As indicated in Section 3 above, freshwater prawn farming in Sindh province seems technically feasible. Furthermore, considerable private sector interest in this form of aquaculture, both by existing finfish farmers and by entrepreneurs, appears to exist. Two major factors remain, which are covered in this section, namely the potential market and an assessment of the economic feasibility of prawn culture in this province.
There is an existing domestic market for prawns in Pakistan. Prawns are found in local markets (for example in Thatta) and appear in restaurants in large cities, especially Karachi. The consensus of those consulted was that the current market is limited by supply, not demand. Both (marine) shrimp and prawns are acceptable luxury food items in Pakistan. Prawns were variously reported to be sold whole at prices from PRs 150–250/kg ($US 4.38–7.23/kg) in local markets, while the monthly averages (November–December 1995) at the Karachi Harbour Market ranged from PRs 90–220/kg ($US 2.63–6.42/kg), according to size (Table 7).
In addition, prawns are landed in Karachi from the capture fisheries. They are not treated as a separate product but are processed for export within the large (Jaira) white shrimp category, which mainly consist of the banana shrimp, Penaeus merguiensis (Table 8). The value of this shrimp category is recorded in Table 9. While I was in Karachi, freshwater prawns were being sold at the harbour for PRs 250/kg and PRs 170/kg (both for large sizes, but the latter for “poorer quality”). These prices were said to be inflated, due to the protest/strike which was on-going at that time. PRs 140–150 was said to be a more normal figure. A similar differential was reported for large marine shrimp - PRs 310–325/kg during the strike but PRs 250/kg normally.
While there is undoubtedly room for further expansion of prawn exports within this large white shrimp category, the availability of sufficient supplies (from aquaculture) in Pakistan would make its separation into a distinct product worthwhile. Generally, prawns benefit from being marketed as a product in their own right, not just combined with other, marine, species. Though some countries (such as Brazil) sell cultured or captured prawns only in their own domestic market, others (such as Bangladesh, Myanmar, Thailand and Viet Nam) also exploit export opportunities. Pakistan should be able to avail itself of these opportunities too but would need to ensure that its product quality controls comply with the requirements of the importing countries.
In summary, therefore, there seems to be both domestic and export potential for farmed prawns from Pakistan and an average farm-gate price of PRs 135/kg ($US 3.94/kg) appears realistic for assessing the feasibility of freshwater prawn culture in Sindh in 1996. Farmed prawns generally have a greater value in other countries (Table 10), so Pakistan should have some potential advantage in this respect.
The unit costs utilized in assessing the economic feasibility of prawn farming (and in estimating the cost of government hatchery and demonstration facilities) in Sindh are contained in Appendix 4. An assessment of the feasibility of existing land owners or lessees initiating the small-scale farming of prawns in Sindh is detailed in Appendix 5. This shows that the capital cost (excluding land) would be PRs 125 000/ha. Anticipated gross income would be PRs 202 500/ha/year. Annual running costs (excluding capital write-off) would be PRs 162 700, leaving an annual gross profit of PRs 39 800/ha/year. This compares with a profit of PRs 34 750/ha/year estimated by PARC (1995), which was based on a lower projected output. In both cases, capital costs were excluded. In the present estimate (Appendix 7), writing off the capital over five years would reduce the profit for that period to PRs 14 800/year.
The above estimates are sensitive to a number of major factors, namely feed and seed costs, productivity, and farm-gate product value. A reduction in average farm-gate product value from PRs 135/kg to PRs 108/kg would reduce gross profit to nil. An increase in feed costs of 50%, caused either by poor Feed Conversion Ratio (FCR) or increased unit feed costs (or a combination of these factors) would reduce gross profitability by nearly 57% and there would be no net profit until the sixth year. If seed costs rose from the estimated PRs 1.0 each to PRs 1.5/juvenile, gross profit would fall by nearly 63%. Lower productivity would be partly balanced by reductions in the two major running costs, namely feed and seed, but would also affect productivity. The profitability of freshwater prawn farming is most sensitive to average farm-gate product value, which could be reduced if the market proved unable to grow and absorb the increased supplies which farming would produce. A similar effect would occur if the average prawn size was smaller than estimated in this study. In view of experience in Pakistan with Macrobrachium malcomsonii. the estimate of a 40 g average at harvest is modest, so the major factor should be the effect of increased supply on demand.
At current estimated costs and farm-gate product values, when based on a single one-hectare pond constructed on existing land and operated under monoculture, prawn farming is viable in Sindh. Whether it would remain viable if land had to be purchased for the purpose would be highly site specific.
However, costing the enterprise purely on the basis of a single one-hectare pond is probably rather unfair because it allows for no economies of scale. Further ponds, with common bunds and water supplies, would have much lower construction costs. Operational costs would also not increase at the same rate as increased production area. In addition, the productivity projected in the analysis (1 500 kg/ha) is quite conservative; it may prove possible to increase productivity later. Though some costs (notably seed and feed) would increase in this scenario, increased income would more than compensate, leading to increased profitability of the venture. Further improvements in profitability should result from experiments, particularly on determining optimum stocking rates and times and harvesting programmes. These experiments should be one of the functions of the government demonstration farm, and should be designed to maximize revenue by tailoring management procedures to match market requirements.
An analysis of the comparative profitability of prawn and carp farming has not been carried out within the current study, and is likely to be highly site specific. The average market value of carps in Pakistan (Table 7) is 25–35 % of that of prawns. However, the running costs of carp farms per unit of production (particularly feed costs) would be lower than for prawn farms. While it may be possible to increase the productivity of carp farming, the productivity of prawn farming may also be higher than used in the current analysis, as noted above. Further study of this question will be necessary, and farmers will soon make their own assessment of the comparative profitability of these two alternatives. Some may well choose simply to raise their income by polyculturing prawns in their existing carp ponds.
The major constraints to the development of prawn farming are the lack of seed and the need to demonstrate technology, which sets the scene for the establishment of government facilities to stimulate the private sector, not only to rear prawns in ponds but also to set up their own small-scale hatcheries.
The establishment of freshwater prawn grow-out facilities in Sindh would have no detrimental environmental impact, since its use of resources and its discharges would not be fundamentally different, in quality or quantity, to existing carp culture. Similarly, the establishment of government prawn nursery and grow-out demonstration facilities should pose no problems. The recommended species, Macrobrachium rosenbergii. is already claimed to be indigenous. Thus, providing reasonable quarantine procedures are employed, the introduction of broodstock from abroad should not be detrimental, provided international codes of practice for introductions and transfers are employed (ICES, 1988, 1994; OIE, 1995; Turner, 1988). Competition for natural resources with other freshwater crustacea should not occur, should escapes from culture facilities take place. The effluent from government or private prawn hatcheries should preferably be treated before discharge, to limit the possibility of disease transfer to wild stock. The same caution applies to the operation of the MFD marine shrimp and finfish hatchery. However, such precautions are, so far, rarely applied in hatcheries elsewhere.
No negative social consequences from the introduction of prawn culture in Sindh are expected; indeed, the consequences should be positive, providing opportunities for increased employment, income, and (ultimately) modest foreign exchange earnings. In India and Bangladesh, the establishment of freshwater prawn hatcheries has posed some social problems because of the effect on the livelihood of the existing wild seed collectors, which is a substantial activity. Since this activity does not exist in Pakistan, there will be no problems of this type. The pond culture of freshwater prawns is probably more sustainable than marine shrimp farming, because it is less intensive in nature and does not compete for the natural resources of the coastal region. Prawn farming will not substantially affect the activities of those utilizing common resources and is most unlikely to cause any social conflict.
