Field studies in the Kepulauan Riau and Kepulauan Anambas included areas selected by examination of navigation charts. Site selection also considered tidal currents, freshwater inflow, and wind and wave direction and intensity during the south monsoon season (April-September) and the north monsoon season (usually October-March). An attempt was made to schedule surveys, first in those areas that appeared to have the best potential for economically viable seafarming considering the coastal topography, the distance from villages, and the logistic problems of bringing supplies to the area and transporting the products to markets. Time did not permit a study of all likely areas, however, those surveyed were probably representative of the better locations.
1. KEPULAUAN RIAU
1.1 Bintan — Matang Island area (Figure 1)
1.1.1 Telok Bintan
This is a large shallow bay just north of Tanjung Pinang harbour somewhat exposed to southwest winds. Much of the shoreline is covered by mangroves and a few oysters Crassostrea glomerata were found attached to the roots. Some freshwater inflow from the five or six small streams as indicated by salinities of 28–29 ppt. Both phosphates and nitrates were low but visual observations indicated moderately high levels of phytoplankton. This should be a good location to try oyster culture using off-bottom methods with seed collected at Los Island or Tanjung Pinang harbour.
1.1.2 Los Island
The rocky shores of Los Island which is located between Telok Bintan and Tanjung Pinang were covered by a band of oysters Crassostrea glomerata. The channel between Los Island and Sengganang Island has potential for the collection seed oysters. Placing collectors in the water would have to be timed carefully to avoid the heavy attachment of barnacles which occurs in this area.
1.1.3 Tanjung Pinang harbour
The waters of this narrow bay which receive the domestic wastes from the city and from vessels in the harbour are high in nutrients resulting in excellent populations of phytoplankton and oysters. Although it would be dangerous to consume shellfish from this bay without thorough cooking, it has good potential for the collection of seed oysters. The seed could then be transplanted to uncontaminated areas for growth to marketable size.
1.1.4 Selat Dompak
The channel between Bintan and Dompak Islands at the mouth of a large stream (Sungai Jang) is moderately high in nutrients and had a salinity of 26 ppt on July 13, 1981. A small grouper farm located under a building has begun operation within the past year with encouraging results. The channel is acceptable for grouper farming, however, rapid changes in salinity may occur during the rainy season. The seaward portion of Selat Dompak has good potential for oyster culture using fixed structures although seed would probably have to be transplanted from Tanjung Pinang harbour or Los Island. There is also a possibility of green mussel culture in the seaward portion of this bay, however, seed would have to be obtained from Jakarta or elsewhere since there are no natural populations of green mussels in this area. It is proposed that experimental plantings of green mussels be made in Selat Dompak as part of the programme of the BPPL field station which is planned for construction at Sungai Jang.
1.1.5 Kawal village
This village located at the mouth of a small stream on the east side of Bintan Island was of interest because a local resident had built a small pond to grow mangrove crabs (Scylla serrata) from juvenile to market size. The design of the pond, however, is not satisfactory because of the lack of circulation which undoubtedly causes adverse water quality especially if uneaten food (fish scraps) remain in the pond. Water samples offshore near a fish trap indicated a salinity of 32 ppt with low levels of phosphate nitrate. This area has no significant potential for seafarming.
1.1.6 Kijang
The water of Selat Kijang, the channel between Bintan and Koyan Islands, is reddish brown because of silt from the bauxite mining on Koyan Island and loading operations at Kijang village. Although this channel is protected from storms and has excellent water circulation, it has little or no potential for seafarming because of the high load of silt in the water.
1.1.7 Mantang — Kekip Island channel
This channel is 11 to 14 meters deep with good circulation and well-protected from storms. Water quality appears satisfactory for shellfish culture with salinities of 30–32 ppt, adequate levels of dissolved oxygen, and moderate levels of nutrients. The native mangrove or rock oyster Crassostrea glomerata is abundant on mangrove roots and on old fish traps. This should be a good location to try collecting seed oysters for culture in this channel or for transplanting to other locations. This area also appears to be satisfactory for culture of the green mussel. However, none are present. Therefore, it is recommended that seed mussels from Jakarta or elsewhere be planted in this area and growth and mortality monitored as described in Section 4 of this report.
