ASEAN/SF/89/Tech. 11 December 1989 BIVALVE FARMING: AN ALTERNATIVE ECONOMIC ACTIVITY FOR SMALL-SCALE COASTAL FISHERMEN IN THE ASEAN REGION

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2 ASEAN/SF/89/Tech. 11 ASEAN/SF/89/Tech. 11 December 1989 BIVALVE FARMING: AN ALTERNATIVE ECONOMIC ACTIVITY FOR SMALL-SCALE COASTAL FISHERMEN IN THE ASEAN REGION by Medina N. Delmendo ASEAN/UNDP/FAO Regional Small-Scale Coastal Fisheries Development Project Manila, Philippines 1989

3 NOTICE OF COPYRIGHT The copyright in this publication is vested in the Food and Agriculture Organization of the United Nations. This publication may not be reproduced, in whole or in part, by any method of process, without written permission from the copyright holder. Applications for such permission with a statement of the purpose and extent of the reproduction desired, should be made through and addressed to the Project Coordinator, ASEAN/UNDP/FAO Regional Small-Scale Coastal Fisheries Development Project, P. O. Box 1184, Makati Post Office, Makati, Metro Manila or 3rd Floor, Arcadia Building, 860 Quezon Avenue, Quezon City, Philippines.

4 POSTAL: P. O. BOX 1184, MAKATI POST OFFICE ADDRESS: MAKATI, METRO MANILA 1299 PHILIPPINES Ref: Dear Ms Gribling, ASEAN/UNDP/FAO REGIONAL SMALL-SCALE COASTAL FISHERIES DEVELOPMENT PROJECT CABLE: FOODAGRI MANILA STREET: 3RD FLOOR, ARCADIA BUILDING TELEX: FAO PN PHONE: ADDRESS: 860 QUEZON AVENUE, QUEZON CITY METRO MANILA, PHILIPPINES 19 September 1990 We are sending herewith the following fisheries reports missing from your library collection as per your Transmittal Slip to Mrs. Medina N. Delmendo, Project Coordinator, RAS/84/016 dated 5 Deptember copies each of the following: Project Progress Reports - ASEAN/SF/PR Technical reports contributed to symposia/meetings, etc.- ASEAN/S'F/Tech The following reports are not yet ready for distribution. We will send you copies as soon as they are available: ASEAN/SF/GEN/9, 10, 11,12, 13, & 15 ASEAN/SF/TECH/11, 12 onward ASEAN/SF/WP/7 I would like to take this opportunity to request the following FAO fisheries reports for our project library if already available for distribution: FAO Fisheries Tech, Pap, series, 308, 309, 310, 311, 313 onward FAO Fisheries Circ. 820, 821, 822, 823, 825 onward. We welcome your donations of other fisheries materials project library. Thank you very much. Armand Gribling Fisheries Library FAO, Rome Yours sincerely, (duplicates) for our Paulina T. Zabala Library Asst./Secretary

5 TABLE OF CONTENTS Page 1. INTRODUCTION 1 2. MOLLUSC FARMING AREAS IN THE PHILIPPINES 5 3. FARMING METHODS Oyster culture Broadcast method Stake method Hanging method Longline method Lattice-tray method Mussel culture Stake method Hanging method Rope-web method Raft method 9 4. POTENTIALS FOR IMPROVEMENT AND FURTHER DEVELOPMENT Shifting of farming sites to deeper waters Improving farming management techniques Spat collection Hardening Hanging of spats for growout Fattening ECONOMIC VIABILITY OF OYSTER AND MUSSEL FARMING POTENTIALS FOR EXPANSION OF OYSTER/ MUSSEL FARMING FOR SMALL-SCALE FISHERMEN RATIONALE FOR EXPANSION ACTIONS NEEDED DEPURATION OF MOLLUSCS, MOLLUSCS FARMING DEVELOPMENT PLANS IN OTHER ASEAN COUNTRIES Indonesia Thailand Malaysia Singapore Brunei CONCLUSIONS 31 REFERENCES 32 APPENDICES Appendix 1 - Prospectus for a one-half hectare oyster farm using hanging method (Philippines) 35 Appendix 2 - A prospectus of m 2 mussel farm using stake method (Philippines) 37 Appendix 3 - Presidential Decree No. 23/1982 regarding seafarming development in Indonesia waters, President of Republic of Indonesia 43

6 BIVALVE FARMING: AN ALTERNATIVE ECONOMIC ACTIVITY FOR SMALL-SCALE COASTAL FISHERMEN IN THE ASEAN REGION 1. INTRODUCTION Most countries in the ASEAN region are faced with the problem of uplifting the socio-economic conditions of small-scale coastal fishermen. This problem has become more serious as a result of dwindling catches from coastal fisheries resources. The rapid population growth in coastal communities has all the more exerted increasing pressure on the productivity of these resources as fishing effort from the artisanal fishing sector has been increasing. A strategy which some developing countries could undertake to find alternative economic activities for small-scale fisher-men would be in bivalve farming such as oysters and mussels. These molluscs are easy to farm; they are nutritious food items and with proper management and direction of bivalve farming development programmes, the product could be a source of foreign exchange. by Medina N. Delmendo 1 The world mollusc production amounted to 4.4 million metric tons in 1985 of which about 2.9 million MT or 65.6 percent were produced from aquaculture (Figure 1). Asia contributed about 72.5 percent of the total while the rest came from Europe, North America, Oceania, South America and Africa (Figure 2). Of the total aquaculture production in Asia, molluscs contribute 20 percent (Figure 3). The major mollusc-pro-ducing countries in the ASEAN region are Japan, Korea and China (Table 1). Among the ASEAN countries, the Philippines is the major mollusc producer where the growth rate over a 4-year period was percent ( ). Oysters made up 55 percent of the country's total mollusc production. Malaysia devotes mainly to cockle farming while Thailand produces more mussels than oysters. Singapore was highly successful in mussel farming but the price and marketability of the product was not that good to encourage fishermen to expand farming operations. Figure 1. World mollusc landings from capture and culture fisheries in 1985 (Source: Lovatelli, 1989)

