The International Development Research Centre is a public corporation created by the Parliament of Canada in 1970 to support research designed to adapt science and technology to the needs of developing countries. The Centre's activity is concentrated in five sectors: agriculture, food and nutri­ tion sciences; health sciences; information sciences; social sciences; and communications. I DRC is financed solely by the Parliament of Canada; its policies, however, are set by an international Board of Governors. The Centre's headquarters are in Ottawa, Canada. Regional offices are located in Africa, Asia, Latin America, and the Middle East.

© International Development Research Centre 1982 Postal Address: Box 8500, Ottawa, Canada K 1G 3 H9 Head Office: 60 Queen Street, Ottawa, Canada

Davy, F.B. Graham, M.

IDRC. Asia Regional Office, Singapore SG IDRC-200e Bivalve culture in Asia and the Pacific: proceedings of a workshop held in Singapore, 16-19 February 1982. Ottawa, Ont., IDRC, 1982. 90 p.: ill.

/Oyster culture/, /molluscs;, /fishery research / , /Asia/, I Papua New Guinea/, /Fiji/, /French Polynesia/ - /technical aspects; /fish production/, /research and development/, /conference report/, /list of participants/, / IDRC mentioned , bibliography.

UDC: 639.4 (5.9) ISBN: 0-88936-343-9

Microfiche edition available

II existe egalement une editionfranraise de cette publication. La edici6n espanola de es ta publicaci6n tambien se encuentra disponible. IDRC-200e

BIVALVE CuLTUREIN As1A AND THE PACIFIC

PROCEEDINGS OF A WORKSHOP HELD IN SINGAPORE 16-19 FEBRUARY 1982

EDITORS: F. BRIAN DAVY AND MICHAEL GRAHAM RESUME

Du 16 au 19 fevrier 1982, sous l'egide du departement de production primaire du ministere du developpement national et du Centre de recherches pour le developpement international, s'est tenu a Singapour un collogue sur Jes modes d'elevage et l'etat actuel de la culture des lamellibranches - huitres, moules, clovisses, palourdes - en vue d'etablir un plan d'avenir dans ce domaine. Le collogue a reuni trente-cinq participants de l'ASEAN (Association des pays du sud-est asiatique) ainsi que des delegues de Bangladesh, Burma, Chine, Fiji, Papouasie Nouvelle-Guinee, Sri Lanka, Tahiti et du Canada. On trouve des bivalves en abondance sur Jes cotes de presque tous Jes pays, ou on Jes recolte comme aliment de subsistance. Mais quelques pays ont commence a Jes cultiver et ils esperent que des recherches appropriees leur permettront de tripler la production. II a surtout ete question, au cours de la reunion, des possibilites d'adapter Jes techniques de culture a l'environnement des pays interesses. Les participants ont ete invites a visiter Jes elevages de moules suspend us a des radeaux et le systeme de traitement mis au point par le departement de production primaire de Singapour. Les domaines de recherche prioritaires determines par Jes participants sont: la formation aux methodes de culture, un approvisionnement de naissain ameliore, des criteres de selection de site mieux definis, des etudes economiques plus detaillees, l'eta­ blissement de normes de salubrite des bivalves destines a la consommation humaine et des mecanismes permettant l'echange d'information technique sur la recherche relative aux lamellibranches.

RESUMEN

Del 16 al 19 de febrero de 1982 tuvo lugar en Singapur un seminario auspiciado por el Departamento de Producci6n Primaria del Ministerio de Desarrollo Nacional de Sin­ gapur y el Centro Internacional de Investigaciones para el Desarrollo, destinado a examinar los metodos y el estado actual del cultivo de bivalvos -ostras, mejillones, almejas y coquinas- en Asia y el Pacifico y hacer recomendaciones sobre programas y actividades futuras en este campo. El seminario conto con 35 participantes de las naciones de ASEAN (Asociaci6n de Naciones del Sudeste Asiatico), asi como de Bangladesh, Birmania, China, Fiji, India, Papua Nueva Guinea, Sri Lanka, Tahiti y Canada. La mayoria de estos paises tienen bivalvos abundantes en las areas costeras, donde son recogidos para consumo local ode subsistencia. Varios de ellos han iniciado el cultivo artificial y se calcula que, con investigaci6n adecuada, las tecnicas de cultivo pueden triplicar la producci6n. El seminario hizo enfasis en la adaptaci6n de las tecnicas actuales de cultivo de bivalvos a las condiciones locales de los paises circunvecinos con miras a aumentar la producci6n. Los participantes tuvieron oportunidad de visitar el sistema de cultivo en balsas y el equipo postcosecha respectivo para mejillones, desarrollado por el Departa­ mento de Producci6n Primaria de Singapur. Entre las prioridades identificadas esta la capacitaci6n en tecnicas de cultivo, la mejora en el suministro de semilla y en los criterios de selecci6n de sitios de cultivo, la necesidad de estudios econ6micos detallados y de normas sobre calidad sanitaria de los bivalvos de consumo humano, asi como de medios para intercambiar informaci6n sobre investigaci6n en bivalvos. CONTENTS

Foreword ...... 5

Workshop Summary Plans and Recommendations...... 8 Sessions ...... 9

Country Reports Bangladesh ...... 20 China ...... 21 Fiji ...... 29 French Polynesia ...... 31 India ...... 34 Indonesia ...... 44 Malaysia ...... 47 Papua New Guinea ...... 53 Philippines ...... 55 Singapore ...... 69 Sri Lanka ...... 72 Thailand ...... 73

Appendices 1. Participants ...... 80 2. Papers Submitted at the Workshop ...... 82 3. Bibliography ...... 83

3 FOREWORD

Bivalves such as oysters, mussels, clams, and cockles are widely distributed throughout tropical waters. Typically, they occur in mangrove areas or in coastal regions where, following a brief period of juvenile motility, they attach to rocks, wharves, fish traps, and other static objects. In many countries of Asia and the Pacific, it is a tradition to collect the naturally occurring molluscs as a cheap source of food. Once upon a time, molluscs were a cheap food for poor people in many European countries. Now, they are expensive, luxury items in Europe and North America. In the tropics, however, they can be harvested from the wild or cultivated relatively inexpensively. Consequently the interest in mollusc culture is growing rapidly in a number of countries. It has been demonstrated in several tropical regions that it is both techni­ cally and economically feasible to culture bivalves to produce a marketable product in high yield in less than a year. Reported yields of green mussels, grown on ropes suspended from rafts, for 5 months are 10-12 kg/ m of rope in a number of countries in the region. The yield of nutritionally high-quality protein per hectare of surface water far exceeds the protein that could be produced on a hectare of land by any known terrestrial plant or animal. Since 1973, the Agriculture, Food and Nutrition Sciences (AFNS) Division of the International Development Research Centre (IDRC) has supported bivalve-culture research projects in several tropical countries. Projects in Asia, Africa, and the Caribbean have studied oysters and mussels; other projects in Latin America have examined oysters, mussels, and cockles. In recognition of the growing interest, a regional meeting was convened to review past and current work in bivalve culture in Asia and the Pacific and to attempt to establish regional priorities for future research. The emphasis of this meeting, held in Singapore from 16 to 19 February 1982, was on bivalves for human food. A mussel-culture raft system, developed by the Singapore Primary Production Department in Changi Strait, was used as a valuable focus for demonstration. The culture of molluscs such as pearl oysters, windowpane oysters, and clams - used in the shellcraft industries - was also discussed because similar culture systems can be used for these economically attractive species. The working meeting reviewed culture practices, postharvest handling, the economics of mollusc management, and future research needs, with some lesser reference being made to the taxonomy of bivalves. The names and pattern of distribution of known species are listed in Table A; throughout the meeting, common names were used where taxonomic identification was not available. Several countries have demonstrated that cultured bivalves will grow more quickly than those that occur naturally. The increase in yield is substantial and offers an attractive opportunity for aquaculturalists, fisheries research and development organizations throughout the Asian region. Some of the con-

5 6 BIVALVECULTURE straints encountered in bivalve culture appear in the status reports presented by participants at the meeting and edited for inclusion in this volume. For some species (e.g., cockles, Anadara granosa), further extensive culture research appears unnecessary, as the present system of relaying or sowing seed cockles appears to be both technically practical and economically efficient. It is hoped that this publication, together with IDRC's earlier contributions to this subject - a bibliography on oyster culture produced in 1975 (IDRC- 052e), a handbook on the culture of tropical oysters published in 1979 (IDRC­ TS17e), and a 16-mm colour film produced in 1979 on oyster farming in the tropics - will be of practical interest and help to all who are engaged in the improvement of mollusc culture as a source of food and greater income for the coastal peoples of the region. IDRC wishes to express its gratitude to Dr Siew Teck Woh, Dr Leslie Cheong, and the staff of the Primary Production Department in Singapore for arranging a field trip and for assisting in the organization and execution of the working group meeting.

Joseph H. Hulse Director Agriculture, Food and Nutrition Sciences Division, IDRC WORKSHOP SUMMARY PLANS AND RECOMMENDATIONS

Bivalves represent a high-quality food source, first step toward relevant training. Also, the with considerable potential in most countries in Food and Agriculture Organization of the Unit­ Asia and the Pacific. although the progress ed Nations ( FAO) Network of Aquaculture Cen­ toward realizing the potential varies widely and tres in Asia offers a I-year training program that suggests the need for regional collaboration includes bivalve culture. between countries with relatively developed sys­ tems and those in initial stages of development. There are other obvious needs for training, information exchange. and research. INFORMAT/ON

Increased exchange of information on the TRAINING results of bivalve research is needed, and future meetings, such as the regional exchange reported Lack of qualified personnel is the major critical here, are recommended. Production of manuals, constraint to further development of bivalve cul­ state-of-the-art reviews, and synopses for mus­ ture. On-the-job training. such as that provided sels, oysters, and cockles is also suggested. Sim­ in Malaysia, is needed, and governments are ple taxonomic keys are needed for species identi­ urged to facilitate its provision. It could be sup­ fication, and, as improved production techniques plemented by special courses, such as the short are established, more extension efforts will be course arranged by IDRC in association with required. Dalhousie University in Canada for practical training in the general biology and culture prin­ ciples needed in tropical regions. This course, RESEARCH PRIORITIES given on a trial basis in June a.nd July 1982, is a Priorities for research in the region include: • Detailed economic studies, particularly related to market information and alterna­ tive culture practices in areas of existing or potential culture; • Standardization of mussel- and oyster­ culture production systems; • Ways to increase seed supply for certain spe­ cies and development of related transporta­ tion techniques; • Depuration studies in a number of countries to ensure a quality food product (such studies should be part of a general bivalve quality-control program that in the short term should concentrate on flesh quality within the marketplace); • Examination of regulations and lease ar­ rangements to provide a stable base for ownership in culture operations; and PraC'liC'al on-rhe-job /raining in oysrer cu/rure using • Development of acceptable quality stan­ raC'ks has been offered 10 farmers in Sabah, Malaysia. dards for local and export markets.