A new grouper farm has been established at Mantang village, however, the design of the enclosures is unsatisfactory. Water circulation is restricted because of the small spacing between wooden poles that have been installed around the sites of the enclosure to protect the netting from damage by crabs. Also, there is not sufficient depth of water in the enclosures at extreme low tide levels and this is undoubtedly the reason for the high mortality that occurred early in the morning of the day of our visit. A better plan would be to farm groupers in net cages supported by rafts located in deeper water. According to the operator, it would be necessary to protect the cages from attack by sharks by installation of a heavy mesh perimeter net.
1.1.8 Telang Besar Island
This island located southeast of Mantang Island has natural populations of seaweed Eucheuma spinosum. Marine Colloids, Inc., attempted seaweed culture on the southeast side of this island in 1976. However, the culture method used proved unsatifactory. Experimental seaweed culture reportedly was continued at this location for about a year by LPPL (now BPPL) but discontinued because of the poor growth rate observed. It may be worthwhile to repeat these experiments using improved culture methods which have been developed recently. The limited time available for the present study precluded observations of this site.
1.2 South Rempang — Sembur Island area (Figure 2)
1.2.1 Pangkil and Karas Besar Islands
These two islands located in Selat Riau between Bintan and Galang Islands has substantial quantities of seaweeds, primarily Eucheuma spinosum. It was reported that about 30 fishermen on Pangkil Island harvest seaweeds and deliver the dried products to Tanjung Pinang or take it directly to Singapore. This appears to be a good location for seaweed farming in the narrow band along the shore when the depth is suitable. There appeared to be good water circulation in this area, however, the nitrate concentration (0.43 mg/l) was the lowest recorded during the present study.
Karas Besar Island is similar to Pangkil and reportedly has seaweeds in moderate abundance.
1.2.2 Sembur Island
The channel between Galang Island and Tanjung Dahan Island is well-protected from storms and is deep enough for grouper farming using net cages suspended from fixed structures or from anchored rafts. One farm growing groupers and siganids is located in the channel between Sembur and Sembibing Islands. This farm which was started within the last year is reportedly successful even though high mortalities of siganids have occurred. The operator attributed the mortality to insufficient food. However, there is a strong possibility that the cause of death was “gill rot” since this reportedly is the major cause of siganid mortality (Chan, Personal Communication, 1981). The Sembur Island fishfarm is ideally located in a channel where there is good water circulation and is designed to permit expansion to about three times the present area.
Some oysters were observed on mangroves in Sembur Island area but residents of Sembibing Island village reported that large natural populations of oysters are found on Senayang Island, about 6–8 hours from this location by fishing boat. Reportedly, oysters are transported from Senayang Island to Singapore by fishing boat, a journey of about 12 hours. The limited time available precluded a survey of Senayang Island. However, it was understood that LPPL (now BPPL) had an oyster culture project on Senayang Island and records of these studies may be available at Jakarta.
Although not observed during the study, Selat Penyabung, the channel between Galang and Galang Baru Islands may also be suitable for fishfarms.
1.2.3 Rempang Island
The east side of Rempang Island is exposed to east and north winds, however, the channel between Rempang and Galang Islands is deep and well-protected. Although only the eastern end of this channel was surveyed because of the use of the northern part of Galang Island, a refugee camp, it appears suitable for cage culture of groupers and siganids. It is reported that a significant siganus fishery is located in this channel.
1.3 Batang-Bulan — north Rempang Island area (Figure 3)
1.3.1 Northeast Rempang Island
The channel around Kinun Island, and between Rempang and Pelanduk Subang Mass Islands are well-protected from wind and waves and have a moderate tidal currents. Much of this area is 3–7 m deep and appears suitable for oyster culture using off-bottom methods in which the seed oysters are suspended from fixed wooden structures. Most of these channels have occasional oysters Crassostrea glomerata attached to mangrove roots, but substantial populations were observed on old fish traps at the north end of the channel near Clambang village. It would probably be necessary, initially at least, to transplant seed oysters collected at Tanjung Pinang harbour. Los Island, or in the Mantang-Kekip channel to this area for growth to marketable size.
