
| N - nitrate (NO3-) | < 200 mg 1-1 |
| N - nitrite (NO2-) | < 6.4 mg 1-1 |
| N - ammonia (free NH3) | < 0.1 mg 1-1 |
| P - phosphate (PO43-) | 0.1–1.0 mg 1-1 |
| Hydrogen sulphide (H2S) | < 0.1 mg 1-1 |
| Carbon dioxide (free CO2) | < 8 mg 1-1 |
| Alkalinity (MgCO3 & CaCO3) | 40–150 mg 1-1 |
| Cadmium (Cd) | < 1 μg 1-1 |
| Chromium (Cr) | ? < 5 μg 1-1 |
| Copper (Cu) | < 0.05 mg 1-1 |
| Lead (Pb) | ? < 2 μg 1-1 |
| Mercury (Hg) | < 1 μg 1-1 |
| Nickel (Ni) | ? < 5 μg 1-1 |
| Zinc (Zn) | ? < 0.05 mg 1-1 |
| Organochlorine pesticides* - | |
Aldrin | < 3 μg 1-1 |
DDT | < 1 μg 1-1 |
Endrin | < 4 μg 1-1 |
Lindane | < 10 μg 1-1 |
| Organophosphate pesticides# - | |
Diazinon | < 9 μg 1-1 |
Endosulfan | ? |
? Tentative value or value unknown.
* May originate from areas of high yield rice production.
# Used as pesticides in shrimp farms in some countries, although the practice should generally be discouraged.
In additional to those parameters which will be measured during the course of this project, others have been included in case it is decided to extend the scope of the project in a second phase. Details of analytical methods for water quality are available in Strickland and Parsons (1968) and Boyd (1979).
Soil samples from the bottom of each of the ponds should be taken down to a depth 60 cm for chemical and physical analysis. The parameters to be measured should include:
These measurements will provide information on the availability of nutrients in the soil in the bottom of the ponds, and on the suitability of the soil type for shrimp culture. Guidelines for minimum standards for soil quality in shrimp ponds are summarised in Table 5. Methods for soil analysis and the subsequent interpretation of the data are available in Russell (1973).
Statistical analysis and interpretation of the results should follow immediately after each season's measurements. The final period of analysis should be completed within two months and result in the formulation of pond and water quality management practices for introduction in Bangladesh.
Specialist Equipment Requirements
The following specialist equipment and supplies will be required:
Table 5. Minimum soil requirements for shrimp ponds.
| Parameter | Acceptable limit |
| Grain size - | |
Clay content | > 20 % |
Silt content | 5–20 % |
Sand content | < 10 % |
| Permeability | As close to zero as possible |
| Soil pH | 7–9 |
| Organic matter* | < 5 % |
| Pyrite content (FeS2) | Preferably not detectable |
| Minerals# - | |
N | > 0.2 % |
P | > 45 mg kg-1 |
K | > 0.5 g kg-1 |
Ca | > 1.2 g kg-1 |
Mg | > 0.6 g kg-1 |
* For the purpose of dyke construction.
# Soil fertility.
The project will require the following manpower:
| - | Principal investigator (team leader) | 1 |
| - | Shrimp biologist | 1 |
| - | Field/laboratory technicians* | 4 |
| - | Boat operator (Cox's Bazar) | 1 |
| - | Driver (Khulna-Satkhira) | 1 |
The budget estimates will be prepared by BS/FRI staff at a later stage.
The principal investigator (team leader) will be responsible for the day to day technical and administrative management of the project under the overall direction of the CSO of the BS. Until such time that the BS is fully operational, laboratory and administrative support will have to be provided by the FRI at Mymensingh, and to a lesser extent laboratory support will have to be provided by the MS at Cox's Bazar.
The assignment of individual work tasks and the timing of those tasks will be the responsibility of the principal investigator in collaboration with the CSOs of the BS and MS, and the principal investigators of other projects. Since the BS will not be operational for some time, the project will need to utilise laboratory facilities of the FS at Mymensingh. The success of the project will therefore be dependent in part on the degree of co-operation between BS, FS and MS scientific staff.
Efficient co-ordination between the CSOs of the BS, FS and MS will permit the shared use of facilities and equipment until such time that the BS becomes fully operational. Where project staff are not required on a continuous basis, they should be temporarily assigned to other projects in order to make the most effective use of their time. It may be possible to combine field sampling and other field work with related projects in order to use FRI and BS resources as efficiently as possible.