7 Figure 2. Mollusc aquaculture production by continent in 1985 (Source: Lovatelli, 1989) Figure 3. Aquaculture production in Asia in 1985 of the major resource groups (Source: Lovatelli, 1989) Among the species of bivalves cultured and harvested from the wild in the region include the oysters, cockles and mussels. Of the species of oysters belonging to Ostreidae, the Crassostrea and Saccrostrea predominate. Oysters of commercial importance belonging to Crassostrea include C. rivularis, C. gigas and C. plicatula, which are widely cultured in Japan, Republic of Korea and China. The subtropical and tropical species of oysters include C. belcheri, C. echinata, C. eredalei, C. lugubris, C. madrasensis, Saccrostrea cucullata and Ostrea folium. Oysters are very nutritious. It also contains a high level of glycogen which makes an excellent source of energy that reduces the work load of the pancreas of the human body. Complex sugars in the bloodstream must be broken down into glycogen by enzymes which the pancreas secretes before these are stored in the liver. Glycogen pro-vided from oysters will reduce the work load of the pancreas (Yamaha Fishery Journal No. 28, 1989). The nutritional content per 100 g portion of oyster compared to other food items is in Table 2.

8 Oysters are a gourmet and luxury food in developed countries. On the other hand, in developing countries such as the Philippines, it is a cheap food but increased demand for local consumption is constrained by poor quality due to the fact that oyster farms are located in shallow coastal areas contaminated with domestic wastes. As Table 1. Total production of molluscs such, the consuming public is wary of eating oysters too often. The Philippines cannot meet the export quality standards required by importing countries for this reason. Oyster and mussel farming is already a viable economic activity in the country despite very traditional techniques used in general. Unit: metric tons Annual values Average annual growth rate (%) Country/region Australia China Hong Kong (U.K.) India Japan Korea, Republic of Malaysia Philippines Taiwan (Province of China) Thailand New Zealand Asia-Pacific Total Rest of world World Source: Csavas, 1985 Table 2. Comparison of nutritional contents (per 100 g portion) Minerals (mg) Vitamins Food Energy Protein Fat Sugar Calcium Iron A B1 B2 C (Kcal) (g) (g) (g) (IU) (mg) (mg) (mg) Oyster raw Eggs Milk Ø Source: Revised Standard Nutritional Contents List of Japanese Foodstuffs

9 The Philippines ranked 8th among the top 10 oyster producers in the world while Thailand ranked 12th. The major oyster producers are the United States, Japan, Korea and France as shown in Table 3 (Chew, 1989). Table 3. Oyster production for several lead countries (total worldwide market = metric tons, 1985) Country Production World mt market (%) United States Korea Japan France China 45.0* 4.1* Mexico Taiwan Phillipines New Zealand Australia Canada Thailand * Estimated Source: Chew, K., 1989 The green mussel Perna viridis is cultured in the ASEAN region, particularly in Thailand, Singapore and Philippines. Thailand ranked 7th and the Philippines 8th in the world production of mussels (Table 4). Table 4. Mussel production for several lead countries (total worldwide market = metric tons, 1985) Country Production World mt market (%) Netherlands Spain China Denmark France Korea Thailand Philippines West Germany Chile United States Italy Source: Chew, K., 1989 For the mussel producers in Asian and Oceania region, the estimate shares of two ASEAN countries in the production of mussels, despite the extensive methods employed is quite substantial as shown in Figure 4. Figure 4. Approximate share of mussel production for major producing countries of Asia and Oceania (Source: Chew, 1989)

10 Cockles, clams and arkshells are other bivalves which are widely cultured in the ASEAN region. The most common species of cockles are Anadara granosa and Arca. Thailand, Indonesia, Malaysia and Philippines are among the lead producers of these bivalves, particularly the cockles (Figure 5 and Table 5). Figure 5. Approximate share of clam, cockle and arkshell production for major producing countries of Asia (Source: Chew, 1989) Table 5. Catches of combined clams, cockles and arkshells for several lead countries in Asia (In Thousand of metric tons, 1975 to 1985) Country China Japan Korea Thailand Indonesia Malaysia Taiwan Philippines Species: China Japan Korea Thailand Indonesia Malaysia Taiwan Philippines Source: Chew, K., 1989 Bivalvia Anadara subcrenata, Mactra sachalinensis, Meretrix lusoria and Venerupis japonica Arca spp, Anadara granosa, Cardiidae, Mactra sachalinensis, Meretrix lusoria and Venerupis japonica Anadara granosa and Paphia spp Anadara spp and Meretrix spp Anadara granosa and Paphia spp Anadara spp, Corbicula spp and Meretrix spp Anadara spp and Paphia spp

11 While molluscs, particularly oysters, cockles and mussels are easy to farm compared to finfish and shrimps, their cultivation techniques have not improved much from traditional methods in the developing countries. Mollusc culture is not capitalintensive; the species use natural food and does not pollute the environment. All molluscs seeds are obtained from natural grounds. 1 Project Coordinator, ASEAN/UNDP/FAO Regional Small- Scale Coastal Fisheries Development Project, 3rd Floor, Arcadia Building, 860 Quezon Avenue, Quezon City, Metro Manila, Philippines 2. MOLLUSC FARMING AREAS IN THE PHILIPPINES Oysters and mussels are the most common molluscs farmed in the country. Oyster farms are located in 17 provinces of the Philippines with major production areas in Cavite and Bulacan provinces which border Manila Bay; Pangasinan in northern Luzon, bordering Lingayen Gulf; Sorsogon in southern Luzon; Capiz and Negros Occidental in the Visayan region. Figure 6 shows the areas where natural populations of oysters are present, existing farming areas and location of potential oyster farming sites. Oyster farming was started in Cavite in 1935 through government demonstration work. After World War II this was reactivated. Mussel farming is a more recent practice compared to oyster farming. Its expansion took place in the early 1960s. The improved culture method known as the rope-web system was developed only in 1974 in Sapian Bay, Capiz. Mussel farming areas are located in Bacoor, Cavite along Manila Bay where there are about 134 farms; Sapian Bay, Capiz approximately 300 farms and Maqueda Bay in Samar, where there are about 250 farms. Figure 7 shows the location of natural mussel grounds, farming areas and potential sites for development of mussel farming.