8 SESSIONS

COUNTRY REPORTS

A review of bivalve exploitation in 13 countries of Asia and the Pacific indicated that, in some countries, resources are not being exploited, whereas, in others, an industry involving several million dollars exists. Exploitation ranges from collection of natural stocks to major culture operations. High production figures for oysters, mussels, cockles, and clams were reported from many countries: in China, 43% of mariculture production is from bivalves; in 1979 alone, Malaysia produced about 6.3 X 104 t of cockles; and Philippine export earnings from shell pro­ duction are 850 million pesos, or more than US$100 million. The economically important genera in the region are Crassostrea, Perna, and Anadara (Table A), although Pinctada, Paphia, Cockles (Anadara granosa) are extensively grown in a Meretrix, and Solen are also valuable. Bivalve- number of countries in the region.

Table A. Occurrence of major groups of bivalves in Asia and the Pacific region.

Ostreidae Mytilidae Arcidae Country (oyster) (mussels) (cockles) Other Bangladesh na' na na Lamellidans marginalis; Parreysia corrugata; Placuna placenta Burma Crassostrea sp. Perna viridis Anadara sp. Solen sp.; Siliqua radiata; · Meretrix sp., Donax sp.; Paphia sp., Pinctada maxima China C. rivularis; Mytilus edu/is; A. granosa; P. martensii; Chlamys farreri; C. plicatula; M. crassitesta; A. subcrenata; C. nobilis C. talienwhenensis P. viridis A. inflata· Fiji C. g/omerata; P. viridis Anadara sp. Batissa violacea C. gigas; C. echinata India C. madrasensis; P. viridis; A. granosa; Pinctadafucata: P. sugillata; C. gryphoides; P. indica A. rhombea Paphia textile; P. malabarica; C. discoidea; Meretrix meretrix; M. casta; Saccostrea cucullata Katelysia opima; K. marmorata; Villorita cyprinoides; Donax faba; D. cuneatus; D. incarnatus; Solen kempi; Placenta placenta

continued

9 /0 BIVALVE CULTURE

Table A. (concluded)

Ostreidae Mytilidae Arcidae Country (oyster) (mussels) (cockles) Other Indonesia Crassos1rea sp. P. \'iridis A. granosa; Pinczada margari1ifera; P. maxima; A. indica; Modiolus spp.; Tridacna gigas; A. amiqua1a; Gafrarium spp.; Solen sp.; A. infla1a Amusium sp. Malaysia C. be/cheri; P. \'iridis A. granosa Paphia sp.; Solen sp.; Elizia sp.; S. cucul/a1a G/auconome sp. Papua New C. amasa; P. margarizifera; P. maxima; Guinea S. echina1a T. gigas Philippines C. ireda/ei; P. \'iridis A. granosa; Modiolus me1calfei; P/acuna S. echina1a; Arca sp. p/acema; P. margarizifera; S. cucul/a1a P. maxima; P1eria sp.; Amusium pleuroneczes; Cyrzopleura cos1a1a (Pho/as oriemalis); Pro1apes sp.; Ka1e~1·sia (Paphia) spp.; A1rina sp.; Pharel/a acu1idens; Ge/oina s1ria1a; Circe gibba; Maczra mera; M. macu/a1a; Donax radians; Corbicu/a fluminea Sri Lanka C. be/cheri; P. perna; A. amiqua1a Larkinia rhombea; Pinc1ada S. cucul/a1a P. \'iridis \'Ulgaris; Pinna bico/or; Ge/oina coaxans; Gafrarium 1umidum; M. mere1rix; Marcia opima; D.faba Tahiti S. echina1a; P. \'iridis P. margari1ifera; Venerupis S. cucul/a1a semidecussa1us Thailand C. commercialis; P. \'iridis A. granosa Modiolus senhausenii; Paphia C. lugubris undu/a1a; Solen abbre\'ia1us; P. maxima; P. margari1ifera; P1eria penquin Singapore P. \'iridis 'na =no information available.

production figures (Table B) based on status exist to various degrees in most countries of the reports reveal considerable yields from raft cul­ region. ture of mussels in the Johore Straits in Singapore A general review of the shellfish industry sug­ and in India ( 135 t ha a year or 12 kg m of rope). gested that the major problems are: The culture of oysters has been promoted in sev­ • Limited market demand and low prices for eral countries and has become an established collected bivalves in some countries; industry in the Philippines. Relaying of seed • C ncertain supplies of seed for culture and cockles in Malaysia and the harvesting of other relaying as well as uncertainty in appro­ bivalves in estuaries throughout the region have priate site selection; demonstrated the recognition of the value of • A shortage of trained personnel for biologi­ these resources. It is apparent, however. that cal studies. culture-processing operations. present production could be considerably and extension activities; increased in most countries if production tech­ • Lack of administrative management, regula­ niques were intensified or culture areas tory, and developmental measures for effec­ expanded. In some countries. culture does not tive promotion of bivalve fisheries; and exist or has had a very brief history, and coopera­ • Inadequate sanitary and processing systems. tion between such countries and those with more Data from the island states of Micronesia indi­ developed industries seems possible. cated generally slower growth rates than As well as the considerable potential for food. obtained in South and Southeast Asia for many there is also the employment that can be provided bivalve species. apparently because of the low in rural communities involved in shellcraft and primary productivity in these waters. Some inter­ pearl-culture activities. Several such enterprises est was expressed in the use of freshwater bivalves Table B. Status of bivalve production in South and Southeast Asia and the Pacific (February 1982).

Production (shell-on, t, except Source of Culture Country Bivalve where noted) seed method' Status of culture Major constraints Bangladesh Oyster; windowpane Wild Bl Experimental Lack of trained personnel, experts oyster; freshwater mussel Burma Oyster; mussel Wild' BI; S Experimental Extreme hydrographic conditions China Oyster; mussel; 2 X I 05 t fresh flesh Wild'; BI; S Highly developed Need mechanization (development razor clam; cockle (1978) hatchery under way) Fiji Oyster; mussel Wild'; s Experimental No local species available for culture imports India Pearl oyster; 21 million pieces Wild' S (except Pearl culture advanced; Limited seed supply for some species clam; cockle; (1958); cockle - R) edible bivalves collected mussel; windowpane 2X 105; 2X103; for sustenance; large oyster 3.1X103; 4X 103 numbers of clam shells used for lime Indonesia Cockle; mussel; 5.1x104 (1979) Wild' Bl; S,R Experimental Low demand (except for cockles); oyster; clam; lack of trained personnel; no pearl oyster leasing arrangements Malaysia Oyster; cockle 12-13 ( 1979); Wild' B,S; B,R Oyster culture Fouling; siltation; seed supply 6.3 x 104 (1979) experimental; cockle of Anadara sp. (in future) likely culture adva need limited Papua New Pearl oyster Wild; s Experimental Red-tide paralytic shellfish Guinea experimental poisoning; mercury occurs naturally hatchery for giant clam Philippines Oyster; mussel; 799; 3.0X103; Wild S,BI; S; Oyster culture developed; Poor sanitation; limited markets; windowpane oyster; _h; 2.0X 103; Bl; Bl; Bl others experimental with irregular spatfall cockle; other 109 (1979) subsistence collection from the wild Singapore Mussel 500 Wild s Developing Inadequate techniques for postharvest processing Sri Lanka Oyster; mussel; Wild' Little work to date clam

Tahiti Pearl oyster; IX 105 (1979); Wild; s Pearl oyster developed; Low-nutrient water; extreme (;I) mussel; clam 2.8 XI 05 oysters;22;9 hatchery others experimental temperatures and salinity t>i (;I) Thailand Mussel; cockle; 9.0 X I 04 (1979) Wild' Bl; S Developed Limited seed supply ~ oyster 0 < 'B =bottom; I= intertidal; S =suspended (raft or rack); R =relaying. (;I) hSmall amounts collected in wild, but exact statistics not available...... 'Bivalves are collected (fished) from the wild at subsistence level...... 12 BIVALVE CULTURE

(Fiji) and tridacnid clams (Papua New Guinea), OYSTER CULTURE spatfall-forecasting procedures, and polyculture. Oyster culture can be divided into bottom and It was acknowledged that bivalve culture is off-bottom systems. In the former, oysters are thriving in the region and is not limited to the grown on the bottom, either intertidally or subti­ major producers in Asia such as Japan, Korea, dally. Intertidal culture requires a relatively firm Australia, and New Zealand. However, it was substrate, the correct tidal height, and protection also recognized that there are considerable dif­ from excessive wave action. For subtidal culture, ferences in the development of bivalve culture a suitably firm substrate, a moderate depth, and among the countries concerned and that, there­ minimal predation are needed. The basic method fore, there is a need to identify and define more involves planting the seed, usually on ground specifically the real potential for bivalve culture particularly suited to small oysters; transplanting in each country. the seed to grounds where growth is rapid; and finally transplanting the oysters to fattening grounds. Procedures vary, depending on the CULTURE METHODS availability of the types of ground. Off-bottom systems include rack culture, sus­ Although a number of bivalve genera occur pended culture, and stake culture. In the first throughout Southeast Asia, those of main con­ system, racks of various designs and materials are cern for aquaculture development are mussels constructed in or near intertidal zones and are (Perna), oysters (Crassostrea), cockles (Anad­ used to suspend trays or strings or to support ara), pearl oysters (Pinctada), and windowpane sticks. The racks are usually 1-2 m high. · oysters (Placuna). The tremendous potential of The stick type of culture is direct and uncom­ these species as a food supply and a source of plicated. Seed is collected on sticks that are rural employment was cited repeatedly. How­ placed horizontally on the racks and where the ever, appropriate technologies must be applied if oysters grow to maturity. Those less than market this potential is to be realized. size when harvested are allowed to continue to To be suitable for culture, a native molluscan grow in trays also held on racks. species must have three attributes: Strings of shells or other types of cultch may be • A reliable, inexpensive supply of seed; suspended vertically from racks or placed hori­ • A rapid growth rate; and zontally like sticks. A great deal of oyster seed is • Relatively high value. collected this way. In the tropics, the first two needs are generally In the suspended-culture system, strings or met. The third depends partially on whether the trays are suspended from floating rafts or long culture is to be artisanal or entrepreneurial. lines. The latter are simply cables supported by In areas where there are not suitable native floats and anchored at each end. They can with­ species, an exotic one may be introduced but only stand greater wave action than can rafts. as a last resort and after thorough analysis of the Stake culture is also a simple system. A stake dangers and consequences. Local species already about 1.5 m long is driven into intertidal ground occupy the environment most suited to their at an appropriate tidal height. A piece of cultch, needs, although they may not be amenable to such as an oyster or scallop shell, is placed on top cultural practices, regardless of whether the of the stake. The cluster of oysters is allowed to environment is oceanic or estuarine. The alterna­ grow to maturity in situ. The equipment is tive culture sites can be subtidal, intertidal, or straightforward, and the system is useful in inter­ mid-water. Site selection usually represents a tidal areas of soft mud. compromise between the ecological requirements of the species and the characteristics of the var­ MUSSEL CULTURE ious types of culture. There are only a few basic systems of mollusc As with oysters, the two main systems for mus­ culture but many variations on these. Many mod­ sels are bottom and off-bottom culture. In bot­ ifications result from the ingenuity of the cultur­ tom culture, mussel seed, collected in various ist and are designed to take advantage of local ways, is spread on the bottom where it remains conditions and materials. Many attempts have until harvest. been made to make mollusc culture less labour There are several methods of off-bottom cul­ intensive, but the cost and supply of labour ture, but the main one is raft culture. Seed is remain the prime factors in selecting a culture collected from natural populations on the shore system. or from ropes suspended from rafts. Sometimes SESSIONS 13