The principal investigator will be responsible for the initial planning of the field investigations, monitoring of the data collection and analysis, and in conjunction with the other members of the team, interpretation of the results and report preparation. The principal investigator should meet with his project team on a weekly basis to ensure schedules are being met and to resolve problems or other project-related issues.
Quarterly progress reports and a final project report should be prepared by the principal investigator with assistance from the other team members. The responsibility for the quality of the quarterly and final reports and their submission on time will be the responsibility of the principal investigator alone. It must, however, be recognised that administrative support to achieve this end will need to be provided by the FRI until such time that the BS is fully operational, after which it will become the responsibility of the CSO of the BS.
The CSO of the BS will also be responsible for reviewing the progress and final reports and making sure that the individual activities of the project have been completed properly and on time. Delays and other problems affecting the success of the project should be identified as early as possible so that corrective action can be taken.
[It should be noted that the bibliography contains not only those references cited in the text of this proposal, but also suggestions for additional background reading prior to the start of the project.]
Ali, M Liaquat, 1983. Shrimp farm survey in coastal area of Bangladesh, Dhaka. [Mimeographed.]
Anonymous, 1979. Draft final report, Annexe B. Proposed fisheries components for an agricultural credit project. Agricultural Credit Studies Project. Prepared by Nathan Associates, USA on behalf of the Bangladesh Bank, Dhaka.
Anonymous, 1984a. National Water Plan Project. Second interim report, vol VII - Fisheries. Master Plan organisation, Ministry of Water Development and Flood Control, Bangladesh. Prepared by Harza Engineering Co Int.
Anonymous, 1984b. Bangladesh coastal aquaculture project engineering study. Draft report, vol 1. Prepared by Development Consultancy Services Ltd and Engineering Consultancy Services Ltd, Dhaka on behalf of the World Bank.
Anonymous, 1985a. Delta Development Project: Bangladesh-Netherlands Joint Programme under the Bangladesh Water Development Board. Shrimp culture in the semi-saline zone of the delta. Technical report no 13, volume I, 60 pp. Arnhem and The Hague, The Netherlands.
Anonymous, 1985b. Delta Development Project: Bangladesh-Netherlands Joint Programme under the Bangladesh Water Development Board. Shrimp culture in the semi-saline zone of the delta. Technical report no 13, volume II, 102 pp. Arnhem and The Hague, The Netherlands.
Anonymous, 1985c. Report on tidal areas study. Draft report prepared by Development Consultancy Services Ltd and Engineering Consultancy Services & Associates Ltd, Dhaka on behalf of FAO.
Anonymous, 1985d. List of projects for the Third Five Year Plan. Planning Commission, Government of Bangladesh.
Anonymous, 1985e. Report on engineering study. Vol 1: Bangladesh coastal aquaculture project. Prepared by Development Consultancy Services Ltd and Engineering Consultancy Services Ltd, Dhaka on behalf of the World Bank.
Anonymous, 1985f. Twenty year fishery development plan for Bangladesh. Prepared by John C Marr & Associates on behalf of FAO/UNDP.
Anonymous, 1986a. Bangladesh Second Aquaculture Development Project. Preparation report. Prepared by Aquatic Farms Ltd, Hawaii, USA on behalf of the Government of Bangladesh and the Asian Development Bank.
Anonymous, 1986b. Draft feasibility report on package 1: Khulna Coastal Embankment Rehabilitation Project (TA no 665-BAN). Vol I. Prepared by Agricultural Development Corporation (ADC), Seoul, South Korea in association with Associated Consulting Engineers (Bangladesh) Ltd.
Anonymous, 1986c. Draft feasibility report on package 1: Khulna Coastal Embankment Rehabilitation Project (TA no 665-BAN). Vol III. Prepared by Agricultural Development Corporation (ADC), Seoul, South Korea in association with Associated Consulting Engineers (Bangladesh) Ltd.
Anonymous, 1986d. Socio-economic impact and constraints of shrimp farming in Bangladesh. Fisheries Research Institute - Bangladesh, project proposal no 4, 59 pp.
Anonymous, 1986e. Brackishwater Aquaculture Research Station (BARS): design - phase 1. Fisheries Research Institute - Bangladesh, FAO/UNDP TA Project BGD/83/010 report no 3, 22 pp.
