DISEASE PREVENTION AND HEALTH MANAGEMENT IN COASTAL SHRIMP CULTURE

Shrimp cultivation in Bangladesh follows broadly similar methods throughout the country and can be loosely categorized as traditional (extensive), improved traditional (extensive) and semi intensive. These classifications for culture practice are based solely on the degree of management intervention and do not relate to the productivity of the system concerned. This is an important point, since yields from both traditional and improved traditional are often similar. The only difference between these two systems is that the production cost in the improved traditional system is slightly higher.

The semi-intensive farms in Bangladesh represent a small proportion of the production area (<10%) and are currently not in production. This is considered to be principally due to the repeated production losses over the past three years. These losses have been attributed to SEMBV (WSBV, white spot virus, China virus) infection and this has been confirmed in some cases. The route of infection in the semi-intensive farms is thought to be via the importation of infected postlarvae from Thailand and other countries (Indonesia, India)

In the traditional and improved traditional shrimp farming system monoculture is not practiced. The production from Bangladesh shrimp farms includes both fish and other shrimp species apart from Penaeus monodon. Fish species caught include: sea bass, gobies, catfish, mullet, tilapia and other brackishwater species. Crustacean species captured are mainly Metapenaus monoceros and Peneaus indicus and assorted Palaemonid species such as Macrobrachium spp. and crabs (Scylla serrata and others).

When considering the importance of shrimp farming in Bangladesh it is essential to include these by- catch species since they have a significant role in this culture system.

Official figures for shrimp production are not available after 1994-1995 preventing a true picture being formed. Unofficial estimates for 1996-1997 place production at approximately 25,742 tonnes - a similar tonnage to the production in 1994-95. A serious constraint to the evaluation of the severity of disease in Bangladesh shrimp aquaculture is that statistics for marine capture and brackishwater aquaculture are combined. Brackishwater aquaculture statistics are further confused by the inclusion of all shrimp species harvested from ponds (i.e. Penaeus monodon, Macrobrachium rosenbergii, Metapenaeus monoceros, Peneaus indicus and other small shrimp).

The proportion of P. monodon produced is available, but only upto 1994. Since P. monodon is the principal economic species produced from brackishwater ponds, the lack of reliable information concerning its production over the past four years prevents obtaining a true picture of the extent of disease losses.

The contribution of freshwater prawns to export income is not clear - the freshwater capture fishery yield is greater than the coastal aquaculture yield for all shrimp. In the export production figures there is no indication of the relative proportions Penaeus monodon and Macrobrachium rosenbergii.

Export figures might be affected by the import of cultured shrimp from Myanmar for processing. The quantity of shrimp imported is unknown but transport restrictions and decomposition limit this activity to the Cox's Bazar area (this might also explain why official production figures for Cox's Bazar are exceptionally high).

Most of the farmers and fisheries officers interviewed consider that Penaeus monodon yields have declined since 1994. Disease is the most common cause mentioned, and this is usually defined as 'white spot disease' (SEMBV), and is considered to have had the greatest impact on the traditional (extensive) farms during 1995 and 1996. This is supported by other reports in the grey literature, however the extent of the problem was poorly reported. The combined shrimp production figures have increased steadily over the past six years, but data regarding P. monodon production is lacking.

Exported shrimp has stabilized since 1994; this again indicates that the captured and cultured export quality shrimp (P. monodon and Macrobrachium rosenbergii) has not changed markedly, despite widespread claims of disease. What has changed over the past six years is the area under cultivation, but this was only 3.2% between 1994 and 1996, and is unlikely to significantly affect the production figures.

The total shrimp yield in 1995 - 96 is estimated at 49, 260 mT (DOF Shrimp Cell) however this yield is not reflected in the export statistics. We are thus faced with the question of what happened to this huge increase (45 % on the previous year) in production if it was not exported.

Figures for expected productions from the shrimp farming areas are too high and do not reflect the yields that are typically produced. This suggests over-optimism on behalf of those predicting production - it is unclear how the expected yields are calculated but they range between 168 - 510 kg/ha/yr. Yields over 200 kg/ha/yr are only achieved in modified extensive farms, therefore this data assumes all farms in Bangladesh are modified extensive. The reality is that most Bangladesh shrimp farms still employ traditional farming methods (i.e. no input). In order to be labelled a modified extensive system, some form of inputs must be applied to the system in the form of limes, fertilizers or supplememental feeds. In many modified extensive farms, application rates of these inputs are arbitrary and often too low to have a significant effect. The result is the classification of farms as modified extensive, when in fact they are actually little different from the lower yielding traditional extensive ponds (typical yields 100-150 kg/ha/yr).

These production figures are equivalent to Peneaus monodon yields of between 0.3 -1.0 shrimp/m2/ yr. This production level appears to be fairly consistent with previous production figures before 1994. Farmers' comments regarding survival may be more concerned with the numbers of postlarvae stocked into the ponds. Whilst the yield from traditional ponds is split between approximately 50 - 70 % Penaeus monodon and 30 - 50 % other species, the income generated from these two sources is markedly different. Penaeus monodon capture represents between 90 - 95 % of the income from the pond, other species represent a mere 5 - 10 %. This is illustrated in Appendix IV (Economics).

Taking an average harvest yield of 100 - 175 kg/ha/yr from an area of 134,448 gives an approximate number of shrimp between 443 - 776 million pieces of shrimp harvested from culture ponds (assuming an average harvest size of 30 grams). The demand for postlarvae for the farms is estimated between 672 million and 2,689 million (assumes a stocking density between 0.5 - 2 postlarvae/m2). From these figures the apparent survival in the traditional and improved traditional systems lies between 16 - 29 % during 1996 (using maximum postlarvae demand of 2,689 million). These figures are consistent with what is being currently reported by the farmers based on numbers of postlarvae stocked and the shrimp harvested. Farmers are reporting yields 100-150 kg/ha and survivals between 10 - 35 %.

Whilst there is data available for shrimp production from ponds, no such information exists for the fish by-catch produced. This limits our ability to evaluate the significance of the by-catch and it's role in production.

Enhancement of P. monondon yield can be made at the expense of other shrimp species (particularly Metapenaeus monoceros) using the techniques detailed later in this report. Whilst this would boost P. monodon production in the ponds, it may not be possible to increase overall biomass yield; the effect is merely to change species composition in favour of P. monodon.

By-catch fish and shrimp play an important role in the shrimp farmers lifestyle by providing alternative (albeit low) income and species diversity. Should P. monodon production fail, there is always the by-catch to act as food security. The advantage of shifting species composition away from Metapenaeus monceros is that income from the pond would be greater. Whether the the environmental conditions that cause disease in P. monodon also can also cause mortality of Metapenaeus monceros is unknown, however larger shrimp (such as P. monodon) are more susceptible to stressors such as low dissolved oxygen than smaller shrimp. It is apparent that Metapenaeus monceros seems to be far more tolerant of zero salinity (freshwater) that P. monodon.; this was evident from the consultants visit (see section 8, Salinity).

It would be more desirable to increase production of both fish and shrimp in Bangladesh brackishwater ponds. This would provide food security and also maintain diversity in the ponds should disease affect the P. monodon population. The suitable rearing environment for P. monodon only exists for one relatively short period of the year, for the rest of the time some other form of land use is required. Alternatives already practiced are paddy production and freshwater fish/shrimp production. The culture environment also differs markedly between the south (Cox's Bazar) and the north (Khulna, Satkhira, Bagherat) and the solutions for each area will be different.

The different potential management strategies for brackishwater ponds have been described in several publications. There does appear to be a reluctance/inability to implement the suggested strategies and this problem has also been discussed previously by various authors (Periodic Monitoring of the Social Support Services to the Third Fisheries Project, Bangladesh Institute of Development Studies,1996; Report of the National Workshop on Fisheries Resources Development and Management in Bangladesh, BOBP/REP/74, 1997).

It is apparent that feasible strategies to improve the problem of low yield (shrimp and by-catch) from brackishwater ponds must take into consideration the environmental and socio-economic constraints to the system. It is with this in mind that this report will propose appropriate methods for improvement of production.

2. Postlarvae

Postlarvae collection in Bangladesh is the principal source of postlarvae for traditional and improved traditional ponds. Wild postlarvae collection has been estimated at approximately 2,033 million per year (BOBP WP/89, 1993). There is mortality in the collection and holding process prior to stocking to the farms. The mortality of collected postlarvae inevitably means that the actual numbers of postlarvae required are higher than those actually stocked.

There are an estimated 120 - 150,000 postlarvae collectors in Bangladesh.This is equivalent to 17,000 postlarvae/collector/year and represents and income between 5,100 - 8,500 TK/yr. Since postlarvae collection is usually a family operation, several members of the family will be collecting postlarvae - this income could be quite significant to the family.

The high demand for postlarvae during the early part of the year has resulted in occasional high prices (900 - 4,000 TK/1000 postlarvae). The highest price (4 TK per piece) reached was in 1995, which is also the year that the most significant effects of SEMBV were reported. There were imports of hatchery produced postlarvae during this period. The route of entry being Cox's Bazar (from Madras) and also Satkhira (which shares a border with India). Cox's Bazar is supposed to supply 70% of the postlarvae demand for Khulna and Satkhira areas, although it is unclear how this is achieved since the majority of the postlarvae collectors are located in Khulna districts. Cox's Bazar may be acting as a clearing point for imported postlarvae, which are trans-shipped to the north and sold to unsuspecting farmers. The importation of postlarvae by boat from India is another route that is probably highly significant.

The lack of information regarding this issue is a constraint to formulation of effective quarantine and health management guidelines.

There are 11 shrimp hatcheries in Bangladesh ( DOF Shrimp Cell), but their contribution to production is relatively small. Hatchery production of postlarvae was estimated at approximately 35 million in 1995 (DOF Shrimp Cell Report, 1995). Local and imported hatchery cultured postlarvae are not acceptable to the extensive farmers since the losses from SEMBV in the semi-intensive farms in 1994 - 1995. However, there is no method by which the farmers can distinguish hatchery postlarvae from wild caught. This undoubtably allows the sale of hatchery produced postlarvae and imported postlarvae to farmers. This has been reported especially in the Khulna -Satkhira areas.

It has been proposed that hatchery development should be supported to lessen the pressure on the wild postlarvae collection process. With current techniques it is still difficult to produce postlarvae that are free from viral disease.

