The selection of a suitable site is of great importance to fish/shrimp pond development. Basic information are needed on topography, vegetation, tidal range, occurrence of floods, weather conditions, availability of farm inputs, type of soil, water supply and presence of pollution.
A topographic survey (for land elevations) was conducted lately by the Office of Jurukur Perunding, a private land surveyor and the results of this survey indicate that the study area outside the bund is most suitable for a balanced cut and fill and for convenient water management of the ponds.
No survey was made inside the bund area, but visual observations revealed areas of high ground.
As mentioned in previous paragraphs, the area outside the bund is a mangrove swamp of Rhizophora and Sonneratia species. Inside the bund, the area is generally “padi” land, with few big trees and nipa palms (Nypa fruticans),
Tidal conditions existing in the study area were discussed briefly above (section 1.3). The tidal data obtained show that the site outside the bund can be suitable for water supply and drainage by tidal energy. On the other hand, more excavations have to be done on the area inside the bund in order to make the maximum utilization of the tidal water.
Deviation in times and heights of low and high tides at the proposed site and the secondary standard port of reference (Tanjong Dawai) are shown in Table 3. Figs. 8 and 9 show the tidal characteristics in the study area.
Water quality surveys of the Ban Merbok area were made in July and August (and continuing) at water sampling stations indicated in Fig. 7. Test procedures were in accordance with the Royal Commission Classification on water quality. Emphasis were on the following parameters (Table 2):
pH - water pH is quite constant at 7.0–7.4. These values are suitable for shrimp/fish culture.
Temperature - average temperature of the water at the sampling sites taken in July was 27°C.
Salinity - the salinity ranges from 18–30 ppt. The lower value of 18 ppt is still above the salinity of 12 ppt. Salinity of 12 ppt to 25 ppt is very suitable for Penaeus monodon culture. Salinity above 25 ppt is favourable for Penaeus merguiensis/P. indicus but at this range, P. monodon growth would be slow.
Dissolved oxygen - the results obtained from samples taken on 1 August 1979 showed that even at 0500 hours, the oxygen level was 4.4 ppm which is considered “fair” and acceptable. Throughout the day, the oxygen levels were above 5.0 ppm and this is interpreted as “good”.
Chemical oxygen demand - the chemical oxygen demand falls in a range of 1.0–4.3 ppm throughout the period of sampling. This indicates that the water is suitable for pond culture. Maximum acceptable value set by the Royal Commission Classification on water quality is 10 ppm.
Total ammonia - the results from most of sampling stations are below 0.2 ppm except for three occasions where 0.34, 0.38 and 0.74 ppm were recorded. These values are below the lethal value of 1.0 ppm level set by the Royal Commission Classification.
Samplings will be continued from the same and other stations.
At Sungai Keluang where a bund gate is located, the release of freshwater is done during low tide periods. This water was analyzed and was found to be acidic. It is suggested that further water quality tests be made at the freshwater drain at Sungai Keluang.
Heavy rains must clearly affect the quality of the water, and these can be seen by comparing the values in Table 2. Water temperature is lowered as could be expected but more interesting is the effect of rainfall on oxygen levels. Increased turbulence during rainfall may not have some pronounced effect on the increase of oxygen levels as expected. Heavy rains may wash organic matter which then oxidizes. It may be that the silt that is brought to the river by runoff water during rains may contain polysulphides which oxidize to sulphates.
Table 1 on preliminary soil analysis partly supports the idea of low oxygen levels during periods of heavy runoff, as it is shown that organic matter is rather high and hence the low oxygen levels.
Surveys on the upstream portion of the Merbok river should be conducted to show the extent of pollution from toxic pollutants such as factory effluents, insecticides, fungicides, etc. and to pinpoint the source of pollution, if there are any. Continuing river water survey shall be carried out as time will tell whether there is any increase in pollution due to industrial and agricultural practices.
Analysis of water for possible presence of zinc needs to be done as zinc is highly toxic to the cultured penaeid species. Information on the chemical constituents of Sungai Merbok water is needed further, over a period of time throughout its length, as it is the water supply of the ponds of the proposed project.
- a continuing seed survey is being conducted and the results of this survey will be processed in the future. Visual observations and information obtained from fishermen indicate that there are Penaeus monodon (udang belang), P. merguiensis/P. indicus (udang kentas), Metapenaeus spp., and Lates calcarifer (ikan siakap) fry in the rivers in the project area. The quantity of fry has not been determined however.
- it is suggested that data on a 15-year flood frequency in the area be available, if ever there is such occurrence of flooding. The information will be needed as a check, among others, on the design of the perimeter dikes.
Inquiries were made however on this subject and information revealed that there has not been a case of bund overtopping by flood from rains since 1965.
- meteorological condition along the west coast of Peninsular Malaysia as to amount and intensity of sunshine, rainfall, and monsoons are favourable and the formulation of farm programmes has been made (see sections of Plan of Operations) by the project team.
- quantity of farm inputs, such as fry and skilled labour have not been investigated. It seems that there is lack of data on the latter. Fertilizers, feeds, pesticides are available and these can readily be obtained at normal costs.
There is an existing all-weather road network up to kampong Segantang Garam and transportation link from this village to the fishpond site is the bund, the repair and widening of which could easily be done. The existing timber bridge can be strengthened to allow passage of vehicular traffic.
- soil investigation has been carried out for the purpose of ascertaining the suitability of soil for pond construction and for algal growth. Analyses indicate that soil inside the bund has potential acid sulphate condition (refer to Inception Report) and low organic content. Soil outside the bund indicates good suitability for fishpond as the soil is fertile for pond culture.
Findings for both areas inside and outside the bund show that the latter is most suitable for shrimp/fish pond culture. This was the consensus of all the members of the Ban Merbok Task Force and the same decision was made during a meeting of the Screening Committee on 10 October 1979.
The project team recommended that the pilot project be implemented outside the bund. The reasons for the decisions are: suitable soil pH, soil fertility, ease of land acquisition, no sociological problems, and a shield for possible intrusion of sea water into the “padi” land.
The pilot development site outside the bund was chosen at the particular area indicated on the general layout plan as shown in Fig. 10 as this area is lower in elevation than higher areas near the bund. It is believed that there would be less concentration of oxidisable sulphur in this low area as sulphur generally increases with depth. A pilot development outside and along the bund, as suggested by a member of the Project Team is likely to have potential acid sulphate condition.