Anonymous, 1986f. Research plans for nutrition and feed technology. Fisheries Research Institute - Bangladesh, FAO/UNDP TA Project BGD/83/010 report no 4, 146 pp.
Anonymous, 1986g. Research plans for the Brackishwater Fisheries Research Station (BFRS). Fisheries Research Institute - Bangladesh, FAO/UNDP TA Project BGD/83/010 report no 5, 24 pp.
Anonymous, 1987a. Fisheries Research Institute - Bangladesh. Five Year Masterplan: General research plan. FAO/UNDP TA Project BGD/83/010. Arnhem: Euroconsult BV, 149 pp.
Anonymous, 1987b. Brackishwater Fisheries Research Station (BFRS): design - phase 2. Fisheries Research Institute - Bangladesh, FAO/UNDP TA Project BGD/83/010 report no 13, 125 pp.
Anonymous, 1987c. Five Year Masterplan: Equipment and civil works (final version). Fisheries Research Institute - Bangladesh, FAO/UNDP TA Project BGD/83/010 report no 14, 26 pp.
Anonymous, 1987d. Advice on literature. Fisheries Research Institute - Bangladesh, FAO/UNDP TA Project BGD/83/010 report no 15, 50 pp.
Anonymous, 1988a. Government of the People's Republic of Bangladesh. Fisheries Research Institute (FRI): Revised project. Mymensingh: Fisheries Research Institute, 112 pp.
Anonymous, 1988b. Project of the Government of the People's Republic of Bangladesh. Integrated resource development of the Sundarbans reserved forest. UNDP project document, BGD/84/056/A/01/12, 27 pp plus annexes.
Anonymous, 1988c. Regional overview, status of facility and coastal aquaculture research proposals. Fisheries Research Institute - Bangladesh, FAO/UNDP TA Project BGD/83/010 report no 19, pag var.
Avault, J W, 1979. Macrobracium rosenbergii culture in Polynesia, pH control in experimental pond waters by phytoplankton limitation with an algicide. Proceedings of the World Mariculture Society, 10: 392–402.
Bangladesh Bureau of Statistics, 1986. 1986 Statistical Yearbook of Bangladesh. Dhaka: Ministry of Planning, 1048 pp.
Bangladesh Bureau of Statistics, 1985. Statistical Pocket Book of Bangladesh 1984–85. Dhaka: Ministry of Planning, 654 pp.
Boyd, C E, 1979. Water quality in warmwater fish ponds. Auburn (Alabama, USA): Auburn University, Agricultural Experiment Station.
Brinkman, R & V P Singh, 1982. Rapid reclamation of brackishwater fishponds in acid sulphate soils. Wageningen: Publication of the Institute for Land Reclamation and Improvement, no 31.
Chowdhury, A Q, 1986. Fishermen community and development of closed water fishery in Bangladesh. [Mimeographed.]
Cruz, C L dela, 1983. Fishpond Engineering: A Technical Manual for Small- and Medium-Scale Coastal Fish Farms in SE Asia. South China Sea Programme, SCS Manual no 5, 180 pp.
Euroconsult BV, 1985. Government of Bangladesh and FAO/UNDP. Second Agricultural Research Project - Fisheries Component. FAO/UNDP TA Project BGD/83/010. Technical assistance report no 1 (revised version). Arnhem: Euroconsult BV, 90 pp.
Funegaard, P, 1986. Shrimp seed - Any to sell? Come to Satkhira, Bangladesh. FAO Bay of Bengal News, no 22.
Gerhardt, H V, 1980. Nitrogen excretion by the juvenile prawn Penaeus indicus Milne Edwards at various temperatures. South African Journal of Science, 76 (1): 39–40.
Hora, S L & T V R Pillay, 1962. Handbook of Fish Culture in the Indo-Pacific Region. FAO Fisheries Technical Paper, (14): 204 pp.
Karim, M, 1986a. Site selection for the Brackishwater Fisheries Research Station (BFRS). Fisheries Research Institute - Bangladesh, FAO/UNDP TA Project BGD/83/010 report no 11, 44 pp.
Karim, M, 1986b. Integrated farming of shrimp, fish, paddy and goat at Satkhira. FAO Bay of Bengal report, Madras, India.
Karim, M, 1986c. Brackishwater shrimp culture demonstration in Bangladesh. SIDA/FAO Bay of Bengal Programme, Madras, India, report BOBP/REP/35, 40 pp.