12 1. Buguey, Cagayan (NG, FA) 2. Ilocos Norte (NG, FA) 3. Ilocos Sur (NG, FA) 4. Aringay and Sto. Tomas, La Union (NG, FA) 5. Lingayen Gulf and Tambac Bay (NG, FA) 6. Agno River, (Manat, Binmaley Pangasinan and Davel, Dagupan City (NG, FA) 7. Binuangan and Malolos, Bulacan (NG, FA) 8. Abucay and Mariveles, Bataan (FA, NG, PS.) 9. Cavite (Bacoor and Ternate Bays) (NG, FA). 10. Balayan Bay, Batangas (NG, FA) FA) 11. Batangas Bay (NG, 12. Tayabas Bay (PS) 13. Makato, Aklan (PS) 14. Sapi-an Bay, Capiz (NG, FA) A) 15. Banate Bay, Iloilo (NG, FA) 16. Bacolod (Port of Banago) (NG, FA) 17. Binalbagan and Hinigaran Negros Occidental (NG, FA) 18. Himamaylan, Negros Occidental (NG, PS) 19. Panguil Bay, Misamis Occidental (PS) 20. Luuk, Bongao Cave, Sacol Island Zamboanga del Sur (PS) 21. Atoll Lagoon, Sta. Cruz Zamboanga del Norte (PS) 22. Malalag Bay, Davao City (NG. FA) 23. Del Carmen Dapa, Surigao del Norte (PS) 24. Calape, Bohol (NG, FA) 25. Cebu (NG, FA, PS) 26. Leyte (PS) 27. Maqueda Bay and Jiabong Samar (PS, NG) PS) 28. Catbalogan, Samar (PS) 29. Sorsogon (NG, FA) 30. Calauag Bay, Quezon (PS) 31. Alabat Island, Quezon (PS) 32. Polilio Island, Quezon (PS) Figure 6. Natural oyster grounds, farming areas and potential sites in the Philippines (From: SCS/82/WP/103) The Philippines has an even temperature which is ideal for year round farming of oysters and mussels. Vast areas with satisfactory salinity, current and phytoplankton are available. Areas which do not have natural stocks of these molluscs could be used as transplantation of seeds from natural grounds to set up a spawning stock to provide natural setting and future selfsustaining population.

13 1. Masinloc, Zambales (NG, FA) 2. Binuangan, Obando, Bulacan (NG, FA) 3. Bacoor and Binakayan Cavite (NG, FA) 4. Tayabas Bay, Quezon (FA, PS) 5. Aklan (PS) 6. Sapian Bay, Capiz (NG, FA) 7. Banate Bay, Iloilo (NG, FA) 8. Bacolod City (NG, FA) 9. Binalbagan and Hinigaran Negros Occidental (NG, FA) 10. Himamaylan, Negros Occidental (NG, FA) 11. Bohol (PS) 12. Babatngon, Leyte (PS) 13. Maqueda Bay, Samar (NG, FA, PS) 14. Catbalogan, Samar (FA) 15. Sorsogon Bay, Sorsogon (PS) Figure 7. Natural green mussel grounds, farming areas and potential farming sites in the Philippines (From: SCS/82/WP/103) 3. FARMING METHODS 3.1 Oyster culture The farming methods of oyster are still generally traditional using the stake, hanging, longline; broadcast methods and lattice-tray method Broadcast method The broadcasting technique is the most primitive wherein empty shells are scattered on the oyster bed. Oyster spats settle on these shells and harvested by diving or hand-picking at low tides. This method can only be used in very shallow areas with firm bottom which are generally exposed at low tides Stake method The stake method is usually practiced in soft, muddy and shallow beds, usually not more than 1 m deep. Bamboo stakes are simply stuck in the oyster bed which serve as spat settlement (Figure 8). The stakes are usually as high as the prevailing. tide level in the area.

14 oysters grow with thinner shells and high quality meat; harvesting is easier; there is less mortality due to predators. However, the cost of production is higher. This method can be applied in places where natural populations do not exist but favourable for growth of oysters or mussels. Figure 8. Oyster farming by stake method (PCARRD, 1983) This method is better than the broadcast method in that the growth of oysters is faster and mortality of spats on settlement to the stakes is reduced. However, they are more prone to predation by crabs, star-fishes and shell borers. Bamboo as stake material is costly; it does not also collect as much spats as the oyster shells. Both the broadcast and stake methods do not transplant spats after settlement They are left to grow where they have settled. This is not so in the hanging method. Some-times when the spat settlement is dense, the strings of cultches are moved farther apart to avoid too much congestion. Smaller oysters are also left behind during harvest for further growth Hanging method This uses strings of empty shells as cultch collectors. Strings made of nylon or polyethylene twine are provided with spacers or knots of 10 cm interval at which the empty shells are held. The length of the string depends on the location of the oyster plot. In most cases these are located in an inter-tidal zone along the coastline with depths of 1 2 m. These strings are hung or fastened to bamboo or wooden framework (Figures 9a and 9b) at cm apart. The advantages of the hanging method are that the productivity is higher; the Figure 9a. Bamboo plot for hanging oyster string-collectors Figure 9b. Harvesting oysters by untying hanging collectors (PCARRD, 1983) Longline method Four parallel lines of about 20 m long and 20 cm apart are strung between two bamboo or wooden posts. Strings of threaded oyster shells held every cm apart by small plastic or bamboo tubes are hung on the line. This