Ropes used/or mussel culture. Clockwise from the top left: 4 m coconut coir rope, 4 m polyethylene rope, 4 m polycoco rope, and 2 m polycoco rope. the seed from the ropes is reattached to other simple method to suit the target user, one must ropes or placed in mesh bags for suspension. In research and evaluate the available alternatives. another method, seed on ropes or mesh bags is Seed production and supply are a problem attached to heavy vertical poles in the intertidal with many species. Hatcheries are often consid­ zone. Mussels may also be grown subtidally on ered to be the panacea for this problem, but these long vertical poles: the seed collects on the poles require expensive, sophisticated equipment and and grows to maturity in situ. qualified personnel. Providing hatchery­ produced seed with food appropriate to the trop­ COCKLE (CLAM) CULTURE ical milieu is also a problem, and the nursery culture of juveniles, in particular, is technically Cockle culture is not an advanced art and is not difficult and costly. as widely practiced as oyster or mussel culture. Spatfall-forecasting techniques are used in Cockle seed is harvested from natural grounds temperate countries and deserve attention, par­ and replanted on areas with a suitable bottom but ticularly in tropical environments where the where seed is not abundant. The cockles are then bivalve-breeding season frequently extends over allowed to grow to market size, several months. Methods include plankton sam­ pling or monitoring of the gonad condition of the PROBLEMS adults, but the most effective method is probably the routine examination of initial spatfall on There seems to be a tendency toward sophisti­ sample collectors put in place for this purpose. cation where simple, inexpensive techniques The introduction of foreign bivalve stocks is would suffice and even be· more appropriate. often proposed as a means of establishing a new Selection of the most appropriate culture tech­ resource or of enhancing a meagre, local seed nique requires consideration of not only the biol­ supply. The problems associated with such intro­ ogy of the species but also the physical and socio­ ductions are that they may be accompanied by economic environment. To develop a low-cost, pests or diseases and there is no guarantee that a 14 BIVALVE CULTURE local, self-sustaining population will result. Suc­ erable utilization of the resources of the region, cessful introductions have been few. their full potential has yet to be realized. Security of tenure of bivalve grow-out areas is important in encouraging ventures in mollusc culture. Current legislation for the leasing of POSTHARVEST MEASURES grounds in the region (Table C) is minimal, and regulations must be considered in the future. Bivalves are an important source of inexpen­ Security of tenure should be contingent on pro­ sive protein; the flesh of green mussels, for exam­ ductive and diligent use of a lease. Also required ple, contains about 67 g protein/ 100 g flesh at 0% are an accurate delineation of boundaries and moisture. They are especially suitable as com­ security against harmful encroachments. minuted products for mass or institutional Throughout the world, many foreshore envi­ markets. At present, however, their sanitary ronments are being destroyed. Mangrove quality is often unreliable. This unreliability swamps are particularly sensitive to disruptions, adversely affects sales and needs to be eliminated and, in Southeast Asia, the maintenance and the through postharvest measures, especially sanita­ extension of bivalve resources are contingent on tion and quality control. their preservation. Because of the reproductive capacity of most SANITATION/ DEPURATION bivalves in the tropics and their growth rates (high enough to produce two crops a year in some Pollution from fecal coliforms and heavy instances), they are a food resource that cannot metals and paralytic shellfish poisoning (PSP) be ignored. And, although there has been consid- from dinoflagellate blooms are health hazards

Table C. Summary of bivalve lease legislation.

Regulations (requiring Country lease or permit) governing Specifications' Bangladesh Windowpane oyster nab Burma None of the bivalves China Oyster; mussel; cockle; pearl oyster; No fee razor clam; little neck clam; etc. Fiji General fishing: inshore areas - Inshore: $4 boat, $4 captain, $1 permission to fish commercially must for each crew member, outside be granted first by the clan owning reef: $10 the area, then by the Fisheries Division; and outside the reef - per­ mission and licence must be granted by the government India Wild pearl-oyster population (no leasing arrangements for culture) Indonesia None of the bivalves (the department of agriculture is coordinating interde­ partmental efforts to establish maricul­ ture legislation) Malaysia Cockle $25 Papua New Guinea Oyster (village owns inshore shelf No fee areas) Philippines Fish traps for shellfish farm: municipal $1 permit (not a lease) Singapore All floating cultures in coastal areas $500 Sri Lanka None of the bivalves (no leases) Tahiti Green mussel, pearl oyster (Pinctada Symbolic margaritifera) Thailand All mollusc culture (cockle, mussel, $3-4 oyster) 'All costs have been converted to US$/ha-year. bna =no figures available. SESSIONS 15 from raw or semicooked bivalves. Food poison­ ing has been reported from Australia, India, and Sabah, and pollution has been associated with periods of heavy rain. Because they are filter-feeders, bivalves can accumulate toxic levels of pollutants in their bodies. Hence, sanitation and quality-control programs are essential, and some are already under way - for example, the New Zealand Standard Recommendations for the Processing, Storage and Transportation of Molluscs and the National Shellfish Sanitation Program instituted by the Public Health Service of the US Depart­ ment of Health, Education, and Welfare. Most countries recognize the importance of quality control; however, personnel constraints in many countries make the introduction of effec­ tive pollution control unlikely. In practice, a pro­ gram to monitor pollutant levels at the end point of farming - sales - rather than at the growing sites may be more feasible, although it is not a substitute for the much-needed controls. Con­ sumers must be educated through pamphlets and brochures on how best to handle bivalves, and personnel must be trained in sanitation methods. Quality control of shellfish imports and exports should also be enhanced so that products meet acceptable standards. To market fresh, shell-on bivalves, one must purge the bivalves of the pollutants and toxins; a simple method is to relay the animals to unpol­ Fresh mussels packed in moist gunny sacks. luted waters or place them in sterilized waters under controlled conditions. Various methods of water sterilization are practiced commercially - era! operations, including the separation of clus­ chlorination, ozonation, and ultraviolet (UV) tered mussels, debearding of byssal threads, and radiation. The UV method may be most suitable deshelling of cooked flesh. The use of steam to for the Asia- Pacific region because it has no facilitate opening of the oyster is also a residual effect, is easy, and is comparatively possibility. inexpensive. The shelf life of fresh bivalves could be In some countries, the poor sales of fresh extended through various forms of dry and wet bivalves are a reflection, partly, of their unreli­ storage. able quality. Thus, quality-control measures should eventually improve consumer acceptance, PROCESSING AND NUTRITIONAL DATA and the increased sales would offset the cost incurred in taking such measures. In some areas, Bivalves eaten in the countries represented at it may be necessary to make depuration manda­ the meeting are either cooked or pickled. Because tory for all bivalves, from natural or culture of their perishable nature, fresh bivalves are not sources, intended for human consumption. readily available in inland areas. Smoking and drying the flesh is suggested as one relatively POSTHARVEST OPERATIONS, SHELF LIFE. inexpensive means of preservation that would make the product available in such areas. With AND STORAGE refrigeration facilities, cooked flesh could be fro­ In all the countries, postharvest operations are zen in blocks or glazed in individual portions. carried out by hand, and the only place needing Interest has been expressed by some countries in mechanization at the moment is Singapore where the use of flesh from bivalves whose shells are large quantities of mussels are handled at one normally used in the shellcraft industry, e.g., time. Singapore is attempting to mechanize sev- Placuna placenta (windowpane oyster). 16 BIVALVE CULTURE

Block and individually frozen mussels.

ECONOMICS and capital, hatchery development, experimental vs commercial operations, comparative resource In many countries of the region, bivalve cul­ use, Iicencing, postharvest technology, levels of ture has not been a significant aquaculture enter­ culture, and private vs social production: prise in terms of size, food produced, resources • Market. The limited market for edible employed in production, or net income received bivalves other than cockles harvested from by producers. Perhaps the reason is that, until natural stocks and cultured supplies is a fairly recently, few attempts were made to powerful economic deterrent to increased research existing tropical bivalves and, thus, to bivalve production. Bivalves are relatively increase the scientific and technical knowledge low priced and are in the preliminary stages for their culture. However, there are now culture of acceptance as food. Although there is a systems in commercial operation, and several long-term, increasing demand for protein in others are being scientifically studied in the hope Asia, research should focus first on species that they will be suitable for commercial with known market acceptance. Increasing application. the culture and improving the acceptability In many cases, detailed information on the for bivalve species now consumed are the biological and technical input- output relation­ best way of improving long-term production ships of specific kinds of bivalve culture is not yet and utilization of a wider range of bivalve available, and the full range of alternatives in species. culture techniques has not been developed. The • Production techniques. In addition to a va­ scarcity of information is particularly critical for riety of species that could be considered, economic analyses. Financial data on bivalve cul­ there are a wide variety of culture tech­ ture and fishing are few, and little documentation niques. More important for economic pur­ exists about markets for inputs, quantities and poses, there is a wide range of alternatives in combinations of inputs in production, or markets terms of material input, labour, sequence of for the product. operations, and engineering design for par­ The major economic concerns involve ticular culture techniques. In the develop­ markets, production techniques, use of labour ment of culture practices, one should con- SESSIONS 17