Karim, M, 1987. Brackishwater aquaculture in Bangladesh: A review. Fisheries Research Institute - Bangladesh, FAO/UNDP TA Project BGD/83/010 report no 12, 36 pp.
Kibria, C, 1983. Prawn and shrimp resources of Bangladesh, Dhaka. [Mimeographed.]
Kungvankij, P, 1984. Overview of penaeid shrimp culture in Asia. NACA, Bangkok, 28 pp.
Lightner, D V, 1982. Toxic effect of certain marine blue-green algae to penaeid shrimp. US National Oceanographic and Atmospheric Administration report no NOAA-NA-79AA-D-00024. [NTIS order no PB83-180109.]
Madenjian, C P, G L Rogers & A W Fast, 1987. Predicting night time dissolved oxygen loss in prawn ponds of Hawaii. Part 2: A new method. Aquaculture Engineering, 6 (3): 209–225.
Mahmood, N, 1986. Effect of shrimp farming and other impacts on mangroves of Bangladesh. Paper presented at the Third Session of the IPFC Workshop on Inland Fisheries/Mangrove, 22–25 June, Bangkok, Thailand.
Majumder, M R, 1983. Shrimp culture status and extent in Cox's Bazar area, Dhaka. [Mimeographed.]
McVey, J P & J R Moore, 1983. CRC Handbook of Mariculture. Vol 1: Crustacean Aquaculture. CRC Series in Marine Science. Boca Raton: CRC Press Inc, 442 pp.
Mevel, G & S Chambroux, 1981. A study on nitrification in the presence of prawns (Penaeus japonicus) in marine closed systems. Aquaculture, 23 (1–4): 29–43.
Moriarty, D J W, 1986. Bacterial productivity in ponds used for culture of penaeid prawns. Microbial Ecology, 12 (3): 259–269.
Motoh, H, 1977. An annotated list of scientific and English common names of commercially important penaeid prawns and shrimps. SEAFDEC Technical Report no 2, 15 pp.
Muir, J F, 1989. Finalisation of engineering plans, Brackishwater Research Station, FRI, Paikgacha. FAO/FIRI report, 5 pp.
Muir, J F & R J Roberts (ed), 1982. Recent Advances in Aquaculture. London and Canberra: Croom Helm; Boulder (USA): Westview Press.
New, M B & S Singholka, 1985. Freshwater prawn farming: A manual for the culture of Macrobrachium rosenbergii. FAO Fisheries Technical Paper, (225): 118 pp. [Revision 1.]
Rackowe, R, H Branstetter, D King & G Kitson, 1983. The international market for shrimp. ADB/FAO Infofish Market Studies, 3: 79 pp.
Rahman, M A, 1986. Socio-economics of aquaculture deveopment. Country paper - Bangladesh. Paper presented at the Workshop on Socio-Economics on Aquaculture Development sponsored by NACA, 28–31 October 1986, Bangkok, Thailand.
Rajamani, M, 1982. Biochemical studies on ‘soft’ prawns. 1: Protein nitrogen and non-protein nitrogen contents in Penaeus indicus. Proceedings of the Symposium on Coastal Aquaculture, Part 1: Prawn Culture, Cochin, 12–18 January 1980. Symposium Series of the Marine Biological Association of India, (6): 349–353.
Rajayalakshmi, T, S M Pillai & A K Roy, 1981. Observations on the interaction of aeration and stocking density on growth and survival of the post-larvae of Penaeus monodon Fabricius. Journal of the Inland Fisheries Society of India, 13 (2): 87–91.
Russell, E W, 1973. Soil Conditions and Plant Growth. 10th edition. London and New York: Longman. [Note: 1st to 7th editions by E J Russell.]
Sakaranarayanan, V N, S Kumaran, T Balasubramanian & R Stephen, 1982. Studies on the environmental conditions of tidal ponds in the Ramathuruth Island. Proceedings of the Symposium on Coastal Aquaculture, Part 1: Prawn Culture, Cochin, 12–18 January 1980. Symposium Series of the Marine Biological Association of India, (6): 362–368.
Santos, C de los, 1978. Modern Aquaculture in the Philippines. Iloilo City: Yuhum Press, 224 pp.
Simpson, H J & M Pedini, 1985. Brackishwater aquaculture in the tropics: The problem of acid sulphate soils. FAO Fisheries Circular, (791): 32 pp.