Increased hatchery production of postlarvae would impact upon the cost of postlarvae and also affect the livelihoods of the postlarvae collectors. The current price of postlarvae from hatcheries is comparable to that of wild caught postlarvae and there is thus little advantage in hatchery produced postlarvae.

A significant restriction on stocking of ponds during a particular season is the supply of postlarvae. Whilst the wild collection of postlarvae might satisfy the demand, this is done at the expense of timing of stocking. The ideal period for stocking shrimp ponds in Bangladesh is February-March. In order to achieve this, the entire demand of postlarvae would fall during this period. The supply of wild caught postlarvae is inadequate to satisfy this and thus stocking occurs continuously until the rainy season (June).

Hatchery production could provide the shortfall in supply, however seasonal stocking such as this would require the hatcheries to be operational for only 2-3 months of the year. This is unlikely to be financially attractive for large hatchery operations due to high investment costs. Small entrepreneurs operating 'backyard' type hatcheries might be a better and more equitable solution, but the lessons of Thailand should be borne in mind. Thai 'backyard' hatcheries were phenomenonally successful in providing postlarvae for booming Thai shrimp culture, but have ultimately made the control of disease at hatchery level impossible.

The disease risks from hatchery reared postlarvae are discussed in section 7

Significant yields of other shrimp species are harvested from the ponds such as Peneaus indicus and possibly Metapenaeus monoceros. These by- catch shrimp are not stocked, but are recruited naturally during water exchanges to the farm (usually during peak high tides at the full moon and new moon). In areas with brackishwater availability natural recruitment from postlarvae entering the ponds during water exchanges might have a significant role to play in the final production of Penaeus monodon from traditional ponds. It might be expected that natural recruitment occurs during the peak time for postlarvae availability in March - May and September - October. If the natural recruitment of Penaeus monodon is significant then those factors which influence the production of wild postlarvae will also affect the production of the ponds. In this case postlarvae collection pressure, climate, nutrient availability and shrimp capture fishery pressure will affect recruitment to the ponds.

3. Health Checks on Production Ponds

Farmers do not check the health of their shrimp during production. The only time that shrimp are seen is during the new and full moon harvesting period. In this case shrimp are observed in the capture pond and during cast netting. Any losses between capture periods are rarely observed, unless there is a mass mortality of shrimp at the pond edge.

Since shrimp tend to moult around the new moon and full moon periods this is a time of maximum stress to the shrimp - it is therefore the time that farmers are most likely to observe any disease related mortalities of shrimp. In many cases of shrimp disease the shrimp delay moulting until an improvement or change in water quality conditions occur. Since feed trays are not used in traditional farms it is impossible to establish when the shrimp started to become affected (in intensive systems a drop in feeding behaviour would be noted first, indicating stress or infection). Water exchange and lunar influenced moulting activity often causes high mortality in a pond and farmers often attribute this to a sudden highly pathogenic disease outbreak. In actuality, the shrimp had been becoming progressively more infected/affected during the previous period and the effort of moulting or inability to moult precipitates large scale mortality.

Due to the promotion of SEMBV as a major source of production losses in other countries and the Bangladeshi semi-intensive farms, there is now a tendency for traditional farmers to blame all production difficulties on SEMBV; this view is often supported by Department of Fisheries Officers diagnosis.

It is important that Department of Fisheries Officers become more aware of other causes of disease losses in the Bangladeshi traditional farm system since many of the situations can be resolved through improved management. The labelling of all shrimp disease as SEMBV is convenient since it absolves the farmers from any suggestion of mismanagement.

In the following sections, comments will be made concerning the potential causes of low yield or shrimp losses in the Bangladesh traditional system.

4. Potential Causes of Low Yield or Production Losses

Since shrimp postlarvae are considered to be a significant source of SEMBV infection to semi-intensive and intensive Peneaus monodon farms, the risk from this source must be considered. In intensive farms systems of other countries, the source of postlarvae is entirely hatchery produced.

Postlarvae produced in hatcheries can have high levels of infection of SEMBV and other viral diseases. The reasons for this high rate of infection might be due to the high densities of larvae in the rearing tanks in hatcheries allowing horizontal transmission of the virus in the hatchery.

Another likely source is the transmission from infected broodstock to the eggs. Since one female may produce 0.5 - 1.0 million eggs, the infection potential is high. Hatcheries use mixed stocks of nauplii from several female broodstock - thus infected and non infected stocks are mixed together in the same hatchery tank.

Stocking farms with postlarvae cultured in hatcheries using SEMBV infected female broodstock is a significant risk for SEMBV infection.

It seems unlikely that the wild postlarvae captured and transferred to traditional ponds are a significant source of SEMBV since the stresses of the larval stages, low density in the sea and the stresses of capture and holding should kill off any susceptible animals.

If SEMBV has caused recent losses in the traditional systems, it seems more likely that carrier crustacean species were involved, or that hatchery produced postlarvae were involved.

It is worth mentioning that there was little evidence of SEMBV infection at the farms visited during this consultancy, although this period is the end of the culture season and any diseased animals have probably died.

There is a tendency to blame all disease losses on viral disease (SEMBV) in Bangladesh ( as in many other countries) although the descriptions of the condition of the shrimp and the manner in which they were affected is not always consistent with what is known about this virus disease.

During 1994-1995 postlarvae from Thailand and Taiwan were imported for stocking in semi-intensive farms in Bangladesh.

The presence of SEMBV in semi-intensive farms was confirmed by a number of sources and the crash of the semi-intensive farms during this year appears to be due to the outbreak of SEMBV from these imported postlarvae.

This outbreak also coincided with SEMBV outbreaks in Thailand and elsewhere in south-east Asia (e.g. India, Indonesia).

The high price of postlarvae during 1995 also increased the cost of production in traditional farms (0.9 TK/pl in 1994 to 4 TK/pl in 1995). This high price for postlarvae undoubtably increased imports of cheap postlarvae from abroad.

Since the importations from Thailand and Taiwan to semi-intensive farms there have also been importations from both India and Indonesia. Importations from India are of the most concern, since SEMBV has also caused serious losses to the Indian shrimp farming industry.

The common border between Satkhira and India and the close proximity of India by boat from Khulna and Satkhira make this a likely route for postlarvae imports.

The losses in Bangladesh traditional shrimp farms during 1996 may have been due to SEMBV disease infecting wild stocks that were subsequently introduced to traditional farms. However, another possible route could be that infected postlarvae were imported to Khulna and Satkhira from hatcheries in India. Fisheries officers in Satkhira district acknowledge that importations from India have occurred and this might explain the reports of SEMBV in this district.

Other potential routes of infection include carrier crustacean species in the ponds, or the migration of infected shrimp/carrier species from Indian to Bangladesh waters in the Bay of Bengal.

If SEMBV infected shrimp are present in the Bangladesh brackishwater ponds then these animals are susceptible to stress, particularly salinity and oxygen stress.

The susceptibility of SEMBV shrimp to osmotic stress might explain why the onset of the rainy season has caused sudden mortality, since salinities can drop rapidly in the culture ponds (although P. monodon does not tolerate absolute freshwater for extended periods even when healthy).

The method of collection of postlarvae P. monodon and the subsequent storage, handling and transport are all severely stressful.

This sector of the shrimp farming operation is extremely wasteful in itself, with high mortality of postlarvae before stocking into ponds. It is known from other countries that the exposure of postlarvae to stressful conditions can cause an increase in the incidence of diseases such as MBV (Monodon Baculovirus) and bacterial/foulng (e.g. vibrio/ zoothamnium) Infections.

These diseases such as MBV may not cause immediate mortality, but they can cause disease in the grow-out ponds if environmental conditions subsequently deteriorate.

The stresses to postlarvae undoubtably lower the survival of postlarvae at stocking, and this immediately limits the potential yield of the pond.

Improvement of postlarvae survival by correct handling and transport accompanied by some supplemental feeding and good acclimation to the pond water will be reflected in better yields from ponds.

The issues of improved larval collection and stocking techniques are dealt with in more detail in the mission report by the Consultant for Extension.

Poor site selection of shrimp farms limits potential production worldwide. This is due to the general rule that farms are built where there is land available, not where there are suitable sites for shrimp farming. In Bangladesh production problems associated with poor farm situations include:

As a result of unsuitable farm situation, many of the production difficulties faced by farms in Bangladesh may not be resolvable. In these cases, the best strategy is diversification out of brackishwater shrimp, into other species. The income may not be comparable, but increased yield per unit area may be possible.

Due to the low land elevation in Bangladesh, many river systems are affected by tidal action great distances inland. This tidal effect allows the intrusion of brackishwater into inland areas. The presence of brackishwater also allows culture of shrimp species such as P. monodon. Unfortunately the high rainfall and freshwater discharge in these rivers means that the brackishwater (upto 15-20 ppt maximum) in these rivers systems is extremely seasonal (usually only between January - June).

In areas such as Khulna and Satkhira the rivers are tidal, but the flow of freshwater in the river prevents the intrusion of salinity, these rivers are thus freshwater but tidally influenced. Such conditions are not suitable for brackishwater aquaculture during the majority of the year.

There are additional problems concerning access to brackishwater water in shrimp farming areas.

As farms are developed further inland, the tidal fluctuation decreases both in daily amplitude and also the spring tide peaks during the new and full moons (twice monthly). This has the effect of limiting the amount of water that can flush the ponds.

Pond flushing is extremely important since the new water that enters the ponds carries nutrients, organic matter and larval animals into the ponds. This nutrient source is vital for the traditional pond systems, which usually have no other nutritional input. The limitation of nutrients is one reason why total production from the Bangladesh brackishwater ponds is low.

As farms are developed further from the brackishwater source salinity also becomes a factor influencing production (see below).

Influential farmers/ landholders monopolize the water gate system in the polders affecting both shrimp farmers and agriculture.

As canal systems in shrimp farming areas become affected by siltation, the flow of water through the channels also becomes a limiting factor in the water available to ponds.

Siltation has affected many shrimp farming areas. It is a natural effect of filling static ponds with silt laden water.

The effect of siltation over time is to make ponds and waterways more shallow. The result of this is less water in the ponds and less water available for flushing. Both of these effects will influence productivity of the system.

Siltation is more severe in ponds which are constructed on elevated land that only receives water at full and new moons. Ponds such as these are unsuitable for shrimp farming and production will deteriorate over time - this has already been observed in the IDA and ADB shrimp culture projects in Rampur, Cox's Bazar.

Due to the limitation of water within the polder systems at Rampur, farmers have blocked water channels to maintain water levels in their own systems at the expense of others. This static water may also cause problems due to the presence of acidic soil in the polders acidifying the inlet water to the farm.