It would also be possible to establish fishfarms in these channels using net cages as suspended from fixed wooden structures.
The deep channel between the north end of Rempang Island and Bakam, Anak, Mati, Ayer and Awi Islands has strong tidal currents and enough depth for grouper or rabbitfish farms using net cages suspended from rafts. Oysters were observed on the rocky shores on some of these islands so this area might also be used for oyster culture using the raft method.
1.3.2 Setoko — Rempang Island channel
This channel has a strong current and deep water and the north part is well-protected from storms. This area appears suitable for fishfarms and perhaps oyster culture using the raft method. The southern part of this channel and the large shallow bay between the Rempang and Panyait Layar Islands is too exposed to oceanic waves from the southwest to be suitable for seafarming.
1.3.3 Panjang Island area
A group of small islands in this area are surrounded by water 10–20 meters deep with good protection from storms and adequate currents for fish culture using net pens supported by anchored rafts. Several of these islands have small fishing villages which could provide labour for seafarming, juvenile fish for seed, and scrap fish for feed. This small area is within easy access by fishing boats to attractive markets at Singapore.
1.3.4 Menkada — Bulan Island channel
This channel is well-protected, deep and has adequate tidal currents from fishfarming using either fixed structures or rafts.
1.3.5 Bulan — Tanjung Kubo — Melantang Island channel
These channels have water from 1–12 m deep and are well-protected from storms. Much of these area appears to be suitable for culture of fish or oysters.
1.3.6 Selat Bulan
The main channel between Batam and Bulan and other islands is 6 to 17 m deep with good water circulation and generally with protection from oceanic storms. Many places in this large channel would be suitable for anchoring rafts for culture of groupers or rabbitfishes. The short distance to Singapore, less than 20 nautical miles, makes fishfarming in this area especially attractive.
Several shallow bays on the south side of Batam Island have potential for oyster farming. These include the cove at the mouth of Sungai Langkai, the cove at the mouth of Sungai Tambesi and the channels between Batam, Traling, and Sekenal Islands. The channel between Asa, Kecil and Asa Besar is especially interesting because of the population of large-size pink oysters Crassostrea mordax on the rocky shoreline. Although culture methods have not been developed for this species, there is a possibility that natural population could be exploited. The excellent flavour of this species would make it attractive to harvest them even though it is difficult to remove the meats from the shell. A small population of pink oysters occurs also on the small islands off the north coast of Menkada Island.
The extensive shallow areas south of Selat Bulan off the coast of Bulan Island, Setoko Island and Rempang Island are exposed to winds from the southeast to the southwest and therefore are not recommended for seafarming.
2. KEPULAUAN ANAMBAS
2.1 Matak Island (Figure 4)
2.1.1 Telok Niulwan
This is a large shallow bay at the southeast end of Matak Island. It is almost completely protected from oceanic storms by hills 200–400 m in height. The entrance to the channel is narrow (80–100 m wide) and 5–15 m deep. This channel would be an excellent location for culture of groupers in net cages. The extensive shallow area at the north end of the bay may be satisfactory for culture of oysters since there are some native mangrove oysters Crassostrea glomerata on the roots of the mangroves that cover most of the shoreline. Although there is no well-defined stream flowing into this bay there are freshwater springs below low tide level. This was indicated by the cooler water near bottom just seaward of the mangroves that was observed during a swim survey. Also, water samples in the channel indicated surface salinity of 34.0 ppt and bottom salinity at a 5 m depth of 32 ppt.
Productivity of Tk. Niulwan as indicated by phosphate was low, however, it was obvious that the water contains substantial quantities of phytoplankton. Characteristically, both phosphates and nitrates are low in the Anambas group because few nutrients are carried to the sea by steams and there is no known upwelling of nutrient in the deep water in this area. However, phytoplankton is sufficiently abundant to provide adequate food supply for a substantial population of filter feeding molluscs. The fact that the oysters collected in Niulwan and other bays in the Anambas group were in good condition, often with fully developed gonads ready for spawning, indicates a satisfactory food supply. Although oysters are present in this bay, it is unlikely that enough spawners are present to provide a good setting in this area. Therefore, it is recommended that seed oysters be collected at Tarempa harbour or at the DGF Fishing Base and then planted in Tk. Niulwan to determine growth and survival. Grouper farming at experimental level is recommended first at the DGF Fishing Base near Tarempa. If this is successful, production scale farms are recommended for Tk. Niulwan and later for other areas.