Smith, W G, 1982. The tidal study area. A preliminary report. Fisheries Resources Survey System FAO/UNDP, Dhaka. [Mimeographed.]
Sohier, L & M Bianchi, 1983. The regulation of ammonia and nitrite rates by nitrifying bacteria in mariculture ponds. Mécanismes Biophysiques et Biochimiques des Transferts dans les Chaînes Trophiques en Milieu Marin. Groupement pour l'Avancement de la Biochimie Marine (France). Oceanis, 9 (3): 265–273.
Spotte, S H, 1979. Fish and Invertebrate Culture: Water Management in Closed Systems. New York: John Wiley & Sons, 179 pp.
Strickland, J D H & T R Parsons, 1968. A practical handbook of seawater analysis. Bulletin of the Fisheries Research Board of Canada, (167): 311 pp. [Revised edition.]
Tareen, I U & A S D Farmer, 1983. Shrimp Pathology Manual. Kuwait: Kuwait Institute for Scientific Research, 116 pp. [Copy deposited in the FRI Library and Documentation Centre.]
Wedemeyer, G A, F P Meyer & L Smith, 1976. Environmental Stress and Fish Diseases. Neptune City, NJ: TFH Publications, 192 pp.
Wickens, J F, 1976. Prawn biology and culture. Oceanography and Marine Biology Annual Review, 14: 435–507.
Yunker, M P & E D Scura, 1985. An improved strategy for building brackishwater culture ponds with iron pyrite soils in magrove swamps. Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4–7 December 1984, Iloilo City, Philippines, edited by Y Taki, J H Primavera & J A Llobrera, p 171. [Abstract only.]
SOLUBILITY OF OXYGEN IN SEAWATER
and
DISSOCIATION OF AMMONIA IN WATER
| Temp (°C) | Salinity (‰) | ||||||||
| 0 | 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | |
| 0 | 14.602 | 14.112 | 13.638 | 13.180 | 12.737 | 12.309 | 11.896 | 11.497 | 11.111 |
| 1 | 14.198 | 13.725 | 13.268 | 12.825 | 12.398 | 11.984 | 11.585 | 11.198 | 10.825 |
| 2 | 13.813 | 13.356 | 12.914 | 12.487 | 12.073 | 11.674 | 11.287 | 10.913 | 10.552 |
| 3 | 13.445 | 13.004 | 12.576 | 12.163 | 11.763 | 11.376 | 11.003 | 10.641 | 10.291 |
| 4 | 13.094 | 12.667 | 12.253 | 11.853 | 11.467 | 11.092 | 10.730 | 10.380 | 10.042 |
| 5 | 12.757 | 12.344 | 11.944 | 11.557 | 11.183 | 10.820 | 10.470 | 10.131 | 9.802 |
| 6 | 12.436 | 12.036 | 11.648 | 11.274 | 10.911 | 10.560 | 10.220 | 9.892 | 9.573 |
| 7 | 12.127 | 11.740 | 11.365 | 11.002 | 10.651 | 10.311 | 9.981 | 9.662 | 9.354 |
| 8 | 11.832 | 11.457 | 11.093 | 10.742 | 10.401 | 10.071 | 9.752 | 9.443 | 9.143 |
| 9 | 11.549 | 11.185 | 10.833 | 10.492 | 10.162 | 9.842 | 9.532 | 9.232 | 8.941 |
| 10 | 11.277 | 10.925 | 10.583 | 10.252 | 9.932 | 9.621 | 9.321 | 9.029 | 8.747 |