There are engineering solutions to siltation of waterways, but these are unlikely to be cost effective. Farms that have been constructed in elevated land will never be successful once sedimentation starts.

Most Bangladesh shrimp ponds are already too shallow - it would be desirable to deepen these ponds, however the cost cannot be borne by the farmers since they are mostly sub-lessees. These farmers do not have the resources and are unwilling to invest in the farms since their sub-lease is renewed annually

Fertilization of ponds can offset the lack of nutrients and increase production, but there is little solution to inadequate supply of brackishwater. Many farms attempt more than one crop of P. monodon per year, or try to extend their cropping period into the rainy seasons of June-July. This is invariably unsuccessful due to low salinity.

There is currently no information available concerning the ability to exchange water in traditional ponds; the collection of this data is part of the workplan for the NC.

Shallow water in shrimp ponds causes problems due to fluctuations in water quality parameters such as temperature, salinity, dissolved oxygen, pH and possibly toxic compounds such as ammonia and hydrogen sulphide.

Deeper water in ponds can stabilize these conditions to some extent and ideal water depths for extensive culture range between 0.6 - 1.0 m.

Many farms are too shallow over most of the pond area (approximately 30 cm) and the result is migration of shrimp into deeper areas and channels when conditions are unfavourable. These deeper areas may also be unsuitable for other reasons (crowding, static water, low dissolved oxygen) and the result is increased stress to the shrimp. This may result in the occurrence of disease and lower shrimp yield from the pond

Many farms are unable to provide deep water for the shrimp due to problems with high pond elevation and low tidal exchange. If water can be introduced to the farm it is desirable to introduce it to the deeper area and channels of the pond.

Shallow water can be a potential problem if the pond is used in alternation with paddy culture - the old paddy roots and stalks provide nutrients, but they also degrade the water quality. Adequate flushing of the pond is desirable in such systems.

The other major effect of shallow water in ponds is that the productive area of the pond is reduced. This means that if the water area is used to calculate production the result is a low yield per unit area. This is because the entire pond is not contributing to productivity.

P. monodon is highly tolerant of brackishwater during its juvenile and young stages. Adult P. monodon are also tolerant of low salinity water. This species does not perform well when water salinities drop below about 5 ppt. Below this point, feeding behaviour is reduced and there are effects on the animal concerned with the moulting process. The result of this is hard shelled animals becoming affected by bacterial infection.

The external signs of chronic low salinity are reddening of the animals, external fouling and empty guts. Animals such as this might be able to moult, but the effect is usually mortality, often associated with soft shelling. Since the moulting peak coincides with the full moon harvesting period the farmer usually observes high mortality at this period.

The effect of white spot virus disease (SEMBV) on a pond may also become more severe if shrimp are exposed to extremely low salinity. It is thought that this is because this virus affects the epithelial tissues of the gills that are concerned with salt and water regulation on the shrimp. Animals affected with white spot virus will die quickly if the salinity is reduced rapidly.

Sudden salinity changes can occur due to the shallow nature of the ponds and the large amounts of freshwater that can enter rivers systems after rainfall. This is a phenomenon that occurs in other countries, however it is particularly acute in Bangladesh.

The result of the rainy season is a rise in brackishwater shrimp mortality (P. monodon) and possibly other brackishwater species (e.g. crabs). Farmers were aware that mortalities occur with the onset of the rainy season but there appeared to be little management reaction to this.

Low salinity water often has low alkalinity and rainwater has extremely low hardness. The result of these two factors is low concentrations of bicarbonate/carbonate and calcium/magnesium in the water. These ions are critical for shrimp survival since they have a role in the animals physiology, particularly the moulting process. There are reports of soft shell shrimp in Bangladesh and low salinity/alkalinity/hardness undoubtably plays a role (see also pH and pesticides).

Liming (calcium carbonate/agricultural limestone) of ponds may alleviate this problem in the short term, but if low salinity persists mortalities can be expected.

There is currently no information available concerning salinity fluctuations in traditional ponds; the collection of this data is part of the workplan for the NC.

Farms constructed on ex-mangrove soil such as the farms in the Cox's Bazar area (soil pH reported 5 - 6.5, but probably lower) will suffer from acidity related problems.

Reclamation of acidic soils is a slow process and requires flushing with brackishwater and application of limes. To some extent the siltation problem in this area acts as a blanketing effect against acid leaching.

Most farmers do not use lime during culture and in many cases it may not be necessary if soil pH is high and brackishwater is available. If flushing of ponds with fresh brackishwater is sufficient, liming of ponds should not be necessary. Low water exchange ponds and low salinity pondwater will require increasing amounts of lime application, especially if the underlying soil is acidic.

The excavation of new potential acid sulphate soils for polder reconstruction/improvement following cyclone damage will result in acidification of water canals. This effect will be most severe during the rainy season as rainwater will leach acids into the canals. The limitation of water circulation in canals such has happened in the ADB/IDA scheme will only aggrevate this problem.

Acid soils lower the alkalinity of brackishwater resulting in soft shelling of the shrimp. Typically the solution to acid soils is the application of limes (CaO to neutralize, CaCO3 to improve alkalinity, see liming rates).

Liming of acidic soils can also improve soil fertility by releasing bound phosphorus, this will increase productivity of the ponds.

The soils in Khulna are reported to lie at ph 6-7 and thus low pH is unlikely. Khulna is affected by low water salinity, and in this case alkalinity could be low.

High daily pH fluctuations can occur in ponds with heavy phytoplankton blooms , but these are unlikely to be a problem in the low nutrient traditional/improved traditional farms.

There is currently no information available concerning pH , alkalinity and hardness in traditional ponds; the collection of this data is part of the workplan for the NC.

Dissolved oxygen concentrations below 4.0 mg/l (ppm) are stressful to P. monodon . If concentrations fall to below 2.0 mg/l the shrimp will be severely stressed and become susceptible to disease.

In shallow ponds dissolved oxygen is not usually expected to reach critically low levels provided the water does not become stratified and provided the sediment oxygen demand is not high.

In hot sunny weather the consumption of oxygen by the sediments and organic material of the pond bottom might cause critically low oxygen levels for periods of the day. This condition occurs in deepwater paddyfields and could be expected to occur in some shrimp ponds (maximum oxygen concentration 1.0 mg/l). 4) The most likely time for this would be the hot season in Bangladesh when wind driven turbulence and mixing is at a minimum. This period coincides with the other peak in reported disease of March-April. Reports of mortalities are consistent with low dissolved oxygen and high water temperatures. Although virus disease has been implicated there is almost certainly an environmental component as well.

If phytoplankton blooms are stimulated in ponds by fertilization, oxygen levels could be increased during the day. Supersaturation may be achieved and this could supply oxygen during the night. Generally some form of destratification is desirable, and in traditional ponds this is principally caused by wind action.

The stratification of deeper areas of the ponds may not be so easily disturbed, thus oxygen levels may be permanently low. This is a problem during periods of extremely high or low temperatures. Shrimp will seek deeper water since it has a more acceptable temperature, however the oxygen conditions might not be so favourable. The result is that the shrimp become stressed and susceptible to diseases.

In intensive pond systems, shrimp affected by white spot virus (SEMBV) suffer rapid mortality following rainfall. One of the effects of this, apart from slight salinity and temperature change, is the decrease in dissolved oxygen due to reduced phytoplankton photosynthesis. Low dissolved oxygen levels in traditional ponds could be expected to produce similar effects, especially if shrimp were infected with SEMBV.

If critically low oxygen conditions occur in a pond, mass mortalities may result and many stressed/moribund animals will be seen in shallow areas. This is consistent with some reports from farmers regarding mortalities of crutaceans (shrimp and crab species) in ponds. Fish are not usually affected since they are not benthic in their habit and are able to move to areas with suitable oxygen conditions.

In acute low dissolved oxygen conditions affected animals will usually display reddening of the body and reddening of the gills.

If the conditions have been sub-lethal for a long period of time, shrimp will display other symptoms such as fouling, lack of moulting and bacterial infection.

There is currently no information available concerning dissolved oxygen fluctuations in traditional ponds; the collection of this data is part of the workplan for the NC.

Temperature fluctuation are stressful to shrimp and can affect feeding behaviour. Long term temperature stresses can reduce growth.

One of the behavioural responses to temperature extremes is the movement of shrimp into deeper areas of the pond. This can cause crowding and the deep areas of the pond may have deteriorated water quality. If these conditions persist the shrimp will eventually become infected by opportunist type diseases such as fouling and bacterial infections.

Temperature fluctuations are a problem in shallow ponds during periods of very hot sunny weather. This is consistent with reports of mortalities during the months of March-April period.

The only solution to the problem of temperature fluctuation is to increase water depth. Providing deep water areas (such as channels and refuges) can also help, provided the sediment in these areas is not highly organic and oxygen concentrations are above 3.0 mg/l.

There is currently no information available concerning temperature fluctuations in traditional ponds; the collection of this data is part of the workplan for the NC.

This does not appear to be a serious problem for shrimp health in Bangladesh shrimp ponds. The first signs of suspended solids loadings causing problems to shrimp is the appearance of gill discolouration. The condition is usually cured when the shrimp moults. If the conditions persist, then in extreme cases the gill will appear blackened due to melanization of damaged tissue.

Suspended solid loadings will increase in shallow ponds where there is wind driven wave action. Deeper water ponds do not suffer from this problem. High suspended solids loadings limit phytoplankton action and a result may be reduced oxygen concentrations in deeper areas of the pond.

High suspended solids loadings in the inlet water increase sedimentation in the ponds and may also affect the oxygen concentration if there is a high organic content.

Pesticides cause rapid mortality of shrimp when exposed to high concentrations. At sub-lethal concentrations soft shelling and moulting difficulties are often observed.

The integration of shrimp culture with rice paddy or other agricultures raises the question of the use of pesticides. Most pesticides are highly toxic to shrimp and extreme care must be taken when treating agricultural land that also has aquaculture activities.

In fish/shrimp cum paddy culture the water level is dropped during pesticide treatment. The shrimp and fish are forced into the deeper peripheral channel and remain until after treatment. When the pond is refilled with water the dilution of the pesticide reduces the toxicity. This is potentially high risk when cultivating shrimp species (e.g. Macrobrachium) which might be more sensitive than fish to pesticides. It should be mentioned that this method of cultivation is already in use. It is not known to what extent the use of pesticides impacts on shrimp.

