The general suitability for the grow-out of prawns, for which freshwater is required, in lower Sindh has been discussed in Section 3.4 and deemed satisfactory. There should therefore be no fundamental environmental obstacle to the establishment of a government demonstration grow-out farm.
The establishment of a prawn hatchery requires access not only to freshwater but also to seawater, because prawn larvae require brackishwater (approximately 12 ppt) to survive and grow. Utilizing a site with extreme variations in salinity and/or limited freshwater availability would pose extreme difficulties.
Four major options exist, namely to establish:
- a combined hatchery/demonstration unit on an entirely new site;
- hatchery and demonstration facilities on two separate (new) sites, one coastal, the other inland;
- a hatchery on a new coastal site and grow-out demonstration facilities on an existing government inland site;
- a combined hatchery and demonstration unit on an existing government inland site, trucking in the necessary seawater supplies.
It is not advisable to set up an entirely new site. The following is therefore a review of the sites available which exist now, or are being developed, both by the provincial and the Federal governments. To improve clarity, a map has been included at the beginning of this report.
One of the critical problems experienced during the operation of the Garho shrimp farm, which contributed to its failure, was extreme variations in salinity. Most of the water in the Indus is used for irrigation purposes and its estuary is virtually eliminated during most of the year (9–10 months) causing the depletion of fish stocks and the loss of hundreds of acres of mangrove forests each year (Mirza and Baquer, 1994). Discharge from the Indus only occurs during the monsoon season. Drainage water (freshwater) is not always available and creek salinity rises to at least 45 ppt (AsDB, 1993). The problem at Garho due to lack of freshwater was exacerbated by poor water retention in the ponds and excessive evaporation. Conversely, during the rainy season ambient salinity was low because of the Indus River discharge (the site is on the banks of one of the main arms of the river, some 30 km inland from the sea), and pond salinity decreased rapidly. Zero salinity was experienced for periods of two or three days. Extreme daily temperature fluctuations were also reported.
Some records from 1988–89 still available at the Garho site were produced (Table 6), confirming the extremely high salinities reported elsewhere. Kuljis (1988) reported that salinities were only suitable at the site for marine shrimp fanning during July–October, making only one crop per year feasible. High temperatures are experienced between March and early July. Substantial and rapid changes in water temperature due to changes in wind direction occur at this exposed site.
The site currently only has caretaker staff and has been, to all intents and purposes, abandoned since 1990 because of a fatal combination of poor site selection, poor construction, and staffing difficulties. The pump house and the end of its jetty have collapsed into the sea. Severe erosion of the bunds and roadways has occurred. Pond bottoms are below the level of the outlet gates. There is no seawater or freshwater supply. Generating and other equipment is out of order, or has been stolen. Professional staff seem unwilling to work or live at this remote site, which is rapidly returning to its pre-project state.
While some further use of the site (e.g., for marine finfish culture; for lease to the private sector) may be feasible, it was not within the consultant's remit to advise on this. However, the Garho site would be totally unsuitable for use for freshwater prawn culture, either for hatchery or grow-out demonstration purposes.
Considerable effort and expenditure, both with government funds and through the AsDB Aquaculture Development Projects, has been devoted to developing this site, which has facilities for carp breeding, for training (including accommodation), and a series of demonstration ponds. It is one of the major sources of carp fingerlings to the private sector in Sindh, which is an expanding sector. However, the facilities appear to be underutilized and it is necessary for government authorities to improve farm management and staffing. It would be far more desirable to concentrate activities on an existing site which has already demonstrated some success.
Before visiting Chilya, an option which the consultant had in mind was the possibility of using (part of) the site not only for demonstrating grow-out technology for prawn culture but also for siting a small prawn hatchery. Chilya, of course, has no seawater availability but it would be possible to truck the quantities necessary for a small hatchery from a collection site (such as Hawkes Bay). Prawn hatcheries, often utilizing recirculation systems, are successfully operated on inland sites in a number of other countries, including Thailand, the Dominican Republic and Brazil. The view was expressed that there would be insuperable but unspecified difficulties in trucking, even though the travel time from Hawkes Bay to Chilya should not exceed 2.5 hours and there should never be a necessity for more than one delivery per day. In addition, if brine were trucked instead of seawater (as is practised in some other countries), the volume to be trucked would be much less. If recirculation systems were utilized, the demand for seawater would also be considerably reduced. However, there are other reasons for preferring another option (see Section 5.3), at least initially.