15 is actually a modification of the hanging method but the framework where the threaded strings of oyster cultches are hung is made of rope or polyethylene twine Lattice-tray method Bamboo splits are woven into a lattice and tied with galvanized wire, nylon or polyethylene twine. The splits are spaced cm apart. The lattice can be positioned like a tray horizontally or vertically. They can be installed in a triangular position supported by bamboo or wooden support. In Malaysia, instead of using bamboo lattice trays, wire mesh trays supported with wooden frames are used. These are held on wooden stands or racks which are installed in tidal flats. All these methods are applied in intertidal zones along shallow coastal areas which become exposed at low tides. Usually they are close to residences of small fishermen and populated localities like Binakayan and Bacoor towns in Cavite province; Binmaley and Dagupan in Pangasinan province. These are major oyster producing areas but domestic waste loading of nearby waters is quite high due to dense population and lack of sewerage treatment systems. 3.2 Mussel culture Stake method Mussel farming techniques also employ the stake method as in oyster farming. Bamboo stakes or mangrove trunk and palm tree trunks are used. As much as stakes could be stuck on a mussel bed with an area of 0.25 ha. About kg/stake could be produced by this method. A modified stake method called the wigwam method is also used. About 7 10 stakes or poles are stuck to the mud bottom in a 2 m radius from a central pole. The upper ends of the poles are tied to the center to form a wigwam. This is used in deeper water areas with stronger water movement. The poles serve as spat collectors but no thinning nor transplantation of spats is made Hanging method The same principle of hanging method in oyster farming is also used for mussel. However, coconut husks are used as cultch collectors besides empty oyster shells. This method is applied in deeper water areas as the mussels do not need exposure like the oysters Rope-web method This method was introduced in Sapian Bay, Capiz. A unit of rope-web consists of a parallel pair of ropes measuring 5 m, positioned at 2 m apart, connected in a zigzag pattern at 40 cm intervals between knots along each parallel rope (Figure 10). Bamboo pegs of 20 cm long and 1 cm in width are inserted in each zigzag rope spaced at 40 cm between pegs. This prevent the oyster clusters from sliding down the rope as they grow bigger and heavier. The distance between posts is 5 m; the rope-web is stretched 3 m apart along the rows. Rope-webs are installed parallel with the water current and positioned 2 m deep at low tide. These are untied at harvest and reused for subsequent cropping cycles. The ropeweb method can produce up to 300 t/ha/yr if the spatfall is heavy; on the average, 200 t/ha/yr is produced (shell on) (Young and Serna, 1982).

16 Figure 10. Diagrammatic drawing of a rope-web tied to bamboo poles (PCARRD, 1983) Raft method A raft may be made of bamboo or wooden pontoons with cross beams buoyed up by empty metal or plastic drums, old car tires blown with styrofoam or ferroconcrete buoys (Figure 11). Rafts are installed parallel to the flow of tide. A unit of raft may be 6 m 8 m or 8 5 m. Collector or growout ropes are hung on the raft. Collector ropes are shorter than grow-out ropes. Both are provided with weights to prevent them from floating. Collector ropes are hung at about 0.5 m apart while the growout ropes at 1 m apart. Abaca rope or polycoco ropes are used as growout ropes. They are provided with bamboo pegs of 25 mm long 1.5 cm wide which are inserted into the lay of the rope at 30 cm interval. These pegs prevent the growing mussels from slipping. A one-meter rope can hold 5 15 kg of mussels. Growout ropes could be as long as 4 m long depending on the depth of the mussel farm.

17 Figure 11. Construction detail of a mussel raft using bamboo framework and floats (Source: Yap, W.G., el. al., 1979) In Singapore, spat collector ropes are hung at 8 ropes/m 2 which are spread out to 4 ropes/ m 2 for growout. At this density the level of production attained ranged from 100 to 160 kg/m 2 every six months (Cheong, 1982). 4. POTENTIALS FOR IMPROVEMENT AND FURTHER DEVELOPMENT Comparing the practices and farming methods used in the Philippines and other developing countries in the ASEAN region with those found in Japan or the Republic of Korea, it is readily seen that there is great potential for improvement and development. This could be accomplished by undertaking certain changes. 4.1 Shifting of farming sites to deeper waters In general, oyster and mussel farms are located in very shallow coastal waters with in 1 2 meters depth. These are often within paddling distance from the shoreline. In Japan, oyster farming evolved from these stages: (a) traditional stonespreading technique; (b) standing-pole culture; (c) standing pole followed by bottom spreading; (d) standing fence culture; (e) simple hanging type; (f) rafttype hanging; and (g) longline hanging type. The hanging type is employed in waters from 5 to more than 10 m deep. The simple hang-ing technique was the