If shrimp are not cultured together with the paddy (i.e. alternation of crops), there is more time for the breakdown of pesticides and flushing with water.

Ideally pesticide use would not occur in such integrated systems and the shrimp may actually used as part of an integrated pest management (IPM) programme.

Since water exchange is a significant source of nutrients, low flushing of the ponds will limit nutrients in the pond. This also limits the production of the ponds.

Productivity can be increased by fertilization or the addition of supplemental feeds. Due to the low value species other than P. monodon supplemental feeding is not advised since there is likely to be little benefit gained.

Competition between shrimp species (e.g. P. monodon and Metapenaeus monoceros) undoubtably limits P. monodon yield and methods for minimizing this effect include screening ponds and the use of nurseries to increase shrimp size before stocking.

There are several predatory fish species commonly found in shrimp ponds these include: sea bass, gobies and catfish.

The stocking of postlarvae shrimp into ponds already containing other species (including other shrimp species) are likely to be predated soon after stocking.

The practice of filling ponds well before stocking will increase the problem of competition and predation.

The practice of stocking at intervals through the crop is also likely to have poor results unless shrimp are reared in a nursery before hand.

Effective screening of ponds to minimize the entry of grown animals to culture ponds is frequently recommended, but rarely practiced by farmers.

5. Management Improvements for Traditional Farms

There are few farms that have access to brackishwater all year round. The majority of farms visited only have brackishwater available during the period January - June.

P. monodon should be stocked during February-March to ensure that the grow-out season has sufficiently high salinity. Harvest should be completed by the commencement of freshwater conditions June-July.

Second crop of P. monodon is possible in areas where brackishwater is available all year.

The seasonality of production is important to farms which practice alternation of crops.

Harvesting of P. monodon in June-July requires drainage of the pond. Small holding ponds can be used for freshwater species also harvested. These can be returned to the ponds for ongrowing during the freshwater season.

The entry of large predators and competitor species into the culture ponds limits the production of P. monodon. Effective screening of the ponds can limit predation and competition. This is extremely important if nursery ponds are to be used.

Ponds and nurseries require gates that are sufficiently large to allow rapid filling of the pond when tidal water is available.

Gate must be screened to prevent entry of large predators (netting 24 mesh per inch)

Ponds should be filled just before P. monodon are stocked from the nursery (1 - 1.5 weeks)

Predator removal using teaseed cake (20-30 mg/l, 120 - 180 kg/ha in pond average water depth 0.6 m)

Mortality at stocking is likely to be high due to different conditions between holding water and pond conditions. The predation of small postlarvae is probably extremely significant.

Postlarvae should be acclimated to salinity and temperature prior to stocking. These conditions can be checked by taste and feel.

The use of a nursery pond is strongly recommended to minimize predation of the postlarvae and provide large strong animals for stocking to the main grow-out pond.

Nurseries provide a predator free environment where the small (1.2 cm) postlarvae are able to be ongrown in good conditions to a 2 - 3 g juvenile (5 cm).

The larger shrimp that are stocked will out compete smaller wild shrimp and the proportion of P. monodon in the crop will be increased.

Use of nurseries allows a single stocking strategy, which reduces the requirement for further stockings.

The nursery strategy also allows better timing of crops and less conflict with other uses of the pond (i.e. second crop of fish, rice, freshwater prawn).

If there is widescale adoption there will be high demand for postlarvae focused on two months of the year. Current supply from wild caught postlarvae would be insufficient to meet demand. This might influence quality and price.

Concentration of postlarvae in the nursery may enable horizontal transmission of infectious disease (e.g.virus disease)

Fertilization and feeding is required - this increases investment cost, however the reduced requirement for postlarvae due to higher survival should offset these costs.

Fertilization incurs cost (although this is usually quickly offset by increased production)

Lime applications in Bangladesh brackishwater ponds are usually low, often too low to have any real effect on the pond conditions.

Lime application before filling a pond can improve quality of pond soil by neutralization of acid conditions

Neutralization of acid may also release phosphorus and increase phytoplankton production

Lime application is essential on ponds with acidic soil (i.e. ponds built on ex-mangrove soils)

The lime commonly used in Bangladesh is calcium oxide (CaO) lime. This is extremely alkaline and can be used on acidic soils. It is not recommended for routine use since it can have a detrimental effect on water alkalinity and pH. Agricultural limestone (CaCO3) is the liming material of choice.

6. Policy

There have been numerous attempts to introduce improved farming practices in Bangladesh brackishwater ponds. The reasons why these improvements have not been adopted are numerous, but can be generalized into the following categories

Farmers did not perceive that improvements were necessary whilst production levels were adequate

Most farmers are sub-lessees and will not invest in land to which they do not have long term tenure

The rents imposed on sub-lessees is a critical factor in the economic viability of the farm. Government lease rates are approximately TK 1,500/acre. Sub-lessees are paying between 4,500 - 6,500/acre.

Many earlier proposed improvements were high cost to the farmer, or involved governmental intervention (e.g. depending of ponds, dredging of canals etc.)

Most improved methods still rely on adequate supplies of water - the monopolization of canals and water gates by influential persons affects surrounding poorer farmers.

Many of the farmers involved in day to day running of the farms are employed by the leaseholder and have little stake in the productivity of the pond.

7. Shrimp Health Management Training Workshops

Two training workshops were performed during this mission in Cox's Bazar (39 participants) and Khulna (73 participants). They were attended by District Fisheries Officers, Tanah Fisheries Officers and Research Officers from the Fisheries Research Institutes of Cox's Bazar and Khulna.

The feedback from the Officers involved in the workshop was positive, although they expressed concern that the recommendations for improved health management would be difficult to implement. This is because there appears to be a lack of faith in the Fisheries Officers by the farmers. This problem emphasizes the importance of having practical demonstrations at private farms. If production is improved in these farms by the adoption of improved techniques, then the extension process is facilitated.

It was evident from the discussions with the Fisheries Officers that diagnosis of disease as white spot (SEMBV) was arbitrary and was a general term used for most disease conditions where mortality was evident. This raises the question as to the extent and severity of the SEMBV problem in Bangladesh. This is an important issue since strategies for shrimp health management can differ according to the underlying cause of the problem.

It appears that the majority of disease cases faced by farms in Bangladesh are a primarily a result of poor pond environments, competition and predation. The strategies proposed to improve shrimp health are therefore targetted at these problems.

Management strategies developed in other countries to counter viral diseases cannot be implemented in the Bangladesh shrimp farm system due to physical (pond size) and economic constraints.

8. National Consultants Selection and Reporting

The National Consultants (NC's) play a central role in the implementation of this project. Their responsibilities shall include:

Assisting in the set-up of new management strategies in the demonstration farms. This will include: postlarvae acclimatization and stocking, nursery techniques, grow-out, harvest, basic health and water quality monitoring

Training and extension of the concepts included in the demonstration farms - Tanah officer and farmers

Collection of data from farms regarding environmental and health management issues.

If the NC's are not effective in their role, a significant part of this TCP will be unsuccessful. While employment of 4 NC's for six months each will secure full geographical coverage, the changeover should not occur midway through the ideal production period for Penaeus monodon.

It is understood that four candidates have been proposed (FIRI Officers Back to Office Report). The best choice of candidates is a compromise between knowledge of shrimp culture and ability to expedite the project requirements in the designated districts.

The initial employment of the first two NC's is scheduled to be six months - it is crucial that the employment of these first two NC's commences no earlier than October 1st 1997. This will ensure that the NC's are able to supervise the setting up of the demonstration farm and monitor the proposed nursery activities.

In order to ensure that the NC's are effective in their roles, it is STRONGLY ADVISED that monthly reports are made a mandatory component of the terms of their employment. The reports should be submitted to both NPD and the FAO Operations Service to ensure proper collection of data and performance of training obligations.

For the duration of their appointments, the NC's shall be based in the district concerned. There is little or no requirement for travel to Dhaka during this appointment . For the effective implementation of their duties the NC's must remain at their duty location for at least 20 days per month.

The existence of data and reports should assist at the time of changeover of NC's, and also allow the information derived from the TCP to be properly evaluated and utilized. The existence of written reports and data collected during the project is essential if the effectiveness of the health management strategies is to be assessed. The lack of simple accurate data regarding farm production, environmental conditions and disease problems is a considerable constraint to the industry in Bangladesh.

Whilst it is the responsibility of the NC's to implement much of the project requirements, it is expected that the Thana fisheries Officers will be used in many instances. This might be advantageous since the Thana officers are generally capable of performing many of the duties of the NC's with respect to data collection from farms and following up the demonstration farm progress. The Thana officers can also assist in the identification of farmers for the extension component of the TCP.

When performing this additional task, the project should reimburse expenses to the Thana Officers (a daily allowance of 200 TK for every full day work performed on the project). The number of days per month can be limited as can the number of officers involved. The timesheets of the officers involved should be submitted at the same time as the NC's monthly report.

Two officers employed for 20 days a month is equivalent to $186 per month at a total cost to the project of $2,232. The Thana officers should work on an 'as needed' basis and the amount of time claimed could be checked via the NC's report - i.e. if little data was collected and there was no progress on the demonstration farm then it would be expected that the Thana officers time would be minimal, and vice versa.

One person is to be recruited for administrative assistance to NPD based in Dhaka. The salary should be 10,000 TK per month ($232).

The workplan for the first six months of NC activity is detailed in Appendix I. As mentioned above it is important for the first two NC's to be employed for 6 months starting October 1st to ensure that the nursery phase of production is successfully completed. This first period is the critical time for extension of the improved farming techniques. The second two NC's would be involved with the demonstration farms during the post nursery grow-out period and would be responsible for collection of harvest data.

9. Selection of Experimental Demonstration Farm Sites

Three potential sites have been evaluated for demonstration farm potential, Rahmpur (Cox's Bazar district), Thala (Satkhira district), Botiagata (Khulna district) and Bagerhat district. One site is administered by the DOF (Cox's Bazar), the other two are private farms. The locations of these farms are known to the District Fisheries Officers in whose districts they lie.

An additional fourth site is recommended for Bagherat district. This district also has substantial shrimp farming activity. Exclusion of Bagerhat district from the demonstration farm programme is likely to cause local resentment and may affect the implementation of the project. A suitable site has already been located, and this site is known to the Bagerhat District Fisheries Officer.

All the sites chosen are typical traditional/improved traditional farms. The adaptation of these farms for the purposes of the project will require some small financial inputs. The principle cost to the operation of a farm is the purchase of the postlarvae. This cost should be met by the farmer since this is the normal expenditure he would make on the farm.