2.1.2 Telok Ulu Mangar
This long narrow cove is located at the north end of Matak Island and the centre of the cove is used as a landing strip for seaplanes servicing the oil drilling operations north of the Anambas group. The shallow cove of the southwest side of Ulu Manager had substantial oysters of three species: Crassostrea glomerata, the mangrove oyster, Crassostrea mordax, the pink oyster, and the large Crassostrea echinata, the giant black-rimmed oyster. Mangroves and rocks along the shores have substantial quantities of spat indicating that this would be a good area to attempt collection of seed oysters by placing collectors such as oyster shells in the water at the appropriate time of year. The fact that most of the oysters appear to be approaching spawning condition, indicates that reproduction, larval development and setting will take place during July or August with a second peak of setting in perhaps six months.
This would be a good location to try collecting seed oysters and determining growth rate and mortality. Since oysters are farmed in shallow water along the shoreline, oyster farming should not conflict with a use of the centre part of the cove for seaplane traffic.
2.1.3 Matak — Beliba Island channel
This had been described by local fishery officers as being one of the few areas in the Anambas group where seaweeds are harvested. Observation indicated moderate abundance of Eucheuma spinosum and Caulerpa spp. The local village had begun a seaweed farm close to a fish trap in this channel in 1977 and according to one resident, they had harvested two crops in one year. The Eucheuma is used for food by boiling to extract the agar which is being used to make gelatin—like food by adding sweetener and coloring. According to the resident interviewed none of the seaweed is dried for shipment to Tanjung Pinang or Singapore for extraction of phycocolloids.
Although the seaweeds in the village farm did not appear to be growing rapidly the farm was producing enough for village use. Test plantings in other locations and depths using improved culture system such as horizontal monofilament lines close to bottom might indicate substantial potential for seaweed culture. However, very few areas observed during this survey appeared to be suitable and no Eucheuma or Caulerpa were found in any other area.
2.2 Mubur Island (Figure 4)
2.2.1 Telok Ayer Bandong
This large deep bay is located on the south end of Mubur Island. Although Mantas Island provides some protection from the southmost of the bay is exposed to south winds and waves making it unsuitable for seafarming.
2.3 Siantan Island (Figure 4)
2.3.1 Tarempa area
Tarempa harbour and the adjacent cove at the mouth of Sungai Baruk where the DGF Fishing Base is located are deep coves with good water circulation. Tarempa harbour is exposed to winds from the north and northwest and is generally unsuitable for seafarming. However, there is a good population of oysters on the concrete piers indicating potential of using this area for the collection of seed oysters for transplanting to more protected areas for growth to market size. The fishing base cove is fairly well-protected from storms and also has a good population of oysters on the pier. Therefore, this cove also may serve as a source of seed oysters. In addition, there is potential for using space under the pier and a deep hole on the west side of this cove for experimental culture of groupers in net cages. Although this area is too small and exposed for use as a production area, it would be a good location for conducting experiments and later demonstrating methods of fishfarming to fishermen who stop at the pier to obtain ice. While the waters in this cove are generally low in nutrients, several species of filterfeeding molluscs occur in substantial number. These include the mangrove or rock oyster Crassostrea glomerata, the giant black-rimmed oyster Crassostrea echinata, and the subtidal “tree oyster” Lopha cristagalli. A substantial population of the giant black-rimmed oyster occur at the mouth of Sunai Baruk and are used locally as food.