Although no written data were provided, the consultant was informed that the hardness of the freshwater at Chilya was 200 ppm (CaCO3), and sometimes higher. Furthermore, difficulties have been experienced with seed production of grass carp, which have been attributed to the hardness of the water at Chilya. Ideally, freshwater supplies for prawn hatcheries should have a hardness not exceeding of 100 ppm (CaCO3) but many prawn hatcheries operate on sites where water hardness exceeds this level. Iron content is also important, and should not exceed 2 ppm, but no data on this criteria was available at Chilya either. Attempts were made to obtain information on this point from the relevant water authorities but were not unsuccessful. Further investigation of this matter was suggested to GOS and MFD staff.
No technical barrier for using Chilya as a site to demonstrate prawn grow-out technology was observed during my visit. The twenty-four carp demonstration ponds (each about 0.6 ha in area), mostly provided under the AsDB project, are underutilized or not used at all. There are twenty-five 116 m3 concrete lined ponds attached to the finfish hatchery, which are only seasonally used. Providing scheduling was good, some of these ponds could be used as nursery ponds for prawns. Some of the earthen demonstration ponds could be used or adapted for prawn grow-out. Prawn culture could then be included in future training courses, for farmers and extension officers, at Chilya. Extension agents would therefore receive information on finfish and prawn culture from the same source. An adequate water supply (usually available by gravity) is immediately adjacent to the Chilya site (the Keenjhar Bager Feeder), which originates from the Keenjhar Lake (formerly Kalri Lake). The lake is 32 km long and 10 km wide. On its banks is the tomb of Noori, a fishergirl from the Mohana tribe who married King Jam Tamachi of the Sammah dynasty, evoking a popular rags-to-riches story in Sindh which, it is to be hoped, might be a good omen for successful prawn culture!
It is recommended that demonstration facilities for prawn grow-out be established at the existing government finfish hatchery site at Chilya. This should not entail any major construction work, though management would need to be modified. However, in costing the establishment of government hatchery and demonstration facilities (Appendix 7), allowance was made for full nursery and grow-out pond construction. Staffing levels would not need to be increased but some consideration should be given to providing incentives to motivate senior staff to work at the site.
Hawkes Bay lies on a sand spit 15 km West of Karachi where the MFD is confident of obtaining good quality, full strength borehole seawater, year-round (Table 11). The consultant has no reason to doubt the results of the survey (Moazzam, 1995) which selected this bay as the site for the GOP marine shrimp and finfish hatchery. The site selected is about 50 ft from the sea on one side and the same distance from a metalled road on the other, with good access to Karachi. The freshwater supply to a nuclear power station is adjacent to the site and can be accessed. Electricity and telephone services are being supplied to the site, which is almost 2.7 ha in area and has been obtained on a 30-year lease (at PRs 12 000/yr) from the Karachi Municipal Corporation.
There would be considerable benefits from siting government prawn hatchery facilities adjacent to, or within the MFD site at Hawkes Bay. Not only would this ensure access to perhaps the most reliable source of good quality seawater on the Sindh coast but it would offer the advantages of synergy with the marine hatchery, both in terms of facilities and staff contact. Clearly, the site is unsuitable for the nursery and grow demonstration work necessary to stimulate private sector development but, as indicated in Section 5.1 above, the existing GOS site at Chilya would be satisfactory for this purpose. There would be no technical problems in transferring p1–15 prawns from Hawkes Bay to Chilya by road.
It is recommended that a prawn hatchery be established within, or adjacent to, the MFD marine shrimp and finfish hatchery site at Hawkes Bay. A secondary option would be to truck seawater from Hawkes Bay to an inland hatchery constructed within the GOS Chilya site. A third option would be to establish the initial hatchery at Hawkes Bay and, later, to introduce a simple recirculation hatchery at Chilya. The latter option would have the attraction that it would demonstrate to prawn farmers mat prawn hatcheries can be successfully operated on inland sites, thus encouraging the establishment of private “back-yard” hatcheries.
The only other site mentioned by GOS staff was adjacent to the Gharo1 creek. This site was rejected unseen, because of its proximity to a large steel mill and other potential sources of water pollution. The only advantage of this site appeared to be its proximity to Karachi (and thus fewer staff location problems).
1 This is a separate place and should not be confused with Garho (see Section 5.1).