The demonstration farms are proposed to have a nursery system to improve postlarvae survival and strengthen the animals prior to stocking in the main pond. Some financial assistance should be provided for the purchase of fertilizer and feed for the nursery. The repair and proper construction of gates and bunds for the nursery will also require financing. The total sum of money envisaged would not be in excess of $ 387 (TK 17,415) per farm (Total $1,548). The FAO contribution is approximately equal to the typical expenditure of the farmer for postlarvae. The additional funds required to assist the demonstration farm sites can be met from savings in the equipment budget.

The FAO contribution is only made once to the farm - the intention is that the farmers perceive the benefit of the improved management strategy and it becomes self-financing after the first crop.

A breakdown of the nursery costings, required improvements and management of the demonstration farms is given in Appendix II

This site is at the ADB shrimp farm site (694 ha, 118 farms) in Rahmpur. The farm site has a disused demonstration unit that is ideally suited for use as a demonstration farm.

The close proximity of this site to other farms in the area is desirable for extension and farmer visits. It is hoped that the demonstration farm will provide a focus for training in improved farming techniques.

This demonstration farm already has a staff funded by DOF and has not previously been successful. It has been suggested that the staff at the farm are poorly motivated and inattentive. There is also a suggestion that theft from the farm occurs; this will be a major disadvantage if the situation persists during the project.

In order to correct this problem, the NPD has proposed to change many of the staff members at the site in order to ensure that the farm is managed properly.

If the NPD is unable to re assign staff to the ADB farm site, there is an alternative private farm site close by. This site would be a possible alternative. The NPD should be given the discretion to choose the alternative site in Cox's Bazar, should be ADB demonstration unit prove infeasible.

It is intended that the income from the first crop at the farm be re-invested to provide funds for the continuation of the demonstration farm activities for further crops.

Some slight re-engineering of the farm (construction of bunds and a box sluice) will be required but this is expected to be low cost.

This traditional private farm is 6.8 ha and situated adjacent to a brackishwater river, although the salinity in the farm may drop to zero during the rainy season.

Yield from the farm is typical of the area and the owner of the farm is a local resident.

There is permanent staff at the farm who can perform duties if properly supervised.

The farm owner is enthusiastic to be involved in the project and will possibly bear some of the costs of the reconstruction of his nursery pond himself.

It is imperative that the NC provide adequate support and extension to the farm owner in order to ensure that the nursery and grow-out phase of his operation is successful.

This site is equi-distant between Satkhira and Khulna, therefore there is no difficulty for either of the two NC's to visit the site.

This farm is smaller than the Thala demonstration farm but is also well located next to a brackishwater river.

The river does become fresh in the June-July rainy season and thus it is intended that the farm be stocked in February so that the crop can be harvested before the rains cause zero salinity in the river.

The farm owner practices improved traditional techniques, using lime and some rice-bran as feed.

During the rainy season the central part of the pond is cultivated and the peripheral canals are stocked with freshwater fish and prawns (Macrobrachium spp.). Information can be gathered on this part of the culture cycle also

It is important that this farmer receive sufficient attention from the NC to ensure that the new techniques suggested are employed effectively and the information generated is reported.

Only slight modifications to the nursery pond are required (principally the construction of a gate with screens).

The NPD is to ensure that this site also receives attention from the NC's during the set-up and culture of the nursery phase

10. International Training

The FIRI Officers back to office report recommends a period of 'hands-on training in shrimp health management' in Thailand.

This timing would be disruptive to the project, since officers proposed for training have roles to play in the project implementation.

Hands-on training in shrimp health management in Thailand is difficult due to the lack of extensive farm systems (this is the case in most south-east Asian countries). Whilst trainees can be shown all the diseases that are found in Bangladesh, the management solutions are not always appropriate.

The best training course on offer in Thailand is the AAHRI course in Shrimp Health Management - this training course has been modified to suit less intensive systems (although does not actually deal with the low yield Bangladesh type system).

A tailor made practical programme might be possible, but this will require consultation with the appropriate persons.

If the training component can be delayed until 1998 there is time to formulate an appropriate training programme.

Tentative timetables and costings for the training will be prepared after formulation of the training programme (Before October 1997).

After consultation with the Consultant on Extension and the NPD, the proposed persons for the hands on training are recommended as follows :

Mr. Masadur Rahman (NPD) - As head of the Bangladesh DOF shrimp cell he plays a central role in defining the DOF/GOB approach to shrimp farming in Bangladesh.

Mr. Swapan Kumaradeb (DFO Bagherat) - Since this district includes both Penaeus monodon and Macrobrachium culture, training would be very timely for this DFO. The consultant feels that this district will shortly be facing problems not only in its P. monodon culture but also in Macrobrachium farms. Many of the culture difficulties faced in P. monodon ponds parallel those of Macrobrachium ponds.

Mr. Mohamed Abdul Alim (Tanah Fishery Officer, Maheshkhali) - This officer showed good knowledge and has practical experience in shrimp farming. His English language ability is excellent.

Mr. Abdur Rouf (Research Officer, ADB Project, Cox's Bazar) - The consultant has not met this candidate, but he was proposed by the Consultant on Extension after his mission to Cox's Bazar.

11. Equipment Requirements

After discussions with both Mr. Masafur Rahman (NPD) and Dr. Siriwardena (Consultant on Extension), it was concluded that certain changes should be made in the final equipment list. Those changes mostly required the shedding of items considered to be of limited use to the project and the redirection of some of the funds to the demonstration farms.

There are no laboratory facilities at the project sites and it is recommended that only basic water quality testing equipment be supplied. The rapid test kits for pondside water quality sampling are the most suitable for the officers collecting data from the field. If these kits are used in conjunction with a pond data check list (see Consultant on Extension Mission Report) good quality data should be obtained surrounding the conditions prevailing at the farm.

The prices provided for equipment are all tax inclusive prices for purchase in Dhaka. The prices may be artificially high since suppliers do not have catalogue prices. It is suggested that the FAOR Dhaka reconfirm these prices.

12. Training Manual

This training manual is to be prepared by the Consultant on Extension according to his terms of reference. Technical inputs have been provided by the Consultant on Health Management in this report in section regarding workshop material and demonstration farm technical information. It is expected that further inputs will be necessary after the completion of the mission.

Translation of the manual into Bangla is the responsibility of the NPD (Mr. Masadur Rahman) according to the work plan of the FIRI consultant (Dr. R. Subasinghe). There will be some costs incurred for the publication of the manual (approximately 200 copies are required for provision to DFO's, TFO's and NGO's). Printing costs are high for limited numbers of copies, so a quote for 500 copies has been included. The training manual will include also include simplified extension material which can be copied and distributed to farmers.

The extension material may be produced as photocopies or offset-litho (Roneo) for distribution to farmers. The number of farmers to be trained is approximately 2000. Since the extension material will need to be simplified and presented in the form of pictures, it is envisaged that some artwork will be required.

13. Conclusions

The status of shrimp health and factors affecting shrimp health management in Bangladesh have been assessed.

Due to the timing of the mission many farms had already ceased operation or were experiencing problems. This is principally attributed to unacceptably low salinity conditions in the ponds.

A second period of problems to the farms is March-April and information for this season is required for a more complete picture of disease problems to be obtained. It is losses during this time that causes farmers to re-stock and attempt culture during the monsoon period. This inevitably ends in failure.

The consultant believes that SEMBV is still a potential threat to Bangladesh shrimp farms. But this cannot be confirmed without data for the period March - April.

Management solutions to the problem have been developed and detailed in this report and the report by the Consultant for Extension

Environmental factors are probably responsible for the majority of shrimp losses and low production in Bangladesh shrimp ponds.

The consultant believes that only one crop of Peneaus monodon can be produced per year in Bangladesh due to climatic limitations. There are a few areas that may be able to produce two crops per year however, these are an extreme minority

There is a considerable lack of reliable data concerning disease and environmental conditions in Bangladesh shrimp farms. The data derived form this TCP will considerably assist in identification of key environmental factors relating to shrimp health.

Due to social and economic pressures on land and resource use, diversification of species is recommended. The improvement of by-catch yields in ponds during the shrimp crop could also be improved

Four Farm locations for demonstration of techniques for good shrimp health management have been identified. These should commence operations mid-February and no later than mid-March

The management recommendations and methods for the demonstration farms have been described

It is essential that the National consultants produce monthly reports detailing progress and results from data collection. These reports should be provided both to the NPD and FAO

Due to potential disruption to the project international training should not take place until early 1998.

The international training programme has not been devised, but will be formulated before October 1997 together with expected costs

The equipment required for the project have been described and provisionally costed

The material for the extension training manual has been detailed and will be put into manual form by the consultant on Extension

Provisional costings for the production of the manual and extension material have been detailed

APPENDIX I

Commencing Early October, the main priorities of the NC's for the first six months are:

Identify farmers for cluster workshop training during the visit of the Consultant on Extension (Dr. Sunil Siriwardena). These training workshops will take place during December '97 - February '98. The farmers identified for the training will also be surveyed (see Consultant on Extension mission report). The information form the survey will assist in identifying problems and needs of the farmers.

The data required is detailed by Consultant on Extension and includes; farm location and characteristics from several shrimp farming districts, basic water quality parameters, basic health checks of shrimp. It will not be possible to derive a great deal of information from farms prior to stocking in February, however the NC's should collect data from approximately 100 farms each regarding the basic conditions in the ponds at the time of surveying. This supporting data will enable better recommendations for pond management during the season June - January to be made. the test kit sets (Hach FF1A) supplied by the project have enough reagent for 100 samples. If more than 100 locations are sampled then an additional kit could be requested. The second kit should not be supplied until data form the first 100 farms is received.

Other crops farmed (e.g. freshwater fish, freshwater prawn, rice, salt , other)

The additional farm information required from the survey is detailed by the Consultant on Extension.

The modifications and improvements to the demonstration farms should be supervised by the NC's. Principally this will involve the development of a nursery pond and the sluice gates and screens. The NC should also supervise and keep records of the following activities:

4) Surveying of postlarvae sellers should also be performed. The data collected should include:

APPENDIX II

FOR THE SUCCESS OF THE DEMONSTRATION FARMS GOOD RECORD KEEPING OF ALL MANAGEMENT ACTIVITIES ARE ESSENTIAL

The nursery pond water must be free of predators, limed and fertilized at least one week before stocking

The nominal costs for the demonstration farm can be broken down as listed in the table below.