2.3.2 Telok Baruk
This cove on the northeast side of Siantan Island is easily recognized by the high waterfall of Sungai Pula on the northwest side of the cove. This bay has rather extensive shallow areas rimmed by narrow mangrove fringes and is well-protected from oceanic storms. The shallow parts in this cove have a moderately large population of clams of several species. This area could serve as a location for clam farming at sometime in the future when culture methods have been developed. In the meantime, this area has potential for oyster culture using the hanging method or the Australian-New Zealand tray system. If seed oysters can be collected at the DGF Fishing Base some should be planted in Telok Baruk to determine growth rate and survival.
The deeper waters near the entrance of this cove have potential for grouper farming using fixed structures or rafts.
2.3.3 Selat Batu Belah
This channel between Siantan and Batu Belah and Masabang Islands is deep (16–27 m) and well-protected from storms. The channel has strong tidal currents which should provide excellent circulation for grouper farms using anchored rafts.
2.3.4 Batu Tambun
This cove has two branches both of which are fairly well-protected from storms but are characterized by large shallow areas without significant channels. This area is not particularly attractive for seafarming at the present time although it might be used in the future for an expansion of oyster culture.
2.4 Badjau Island (Figure 4)
2.4.1 Telok Dumang
This is a large bay at the southwest side of Badjau Island with channels 12 to over 20 m in depth. This bay is exposed to south and southwest storms making it generally unsuitable for anchoring rafts for farming of groupers or oysters.
2.4.2 Nyamuk village cove
This cove and two adjacent coves are located on the southeast side of Badjau Island and all three have deep channels in the centre and shallow corals flats near shore. The inner part of Nyamuk cove is fairly well-protected and could be a suitable place for grouper culture using fixed structures or anchored rafts. Although the physical environment is not exceptionally good, the fact that a large village is located here suggests a demonstration grouper farm and training courses for interested local fishermen.
2.4.3 Cove west of Tanjung Lanting
This is a large cove with two branches with deep water (12–21 m) throughout the centre section and shallow coral areas along the shore. The cove is exposed to north and northeast winds which might destroy grouper culture rafts during the north monsoon season.
2.4.4 North bay
This large bay located at the north end of Badjau Island is exposed to north and northeast winds and therefore is not recommended for seafarming.
2.4.5 Selat Taburik
The channel between Badjau Island and Masabang Island is 18–29 m deep with excellent water currents. However, this area is exposed to northeast storms and therefore is not recommended for seafarming.
2.5 Jemaja Island (Figure 5)
2.5.1 Telok Tiru
This large bay is located on the southeast side of Jemaja Island. Although it is protected from southwest and north to northeast winds, it is exposed to southeast to east winds. The bay has channels and coves 14–27 m deep interspersed with coral heads and reefs making navigation difficult. The inner part of the bay has fringes of mangroves with some freshwater drainage from the land. Nutrient levels were low, however, filter feeding molluscs including oysters and clams were found to be moderately abundant. Although this area could be used in the future for farming of groupers and perhaps oysters, the fact that it is virtually uninhabited at the present time indicates a low priority for aquaculture development.
2.5.2 Punisan Island cove
The cove behind Punisan Island is well-protected from storms and has a combination of deep and shallow areas needed for seafarming. A small fishing village is located at the mouth of Sungai Selubung at the head of the cove. Oysters were present on the mangrove roots, however, in low abundance. This area is not recommended for oyster culture. However, some protected areas are available for grouper farming with labour provided by the village.
2.5.3 Telok Kuala
This is a deep, narrow cove with well-protected areas. A small stream flows into the cove and mangrove fringes in that area have both Crassostrea glomerata and Crassostrea echinata. Three or four species of clams were also found in the shallow water. This area is attractive primarily for grouper culture but with some future potential for oyster farming. The local village, Kuala Maras, with a population of 600 could provide labour. Discussions with people in the village indicated that they are interested in seafarming.
A rocky area on the north side of the cove has excellent populations of a number of bivalves indicating substantial productivity. Nitrate samples taken in this area were the highest found in the Anambas group indicating the nutrient enrichment from the village.
2.5.4 Letong area
Although time did not permit, observations in the Letong area, it appears likely that suitable areas could be found in the vicinity for grouper farming. This area is especially attractive for seafarming because of the population of Letong and the fact that this is the major port on Jemaja Island.