18 basis for the large-scale oyster farming development in Japan. Although the hanging method is used in the Philippines, the farm sites are still limited to very shallow tidal areas. The advantages gained in using deeper waters are: a. Growth and fattening characteristics of the oysters are improved. b. The three-dimensional use of the surface water is effected, hence, less area is required for an equivalent amount of production. c. Culture operation could be conducted regardless of sea bed quality. d. Unused deeper water areas could be used for culture purposes. e. Work could be performed regardless of tide condition. f. Predator organisms are avoided. It will be noted that the Japanese oyster farming had shifted from the shallow tidal oyster farm sites to the deeper water areas as illustrated in Figure Improving farming management techniques Farming management techniques have to take into account the growth pattern of the oyster since it remains stationary for the rest of its life. It therefore cannot search for a better environment. The farmer, there-fore, has to move the oysters to grounds which can provide the best conditions possible to meet its biological and physiological requirements at each stage of growth period. A good choice of farm sites, timing and combination of their uses spells the difference in oyster farming management. Water temperature and salinity are the most important growth factors governing the life of the oyster. In temperate countries like Japan and Korea, the most productive period for spawning of oysters is during summer (June August) when temperature increases to 24 C 25 C. Egg release and fertilization are triggered by a rapid rise in temperature or a sudden decline in salinity. In the Philippines and other ASEAN countries, water temperature is ideal all year round and oysters become marketable within 4 6 months. Rainfall, although seasonal, is adequate to maintain the flow of streams and rivers to provide suitable salinity levels for growth as well as for spawning. Reproduction of oysters is found excellent in many areas of the country. Setting continuous throughout the year with peaks during March May and September November. This situation makes it possible to collect spats at least twice a year. A system of spat collection should be developed other than what is traditionally practiced to insure a year round production and supply of oysters or mussels.

19 Figure 12. Diagram of the historical development of oyster farming in japan (Source: Yamaha Fishery Journal No. 28, Jan. 1989) From the experience of Japan, oyster farming also started in very traditional practices which dates back about 400 years ago. Shallow tidal areas were also used until they found out that oyster larvae could also be collected in deeper waters. From the simple hanging method, the large-scale hanging type developed (Figure 13). Spat collection is used to be done in shallow tidal areas. However, in Japan, spats are being collected offshore since the 1960s. This practice was influenced by the loss of natural shallow tidal spawning grounds as a consequence of industrial and agricultural reclamation works and more significantly, due to improvements in oyster culture technology. Research work was steadily continued which determined oyster spat resources and their distribution. This led to a reliable method of predicting spat falls and gathering grounds. Hence, under Japanese conditions, the routine process of culturing oysters had been established. The management schedule of oyster farmers are easily programmed as shown in Figure 14. In the Philippines and other ASEAN countries, oyster spats are collected mainly in shallow tidal areas where growout plots are also located. Information in the Philippines on spat resources and their distribution are hardly known other than what is only traditionally known by local farmers.

20 Figure 13. Evolution of the simple small-scale hanging type to large-scale hanging method (Source: Yamaha Fishery Journal No. 28, 1989) A mature oyster produce from million eggs. After fertilization the eggs and larvae undergo a random dispersion and distribution depending on tide, wave motion and edding currents. Portion of the eggs are carried offshore. After 2 3 weeks of their drifting stage the larvae settle down. While the distribution of larvae are highly uneven, it is important to know where densest settlement of spats occur. The Japanese found that spat collection is better offshore such that they have established their routine activities of industrial oyster farming operations which include the following steps: Spat collection In view of the knowledge about spat resources and their distribution, the Japanese and Korean oyster farmers collect spats off-shore. They use empty scallop shells strung through a wire which are then hung to bamboo rafts which are either movable or fixed (Figure 15). Design and construction is shown in Figure 16.

21 Figure 14. Routine oyster farming management technique in Japan (Source: Yamaha Fishery Journal No. 28, 1989) Figure 15. Cultch collectors and spat holding rafts (Source: Yamaha Fishery Journal No. 28, 1989)

22 Figure 16. Design and construction of oyster raft and longline hanging method of oyster culture (see photographs 1 and 2) (Source: Yamaha Fishery Journal No. 28, 1989) In the case of the Pacific oyster (Crassostrea gigas), the water layer in which it could settle or adhere to is from the high tide to 1 and 2 m below the ebb tide line. It was reported (Park, et. al., 1988) that in this range, the middle layer of water provides the best opportunity for settlement of the oyster (Figure 17). The nature of settlement and adherance vary according to depth of water and collecting method. In shallow areas the fixed collecting method is used as the range of vertical adherance is narrow. Conversely, this becomes wider in deeper waters and in this case the hanging method is used (Figure 18). Spat setting is highly affected by water current. Settlement does not occur where water flow is more than 5 7 cm/sec. The density of larvae during the planktonic stage indicates the degree of settlement levels that could take place. It is estimated that oyster spats developed per million eggs is about 1 percent (Park, et. al,, 1988).

23 Figure 17. Depth range where natural setting of the Pacific oyster occurs (Source: Park, Byung Ha, et al., 1988) Figure 18. Distribution of oyster larvae by water depth (Source: Park, Byung Ha, et. al., 1988)

24 Photograph 1. Oyster raft for hanging method of oyster culture (Courtesy of Mr. Alessandro Lovatelli, RAS/86/024) Photograph 2. Longline hanging method of oyster culture (Courtesy of Mr. Alessandro Lovatelli, RAS/86/024)

25 4.2.2 Hardening After the oyster spats have settled on the cultch collectors, these are transferred to hardening racks located in shallow tidal areas as shown in Figure 19. This area is the highest portion of the tidal zone which becomes exposed during low tide. The hardening process undergoes a gradual period of increased exposure each day to encourage optimal growth of oysters. Exposure to air eliminates the weak individuals and ensures the survivors to mature properly by hardening their shells. This makes them endure environmental changes; mortality is reduced as the oysters become more resistant; growth is rapid and none gets lost in harvesting and handling. The period of hardening lasts from 6 8 months which coincides with the decline of temperature beginning October up to the end of spring in May. In the ASEAN countries where there is no pronounced change in temperature except slightly during the months of December to January, such hardening process will not take that long. However, naturally grown spats from the time of settling could be hardened by intermittent exposure before they are transplanted to deeper areas and proceed to growout. Most oyster farmers do not practice the hardening process as the oyster plots are periodically exposed at low tide. Other considerations such as water quality and elimination or control of predators could increase production. The hardening effect under tropical conditions could take place as well by exposure of the spats during low tide if spat collection is done in deeper areas where no such expo-sure is possible. More refinement of rearing techniques is necessary to improve the present traditional methods Hanging of spats for growout Transplantation of the spats to the grow-out rafts in deeper areas are carried out. This is done by re-stringing the hardened seed oysters on a 9-m long wire for hanging on the growout rafts (Figure 20). Usually, the spat collector strings contain shells. These are restrung into shells per growout string and are hung at cm apart along the bamboo poles of the raft. A raft of 10 m 20 m will contain from strings of oysters containing from shells with oyster spats.