Some flexibility has been included since not all the nursery ponds will be the same size, volume and have the same stocking density.

The bunds of the nursery should be complete to give a nursery area of approximately 1 acre

Add 1-2 kg TSP and 1-2 kg urea to 1 acre nursery of water depth 0.6 m. every day for 5 days (or until pond colour becomes light green or brown).

Once pond colour develops do not fertilize for 2 -3 days until colour starts to become pale

Try to equalize salinities of nursery and postlarvae holding tank one day before stocking

If shrimp in the nursery appear to have empty guts, but appear in good health the feeding may be increased slightly.

Check the condition of the nursery pond bottom, if it has become fouled and black, exchange water and feed in a different area.

The following table is for nursery stocking densities of 10 and 20 postlarvae/m2

4) Mash all the ingredients and rub though a sieve to give small particles (diameter = 2 mm)

After 2 weeks use a lift net with some feed to attract the shrimp - are they growing?

Check the shrimp for external fouling (dirty shell, gills, dirty legs) - change water in nursery and feed in different area

Check the shrimp for red gills (low oxygen) - try to change water and move water in pond. Reduce feeding

Check the shrimp for full guts - indicates normal feeding. if empty disease is possible look for other indications.

Check the shrimp for soft shells - indicates low alkalinity or low salinity - lime pond (50 kgs)

Check the shrimp for abnormal behaviour - swimming at surface, moribund at edge - this indicates disease condition - look for further evidence of cause.

It is vital that some estimate of the survival of the juveniles in the nursery is made - only in this way can an estimate be made of the stocking density to the main grow-out pond. If this data is not obtained the value of the nursery cannot be derived

Alternative method of harvest is to cut the bund - but the juveniles should be gathered using a seine net to estimate numbers

APPENDIX III

Disease can be EITHER an infectious agent (bacteria, protozoa or virus) OR due to poor environmental conditions (low dissolved oxygen, high temperature, low pH, toxic substances etc.).

Pond conditions that are stressful will make shrimp weak and disease conditions will be common

This begins with loss of appetite (empty gut) and lack of moulting (hard chalky shell, external fouling)

If the conditions persist, infections will start to occur - bacterial disease, fouling organisms and some virus diseases

This is when the shrimp will start to appear at the edge of the pond in high numbers and display abnormal behaviour (e.g. swimming at the surface, moribund at edge of pond, do not escape when disturbed)

In severe cases mortality will occur on the pond bottom and few signs will be seen at the edge of the pond

Too low (< 18oC) is stressful and shrimp seek deep water or bury in the sediment - this can cause fouling and expose shrimp to toxic conditions

Shrimp often move to deep water to avoid temperature extremes and this can cause crowding. If deep areas of the pond are sampled with a cast net and many shrimp are caught , this indicates that the shallow areas of the ponds are stressful to the shrimp (usually larger animals)

If dissolved oxygen is < 4 mg/l the condition is stressful and shrimp will slow down feeding

If this occurs frequently, slow growth and lack of moulting will be observed, shrimp will become weak and develop other infections (bacteria and/or external fouling)

Shrimp already infected by white spot virus (SEMBV) appear to be very susceptible to low oxygen conditions. If these conditions occur it can cause very rapid, high mortality.

If dissolved oxygen is below <2 mg/l this can be lethal, especially to larger shrimp

Dissolved oxygen concentrations above 2 mg/l can still be lethal if other conditions exist such as gill fouling or other stressors (e.g. pH too low, temperature too high, etc.).

Shrimp affected by low dissolved oxygen will often display red gills in the early stages. If the conditions persist there will be other infections and problems making diagnosis more difficult - since shrimp will appear to have bacterial disease and fouling.

Usually low water pH indicates that the pond bottom has an even lower pH. This means the conditions at the pond bottom are even more stressful (an exception to this is after rainfall when acid is washed out of acid soil at the edge of the pond or the bunds)

Indication on shrimp are blackening or erosion of swimming legs or the tail. Shrimp may also appear red as a stress reaction.

Low pH also increases the toxicity of hydrogen sulphide (H2S). This is produced in very dirty pond bottoms and has a 'bad egg' smell. Hydrogen sulphide is very toxic to shrimp.

High pH is also stressful, although this is mainly due to the effect of increased toxicity of ammonia. If there is little ammonia in the pond then high ph can be tolerated.

If salinity is too high (> 35 ppt, this does not occur in Bangladesh) then shrimp stop feeding and growth becomes very slow

Since the shrimp do not moult there will be an increase in external fouling and eventually bacterial disease.

Shrimp tolerate low salinity very well and will grow normally at salinities as low as 5ppt.

At salinities below 5 ppt conditions become more stressful and growth may slow down, also moulting may be affected

Shrimp will tolerate freshwater 0 -1 ppt for a short time, however they will not moult. If they do not moult they will not feed and gradually weaken. Eventually they will die trying to moult and appear to have soft shells. Otherwise they will die of bacterial disease with very hard shells because they have been unable to moult

In Bangladesh shrimp ponds, the change of salinity of freshwater in ponds usually causes the mortality of many of the big shrimp for this reason

Shrimp infected with white spot virus (SEMBV) are also very sensitive to salinity change and very low salinity will kill infected animals rapidly. This is especially the case if a large water exchange takes place and the incoming water is fresh (i.e. during June - July).

Since low salinity water contains little alkalinity and low calcium and magnesium, soft shelling of the shrimp after moulting is common. This is particularly severe if the pond soil is acidic.

Short term measures to improve this condition are to lime the pond with agricultural limestone (50 - 100 kg/ha). Flushing the pond with brackishwater (if available) will alleviate the problem quickly

Water exchange on the rising tide may provide water of higher salinity in some areas

High suspended solids loading is stressful to shrimp since it blocks the gills and reduces the transfer of oxygen to the animal.

In this condition the actual stress is low oxygen , but it is caused by the suspended solids

Suspended solids may also contain a high organic component. This acts as food for bacteria and protozoa which will infest the gills of the shrimp.

high suspended solids loading reduces the transparency of the water and reduces the production of oxygen by phytoplankton. This causes lower than usual oxygen concentrations.

In these conditions there are two factors influencing the availability of oxygen to the shrimp - gill blockage and reduced oxygen concentration in the water.

The condition of the shrimp in these circumstances is that of fouled or discoloured gills (brown, grey , black). The shrimp will often be seen at the edge of the pond and display a reddened appearance. Often the shrimp will be covered in external fouling.

Toxic conditions are common in intensive systems where there is a high input of feed

Toxic conditions can occur if too much fertilizer is used in a pond. This is especially the case if the fertilizer does not dissolve and lies on the pond bottom

The result is a high use of oxygen and formation of ammonia or hydrogen sulphide in the water.

These conditions will be made more severe if the pH of the water is too high or too low.

If there is a high loading of organic silt in the pond this can settle and cause the formation of black (anoxic - no oxygen) muds. Muds such as these can produce toxic conditions if water is not exchanged regularly (or if the water in the pond is not well mixed).

Deepwater areas of ponds often have conditions such as this. The oxygen concentration may also be low in these areas. This can be a problem if the shrimp move to the deepwater to extreme temperatures in the shallow areas of the ponds.

Pesticides can cause mortality, deformity or soft shelling of shrimp if present in the pond environment. This is a concern if the inlet water contains pesticides from agriculture, or if the ponds are used in rotation with rice cultivation (paddy). In these cases is best to check what chemicals are used in the pond during the paddy crop.

The result of these combination of stresses is usually more severe than any one individual stress

E.g. When stocking postlarvae in a pond, as much as 50 % can be killed by a 10ppt salinity shock OR by a 10oC temperature shock.

BUT if postlarvae are exposed to BOTH temperature and salinity shock at the same time, then only 5 ppt and 4oC are required to create the same mortality (50%).

In deep water there may be low oxygen conditions therefore the shrimp become stressed

If the temperature becomes too high the oxygen concentration of the water is reduced

Since it is raining there is little sunlight, so phytoplankton production is reduced - this reduces oxygen concentration in all the water

The rain may wash acidity from the walls of the pond lowering pH and increasing the toxicity of hydrogen sulphide in the deepwater area

The shrimp are now exposed to low temperature, low dissolved oxygen, low pH and also toxic hydrogen sulphide

Suspended solids reduce light penetration to the pond, reducing phytoplanton production of oxygen

Suspended solid can block the gills of the shrimp reducing the availability of oxygen to the shrimp

If stressful conditions occur regularly, or occur over an extended period of time what is the effect?

This is displayed as external fouling, hard shells, thin tail muscle, and hard chalky shells that crack easily

The hepatopancreas may become infected with bacteria - changing colour, size and texture

Gill colouration may change depending on the cause of the condition - displaying grey, brown, red or black colouration

Brown gill indicates plankton fouling (plankton crash), or iron salts leaching from acidic soils (low pH)

Black gill - all of the above gill conditions will eventually give black gills if the condition persists for a long period. This is because the gill tissue eventually dies, and this dead tissue becomes blackened (with melanin).

After an infection starts the shrimp may still be able to recover if suitable conditions are restored in the pond.

If the shrimp are too weak to moult (i.e. the condition has persisted for a long time) then the chances are slight that the animals will recover.

If the problem is caused by deteriorated water quality (i.e. toxic conditions, low pH, low dissolved oxygen) then water exchange may improve the situation.

In this case water exchange and slight feeding may assist the animals in moulting and increased available feed after the moult.

If the problem is caused by low temperature or low salinity then water exchange will not be effective.

1. Appendages should be clean and intact (pleopods, legs, antennae, telson and uropods)

3. Shell (carapace) should not be SOFT or should not CRACK easily (normal moulting)

If pond conditions are improved there is a good chance that some of the stock will survive.

Eating dead infected animals in the pond (causes spread within the pond population)

Water containing virus particles (If water from infected ponds discharged this may be possible, but is the least likely of all three)

Shrimp often require stress for this disease to spread in the population and cause high mortality

The two main stresses that encourage this virus to cause large scale mortality are

Periods of heavy rain have been found to cause large scale mortality for this virus also

Shrimp cannot moult and often show external fouling. There are usually large white spots within the carapace (head and tail). the white spots usually have a slightly clearer centre.

Heavy mortalities following a sudden environmental stress in the pond such as low dissolved oxygen, low salinity, rainfall, low pH etc.

When heavy mortalities occur, many of the shrimp may not have the characteristic white spots.