| 11 | 11.016 | 10.674 | 10.343 | 10.022 | 9.711 | 9.410 | 9.118 | 8.835 | 8.561 |
| 12 | 10.766 | 10.434 | 10.113 | 9.801 | 9.499 | 9.207 | 8.923 | 8.648 | 8.381 |
| 13 | 10.525 | 10.203 | 9.891 | 9.589 | 9.295 | 9.011 | 8.735 | 8.468 | 8.209 |
| 14 | 10.294 | 9.981 | 9.678 | 9.384 | 9.099 | 8.823 | 8.555 | 8.295 | 8.043 |
| 15 | 10.072 | 9.768 | 9.473 | 9.188 | 8.911 | 8.642 | 8.381 | 8.129 | 7.883 |
| 16 | 9.858 | 9.562 | 9.276 | 8.998 | 8.729 | 8.468 | 8.214 | 7.968 | 7.730 |
| 17 | 9.651 | 9.364 | 9.086 | 8.816 | 8.554 | 8.300 | 8.053 | 7.814 | 7.581 |
| 18 | 9.453 | 9.174 | 8.903 | 8.640 | 8.385 | 8.138 | 7.898 | 7.664 | 7.438 |
| 19 | 9.261 | 8.990 | 8.726 | 8.471 | 8.222 | 7.982 | 7.748 | 7.521 | 7.300 |
| 20 | 9.077 | 8.812 | 8.556 | 8.307 | 8.065 | 7.831 | 7.603 | 7.382 | 7.167 |
| 21 | 8.898 | 8.641 | 8.392 | 8.149 | 7.914 | 7.685 | 7.463 | 7.248 | 7.038 |
| 22 | 8.726 | 8.476 | 8.233 | 7.997 | 7.767 | 7.545 | 7.328 | 7.118 | 6.914 |
| 23 | 8.560 | 8.316 | 8.080 | 7.849 | 7.626 | 7.409 | 7.198 | 6.993 | 6.794 |
| 24 | 8.400 | 8.162 | 7.931 | 7.707 | 7.489 | 7.277 | 7.072 | 6.872 | 6.677 |
| 25 | 8.244 | 8.013 | 7.788 | 7.569 | 7.357 | 7.150 | 6.950 | 6.754 | 6.565 |
| 26 | 8.094 | 7.868 | 7.649 | 7.436 | 7.229 | 7.027 | 6.831 | 6.641 | 6.456 |
| 27 | 7.949 | 7.729 | 7.515 | 7.307 | 7.105 | 6.908 | 6.717 | 6.531 | 6.350 |
| 28 | 7.808 | 7.593 | 7.385 | 7.182 | 6.984 | 6.792 | 6.606 | 6.424 | 6.248 |
| 29 | 7.671 | 7.462 | 7.259 | 7.050 | 6.868 | 6.680 | 6.498 | 6.321 | 6.148 |
| 30 | 7.539 | 7.335 | 7.136 | 6.943 | 6.755 | 6.572 | 6.394 | 6.221 | 6.052 |
| 31 | 7.411 | 7.212 | 7.018 | 6.829 | 6.645 | 6.466 | 6.293 | 6.123 | 5.959 |
| 32 | 7.287 | 7.092 | 6.903 | 6.718 | 6.539 | 6.364 | 6.194 | 6.029 | 5.868 |
| 33 | 7.166 | 6.976 | 6.791 | 6.611 | 6.435 | 6.265 | 6.099 | 5.937 | 5.779 |
| 34 | 7.049 | 6.863 | 6.682 | 6.506 | 6.335 | 6.168 | 6.006 | 5.848 | 5.694 |
| 35 | 6.935 | 6.753 | 6.577 | 6.405 | 6.237 | 6.074 | 5.915 | 5.761 | 5.610 |
| 36 | 6.824 | 6.647 | 6.474 | 6.306 | 6.142 | 5.983 | 5.828 | 5.676 | 5.529 |
| 37 | 6.716 | 6.543 | 6.374 | 6.210 | 6.050 | 5.894 | 5.742 | 5.594 | 5.450 |
| 38 | 6.612 | 6.442 | 6.277 | 6.117 | 5.960 | 5.807 | 5.659 | 5.514 | 5.373 |
| 39 | 6.509 | 6.344 | 6.183 | 6.025 | 5.872 | 5.723 | 5.577 | 5.436 | 5.297 |
| 40 | 6.410 | 6.248 | 6.091 | 5.937 | 5.787 | 5.641 | 5.498 | 5.360 | 5.224 |
Table 7. Percentage of free ammonia (NH3) in aqueous* ammonia solutions in relation to temperature (0–30 °C) and pH (6.0–10.0).