26 Figure 19. Hardening racks of oyster seeds (Source: Yamaha Fishery Journal No. 28, 1989) Shells with spats are restrung for growout in offshore rafts or longline Real long-term hanging method in Japan Figure 20. Preparation of seed oysters for hanging in growout (Source: Yamaha Fishery Journal No. 28, 1989) Fattening This is carried out for 1 2 months prior to harvesting. This entails the transfer of the oyster strings to the higher or shallower strata of the water to take advantage of better nutrition and abundant food. In Japan, the rational for lowering the oyster strings to deeper water during part of the growing period is to avoid high temperatures near the surface water and avoid attachment of barnacles and ascidians on the oyster. With the above routine, a single oyster raft of 10 m 20 m produce 2 4 tons of shucked oysters. The Philippines would do well in oyster and mussel production if farming sites are shifted from heavily polluted shallow coastal areas to deeper and cleaner waters and farming management techniques improved from the traditional methods. Government research institutions must undertake a thorough study of the spat resources, their distribution and grounds for

27 development of oyster farming to provide alter-native economic activity of small-scale fishermen. Besides mollusc farming, the fishermen could still engage in part-time fishing in the vicinity of the oyster or mussel rafts. Certain fishes would also be attracted below the rafts to feed on epiphytic organisms which grow below the rafts or the oyster shells. This aspect needs to be looked into. 5. ECONOMIC VIABILITY OF OYSTER AND MUSSEL FARMING The profitability of oyster and mussel farming in the Philippines was studied by Librero, et. al. (1976). The farms surveyed were small (50 m 2 ), medium ( m 2 ) and large farms more than 500 m 2. The study showed that farms of all sizes could be profitable under certain conditions such as farm size, location of farm and method of farming. Larger farms had greater income than small farms but they require more labour input. Smaller farms usually use family labour. Farms located far from market outlets spend more for transport of their crops. Overall, the profitability of oyster farming is attractive enough. This is borne out by the fact that there are over private oyster farms operating in the country. Profitability of oyster farming by size of farm and method of farming ranges from 10 to 73 percent depending on culture method used. A prospectus for oyster farming is in Appendix 1. Although current prices of materials used for oyster farming has gone up, the market price of oysters also went up. In 1987 the total oyster production of the country was MT valued at million (unshelled). On the other hand, mussel production was MT valued at milion. A survey of the profitability of mussel farming by stake method showed 56 percent (Librero, et. al., 1976). Other methods of culture could earn a profit ranging from 74 to 76 percent per ha per year (SCS, 1982). A prospectus for a mussel farm is shown in Appendix POTENTIALS FOR EXPANSION OF OYSTER/MUSSEL FARMING FOR SMALL-SCALE FISHERMEN Improved techniques of oyster farming is available; there are abundant natural oyster grounds and environmental conditions for. growing oysters are favourable all year round. What is lacking is government incentive by way of policy on small-scale coastal fishery resource uses supporting the development of oyster and mussel culture in new areas other than those traditionally used at present. Identification of such areas for this would be required to provide small-scale fishermen with alternative fishery occupations. Oyster and mussel farming activities in certain grounds could form part of the overall fishery activities of fishermen as part of a coastal resource management system. In 1982 a Seafarming Study made by the South China Sea Fisheries Development and Coordinating Programme estimated the potentials for expansion of oyster and examined the extent of possible municipal fishermen that could enjoy the benefits of said expansion nationwide. Tables 6 and 7 summarize the location and number of farms and potential areas for development.

28 Table 6. Estimated potential for expansion of oyster farming Area now used Potential area Province or Number of Source of Source of Region location farms (ha) information (ha) estimate NCR Manila Bay - none BFAR 35 BFAR I Pangasinan BFAR Sanitation (estimated) Grossly polluted Remarks Navotas Paranaque Las Piñas BFAR/RO April BFAR/RO May CDS/CDS Bolinao Bay Clean 330 PSF Bolinao to Caquiputan Clean SFS Tambac Bay Clean Accepted estimate (ha) none 100 SFS Dagupan/Binmaley Polluted La Union BFAR BFAR/RO 200 SFS Sto. Tomas Polluted 200 Sta. Lucia San Fernando Ilocos Sur BFAR 100 SFS Sta. Maria, Vigan Polluted 100 Ilocos Norte BFAR 20 Badoc, Laoag Polluted 20 II Cagayan BFAR 26 BFAR Clean 30 III Zambales - none BFAR 20 BFAR SFS Port Matalvis Clean 20 Bulacan BFAR 17 BFAR Polluted 20 Bataan - none BFAR 10 BFAR 10 IV Cavite PCARR 2 BFAR ha (BFAR) Polluted none To be terminated by reclamation within ten years Marinduque - none BFAR 5 BFAR Clean 5 Mindoro - none BFAR 10 BFAR Clean 10 Palawan - none BFAR 20 BFAR Clean 20 Batangas none BFAR none BFAR Clean 100 SFS 100