There are many carrier species of the virus (e.g. Metapenaeus monoceros, Macrobrachium rosenbergii other wild crustaceans).

Use of wild postlarvae may reduce risk of infection due to lower incidence (weak infected animals die before stocking)

Importation of postlarvae from Thailand and India is a significant risk due to the high incidence of the virus in some hatchery stocks.

Use of a nursery system can provide a large healthy animals to stocking the main pond. This should reduce infection at the juvenile stage.

Are you sure that the postlarvae are from the wild and not from a hatchery? Many operations merely hold postlarvae from hatcheries in other areas.

Other shrimp (M. monoceros, P. indicus, Macrobrachium spp.) and fish (catfish, sea bass and gobies etc.) provide 30 - 40 %

Other shrimp (horina, loilla, chaka) and fish (catfish, sea bass and gobies etc.) provide 10 - 20 %

It would be better to increase Bagda yield and reduce other shrimp species for increased income

If the water becomes too dark coloured exchange some water and reduce fertilization

If too much manure is applied then the pond bottom will become fouled and cause problems for the shrimp

Netting screens can reduce the entry of large predators to the pond (24 holes per inch)

Deep water areas should have clean mud bottoms (i.e. mud is not black or foul smelling)

Lime application can improve the condition of acid soils and increase water fertility

Lime should be applied after rainfall in ponds with acid soils (e.g. mangrove soils)

Re-stocking ponds during culture may not be effective because the postlarvae are eaten after stocking

Use of a nursery pond can provide a safe healthy environment for small postlarvae

All predators removed (by draining and drying and/or using Teaseed : 48 - 72 kg/acre, water depth 0.6 m)

Transfer by using baited lift net (2m x 2m), do not feed pond, only feed capture net

Transfer by breaking bund (not a good method since no estimate of shrimp released is obtained)

After 2 weeks use a lift net with some feed to attract the shrimp - are they growing?

Check the shrimp for external fouling (dirty shell, gills, dirty legs) - change water in nursery and feed in different area

Check the shrimp for red gills (low oxygen) - try to change water and move water in pond. Reduce feeding

Check the shrimp for full guts (indicates normal feeding) - if gut is empty, disease is possible, look for other indications.

Check the shrimp for soft shells - indicates low alkalinity or low salinity - lime pond (50 kgs/ha)

Check the shrimp for abnormal behaviour - swimming at surface, moribund at edge - this indicates disease condition - look for further evidence of cause.

If shrimp in the nursery appear to have empty guts, but appear in good health the feeding may be increased slightly.

Check the condition of the nursery pond bottom, if it has become fouled and black, exchange water and feed in a different area.

The following table is for nursery stocking densities of 10 and 20 postlarvae/m2

4) Mash all the ingredients and rub though a sieve to give small particles (diameter = 2 mm) and dry

APPENDIX IV

Item	Unit cost	Traditional	Traditional Sub-lessee LOW	Traditional Sub-lessee HIGH	Improved Traditional Sub-lessee LOW	Improved Traditional Sub-lessee HIGH	Improved Traditional Sub-lessee + Nursery
Stocking density	Pieces / sq. metre	2/m2	2/m2	2/m2	2/m2	2/m2
Yield shrimp/fish	kg/ ha	70 kg/ha	75 kg/ha	120 kg/ha	120 kg/ha	150 kg/ha	100 kg
Yield P. monodon	kg / ha	70 kg/ha	100 kg/ha	150 kg/ha	150 kg/ha	200 kg/ha	288 kg
P. monodon Survival	%	12 %	17 %	25 %	25 %	33 %	48 %
Costs (TK / ha )
Rent govt	TK 3750 / ha	3,750	-	-	-	-	-
Rent sub	TK 4,500 -	-	11,250	11,250 1	11,250	11,250	11,250
Postlarvae	TK 0.6 each	12,000	12,000	12,000	12,000	12,000	12,000
Labour	TK12,000 / 6 man months	6,000	6,000	6,000	6,000	6,000	6,000
Screening	TK 1,000	1,000	1,000	1,000	1,000	1,000	1,000
Fertilization	100 kg @TK 12/kg	-	-	-	1,200	1,200	1800
Limes	500 kg @ TK 5/kg	-	-	-	2,500	2,500	2,500
Nursery2 Teaseed Fertilizer Screens Feed	150 kg @ TK 45/kg 30 kg @ TK 12/kg TK 1,000 76 kg @ TK 40/kg	-	-	-	-	-	6,750 360 1,000 3,040
Income (TK / ha )
Shrimp and fish	TK 60/kg	4,500	4,500	7,200	7,200	9,000	6,000
P. monodon	TK 300/kg	21,000	30,000	45,000	45,000	60,000	86,400
	Total cost (TK)	22,750	30,250	30,250	33,950	33,950	45,700
	Total income (TK)	25,500	34,500	52,200	52,200	69,000	92,400
	Net profit (TK)	TK 2,750	TK 4,250	TK 21,950	TK 18,250	TK 35,050	TK 46,700
	Net profit ($ US)	$ 64	$ 99	$ 510	$ 424	$ 815	$ 1,086

2 Nursery survival assumed at 60 %, grow-out survival assumed at 80 %. the overall survival is 48%.

Profit increases with increasing inputs, provided production losses are not significant.

The low yield figures reflect the effect of disease losses or low yield. Lowest yields reported lie around 70 kg/ha/yr. At the low yield figures traditional and improved traditional farms are borderline profitable and in many cases have lost money when farmers have attempted to restock ponds to make up for losses earlier in the year.

The effect of low yield in Improved traditional system is to lower profitability below traditional system. This may explain why many farmers have not adopted the improved traditional method or have reverted to the traditional method

The use of the improved traditional method and/or the use of nurseries can significantly improve production. However, the input costs are greater and many farmers are unwilling/unable to risk the additional finance required.

The additional costs of the nursery system (Tk 11,150) are equivalent to an extra 18,000 postlarvae. Farmers appear more ready to risk money in restocking than in ensuring that survival is higher in the system. If survival is improved in the nursery system, the requirement for postlarvae would be reduced - this would be a significant saving in this system.

Profitability is highly sensitive to rental price of the farm in the traditional and improved traditional systems. The figure used is relatively low and higher rental costs have been encountered (TK 15,000 / ha/year).

As in all shrimp farms profit is also highly sensitive to sale price. If the shrimp harvested are too small then profits will be greatly reduced. Similarly, any effects of markets on shrimp price will influence farm viability (e.g. EUC Ban on shrimp).

No account has been made of potential opportunity costs of labour, costs of earthworks and sluice repairs/construction. Similarly the opportunity cost of the investment has also not been considered.

The harvest of other species contributes little to income, but may be significant in terms of food security for the farmers, since harvesting of by-catch is continuous.

APPENDIX V


No	Item	Make/model	Total Cost	Source	Comments
1	Computer	1 gb hard drive, 133 mHz CPU, floppy disk, (CD rom optional)	$3,000 ??	Purchasing dept in FAOR Dhaka mto advise	Include Microsoft Office software Located at DOF Shrimp Cell
1	Laser printer (b/w)	Basic laser printer as used in FAOR Dhaka	$ 1,300 ??	Purchasing dept in FAOR Dhaka mto advise	Located at DOFShrimp Cell
1	Photocopier	Canon 1215 as used in FAOR Dhaka	$ 3,000 ??	Purchasing dept in FAOR Dhaka mto advise	Located at DOF Shrimp Cell
1	Outboard motor	Yamaha 55 hp (no larger)	$ 8,000 ??	Purchasing dept in FAOR Dhaka mto advise. The Yamaha dealer in Dhaka is Karnapully Ltd, Kaknail, Dhaka	Cox's Bazar District Fisheries Office
2	Salinity refractometer	Atago S/Mill Salinity 0-100 o/oo	$ 488 - 556 ($ 278 each) ($ 244 each)	D. U. Instruments Ltd. Halim Foundation PVT. Ltd	For NC/TFO use during project To be returned to DOF Shrimp Cell on project termination
2	Field pH meter and pH probe	Hach 1, pH meter Catalogue no: 43800-00	Approx: $ 1000 (approx $500 each)	D. U. Instruments Ltd. Hach Ltd. USA	For NC/TFO use during project To be returned to DOF Shrimp Cell on project termination
2	Secchi disk	-	$ 20 ($ 10 each)	DOF / Local construction	For NC/TFO use
6	Aquaculture water quality test kit	Hach FF1A Catalogue no: 2340-02	$ 2,934 ($ 489 each)	D. U. Instruments Ltd. Hach Ltd. USA	For NC/TFO use for field data collection during project. This item is disposable after chemical reagents are finished
4	Soil ph test kit	Orbeco analytical systems, Hellige-Truog Soil reaction pH tester	$ 222 ($ 55 each)	D. U. Instruments Ltd.	For NC/TFO use for field data collection during project. This item is disposable after chemical reagents are finished
	Total cost		$ 20,032
	Halim Foundation Pvt. Ltd., 31 Bangabandhu Ave., Dhaka - 1000, G. P.O. Box 2176, Telephone: 9552045, 9568338 D. U. Instruments Ltd., 30 Bangabandhu Ave., Dhaka -1000, G.P.O. Box 2829, Telephone: 9551253-4, Fax: 9568340

APPENDIX VI

Under the general direction and supervision of the Chief, Operations Group, RAPR to whom the staff member will be directly responsible, the guidance of the designated technical and operations officers and with frequent referral to the national authorities directly concerned in the Government Executing Agency, in particular the project National Co-ordinator, the consultant will carry out the following duties as described under the work plan :

- The consultant will assess the status of shrimp culture with special reference

- The consultant will evaluate the timely needs for a strategic health management programme for the sustainable development of shrimp industry

- The consultant will conduct two 3-day training workshops on low-tech health management strategies and pond husbandry management practices to