| Temp (°C) | pH | ||||||||
| 6.0 | 6.5 | 7.0 | 7.5 | 8.0 | 8.5 | 9.0 | 9.5 | 10.0 | |
| 0 | .00827 | .0261 | .0826 | .261 | .820 | 2.55 | 7.64 | 20.7 | 45.3 |
| 1 | .00899 | .0284 | .0898 | .284 | .891 | 2.77 | 8.25 | 22.1 | 47.3 |
| 2 | .00977 | .0309 | .0977 | .308 | .968 | 3.00 | 8.90 | 23.6 | 49.4 |
| 3 | .0106 | .0336 | .106 | .335 | 1.05 | 3.25 | 9.60 | 25.1 | 51.5 |
| 4 | .0115 | .0364 | .115 | .363 | 1.14 | 3.52 | 10.3 | 26.7 | 53.6 |
| 5 | .0125 | .0395 | .125 | .394 | 1.23 | 3.80 | 11.0 | 28.3 | 55.6 |
| 6 | .0136 | .0429 | .135 | .427 | 1.34 | 4.11 | 11.9 | 30.0 | 57.6 |
| 7 | .0147 | .0464 | .147 | .462 | 1.45 | 4.44 | 12.8 | 31.7 | 59.5 |
| 8 | .0159 | .0503 | .159 | .501 | 1.57 | 4.79 | 13.7 | 33.5 | 61.4 |
| 9 | .0172 | .0544 | .172 | .542 | 1.69 | 5.16 | 14.7 | 35.3 | 63.3 |
| 10 | .0186 | .0589 | .186 | .586 | 1.83 | 5.56 | 15.7 | 37.1 | 65.1 |
| 11 | .0201 | .0637 | .201 | .633 | 1.97 | 5.99 | 16.8 | 38.9 | 66.8 |
| 12 | .0218 | .0688 | .217 | .684 | 2.13 | 6.44 | 17.9 | 40.8 | 68.5 |
| 13 | .0235 | .0743 | .235 | .738 | 2.30 | 6.92 | 19.0 | 42.6 | 70.2 |
| 14 | .0254 | .0802 | .253 | .796 | 2.48 | 7.43 | 20.2 | 44.5 | 71.7 |
| 15 | .0274 | .0865 | .273 | .859 | 2.67 | 7.97 | 21.5 | 46.4 | 73.3 |
| 16 | .0295 | .0933 | .294 | .925 | 2.87 | 8.54 | 22.8 | 48.3 | 74.7 |
| 17 | .0318 | .101 | .317 | .996 | 3.08 | 9.14 | 24.1 | 50.2 | 76.1 |
| 18 | .0343 | .108 | .342 | 1.07 | 3.31 | 9.78 | 25.5 | 52.0 | 77.4 |
| 19 | .0360 | .117 | .368 | 1.15 | 3.56 | 10.5 | 27.0 | 53.9 | 78.7 |
| 20 | .0397 | .125 | .396 | 1.24 | 3.82 | 11.2 | 28.4 | 55.7 | 79.9 |
| 21 | .0427 | .135 | .425 | 1.33 | 4.10 | 11.9 | 29.9 | 57.5 | 81.0 |
| 22 | .0459 | .145 | .457 | 1.43 | 4.39 | 12.7 | 31.5 | 59.2 | 82.1 |
| 23 | .0493 | .156 | .491 | 1.54 | 4.70 | 13.5 | 33.0 | 60.9 | 83.2 |
| 24 | .0530 | .167 | .527 | 1.65 | 5.03 | 14.4 | 34.6 | 62.6 | 84.1 |
| 25 | .0569 | .180 | .566 | 1.77 | 5.38 | 15.3 | 36.3 | 64.3 | 85.1 |
| 26 | .0610 | .193 | .607 | 1.89 | 5.75 | 16.2 | 37.9 | 65.9 | 85.9 |
| 27 | .0654 | .207 | .651 | 2.03 | 6.15 | 17.2 | 39.6 | 67.4 | 86.8 |
| 28 | .0701 | .221 | .697 | 2.17 | 6.56 | 18.2 | 41.2 | 68.9 | 87.5 |
| 29 | .0752 | .237 | .747 | 2.32 | 7.00 | 19.2 | 42.9 | 70.4 | 88.3 |
| 30 | .0805 | .254 | .799 | 2.48 | 7.46 | 20.3 | 44.6 | 71.8 | 89.0 |
Notes:
As salinity increases the percentage of free ammonia is reduced slightly. For the purposes of water quality management in aquaculture the difference between fresh and saline water is insignificant.
The percentage ammonia (NH3) in aqueous solution at different temperatures and pH is based on the following two expressions:
pKa = 0.09018 + (2729.92/t),
where pKa is the ionization constant, and t is the temperature in degrees Kelvin (°K); and
% unionized NH3 = 1/[10(pKa - pH) + 1]