29 50 BFAR Quezon - none BFAR CDS Padre Burgos 200 SFS Padre Burgos Clean 200 Romblon BFAR none BFAR none V Camarines Norte - none BFAR 13 BFAR Camarines Sur BFAR 4 BFAR Albay - none BFAR 2 BFAR Catanduanes BFAR 6 BFAR Masbate - none BFAR 3 BFAR Sorsogon BFAR BFAR SFS Clean 530 VI Capiz BFAR/RO 45 BFAR 1 Tinagong Clean Dagat only = 30 ha BFAR/RO 2 Est. including Clean 500 Visan, Panay, etc. Aklan BFAR 10 BFAR 100 SFS Inshore of Clean 100 mussel farms and at Bata Iloilo BFAR 15 BFAR Banate Bay Polluted 15 Antique - none BFAR 2 BFAR - 5 Negros Occ BFAR/RO 49 BFAR 1.2 ha - BFAR 100 SFS Hinigaran Himamaylan Polluted 100 VII Cebu - none BFAR none BFAR 100 SFS Carmen Bay Clean 100 Negros Or. - none BFAR none BFAR none Bohol none BFAR none BFAR 100 SFS Calape Inabanga Polluted 100 Siquijor - none BFAR none BFAR none VIII Leyte - none BFAR none BFAR

30 IX X XI XII CDS/SFS Biliran St. Clean Leyte Bay 200 CDS/SFS Cancabato Polluted Samar BFAR none BFAR Bay, Tacloban 200 CDS/SFS Silanga Bay Catbalogan Polluted 500 SFS Maqueda Bay Clean 500 Zamboanga del Norte - none BFAR 1 BFAR Zamboanga del Sur - none BFAR 1 BFAR Basilan - none BFAR 3 BFAR Tawi-tawi - none BFAR 3 BFAR 10 Misamis Occ. - none BFAR 10 BFAR Misamis Or. - none BFAR 10 BFAR Surigao del Norte - none BFAR 10 BFAR Camiguin - none BFAR 10 BFAR 50 SFS For region 50 Davao del Sur - none BFAR 25 BFAR Davao Oriental - none BFAR 170 BFAR Surigao del Sur BFAR BFAR SFS For region 400 Cotabato - none BFAR none BFAR none Lanao del Sur - none BFAR none BFAR none Total BFAR = Bureau of Fisheries and Aquatic Resources BFAR/RO = BFAR Regional Office BFAR/LAB = BFAR Laboratory CDS = Center for Development Studies (1975) SFS = Sea Farming Study reported herein NCR = National Capital Region Source: SCS/82/WP/103

31 Table 7. Number of municipal fishermen who could benefit from expanded oyster culture Number of Potential Average area Additional Percent of Region municipal expansion per farm farms fishermen who fishermen (ha) (assumed) could grow (1977) (ha) oysters I * ** II III IV ** V VI VII VIII ** IX X XI XII Total * BFAR, 1977 in "Expanded Fisheries Development Program" quoted in Smith, et. al., (1080) ** Priority regions (Provinces of Pangasinan, Quezon and Samar) Source: SCS/82/WP/1 03 For the expansion of oyster farming, a total of ha could be developed which could benefit 9.1 percent of municipal fishermen. In the case of mussel farming, a total estimate potential of ha is available for development which could benefit about 9.8 percent of municipal fishermen (Tables and 9).

32 Table 8. Estimated potential for expansion of mussel farming Area now used Potential area Region Province or Number of Source of Source of (ha) (ha) location farms information estimate 1 Remarks Sanitation Accepted (estimated) estimate (ha) NCR Manila Bay BFAR 25 BFAR Navotas Polluted none I All - none BFAR none BFAR none II All - none BFAR 15 BFAR none III Zambales - none BFAR 23 BFAR 25 Bulacan - none BFAR 10 BFAR 10 Bataan - none BFAR 9 BFAR 10 IV Cavite BFAR 2 BFAR To be terminated Polluted none by land reclamation within ten years Marinduque - none BFAR 5 BFAR 5 Mindoro Or. - none BFAR 10 BFAR 10 Palawan - none BFAR 25 BFAR Clean 25 Quezon - none BFAR 35 BFAR CDS Padre Burgos 200 SFS Padre Burgos Clean 200 Romblon 1 2 BFAR 2 BFAR 5 V Albay - none BFAR 2 BFAR Camarines Norte - none BFAR 5 BFAR Camarines Sur - none BFAR 2 BFAR Catanduanes - none BFAR 5 BFAR Masbate - none BFAR 2 BFAR Sorsogon - none BFAR none BFAR Total for region 20 VI Capiz BFAR/RO 25 BFAR 200 SFS 200 Iloilo - none BFAR 10 BFAR 10 Aklan - none BFAR 10 BFAR 100 SFS 100

33 VII VIII Antique - none BFAR 2 BFAR - 5 Negros Occ. 6 2 BFAR 86 BFAR 100 SFS 100 Cebu - none BFAR none BFAR 50 1 SFS 1 Carmen Bay 50 Bohol - none BFAR none BFAR 50 1 SFS 1 Calape, etc. 50 Leyte - none BFAR none BFAR SFS 1 Babatngon 100 Samar BFAR Lab BFAR/RO 1 Jiabong only Rabanal 1 Maqueda Bay FIDC/FAO FAO IBRD Proposal Longline culture in Maqueda Bay IX All - none BFAR none BFAR none X All - none BFAR none BFAR none XI All - none BFAR none BFAR none XII All - none BFAR none BFAR none Total BFAR = Bureau of Fisheries and Aquatic Resources BFAR/RO = BFAR Regional Office BFAR/LAB = BFAR Laboratory CDS = Center for Development Studies (1975) SFS = Sea Farming Study reported herein NCR = National Capital Region Source: SCS/82/WP/