20 July	Hatyai - Bangkok	Arrive 17.40
21 July	Bangkok/FAO Dr. Rohana Subasinghe (FAO) Dr. A. Tacon (FAO) Dr. M. Halwart (FAO) Dhaka Dr. S. Siriwardena (Consultant on Extension) TCP/BGD/6714(A) Mr. H. Konuma (FAOR Dhaka)	Pre-mission briefing TCP/BGD/6714(A) Arrive Dhaka 12.00 Discuss progress and mission objectives Explain mission objectives
22 July	Dhaka - Chittagong Dr. S. Siriwardena (Consultant on Extension) Chittagong - Cox's Bazar	Arrive 1.00 pm Arrive 5.00 pm Visit District Fisheries Office (DFO) Cox's Bazar arrange itinerary. Informed of unavailability of DFO Cox's Bazar
23 July	Teknaf district Dr. S. Siriwardena (Consultant on Extension) Mr. Alim (TFO Teknaf)	Visit traditional farms and discuss production problems with sub-district (Thana) Fisheries Officer and farmers Visit disused semi-intensive farm and nursery now converted to fish culture
24 July	Rahmpur district Dr. S. Siriwardena (Consultant on Extension) Mr. Alim (TFO Maheshkhali) Cox's Bazar Dr. Masadur Rahman (NPD) Dr. Nitya Nanda Das (DFO, Cox's Bazar)	Visit ADB shrimp project site and demonstration unit Visit IDA shrimp culture site and discuss problems with farmers Discuss shrimp production problems in Bangladesh Finalize workshop arrangements
25 July	Cox's Bazar Dr. S. Siriwardena (Consultant on Extension) Dr. Masadur Rahman (NPD)	Day 1 - Officers discussions and lectures Thana Officers training workshop in shrimp health management and improved production techniques
26 July	Cox's Bazar Dr. S. Siriwardena (Consultant on Extension) Dr. Masadur Rahman (NPD)	Day 2 - lectures and practical problem solving Thana Officers training workshop in shrimp health management and improved production techniques
27 July	Cox's Bazar Dr. S. Siriwardena (Consultant on Extension)	Day 3 - field visit Thana Officers training workshop in shrimp health management and improved production techniques
28 July	Cox's Bazar - Chittagong Dr. S. Siriwardena (Consultant on Extension) Chittagong - Dhaka	Finalize arrangements for travel to Khulna Arrive Dhaka 6.30 pm
29 July	Dhaka - Jessore Dr. Rezaul Hasan (DANIDA Oxbow Lakes Small Scale Fisherman Project) Dr. S. Siriwardena (Consultant on Extension) Satkhira Dr. S. Siriwardena (Consultant on Extension) Thala Dr. S. Siriwardena (Consultant on Extension)	Arrive 8.30 am Discuss production strategies from extensive freshwater systems and potential problems of freshwater shrimp production. Discuss potentials of cage fish cultivation in Bangladesh Meet Satkhira Thana Fisheries Officer visit farms Visit shrimp processing factory discuss current market and shrimp collection / processing strategy Visit proposed Demonstration Farm. Evaluate changes required and discuss production history of farm with owner
30 July	GENERAL STRIKE Khulna Mr. Md. Rezaul Karim (DFO Khulna) Dr. S. Siriwardena (Consultant on Extension)	NO TRAVEL POSSIBLE Further discussions of shrimp farm situation and coastal aquaculture development Finalize arrangements for training workshop Request inclusion of all sub-district fisheries officers in training workshop
31 July	Domuria Dr. S. Siriwardena (Consultant on Extension) Md. Rezaul Karim (DFO Khulna) Botiagata Dr. S. Siriwardena (Consultant on Extension) Md. Rezaul Karim (DFO Khulna)	Visit shrimp farms and discuss culture problems with local farmers Visit potential demonstration farm Discussions regarding requirements for farm with owner
1 August 2 August	Khulna Dr. S. Siriwardena (Consultant on Extension) Khuna Dr. S. Siriwardena (Consultant on Extension)	Day 1 - Lectures and Officers discussions Thana Officers training workshop in shrimp health management and improved production techniques Day 2 - Lectures and practical problem solving
		Thana Officers training workshop in shrimp health management and improved production technique
3 August	Khulna (Botiagata) Dr. S. Siriwardena (Consultant on Extension) Jessore Dr. Rezaul Hasan (DANIDA Oxbow Lakes Small Scale Fisherman Project)	Day 3 - Field visit Thana Officers training workshop in shrimp health management and improved production techniques Visit Macrobrachium hatchery and advise on health, water quality and nutrition problems causing low production and survival.
4 August	Jessore - Dhaka Dhaka	Arrive 10.00 am Prepare project material with Dr. Siriwardena
5 August	Dhaka Mr. Hiroyuki Konuma (FAOR) Mr. Masadur Rahman (NPD) Dr. S. Siriwardena (Consultant on Extension) Dr. Md. Liaquat Ali (DG, DOF)	Discuss mission progress Discuss recruitment of NC's Discuss overseas training Finalize equipment list Discuss NC workplan, reporting and assistance Current problems surrounding shrimp culture in Bangladesh
6 August	Dhaka Mr. Chris Price (Field Manager, FMS/DFID)	Discussions regarding situation of FMS/DFID assistance in the freshwater shrimp sector in Bangladesh. Potential future projects and complementarity with FAO TCP 6714(A).
7 August	Dhaka FAOR Office DOF Office	Equipment sourcing and costing
8 August	Dhaka	Report writing
9 August	Dhaka	Report writing
10 August	Dhaka FAOR	Finalize equipment budget
11 August	Dhaka NPD / DOF	Final data collection Discuss project and mission
12 August	Dhaka - Bangkok FAOR Bangkok	Submit mission report Depart 14.00 Arrive 17.20
13 August	Bangkok Ms. Dora Blessich (FAO/RAP)	Mission debriefing
14 August	Bangkok - Hadyai

Year	Export	Shrimp yield from coastal aquaculture	Proportion of shrimp yield that is P. monodon	Estimated P. monodon yield1	Prod'n area	Yield per ha2
	mT	mT	%	mT	ha	kg/ha
1985 - 86	13,631	14,658	68	9,967	87,300	114
1986 - 87	16,275	14,773	-	-	-	-
1987 - 88	15,023	17,889	-	-	-	-
1988 - 89	15,386	18,235	63 - 68	11,488 - 12,400	108,280	-
1989 - 90	17,505	18,624	57 - 62	10,615 - 11,547	-	-
1990 - 91	17,985	19,489	51 - 60	9,940 - 11,693	-	-
1991 - 92	16,730	20,335	59 - 60	11,998 - 12,201	-	-
1992 - 93	19,224	23,530	62 - 68	14,589 - 16,000	110,280	139
1993 - 94	22,054	28,302	65 - 71	18,396 - 20,094	125,000	154
1994 - 95	26,277	34,030	-	-	-	-
1995 - 96	25,227	49,260	-	-	129,689	-
1996 - 97	25,742	-	-	-	134,4483	-
Source: DOF Shrimp Cell Reports 1The percentage proportion of P. monodon represents the species composition from the two main culture areas (Cox's Bazar and Khulna). The estimated yield of P. monodon lies between the upper and lower value. 2 Estimated as the mean yield of P. monodon divided by total culture area (this value will be higher due to the use of total farm area in the calculation). 3 This area is an unofficial estimate and might not be reliable.

District	Area	Targeted Yield				Actual Yield1
	ha	mT	mT/ha	mT	mT/ha
Khulna	36,719	8,200	223	3,882	106
Satkhira	34,858	8,900	255	3,309	95
Bagherat	45,259	7,600	168	5,760	127
Cox's Bazar 2	17,652	9,000	510	7,465	423
Total	134,448	33,700	250	20,416	152
1) This yield data was taken until May 1997 and so is not complete, final figures reported by DOF Shrimp Cell total approximately 25,742 tonnes. 2)Earlier data reports a culture area of 28,209 ha for Cox's Bazar. It is unclear whether this discrepancy is due to farms in production or out of production. The target production figure and the actual production figures are far too high, suggesting that the area of production may well be closer to the earlier value.

*P. monodon*	By-catch	Information Source
kg/ha/yr	kg/ha/yr
100 - 200	-	FAO/FIRI Fishery Resources Officer
100 -150	60	Cox's Bazar TFO
133	83	Farmer, Teknaf
62	68	Farmer, Rahmpur
187	-	DOF Report, 1994-1995
171	148	Farmer Thala, Average 1994 - 1997
94	-	Tanah officers workshop, Khulna
175	-	BOBP, 1997
170	-	DOF, 1992 figures for area and production

	Copies	Cost /copy	Total
Full extension manual ( > 20 pages, colour)	500	$2.32	$1,162
Extension material (10 - 15 pages, photocopy)	2000	$ 0.23 - 0.35	$ 460 - 698
Artwork (10 - 20 pictures)	-	-	$ 50- 100
Total cost			$1,672 - 1,960

Item per farm	FAO cost $ US	Farmer cost $ US
Nursery bund construction	75	-
Postlarvae cost (20 - 40,000)	-	444 - 888
Screens and sluice construction	67	-
Teaseed	70	-
Fertilizer	30	-
Supplemental feed	90	-
Lime	55	-
Total	387	444 - 888

DISEASE PREVENTION AND HEALTH MANAGEMENT IN COASTAL SHRIMP CULTURE

Table of Contents

1. Disease and Production in Bangladesh Shrimp Culture

2. Postlarvae

3. Health Checks on Production Ponds

4. Potential Causes of Low Yield or Production Losses

5. Management Improvements for Traditional Farms

6. Policy

7. Shrimp Health Management Training Workshops

8. National Consultants Selection and Reporting

9. Selection of Experimental Demonstration Farm Sites

10. International Training

11. Equipment Requirements

12. Training Manual

13. Conclusions

APPENDIX I

APPENDIX II

APPENDIX III

APPENDIX IV

APPENDIX V

APPENDIX VI

	%	10/m2	20 /m2
Day	Survival	Feed per day	Feed per day
0	99	0.4	0.8
1	97	0.4	0.9
2	95	0.5	0.9
3	93	0.5	1.0
4	90	0.5	1.1
5	88	0.6	1.2
6	86	0.6	1.3
7	84	0.7	1.4
8	83	0.7	1.5
9	81	0.8	1.6
10	79	0.8	1.7
11	77	0.9	1.8
12	75	0.9	1.9
13	74	1.0	2.0
14	72	1.1	2.1
15	70	1.1	2.2
16	69	1.2	2.4
17	67	1.2	2.5
18	66	1.3	2.6
19	64	1.4	2.7
20	63	1.4	2.8
21	61	1.5	3.0
22	60	1.5	3.1
23	59	1.6	3.2
24	58	1.7	3.3
25	56	1.7	3.5
26	55	1.8	3.6
27	54	1.9	3.7
28	53	1.9	3.9
29	52	2.0	4.0
30	51	2.1	4.1
30	51	2.2	4.3
	Total Feed (kg)	38	76

	%
Ingredient	Inclusion
Whole wet fish	50 - 60
Rice bran	20
Cooked rice / potato	20 - 30