sider the costs and returns from all tion. Polyculture may be a means for max­ alternatives possible for each major compo­ imizing both biological and financial nent in the total culture or fishery practice. returns, but the potential from investments • Use of labour and capital. Given that rela­ in polyculture systems must be weighed tively limited markets exist for some against that from the same investments in bivalves, that they have low (relative to fin­ the expansion of the existing monoculture. fish) local-market prices, and that the cost of • Licencing. Licencing fees for bivalve culture labour is generally lower than that for capi­ vary widely in the region (Table C), ranging tal in Asia, culture practices that depend on from no fee to S$250/0.5 ha annually. The intensive capital use would probably have fee allows the state to realize some return less chance of being economically viable from its resource - the production site. than those involving relatively more labour. From an economic viewpoint, the fee should This will depend, of course, on the biological equal the amount that the site contributes to environment, the relative prices of capital production. The principle underlying the and labour, and the competition from other licencing fee is similar to that for wages or production activities for the inputs (particu­ rent. However, the fee should not be so high larly water). initially that it deters new entrants into • Hatchery development. Seed supply is a bivalve culture. This is particularly true for serious constraint in a number of countries sites that are not used for other purposes. (Table B), and establishing government or • Postharvest technology. Given the often commercial hatcheries has been considered limited local market for fresh bivalves, some as a means to guarantee supplies. However, postharvest handling and processing seem to the costs of establishment and of measures be required, and the operations should be as to protect the spat during transport from the simple and low cost as possible, while allow­ hatchery to the culture site should be ing for reasonable productivity. However, weighed against the costs of identifying they should ensure a relatively high standard alternative sources of natural seed. Thus far, of quality. There is a potentially high payoff the spawning sites and the period and dura­ from research that develops appropriate tion of spatfall are only broadly defined for technology for postharvest operations, par­ some species and need further study. ticularly depuration, and that also improves • Experimental vs commercial operation. In traditional methods of shucking, boiling, countries where a commercial culture roasting, and drying. Production of a high already exists, its economic efficiency in quality, sanitary product would help to resource use should be assessed. Such an remove a market bias against bivalves as assessment would involve economic (rather human food and therefore allow a relatively than a simple, financial) analysis of the earn­ low-cost source of protein to compete with ings from the use of water, labour, and capi­ other, relatively high-cost, sources. tal in the culture operation compared with • Levels of culture. The economics of a rela­ potential or actual earnings from alternative tively capital-intensive operation, as exem­ uses. If commercial culture is just being plified by Singapore, need to be compared introduced in a country, researchers should with those for an intermediate type of cul­ monitor the operations and record devia­ ture emphasizing low capital costs and a tions from those recommended in the exper­ significant use of labour. Such a compari­ imental design. Any gap in production son, along with market studies, could assist between the private commercial operator potential producers in determining the feas­ and experimental practice should be exam­ ibility of the two levels of cultural practice in ined, and production improved with appli­ areas where bivalve culture has not yet been cations of new or existing technology not introduced. used by the commercial operator. • Private vs social bivalve production. In • Comparative resource use. In the develop­ some areas, governments may consider ment of bivalve-culture systems and the bivalve culture as a means to fulfill social encouragement of their practice, the eco­ objectives - for example, to produce pro­ nomic returns from resources used (water, tein for a specific group of people in a capital, and labour) compared with those society. Economic analyses could assist the from alternative-production activities will policymakers to determine the least-cost be an important factor in commercial adop- method of achieving a particular objective. 18 BIVALVE CULTURE

Although the social objective may preclude the marketing cost for different species, the major profitable production, an attempt should be factors behind the demand for different species, made to minimize its costs. and, therefore, their potential market growth The priorities for economic research on bivalve over time. Such studies are particularly impor­ culture are studies to define potential local, tant for species whose culture is being researched regional, and international markets for various or planned but for which the market is not readily species. These studies should also help to define apparent. ... ' COUNTRY REPORTS BANGLADESH

Masud Ahmed Ministry of Fisheries biology, ecology, and population dynamics of the and Livestock, Government of the Peo­ bivalves. Useful findings have related to: ple's Republic of Bangladesh, Dacca, • The culture of pearls and mussels. For example, freshwater mussels (variety Obesa) Bangladesh were sorted by length: 5 cm, 5-7 .5 cm, 7.5-10 cm, and> 10 cm; those belonging to Bangladesh is blessed with many natural the first three groups were reared in enclo­ resources; among them are bivalves, which pro­ sures made of 0. 9-m bamboo pegs that were duce protein-rich flesh, calcium-rich shells, and pushed 15 cm into the mud. This system pearls. Because Bangladesh is a riverine country, proved to be very efficient; it allows water it has many ponds, lakes, canals, and rivers con­ circulation and navigation between the taining freshwater mussels, thousands of which enclosures, and mature mussels can be col­ are being harvested annually. According to a sur­ lected and harvested quickly. Those larger vey conducted by the East Pakistan Small Indus­ than 10 cm are harvested for pearls. tries Corporation (now the Bangladesh Small • The cause of pearl formation. In about 6% of Industries Corporation), in 1964 about 165 kg of the mussels, natural pearls are produced, natural pink pearls were produced, with a value and research suggests that the tension at the of about Tk 1.4 million (Tk 19 = US$ l ). The points of attachment of adductor muscles number of pearl and mussel collection centres in causes powder-like substances or shell parti­ 1964 in Bangladesh was 98: 8 in Bogra, 4 in cles to dislodge from the shell and fall on the Rajshahi, 9 in Pabna, 7 in Faridpur, 3 in Dacca, mantle. It is from these granules that pearls 40 in Mymensingh, and 24 in Sylhet. are produced. Windowpane oyster beds near Cox's Bazar • The frequency of seed-pearl formation in cover an estimated 220 ha. Although the pearls freshwater mussels. An examination of 1791 from these oysters are generally white and infe­ freshwater mussels revealed that 6% contain rior, the shells are used for various purposes. The seed pearls. flesh of these and other oysters is eaten by local • The taxonomy of freshwater mussels. peoples and may have potential for export. Edi­ Studies on mussels in five districts found ble oysters are found mainly in the Maiskhali seven different types or varieties. (These channel (Bay of Bengal) and in the Bakkali and results have not been confirmed.) Naf rivers in the Chittagong district. The largest • The fecundity and longevity of mussel lar­ bed (33 ha) is in Gotibhanga in the Maiskhali vae. The female mussel has been found to channel. The commercial species of edible oysters produce more than 100 000 eggs, and the available near Cox's Bazar belong to the genera larvae remain alive in pond water for fewer Crassostrea and Ostrea. than 45 h. In the early 1960s, the government realized the • Induced or forced pearl culture. In efforts to potential of pearl and mussel culture and force pearl formation, spherical pearls, the launched a project to investigate windowpane eyes of small fishes, and small pieces of man­ oyster fisheries and the artificial culture of pearl tle were tried as nuclei, but only cut pieces of oysters at Cox's Bazar. At the same time, a mala­ mantle produced pearls, and the mortality of cological unit was set up under the Freshwater the mussels was very high (about 90%). Fisheries Research Station at Chandpur in the Because of the limited progress so far on the Comilla district, and, during 1975-80, a pilot artificial culture of pearls in freshwater mussels project on the culture of pearl-bearing mussels and marine oysters, a consultant on shellfishes was set up in Tangail district. The research to was brought in and is working in the country date has produced essential information on the now.

20 CHJNA 1

Nie Zhong-Qing National Fish Admin­ and 8.3 X 10 4 ha for extensive culture. The yield istration, Yellow Sea Fisheries Research of bivalves in 1978 was about 2.0 X 1os t, 44% of Institute, Qing Dao, China the total mariculture yield. This production included 3.0 X 104 t of oysters (fresh flesh), 9.0 X 104 t of mussels, 4.0 X 104 t of 4 China has about 1.8 X 10 4 km of coastline, razor clams, 4.0 X 10 t of cockles, and a small large islands, and many archipelagoes (in the amount of small-necked clams and hard clams East China and South China seas). The main (fresh flesh). coastline extends from the temperate zone in the Bivalve culture is not extensively developed in North to subtropical and tropical zones in the Fujian, Guangdong, Zhejiang, Shandong, or South. There are intertidal beaches and flats and Liaoning provinces. However, the culture of shallow seas all along the coast, which provide pearl oysters was started recently in Guangdong about 2 X 106 ha suitable for mariculture. and Guangxi provinces, and the coastal waters of Bivalve culture in China has a long history and Liaoning and Shandong are used for mussel and an important position in modern mariculture. scallop culture. Mussel culture has been con­ Oyster culture began in the Han Dynasty about ducted there for about 20 years but scallop cul­ 2000 years ago and may have equaled European ture only recently. In the South, oysters, razor oyster culture during the ancient Roman period. clams, cockles, and small-necked clams are called Yelikou (Manual for Oyster Culture), written by "the four well-known cultured bivalves." A great Zhen Hongtu in the Ming Dynasty ( 1368-1644 deal of knowledge and skill in their culture has AD), gave systematic, practical information on been accumulated over the years. oyster culture. Other species of bivalves, such as The traditional culture method in the South is cockles and razor clams, also have long histories bottom culture in the intertidal zone. In the of culture. For example, the Compendium of North, mussels and scallops are cultured on float­ Materia Medico written by the famous medical ing rafts, and the culturists mainly depend on man Li Shizen in the Ming Dynasty records natural spat. These bivalves are reared and har­ razor-clam culture. vested with little effort. Under the government of the People's Repub­ lic of China, aquaculture has received attention and strong support. Experimental stations have OYSTERS been established, and scientists have been encouraged to join workers' teams to develop the The most commonly cultivated oyster species field. More than 10 species of bivalves are now are Crassostrea plicatula and C. rivularis. There cultured successfully along the coast. The major is also small-scale culture of C. talienwhenensis in groups are oysters, mussels, razor clams, short­ Liaodong and Shandong peninsulas. The C. pli­ necked clams, pearl oysters, scallops, and hard catula culture is mainly in Fujian and Zhejiang, clams. The area used for culture was about 1.48 X and the C. rivularis in Guangdong. The C. p/icat­ 10 5 ha in 1978: 6.5 X 104 ha for intensive culture ula yield is very high and accounts for about five-sixths of the total yield of cultured oysters. Crassostrea plicatula is a common species 1This country report is based on two papers pre­ sented during the workshop. The main report was pre­ along the coast. It grows rapidly and has a short sented by Mr Nie. The appendix on oyster-culture culture period. It produces spat all year, with techniques in Guangdong was presented by Mr Qiu spatfall peaks in May and September. Typical Li-Qiang, South China Sea Fisheries Research Insti­ culture methods are the barn boo-stake method in tute, Singanglu, Hai Zhu Qu, 2389 Canton. the northern and eastern parts of Fujian and the