34 Table 9. Number of municipal fishermen who could benefit from expanded mussel culture Number of Potential Average area Additional Percent of Region municipal expansion per farm farms fishermen who fishermen (ha) (assumed) could grow (ha) mussels I * ** II III IV ** V VI VII VIII ** IX X XI XII Total % * BFAR in Expanded Fisheries Development Program (Smith, et. al., ICLARM, 1980) ** Priority regions (Provinces of Pangasinan, Quezon and Samar) Source: SCS/82/WP/ RATIONALE FOR EXPANSION Coastal fisheries in the Philippines and most other ASEAN countries have been over-fished and the coastal (subsistence) fisher-men have remained the poorest of the poor. By helping these fishermen become partly seafarmers (oyster or mussel farmers) would reduce fishing effort on the already over-exploited coastal resources. Finding alter-native occupations for this sector of society has been a serious problem of fishery management. The 1982 Seafarming Study concluded that there are sufficient suitable sites in the country to provide space for over oyster farms and about mussel farms. The capital costs involved per farm are not high. Financing assistance to be extended to small fishermen for this purpose should not be difficult to obtain since the farming methods are known and proven to be profitable. Oysters and mussels are highly nutritious food items and have export potential provided export quality standards are met. 8. ACTIONS NEEDED In order that this expansion plan could materialize there are certain actions which the government must undertake. 8.1 Confirm oyster and mussel farming sites identified earlier by conducting spat resources survey and distribution in the areas proposed. 8.2 Allocate space for oyster and mussel farming with highest priority to local resident small-scale fishermen. Such allocation should be based on economic farm size for small-scale operations large enough for municipal fishermen but small and unattractive to corporations and wealthy individuals; charting of coastal waters for seafarming purposes would be essential and allocation for their uses to groups of fishermen, pre ferably, cooperatives or associations. 8.3 Organize marketing cooperatives to avoid competition in the

35 market place and stabilize the price and supply. Quality standard of fresh and processed products must be set by government. 8.4 Provide strategic depuration facilities to be operated by marketing cooperatives of fishermen associations or provide clean sing services free of charge or at nominal cost to producers. 8.5 Organize training programmes on farming management techniques, cooperatives management and marketing or pro vide management services free of charge until the fishermen associations are capable enough to do so. 8.6 Research institutions must continue to undertake research to improve farming techniques, product quality standards, promote domestic consumption and develop export markets for oysters and mussels. More importantly, oyster and mussel seeds grounds must be identified so that seeds collection areas could be developed. Trans-plantation to growing areas could easily be made since these could be transported easily. 8.7 The government must establish or designate oyster and mussel grounds according to health standards and set the guide-lines by which to instruct oyster and mussel producers as well as distributors on product quality for consumption and export purposes. These actions would encourage consumers to buy oysters and mussels more often as they do with fish and meat for daily consumption. Thus, demand for the product will increase. 9. DEPURATION OF MOLLUSCS Molluscs are filter feeders and are most affected by red tide organisms which are harmful to human beings. Some incidences of red tide poisoning due to consumption of mussels occurred in the Philippines which were fatal to the consumers. When this happens, shellfish farmers lose their market and their business also slumps. In order to prevent consumer bias against the consumption of oysters and mussels and also to upgrade the quality standard of molluscs in the market, depuration should be required. This is a service which could be provided by marketing authorities particularly at the market centers. Depuration facilities could be installed so that retailers or wholesalers of molluscs could be given such services prior to selling mussels and oysters in the retail markets. It was estimated that a 5-ton capacity shell-fish depuration plant operating every 24 to 36 hours would be able to depurate shellfish at a cost of 0.10 per kilogram of oyster or mussel (Personal Communication, 1989). A schematic illustration of a depuration plant is shown in Figures 21 and 22. It would be strategic to install a depuration plant at the vicinity of shellfish producers such that the cost of depuration may be borne by the producers as part of their costs of production. Buyers could, therefore, purchase their products from the plant. A government policy on quality standard of molluscs in the market for sale and consumption should be made so that the public's health and safety is assured.

36 Figure 21. Perspective view of shellfish purification plant (From: Almazan, R., 1989) Note: Arrows indicate water flow Figure 22. Schematic drawing of shellfish purification plant (From: Almazan, R., 1989)

37 Table 10. Potential areas for mussel culture Location Potential area Sources (ha) North Sumatera 200 2, 3 1. Tj. Balai Riau Teluk Bintan Lampung Kuala Penet, Maringgai West Java Banten Bay 5. Ketapang, Tangerang Jakarta Kepulauan Seribu Central Java Jepara East Java , 4 8. West part of Madura 9. Pasuruan 10. Probolinggo (Gili Ketapang) 11. Kwanyar, Madura West Nusa Tenggara Labuan Lombok 13. Batu Nampar Total Estimated from topography map 2 Estimated from actual sites 3 Interviewed resource person 4 Pagcatipunan, et. al., 1981 From: Mintardjo, Kisto, MOLLUSCS FARMING DEVELOPMENT PLANS IN OTHER ASEAN COUNTRIES 10.1 Indonesia The government of Indonesia, through the UNDP-assisted Seafarming Project, INS/81/008, has already identified potential areas for oyster and mussel culture sites as shown in Tables 10 and 11. Mussel culture is still at a very experimental stage in Indonesia. On the other hand, oysters are cultured by stake method at a very limited scale. Mollusc production of Indonesia is mainly from wild harvesting from natural grounds. The blood cockles (Anadara granosa) is the most important species produced. Cockle farming is used to be practiced by local fishermen in West Java. However, due to lack of seeds, this was no longer practiced since 1975 (Mintardjo, 1988). In an effort to provide coastal fishermen with alternative fishery-related occupations and improve their levels of living, the government puts high priority to seafarming development. For this purpose, Presidential Decree No. 25 was proclaimed on 25 May 1982 (Appendix 3) which was followed by a Ministerial Decree No. 473, issued 8 July One of the seafarming activities to be developed is oyster and mussel farming.