Discussion with the team leader was made immediately upon arrival in Indonesia with a view to obtaining a general briefing on the nature of the consultancy assignment. Consultations with the responsible staff of the Directorate General of Fisheries and other institutions were also carried out for the purpose of finalising a work programme and acquiring a general understanding of the problems to be encountered. Before the initiation of survey work in an area, detailed discussion with the provincial fisheries staff concerned was particularly helpful.
A total of five areas was investigated, from which thirteen locations have been found suitable for the siting of pilot culture trial farms.
(Fig. 1)
This is primarily a coral reef area with numerous water channels separating the Bintan proper from a number of islets. The intertidal and subtidal zones are occupied by narrow and, in some parts wide, fringing reefs. In most of the area, the reefs have been damaged to varying degree. Off the outer edge of each reef, the topography of the seabed drops down considerably forming excellent locations for the siting of floating net cages. The wide tidal fluctuation averaging 2.5 metres, coupled with the overall conformation of the water channels, tidal water and current movements should provide a considerably high oxygen budget, at least through thinning out actions, for high density stocking culture operation, and minimal adverse effects of living space limitations on the stocked fish would be expected.
Based on depth contour of a navigation chart and also monsoonal weather characteristics, six sites were selected for investigation. These are (Fig. 1):
| (a) | eastern tip of Dompak island; | Riau Archipelago, Southern District |
| (b) | coast off Mantang fishing village; | |
| (c) | west Besar channel; | |
| (d) | east Besar channel; | |
| (e) | southern shore of Siulung island off Pulai Serai fishing village; and | |
| (f) | northern coast of Telang island |
At all these six sites the water column was considerably uniform without any indication of thermocline or halocline suggesting active vertical mixing of water layers, if any. Salinity values remain consistently at 32–33 ppt and water temperatures at 30–31°C.
At the Tanjung Pinang fish landing site and at the six sites visited, a total of 139 species of fishes was identified, all being typical coral reef forms. Serranids, lutjanids, etelids, caesiodids, scombrids, carangids, clupeids and engraulids are the predominant groups. From their conditions, trap, gillnet and seine were probably the main fishing gear; and the fishing grounds at which they were caught should be within less than 12-hour sailing distance away from the landing places. There were however, fishes possibly caught with the use of dynamite.
Of these, the serranids are known to be the more hardy fishes and therefore, suitable for culture purposes. Detailed discussion with fishermen has shown that based on 20 fishing days per month, a trapper's total catch averages 200 kg of serranids, of which a third comprises fingerlings and early juveniles. The mesh of the trap used is hexagonal with a width of 4.5–5.0 cm, suggesting that if smaller mesh is used the quantity or proportion of smaller size serranids can be obtained.
Of these serranids, Epinephelus tauvina and E. malabaricus, both bottom dwelling groupers, and Plectropomus maculatus and P. leopardus, both off bottom swimmers, are of consistently high value in the Singaporean market. At the same time, all four species are comparatively faster growers than other serranids having an average daily weight increment of about 4 gm from a size of 100–150 gm, or a mean of 125 gm. Another factor in favour of the choice of these species is the fact that they can be grown or fattened under crowded conditions. At harvest, each cubic metre of caged water could be anticipated to carry not less than 10 kg for the Bintan situations.
Lutjanids, particularly Lutjanus argentimaculatus, L. johni, L. sanguineus and L. sebae are also desirable species. The facts that they cannot be stocked at such high density and that their value at the Singaporean market is only one-fifth that of the serranids, automatically rule out their choice.
Under-utilized and low-value fishes such as Euthynnus affinis (small tuna) and other similar but abundant species can be earmarked as feeds for the serranids. The higher protein and fat contents in the flesh of this scombroid make it a superior feed species.
(Fig. 2)
The bay off the township of Batimenyan receives the direct intrusion of oceanic waters via the strait between Java and Sumatra. Excepting the inner bay receiving the outflow of two small creeks, the outer bay is primarily marine with growths of coral in the subtidal zone, from which the topography of the seabed slopes down providing excellent location for the siting of floating net cages. The inner bay at site number 3 is however brackish, having salinity values ranging from 12 to 25 ppt but without any significant stratification in the water column.