21 22 BIVALVECULTURE stone-bridge method in the sou~ hern part of when salinity is at its minimum and temperature Fujian. The former is good where the bottom is at its maximum for the year. . soft. Bamboo -stakes, 1.2 m long and 1.5 cm in Since the early 1960s, fisheries scientists have diameter, are planted in midtidal flats before successfully helped the oyster farmers predict the spatfall peaks, with 4-5 bamboo stakes in a bun­ best time for putting out the collectors. The crite­ dle. The bi,mdles are spaced regularly in rows. ria used are the numbers of pelagic postlarvae in About 1.5-1.8 X JOS stakes/ ha are used as spat the water and the hydro graphic conditions (salin­ collectors, and these are thinned once or twice ity 7.0-17.5 ppt and temperature 26-29°C). The during the growth period, so that there are about postlarvae settle during low tide, to a depth of 1.2- 1.5 X JOS stakes/ ha at harvest. The spat set­ I 0 m, with a maxim um density within 0.4 m of the tling in May require 11-15 months to grow to lowest tide line. This method of forecasting has harvestable size and those in September, 16-18 ensured a stable yield. months. The average yield is 60 t/ ha, but yields The culture area is usually divided into rectan­ sometimes reach 110 t/ ha. The harvesting season_ gular bl9c~s_.. and the spat collectors are lined up is winter and spring. in rows. There are usually 3.0-3.8 X 104 cement The stone-bridge method is used in sandy mud bars or 1.0-1.4 X JOS cement plates/ ha. The bottoms. Bridges made of stone bars (80 cm X 20 growth period of C. rivularis is 3-4 years. Before cm X 8 cm in diameter) collect spat on midtidal harvest, the oysters are moved to fertile waters flats in May and June. During the growth period for a few months of fattening. The yield is (7- 12 months), the bridges are moved periodi­ 45-llOt/ ha. cally as a means to ensure abundant food supplies Because of the potential damage by typhoons, for the oysters. Fifteen thousand stone bars can oyster culture in the South has been limited to be put in I ha, and the average yield is 30 t/ ha, traditional bottom culture. Recently, however, although yields sometimes reach 80 t/ ha. experimental raft culture, which gives a higher Crassostrea rivularis lives in estuaries of low yield in as horter period than bottom culture, has salinity and is cultivated mainly on the bottom. shown potential. An 84-m2 raft produces the Gravel, oyster shells, and cement plates (17 ~24 same yield in 2 years that 667 m2 of bottom cm X 14- 19 cm) or bars (40-80 cm X 6 cm X 4 cm culture does in 4 years. In addition, the rafts in diameter) are used to collect spat. The last two, withstand typhoons better than expected. introduced in the 1960s, are reinforced, with bamboo being embedded in the cement. They are lighter than other collectors, have a larger surface MUSSELS area for spat settlement, and are not as easily covered by silt. The culture cycle has three There are three commercial species of mussels phases: spat collection, adult rearing, and fatten­ in China: the common mussel (Myti/us edu/is), ing. The peak of spatfall occurs in June-August, the black mussel (M. crassitesta), and the green mussel (M. smaragdinus). The common mussel occurs in Liaodong and Shandong peninsulas in the North, and the black mussel from the Bohai and Yellow seas to the East China Sea. The natu­ ral stocks of the black mussel are historically quite abundant, especially in Zhejiang and northern Fujian. The green mussel is distributed in the southern part of the East China Sea and in the South China Sea. The black mussel is the largest (shells 20 cm long), and the common mus­ sel the smallest (shells 12 cm long). The common mussel is the most widely cultured species, where­ as the green mussel is cultured in Guangdong on a much smaller scale. Mussel culture in China began in the late 1950s. Mussels grow quickly, have a short culture cycle, and produce a high yield. At first, spat were quite sparse, but, as the scale of mussel culture increased, the numbers of natural spat quickly increased. The major culture areas are in Shan­ Stone-bridge method of culture. dong and Liaoning. Artifici~l culture has spread CHINA 23

Mussels under culture. successfully to Zhejiang and, in the South, to the The shells of seed mussels from spring spat can northern part of Fujian. grow to more than 1.5 cm by July or August, Mussel culture uses the same floating racks when they are transplanted to the rearing rack that are used for Laminaria (kelp) culture. The and wrapped around the mussel strings with rack is made of a rope 60· m long and glass or pieces of net. The net pieces can be removed after plastic floats 28 cm in diameter. It is anchored by 1-2 days. large cement blocks or wooden stakes. Each There are two culture cycles. One is about 8 floating rope is a culture unit and about 100 months ~ from summer to March - by which mussel strings are hung from each line. The time the mussel shells are just over 4.5 cm long, strings used for rearing adult mussels are about and the other is about a year - from summer to 1.5- 2.0 m long. August - when the mussel shells are just over 6 Mussel culture is simpler than other types of cm long. Most culturists adopt the shorter cycle bivalve culture and can be divided into two and harvest in the spring when the density should_ stages: seeding and rearing. Seed mussels are col­ be about 1000-1200 individuals/ m of string. In lected from nature. The two major spawning sea­ summer, harvest densities are 600- 700 / m. The sons are April and late September. The spring densities affect total yield and quality, and yields spawning produces many more eggs than the fall vary considerably among sea areas with different and, hence, is the main source of seed. The pro­ productivities. However, the yield from spring duction from the autumn spawning depends on harvesting is generally about 0.6 t / rope, and, in the temperature during the following winter. In some regions, it reaches about 1.5 t. The yield the coastal area of the North, the thousands of from summer harvesting can be as much as 66% ropes used for Laminaria and mussel culture are more but is vulnerable to summer storms or good collectors for seed mussels. In some produc­ typhoons. tive areas (e.g., inside a bay), new rafts and ropes Because natural seed mussels were scarce dur­ are used to collect the spat. ing the early stage of mussel culture in China, 24 BIVALVECULTURE

Harvesting razor clams. fisheries scientists worked to develop practical sexual products by the parent stock and exami­ techniques for artificial spat rearing. In 1973, one nation of the seawater in an attempt to determine of the experimental tanks produced 2.8 X J06 the number of postlarvae nearly ready to settle spat/ ml of seawater. Spat rearing, feeding, and (the pelagic larva stage lasts for 6-10 days). Just managing techniques were studied, and much before the postlarvae settle, the spat beds are useful information was accumulated. With the loosened and flattened on the site. The spawning tremendous increase of natural spat in the north­ season is from late September to January, with ern areas, artificial rearing is now important only the peak from mid-October to mid-November. in Zhejiang, Fujian, and Guangdong. The intensive discharge of sexual products usu­ ally occurs at the end, but sometimes at the beginning, of a spring tide. RAZOR CLAMS Seed clams are harvested and sown into rear­ ing beds from January to March of the next year. Sinonovacula constricta (razor clam) is found The number to be sown depends on the size of the only in the cold waters of China and Japan, in clams, the condition of the substrate, the tide bays where there is an input of fresh water. The level, and the season. Generally, 9-18 X J06 I-cm clams inhabit the middle and low intertidal mud long seed clams/ ha are suitable. With proper flats and can be found in all parts of China. They management, they can be harvested in August of are the major species of cultivated bivalves in the same year. Marketable size is about 5 cm in Fujian and Zhejiang and account for more than shell length. The average yield is 15-22 t/ ha. half the total yield of cultivated bivalves in the Sometimes, the clams are allowed to grow until two provinces. These clams are an important March or April of the following year. Then they source of income, and intensive culture tech­ yield, on average, 30-37 t/ ha; yields as high as niques have been developed. 82.5 t/ ha have been recorded. For a long time,. development of razor-clam culture was limited by natural seed production. In the late 1950s, Chinese fisheries scientists devel­ COCKLES oped a procedure to predict the best time for natural spat collection, and this development has Arca (Anadara) granosa - cockles - are one greatly increased the production of seed clams. of the major cultivated species in Shandong, Zhe­ The forecasting procedure is based on observa­ jiang, Fujian, and Guangdong and are the pre­ tion of the time of intensive discharge of the ferred seafood in many coastal parts of south CHINA 25

Sieving and washing cockle spat.

China. Cockles inhabit soft, muddy flats in estu­ SMALL ~NECKED CLAMS aries and bays where winds and waves are weak and tidal currents as well as inflow of fresh water The small-necked clam (Tapes philippinarum) are unimpeded. The spawning season is. July­ occurs in China, Japan, and the Philippines and September. The spat settle on fine, sandy mud inhabits muddy, sand beaches in intertidal zones flats where there is little wave action - usually in and the bottom of shallow waters near estuaries. the middle and low intertidal zones. The natural stocks are abundant in some areas of The culture cycle for cockles is longer than that the Liaodong and Shandong peninsulas, and for other bivalves cultured in China. Cockles they support a local fishery. The small-necked possess no siphons and can only live in the shal­ clam is one of the important cultivated bivalves in low surface layer of the mud flat; therefore, both Fujian. Its spawning season is in October­ freezing temperature and exposure to the sun can N ovember. The pelagic larvae live in the water kill them. Also, carnivorous predators are quite for about 2 weeks and then sink to the bottom to numerous. These hazards demand careful man­ metamorphose. Settling sites are beaches in the agement. In traditional culture, seed cockles are lower tidal zone of water passages in clam bays. raised from natural spat and then reared in The culture beds are loosened and smoothed enclosed water po"ols. They are thinned several shortly before spat settlement. The spat grow to times, transplanted in rearing grounds in the juveniles (0.5 cm) by April or May, and they are lower tidal zone. collected and cultured for another year to pro­ It takes about I year for the seeds to grow into duce 1.4-cm seed clams, which are sown in the young cockles (800 cockles/ kg), and another 2- 3 culture beds. The number of seeds sown is about years to attain 2 cm, marketable size (120 1.8 X 106 /ha. It takes up to a year for the clams to cockles/ kg). The yield is 22.5-60 t/ha. Harvest is grow to marketable size (3.5 cm). Harvesting usually in winter to meet the market demand takes place in spring or summer, and the yield is created by the Chinese spring festival. about 18.7 t/ ha but is sometimes as high as In the last decade, cockle culture has rapidly 45 t/ ha. declined, mostly because of the great changes in Before 1975, the development of small-necked the condition of the coastal mud flats. Many clam culture was hindered by a sparse seed traditionally productive areas for seed rearing supply, but fisheries scientists in Fujian have have been lost, especially in Guangdong, Fujian, developed a technique for the artificial rearing of and Zhejiang, and, therefore, artificial seed­ spat, which has increased production. The rear­ rearing experiments are now in progress. ing work is done in the field, in the lower interti- 26 BIVALVE CULTURE

dal zone. Shallow ponds with several hectares of For example, in Changdao county of Shandong, smooth bottom are used. Pests, enemies, and each polyethylene spat-collecting bag (35 cm X 23 sea weed are removed, and then the pond water is cm) suspended from a floating rack yields fertilized and inoculated with Chaetoceros 300-500 juveniles. If natural seeds continue to mueller, a good food organism for bivalve larvae. increase, artificial rearing may be unnecessary. Sperm and eggs are obtained from mature clams, Another species of scallop ( C. nobilis) has which are artificially induced to discharge their recently been cultured in south China. It is larger sexual products, and then introduced into the and grows faster than C. farreri and can reach ponds. Soybean milk is sometimes added as a shell height of 12 cm. It has been commercially supplement to allow the larvae to complete their cultured in southern Fujian and Guangdong. early development and to metamorphose. Each Spat are artificially reared and the production, as pond can rear two or three batches in a breeding for C. farreri, is about 3.0-4.0 X 105 spat/ mJ of season. About 7.5-15.0 X 106 seed clams (0.5 cm seawater. The culture cycle lasts about 1.5 years, long) can be harvested from a I-ha pond. and the scallops are marketable size when their shells are 7 cm high. The yield is about 750 kg/ rope, and all of the scallops cultured in SCALLOPS Guangdong can be exported directly to Hong Kong. The adductor muscle of the scallop, known as Racks and methods used for C. nobilis culture gan-bei, is considered a luxury among seafoods are similar to those used for other scallops in the in China. It is usually dried and sold. The most North. The main difference is that, to prevent important species of scallop in China is Chia mys typhoon damage during May-October, the cul­ farreri, which occurs naturally in Liaodong and turists tie stones to the ropes to lower them 2 m Shandong peninsulas. It inhabits the sea bottom below the surface. This anchoring is similar to in areas with swift currents and high salinity, measures taken in a few areas of northern China from the low tide line to a 20-m depth. Adult to protect kelp from freezing during winter. scallops have shells 6-9 cm high. Sustaining a regular fishery is becoming increasingly difficult as natural stocks decline. PEARL 0 YSTERS Scallop culture in China began only a few years ago but has developed rapidly. Usually, floating Pearls, used for ornaments as well as a rare racks and plastic-screen cages are used. The racks Chinese medicine, occur only in Guangdong and are similar to those used for Laminaria and mus­ Guangxi. Among the few commercially impor­ sel culture. Some people prefer to drill holes in tant species, Pteria (Pinctada) martensii is the the ears of the shells, string the scallops together, most abundant and is probably what is known as and hang them from the racks. Each rack (or the mother of pearl in Chinese history. Although rope) yields about 750 kg of marketable scallops. the artificial culture of this bivalve is recent, Mixing cultures of scallop and Laminaria - many pearl farms are now run by the state and hanging scallop strings between the Laminaria collectives in Guangdong and Guangxi. Great strings - has proved successful, increasing the achievements have been made in the artificial total yield of organic products from a given area rearing of spat, the culture of adults, techniques of sea. for inducing pearl formation, and the direct utili­ The optimum temperature for growth of C. zation of pearl nacreous substance. farreri is 12-20° C. Temperatures lower than 5° C Pteria (Pinctada) maxima of Hainan Island is halt growth. The culture cycle from spat to mar­ the largest of the pearl oysters. Its shells are ketable size (6-7 cm) takes about 1.5-2 years. widely used in handicrafts, and, recently, tech­ At present, most scallop culture depends on niques for artificial spat rearing and nucleus spat artificially reared by techniques developed in insertion for pearl production with this species 1974. The scallop spawns in May-June and in have been studied. late September. Usually, the larvae can be reared Meretrix meretrix, Mactra antiquata, Brachy­ indoors to a size of 600 µm, with a yield of dontes senhousei, and Aloidis sp. are also cul­ 3.0-4.0 X 105 spat/ mJ of seawater. They are then tured in some regions. Meretrix meretrix is transferred to the sea in screened cages to grow broadly distributed along the coast of China in into seed scallops (I cm high). The survival rate of fine sand beaches. Its natural stocks are abun­ this stage is low ( 10-50%). dant, and culture has been extensive in some With the rapid developments in scallop cul­ areas. It is a good seafood product for export. ture, natural spat have increased in some areas. In conclusion, bivalve culture in China has a CHINA 27

long history. There are numerous species suitable marked grounds at high tide and are thrown uni­ for cultivation and the potential culture area is formly over the area from slowly moving boats. vast and diverse. However, less than one-tenth of Cement bars are placed at a density of 3000 /mu this area is currently exploited. Because the (4.5 X 104 /ha) and cement tiles at 3000-3500/mu importance of mariculture is now more widely ( 4.5-5.3 X 104 /ha). At low tide, the collectors are recognized, it is expected that bivalve culture will arranged in blocks. Between the blocks, a space expand at a greatly accelerated pace and that the of 3-4 m is left for boat navigation. Within the yield will greatly increase. blocks, collectors are arranged in rows I 0-12 m long. In each row, pairs of cement bars are crossed to form an "X" at intervals of 0.3 m. The APPENDIX: space between the rows is 1-1.5 m. The cement 0 YSTER CULTURE IN GUANGDONG bars are inserted 0.3-0.5 m into the mud so that they will stand straight and firm. SEED COLLECTION MANAGEMENT One year after attachment, at sexual maturity, oysters begin to reproduce. In the annual gonadal Between being collected as seed and reaching cycle, a large number of the original sex cells marketable size, the oysters need good manage­ formed in February are differentiated in March. ment for growth and survival. The collectors are Sex cells mature and are discharged from April to frequently checked and adjusted. During fall and October with a recovery stage in November. winter each year, the collectors are lifted by hand Small quantities of spat appear in April, but spat­ and stripped of the oysters. Then they are rein­ fall peaks in May-June and gradually decreases serted in the mud in a different position so that from June to September. the oysters have sufficient food and space for The seed-collecting ground is generally an growth. During this time of year, the water internal bay receiving river water. For good seed temperature is at a minimum and the salinity is collection, there should be an abundant oyster increased. The reproductive period is completed, population and tidal water circulation. The inter­ and the oyster begins to recover and grow tidal zone between midtide and I m above the low rapidly. After 3-4 years, when the length of the tide line is the seed-collecting ground. From June shell has reached 12-18 cm and the height is 6-8.5 to August, under normal oceanographic condi­ cm, the oysters are transferred to the fattening tions, when the water salinity is 5-20 ppt and the ground. water temperature is 27-31° C, the fertilized eggs metamorphose into larvae at a density of about FATTENING 60 individuals/ m3 water, and, when they begin to settle in sufficient numbers, the collectors Most seed-collecting grounds in Guangdong (cultch) are set out. can be used as both growing and fattening The traditional types of cultch are 3-8-kg grounds. Oyster fattening is important for high stones, ceramic pieces, tiles, or large oyster shells. yield. Three-year-old oysters are transferred to All are inexpensive and are easy to handle. Their the fattening grounds at the river mouth and are disadvantages are that they provide only small arranged in the same pattern as earlier. About surfaces for spat attachment, they sink in soft 11-15 m3 of cement bars or 11 m3 of cement tiles mud, and they have a low unit yield. From seed are used per mu (I/ 15 ha). The fattening season collection to oyster harvest requires 3-4 years, begins in August-September and continues until and the yield of flesh is 500-700 catties/ mu April of the following year. The oceanographic (~3750-5250 kg/ha). Since 1965, most of the conditions are important: traditional types of cultch have been replaced by • At the beginning of the fattening season, the a cement cultch, and yields have increased to salinity near the river mouth rises in I month 1000-1200 catties/mu (~7500-9000 kg/ha). The from 4-10 ppt to 14-20 ppt; advantages of the cement cultch are that it • Mean temperature of the water is 28° C in remains on the surface of the mud and extends August-September, 24°C in October, 21°C the spat-attachment areas. There are two types - in November, l9°C in December, 15°C in the cement bar and cement tile. January and February, 18.5°C in March, Immediately before seed collection begins, and 23°C in April; bamboo sticks are placed in the collecting • The NOrN content is more than 60 mg/m3 3 grounds to outline the area in which the cultch and that of P04 -P is more than 6 mg/ m ; and are to be set. Collectors are shipped to the • The pH value is stable, between 7.9 and 8.4. 28 BIVALVECULTURE

HARVESTING • When the water is 0.5 m or shallower, a boat is anchored over the harvest ground and the The percentage flesh of the oyster is calculated oysters are dredged with bamboo tongs; or by the formula: weight of dehydrated flesh/total • When the fattening ground becomes an weight of oyster in shell X 100. When the percen­ exposed beach, the oysters are harvested by tage has reached 12-16%, the oysters can be a specially made wooden horse that supports harvested. The age at harvest is usually 4 years. the collector in the soft mud and carries the There are two steps in harvesting: collecting the oysters to the boat. oysters and shucking the flesh from the shell. The Oysters are shucked by hand with a special oysters are collected in low tide in one of two knife. Oyster flesh may be sold fresh or dried or ways: canned with a by-product (oyster sauce). FIJI

J. Navakalomana Fisheries Division, 10-12 g. After 3.5-4.0 years, the average maxi­ Ministry of Agriculture and Fisheries, mum shell length was 136 mm and the wet-flesh weight was 40 g. Unfortunately, the quality of the Suva, Fiji flesh was not very good. Management included repairing racks and Trials on the culture of green mussels (Perna rafts, providing protection from predators and viridis) in Laucala Bay near Suva were carried fouling organisms, and cleaning the cages. out by the Fisheries Division from 1979 to 1981. Predators - crabs, mangrove eels, fish, shell The spat were obtained from the Centre national borers, etc. - were a major problem for the pour !'exploitation des oceans (CNEXO), Tahiti. mussels at all stages of development. Fouling Earlier attempts (appendix) had been made to organisms were also troublesome, clogging the introduce the Philippine green mussel (Mytilus mesh of the protective cages and making regular smaragdinus) to Fiji, and the results were encou­ cleaning necessary for good water circulation. raging. They prompted this latest series of trials. These problems, however, are probably sur­ mountable; however, another problem may be less so: there has been no evidence of natural CULTURE PRACTICES spatfall of this introduced mussel species in Fiji. Soon after the spat arrived, they were spread evenly on perforated (shellfish) trays, which were CONCLUSION tied together and suspended 0.5 m below the water surface. After 4-6 months, the spat were Growth of the introduced species of mussels picked out and trained for attachment onto cul­ compared poorly with that in other countries, ture ropes, made of natural fibre. Training takes although the reason is unclear. Whether the poor about 10-14 days. The mussels were thinned to performance reflects inappropriate management, 250 / m of rope and then transferred either to improper site selection, or some other factor is a bamboo rafts or mangrove racks for maturation. question beyond the scope of the trials. Neverthe­ In the rack system, wire-mesh cages were less, the trials did show that the predator problem placed on mangrove racks constructed in the is significant and the lack ofnatural spawning is a intertidal zone and raised 20 cm from the sea major constraint to the future of mussel cultiva­ bottom. The mussels were exposed during low tion in Fiji. tide and submerged about I mat full tide. In the raft system, the bamboo rafts were anchored in water 6 m deep. The mussel ropes were placed APPENDIX: inside cylindrical mesh cages and suspended from PRELIMINARY BJVAL VE CULTURE TRIALS1 the rafts about 1-3 m below the surface. Thus, the mussels were submerged throughout the culture Natural populations of the mangrove oyster period. Crassostrea glomerata are abundant in Fiji, but Most trials were carried out in the shallow (3-5 m), turbid waters close to shore. Salinities 1This appendix was abstracted from a 1977 FAQ ranged from 26 ppt to 36 ppt and temperatures report on oyster culture prepared by T.P. Ritchie for at the surface of the water from 26° to 28° C. On the government of Fiji. The report was circulated at the arrival, the spat were 3-12 mm in shell length. workshop as background information and its general The mussels on the rafts grew faster than those on conclusions are summarized here. The conclusions are the racks, reaching an average shell length of those that were considered appropriate when the origi­ 90 mm after 18 months and a wet-flesh weight of nal report was prepared.