Batimenyan is essentially a fishing village with about 30 to 35 houses or families. At each of location 1, 4 and 5 there is one to two families some 10–15 metres from the shore. Location 2 is an anchorage point for a small number of fishing craft and its adjacent land accommodates some 10 or so families. These activities are not considered having any significant conflict with cage culture requirements in both pollution and interference terms. On the contrary, especially for sites 1, 4 and 5 the presence of families presumably of a fishery background actually provides the required resources for the on-the-spot management of at least one pilot culture trial farm.
On the other side of Teluk Lampung, there are a cement factory and other land-based developments. The impact of such activities on the proposed pilot culture trial sites is difficult to assess in view of a lack of tidal water and current studies. From the topography of the seabed of T. Lampung, and the presence of numerous sand bars and islets bordering the coast of the bay proper, any pollutant transfer could only take place through water transport within the upper layer of the bay water. This should therefore be directly dependent upon wind drift on the one hand and the movement of stratified upper water layers on the other via tidal transport. This theory should however, be clarified if the bay in question is to be developed for commercial cage culture purposes. In the meantime, pilot culture trial can be undertaken in one of the five sites investigated.
At the fish landing site at Teluk Betung, over 90 species of fishes were identified. The predominant groups comprise clupeids, engraulids, carangids, lutjanids, caesiodids, scombrids and serranids. Their state of freshness and overall condition suggest that the main bulk of the landing came from trap, gillnet and seine catches in the nearby fishing grounds. Lates calcarifer was also present in the market but in small quantities coming from nearby tidal ponds.
From discussion and observation, the serranids are still the preferred fishes for culture trial purposes. In general, species selection should conform with the proposal made for the Bintan area.
Great interest on the culture of Lates calcarifer was expressed by the provincial fisheries personnel. In view of the need for much higher level of technical input in the culture of this species, it is not suggested to be included at this stage. Separately, a Lates calcarifer culture scheme will be designed.
Unlike the case of Bintan, the fish grown in this area are catered for the Jakarta market being six-hour sailing time away. The supply and demand trend in relation to the value of these species in that market should therefore, be surveyed with a view to arriving at a marketing strategy and schedule for the products.
(Fig. 3)
Between Bulalang and Gilimanuk off the northern coast of Bali, only Teluk Dalem and Teluk Gilimanuk are considered suitable for cage culture. The large bay between these two presently earmarked for marine park development and therefore under conservation, is in fact an ideal location also. Of the former two areas, Teluk Dalem is a small cove and from its depth contour it certainly suggests that there is considerable scarring effect over the seabed by the intrusion of oceanic waters. In all probability, the column of the water is also predominated by open sea waters. Such a natural setting suggests good seawater exchange between the bay and the sea and therefore good oxygen budget for the caged fish can be anticipated. The only disadvantage of this area is its remoteness from any marketing centres.
Teluk Gilimanuk is a seaport with facilities and population centered on its outer southern shore while a few fishing boats are based also immediately next to the eastern periphery of these activities. The limited time unfortunately did not permit a survey of this fairly large bay; but from visual observations the clarity of the shore waters, and the presence of lutjanid fingerlings (Lutjanus argentimaculatus and L. johni) right next to the shore, suggest that this bay area is still being utilised by the species at least as a nursery ground despite the presence of the observed human activities. The presence of these species at this early fingerling size also suggests that Lates calcarifer and Epinephelus tauvina, two closely associated species, should also be present in this bay. Since the noted conflicting activities are all very much localised, and since little or no pollution indications could be observed, this area could serve at least as the site of a pilot culture trial farm. In this consideration, its easy access to the Surabaya market is also a significant qualification. Subject to later survey(s), if the fry and fingerlings of these required species were present in quantities, the potential of this area as a cage culture area would even be more significant.
The main commercial fish taxa in northern Bali as a whole are clupeids, engraulids, scombrids (principally Thunnus tonggol), billfishes, sharks, carangids, exocoetids and anguillids (mainly elvers directly utilised for human consumption). Other coral reef fishes especially on the western half of this coast are equally abundant; and the species observed are similar to those in the Bintan and Teluk Lampung areas.