29 30 BIVALVECULTURE the species is small, seldom longer than 50 mm, that C. gigas spat survive and grow exceptionally and appears to survive only in the intertidal zone. well during the first 8 months of culture in Fiji but Experimental attempts to rear this species to their survival and growth rate decrease rapidly marketable size have been unsuccessful. Data thereafter. The presence of wild C. gigas has been from observations indicate that, under the condi­ recorded and indicates that the species repro­ tions found in Fiji, the species dies after it has duces naturally under the conditions found in the grown a maximum 50 mm. It grows in subtidal country. conditions but survives only a short time. Com­ The Australian or Sydney rock oyster (C. mercial culture methods would probably not commercialis) was experimentally introduced to appreciably alter the basic growth characteristics Fiji in 1973. Data accumulated over 7 months of this species and, therefore, would be futile. indicated that growth and survival rate of cultch­ Natural populations of C. echinata are rare in less spat of this species in Fiji were not sufficient Fiji, but there is one substantial population in a for commercial-culture attempts. It was tenta­ lagoon on Mago Island. This species appears to tively concluded that seawater temperatures in be the only indigenous Crassostrea species that Fiji are too warm for the successful culture of the has potential for commercial culture in Fiji. It has species. evolved the ability to survive and grow past mar­ The Philippine oyster C. iredalei was experi­ ketable size. Although its growth rate is slow mentally introduced into Fiji in April 1975. Its compared with that of other, experimentally commercial-culture potential cannot be esti­ introduced, species, its survival rate is likely to be mated yet because observations are continuing, much higher than that of nonindigenous species. but the data are encouraging. Crassostrea ireda­ Its hard, thick shell affords adequate protection lei is a tropical species and should be more geneti­ from most predators and many shell-boring cally capable of surviving and growing in Fiji sponges; a uniform size and shape should be than many oysters already experimentally intro­ obtainable through special commercial-culture duced. If progeny can be obtained from this spe­ techniques. cies, they, and successive generations, should be In the Mago Island lagoon, dense populations even more acclimated to survival and growth in of C. echinata spat settled on the hull of a fiber­ Fiji. glass boat, and several hundred single spat were easily removed without damage. The owner of Mago Island is conducting additional experi­ NON/ND/GENOUS MUSSELS ments with artificial setting substrates to obtain single seed oysters for tray-culture experiments. The green mussel (Mytilus smaragdinus or Growth and survival of C. echinata are currently Perna viridis) was experimentally introduced being monitored by oyster project staff in Lau­ into Fiji in April 1975. Although growth and cala Bay. survival observations were only conducted for 1 Although the prospects for commercial culture year, the results were encouraging. The total sur­ of C. echinata in Fiji look good, the experiments vival rate was relatively high and the growth rate and observations so far are not definitive. appeared adequate for commercial culture. Pre­ liminary market surveys indicated that mussels NON/ND/GENOUS OYSTERS could be readily marketed in Fiji. Commercial mussel-production costs should be less than Most commercial oyster-culture experiments those for commercial oysters. Many Mytilus spe­ in Fiji have been conducted with the Pacific oys­ cies are commercially cultured in high-salinity ter C. gigas, which was introduced to Fiji in 1969. areas, and oyster project staff are currently con­ Although information on this species' survival ducting experiments in such areas in Fiji. It is and growth is still being collected and is essential tentatively concluded that M. smaragdinus has for definitive conclusions, data thus far suggest commercial-production potential in Fiji. FRENCH POLYNESIA

AQUA COP (Aquaculture Team of the rounded by barrier reefs delimiting lagoons. The Centre oceano/ogique du Pacifique), lagoons are fed by ocean combers swelling over Tahiti 1 the reefs. The water flows back out to the ocean through passes, and the renewal rate is generally Two research and development agencies are rapid. Thus, the water inside the lagoons typifies focusing on bivalve culture in French Polynesia. oceanic characteristics and precludes bivalve cul­ At present, they are involved in a spat­ ture in most of the sites. However, some of the production program for pearl oysters (Pinctada islands have deep, sheltered bays that receive margaritifera) and are searching for edible spe­ river water and harbour natural beds of Saccos­ cies capable of withstanding the peculiar condi­ trea cucullata. The bays are rich in nutrients tions of the Polynesian environment. The Centre leached from surrounding basaltic soils. Some, national pour !'exploitation des oceans like Tatutu Bay in Tahiti Island, have been separ­ (CNEXO), a French agency, through its labora­ ated into two parts by roadway dikes, the parts tory at Tahiti (the Centre oceanologique du Paci­ being connected by pipes. Water exchange is by fique, COP), is studying spat production in a means of the tide. At Tatutu Bay, the tide ampli­ hatchery, and the Service de la peche, a French tude is 0.4 m, the mean depth 0.6 m, and total Polynesian agency represented in many of the area 3.5 ha, the pond having been used for 10 islands, is working on spat collection, culture years for experimental culture of oysters, mus­ problems, and implantation techniques. sels, and clams. In such a pond, the equilibrium The area with potential for bivalve culture is of environmental factors is fragile, and great located in the trade-wind belt 15-25° S and variations in physicochemical parameters have 135-155° W. The superficial seawater typifies been recorded, especially after the heavy rains in ocean water, with an annual temperature range December-March and during periods when the of 25-30° C; an annual salinity range of 34-36 tide amplitude is low and water renewal minimal. ppt; and poor nutrient content. The two island In Uturoto Bay (Raiatea Islands), a similar setup groups considered here are the Tuamotu­ was improved by the addition of a second dike to Gambier Archipelago, for pearl-oyster culture, channel fresh water. Thus, the salinity can be and the Society Islands for edible-bivalve culture. controlled, although increases in temperature The Tuamotu-Gambier Archipelago is com­ during the periods of low seawater renewal posed mainly of atolls, with some volcanic remain a problem. islands, like the Gambiers. The atolls have large Except for the culture of P. margaritifera, lagoons, some of which - generally the closed which is adapted to the natural environment, ones - shelter natural populations of P. marga­ bivalve culture in French Polynesia faces difficult ritifera. These lagoons have potential as sites for environmental conditions: the suitable sites are pearl-oyster farms composed of floating or fixed, limited to the furthermost part of some shallow underwater-culture platforms. bays and are subject to great variations in salin­ The Society Islands are composed of the ity, temperature, and nutrient content. Windward and Leeward islands, most of them being high - of volcanic origin - and sur- PEARL 0 YSTERS 1This report was presented at the workshop by D. Coatanea, Centre national pour !'exploitation des oceans, Centre oceanologique du Pacifique, B. P. 7004, The black-lip pearl oyster (P. margaritifera Toravao, Tahiti. The data concerning pearl-oyster cul­ var. cumingi) has long been fished for the ture were kindly contributed by Martin Coeroli, Ser­ mother-of-pearl industry and has recently been vice de la peche, Papeete, Polynesie fram;aise. collected for culture farms involved in black-

31 32 BIVALVE CULTURE

pearl production. Natural populations of P. EDIBLE BIVALVES margaritifera, which are limited to some atolls and islands of the Tuamotu-Gambier Archipe­ lago, have been overfished and are dwindling Edible-bivalve culture is not well developed in rapidly. Obtaining 3-year-old pearl oysters for French Polynesia. The few available sites are implantation is increasingly difficult - a fact located in some of the Society Islands, and S. that has prompted CNEXO and the Service de la cucullata is the only traditionally cultured species peche to investigate spat production by hatchery able to withstand the hard and unstable environ­ rearing and by collection in atolls with natural mental conditions. Spat are collected on Tri­ populations. dacna shells or laths that also serve as growing structures. Oysters reach 6-8 cm after about 2 Hatchery experiments have been carried out at years(Millaud 1971). In 197S, because of efforts COP. Spawnings were obtained from brood­ of the Service de la peche, oyster production stock native to surrounding atolls and islands, reached a maximum of 22 tin Raiatea and Tahaa but larval-rearing experiments with different islands, compared with SS t of oysters imported combinations of temperature, food, and light from New Zealand, Australia, and France. Since were unsuccessful in promoting growth beyond then, production has continually decreased the 10th day (Millous 1980). Only a few larvae because of the development of Polydora sp. in the developed normally to the attachment stage, and culture sites. To overcome this problem, no explanation based on rearing conditions researchers have experimentally introduced could be given for the mortality. other species of bivalves into the Polynesian Spat collection was studied by the Service de la environment. peche in Takapoto atoll (Mizuno and Coeroli Crassostrea gigas was introduced in l 97S, and 1980). Collectors made of polyethylene sheets spat were produced in the COP hatchery and protected against predators by plastic net (AQU ACOP 1977). Growing experiments were bags gave best results. The collecting period lasts carried out in Tahiti, Raiatea, and Tahaa islands from November to January, and collectors that by the Service de la peche. After 3 years of exper­ are placed in October are recovered 6 months iments, this species was abandoned because it later. In June and July, a secondary spatfall peak could not adapt to local conditions. Poor phyto­ occurs. Collectors are recovered and spat are put plankton production, plus a generally high water into polyethylene net baskets; when they reach temperature, resulted in very thin and fragile 9 cm, they are drilled, put on strings suspended shells and made C. gigas extremely sensitive to from underwater platforms, and left to grow 3 Polrdora attack. years. The average yield is SO spat/ collector. Suf­ Saccostrea echinata was introduced in 1978 ficient spat have not yet been collected to supply from New Caledonia and proved better adapted farms with 3-year-old oysters for implantation. to tropical conditions. More than 2 million spat The 3-year-old oysters are implanted with have been produced in the COP hatchery, and spherical nuclei by Japanese experts. Implanta­ growth has been studied. This oyster is able to tions are made in or around the gonad. Oysters withstand the environmental conditions and is are then returned to underwater platforms and less sensitive to Po(vdora attack than is C. gigas. remain there 2 more years - the time required to Marketable size is obtained within 2 years, and obtain a mother-of-pearl deposit of about an experimental production of hundreds of kilo­ I. S mm. Only 30% of implanted oysters will pro­ grams was realized in 1981. However, this oyster duce a marketable pearl 9-12 mm in diameter. is not well liked by Polynesian consumers Further studies at the Service de la peche will because of its harsh taste, and the larvae are focus on implantation techniques and growth difficult to rear. To solve these problems, control of oysters and pearls. In 1980, about researchers are attempting to cross S. echinata 280000 oysters were implanted. Most of these with S. cucullata to obtain a resistant oyster with came from the natural population. a less harsh taste. Fourteen cooperative societies and eight pri­ Perna viridis was also introduced in 1978, and vate companies, directly or indirectly employing spat are now produced by the COP hatchery 200 persons, are involved in pearl-oyster culture (AQUACOP 1979, 1980). Two culture sites are in French Polynesia. Pearl exports yielded US$ I used by the Service de la peche: Tatutu Bay and million in 1980 and are expected to have earned Uturoto Bay. The 10-mm spat are allowed to more than US$2 million in 1981. Pearls have attach to iron bars that are then hung in the bay. become the second largest export product, copra The culture area is enclosed by wire net and, being the largest. thus, is protected from predators (mainly Scylla FRENCH POLYNESIA 33 serrata). During the growth period, the culture December before the environmental conditions bars are moved up or down according to temper­ deteriorate. ature and salinity conditions. Marketable size is obtained within 1 year of culture. Experimental CONCLUSION production of about 9 t has been obtained. Cultur­ Only pearl-oyster culture plays a significant ists hope to satisfy the local market (i.e., role in French Polynesia at present because natu­ 30-50 t/year) once the Uturoto Bay culture site is ral conditions are generally unfavourable to in full production. edible-bivalve culture, with extreme variations in Venerupis semidecussatus, a clam known as salinity, temperature, and food being common. palourde in France, was introduced 2 years ago. The rainy season causes the variations and is the The first experiments gave good results, and principal obstacle to bivalves that take longer commercial size was obtained in less than 1 year. than a year to reach marketable size. Mussels and However, this species is very sensitive to the drop palourdes show some potential because they are in salinity common in the rainy season (December­ quick growing: the spat can be produced in con­ March). To overcome this problem, culturists trolled conditions during the rainy months, have relegated the rainy months to hatchery and seeded on sites later, and harvested before the nursery purposes so that the 8-12-mm spat are next rains. Future prospects are uncertain, but it then available in March for direct sowing on the is hoped that at least the local market can be culture site. The palourdes are harvested in early satisfied through culture operations. INDIA 1