The choice of species should conform with the proposal made for the other areas to include only the serranids. This is to provide directly comparable performance data for the planning of future commercialscale cage culture development.
In addition to the groupers, lutjanids and particularly the fast-growing species of the genus Caranx should also be potentially choice species. The final decision on the future prospects of these species is unfortunately one with a strong bias on investment viability, a matter to be discussed in the latter part of this report.
(Fig. 4)
(Fig. 4a)
The natural conformation of Pangpang Bay as a deep, narrow indentation of the coast, coupled with high density living and industrial activities along the length of its shore line, render this area unsuitable for cage culture. The breakwater transecting almost half the width of the entrance of the bay increases the residence period of pollutants from these sources. Although there are evidences of the intrusion of the Bali Strait waters, it does not necessarily mean that the thinning out of the trapped pollutants could be effective. From the substrate of the bay, it can be reliably predicted, subject to further benthos investigation, that the whole area is very much deteriorated as judged by the thick layer of silt covering black, smelly (hydrogen sulphide) mud; and the turbid, brown-coloured marine waters also suggest a high level of nutrients and organic matters. Under the circumstances and despite the keen interest to develop this area, the author is not inclined to recommend the choice of Pangpang Bay even as a site for a pilot culture trial.
(Fig. 4b)
This is essentially a fishing village with some 800 fishermen and a fleet of 96 11-metre (l.o.a.)1 motorised (diesel outboard, side mounted) and about 50 small wind-driven craft. Daily fish landings averaged 45 metric tons for the April-October period with peak landings during August-September at a daily average of 80–90 metric tons. During the wet monsoon in December-February, fishing activities normally come to a halt. Before and after this period in November and March, respectively, fish landings normally begin to resume.
The Segara Anakan takes a course in an east-west direction along the inner shore of the bay, discharging its waters into the northwestern corner of the bay through a narrow entrance, at which extremely vigorous mixing between the riverine and oceanic waters takes place. West of the Grajagan Bay is the Peturon Bay. It is considered that both these bays and the estuary of the Segara Anakan are suitable for cage culture. In particular, the latter area has a fairly high level of salinity (30–31 ppt) for a considerable distance upriver and a homogenous water column entirely devoid of stratification.
The natural setting of the Segara Anakan suggests that it could be a spawning and nursery ground of percoids of good culture value. From over 100 species of fish landed, it had been observed that while the main bulk comprised coral reef forms, large and small Lutjanus argentimaculatus, Lates calcarifer and Epinephelus tauvina were also present. The coloration of these latter fishes suggests that they came from estuarine rather than marine waters. The latter species together with other fast-growing serranids and perhaps lutjanids can be utilised for culture trial purposes in this area. The presence of different size groups of these fishes in Segara Anakan clearly indicates that this river could serve as both the spawning and nursery grounds of these species. To cater for the future development of cage culture in this area, it is essential to conduct a fish seed resources survey along the length of Segara Anakan.
(Fig. 5)
Examination of detailed navigational charts and discussion with local fisheries officials have shown that the two bays located between Poteran island and Madura proper is far too shallow for cage culture practices. It does not however, mean that these areas are of no fish culture value. According to the natural setting, the two bays could serve as the nursery ground of species of culture value, especially Lates calcarifer, Epinephelus tauvina, Lutjanus argentimaculatus and L. johni.
In the southern bay of Gili Genteng on the other hand, the natural setting is ideal for cage culture. The outer reefs serve as a breakwater while the direct thrushing of the bay by oceanic waters could provide an excellent oxygen budget. It is therefore recommended that if cage culture is to be tested for the Madura area, this Gili Genteng site be selected as one of the pilot culture locations. The only constraints of this area are: (a) its remoteness from Sumenep which presumably provides the marketing centre of the product; and (b) the relatively low value and possibly also low demand of fish in Sumenep may rule out the future potential of this bay or any other eastern Madura areas. From the point of view of job creation, on the other hand, cage culture can be considered as an additional engagement for the islanders.
The natural setting of this bay is fairly similar to that of some of the outlying islets in the Bintan area. The coral reef fish fauna as judged by observations made is also comparable. If a pilot culture farm is to be located in this bay, the species to be selected and the practices to be adopted can conform with those noted for the Bintan area.