E.G. Silas, K. A lagarswami, K.A. Nara­ PRODUCTION simham, K.K. Appukuttan, and P. Muthiah Central Marine Fisheries A number of oyster species occur in Indian waters (Rao 1974); those that are exploited are Research Institute, Cochin, India Crassostrea madrasensis, C. gryphoides, and C. discoidea, which occur in estuaries, backwaters, India has a 6100-km coastline, numerous estu­ and creeks. Crassostrea cucul/ata is found on aries and backwaters, and abundant marine intertidal rocks but is not exploited. bivalve resources that are exploited on a subsis­ Alagarswami and Narasimham ( 1973) have tence level at several centres. The major bivalves, reviewed Indian oyster resources: C. discoidea in order of importance, are clams, mussels, win­ occurs along the coast of Gujarat State (Fig. I) dowpane oysters, and edible oysters. Pearl oys­ and C. gryphoides along the Maharashtra coast. ters are intermittently exploited - sometimes Crassostrea discoidea and C. madrasensis are not for several years. The pearl fishery is man­ present in Karnataka. The entire east coast and aged by the state, and, for some clam beds, fish­ Kerala are dominated by C. madrasensis. Oyster ing licences are required. fishing centres along the west coast include the Indians have traditionally cultured finfish and muddy creeks of Kutch, Aramra Creek, Poshetra prawns, particularly in Kerala and West Bengal. Point, Port Okha, Dwarka, and Porbandar in Recently, in a small way, they have engaged also Gujarat; Malad, Boiser, Satpuri, Palghar, in mollusc culture in centres near Bombay and Kelwa, Navapur, Utsali, Dahisar, and Mahim Madras, and interest in all forms of aquaculture Creek around Bombay, and Alibag, Ratnagiri, is growing rapidly because of improved tech­ Purnagad, Jaytapur, and Malwan in Maharash­ niques developed during the last decade by the tra; and Ribander, Siolim, and Curca in Goa. In research institutes of the Indian Council of Agri­ Karnataka and Kerala, small oyster beds exist at cultural Research. The federal and some state several centres but are little exploited. Along the governments have accorded high priority to coast­ east coast, exploitation is limited to Ennur near al aquaculture in the Sixth Five-Year Plan. Madras and Sonapur backwaters in Orissa. Pro­ The Central Marine Fisheries Research Insti­ duction of oysters has not been estimated so far tute pioneered developments for the culture of because the fishery is only operated seasonally on marine prawns, pearl oysters and cultured pearls, a subsistence basis at several small centres. edible oysters, mussels, clams, finfishes, and sea­ Traditional oyster farming is practiced at weeds. Advanced research has been initiated to Kelwa, Navapur, Utsali, and Ennur. Elementary identify and solve problems related to production principles of transplantation for growth are used, and quality, and production-oriented programs and production is minimal at present. The Cen­ using available technology have also been tral Marine Fisheries Research Institute at Tuti­ encouraged. The high production rates obtained corin hopes to improve outputs by demonstrat­ for mussels and oysters indicate that bivalves ing and, hence, transferring more appropriate have a high potential for increasing seafood techniques in oyster culture. production. Both the green mussel (Perna viridis) and the brown mussel ( P. indica) occur in India, although 1This country paper from the Central Marine Fisher­ the former has a wider distribution. It is found on ies Research Institute, Cochin, was presented at the small beds along Chilka Lake, Vishakhapatnam, workshop by K.A. Narasimham, Kakinada Research Kakinada, Madras, Pondicherry, Cuddalore, Centre, Central Marine Fisheries Research Institute, and Porto Novo along the east coast, and exten­ Kakinada 533002, Andhra Pradesh, India. sively around Quilon, Alleppey, Cochin, Calicut

34 ., 24° ·,, ' '> . 1.WEST BENGAL (!....,_ .., c:-0> 22° !"' L.r-J """\... Ji·= \...... ,.,..-) .... .l ~l,r ·~·-.,._,i -.....r--..r ...... ,,_)? rf' r' OR ISSA ·"'-· l J \ 20° ;i ('~ MAHARASHTRA ~"'-"} ~ \ {" \ I J ;""i.J'· J -~ , ( ,f'1 \ (.J'\.,..J 1g 0 ARABIAN SEA ./ ., \..,~-' ~.J -~ ANDHRA PRADESH ,...,.~ ~

____ ...... ---- ,,_./' j \ 16° ~.....-C-O_C_K_L_E___, .,,..- I 93° ------~.c;;....., ------GOA ' GREEN MUSSE; 1==----IS.~~r l BAY OF BENGAL 14° ' ', 4~"-• ', I CLAM l U"'i,.-"\ '....::', KARNATAKA 'l ... / 12° 'Mangalore . .Jr-·f JAndaman -, '\ r' .,,. ', "\ ':.> ' ' ·I)" and 12° I...... , ..... "" . ..,.I ' ,,, GREEN MUSSEL Nicobar Is. c''-J Pondicherry1~------" 100 I ' '°\...... 1, TAMIL NADU LAKSHADWEEP , .. \., 100 =...... : i go~ BROWN MUSSEL l_ Quilon KE~·ALA . '·:-:--..) ----- ) uhcorm PEARL OYSTER ~ I INDIAN Vizhin]am Gul/oT EDIBLE OYSTER go Kanniyakuman Mannar 93° N

6g 0 E 70° 720 74° 76° 7go goo g2° g4° g6° ggo

Maritime states of India. 36 BIVALVE CULTURE to Kasaragod, Mangalore, Karwar, Goa, Bhatia cement, calcium carbide, bricks, shell lime, etc. Creek, Mal wan, Ratnagiri, and the Gulf of Kutch The clam resources of Vembanad Lake, which is (Kuriakose l 980a). In contrast, P. indica is found a backwater ecosystem, are very important for only along the southwest coast from Varkalai the state. Ashtamudi and Kodungallore lakes near Quilon to Kanniyakumari, and from Kan­ and the estuaries of the Kadalundi and Kora­ niyakumari to Tiruchchendur along the south­ puzha rivers are the other important sources of east coast. Regular fisheries exist for the green clams. There are two dominant species - M. mussel from Calicut to Cannanore along the case a in the saline areas and V. cyprinoides in the Kerala coast, and annual landings are estimated less saline and freshwater areas. About 2.0 X 10s t at 2.6 X 103 t. Fisheries for brown mussel between of lime shells are exploited annually ( 1968) from Kovalam and Muttom yield 427 t/year. The total Vembanad Lake alone, and live V. cyprinoides annual production of both species from tradi­ constitute about 2. 7 X I 04 t (Rasalam and Sebas­ tional fisheries exploiting natural beds has been tian 1980). estimated at 3.1 X J03t (Alagarswami et al. Along the east coast of India, clam resources l 980c). Production from culture is small, being are less abundant. In Tamil Nadu, K. opima and limited to demonstration and technology­ M. casca, which were once plentiful in the Adyar transfer programs. estuary near Madras (Abraham 1953), have large­ The blood clam (cockle) Anadara granosa is ly been depleted by domestic sewage pollution. exploited in Kakinada Bay and has been experi­ Meretrix casta is fairly abundant in Pulicat Lake, mentally cultured there. Total annual production Kovalam backwaters, Muthupet swamps, Vellar is about 2.0 X 103 t, 10% of which is used as estuary, and Vaigai estuary. Clam production in human food. The shells are used in the produc­ Vellar estuary is about 730 t/year. In Andhra tion of lime. Pradesh, M. meretrix occurs conjointly with A. granosa in Kakinada Bay. Along the Orissa Clams are by far the most important bivalve coast, Meretrix spp. occur in Chilka Lake and resource in India, and the west coast accounts for Sonapur backwaters. the bulk of production. The species resources are The species Placenta placenta is fished mainly rich, and the major exploited ones are Meretrix for the shells but also for seed pearls. The major meretrix, M. casta, Katelysia marmorata, K. centre for windowpane oysters is Kakinada Bay, opima, Villorita cyprinoides, Paphia malabarica, which produces about 4.0 X 103 t/year (Narasim­ P. laterisulca, and P. textile. Although a small ham 1973). The shells are used for production of percentage of the clams are eaten, production is lime, and small quantities (right valves only) are mainly for shells for lime and cement. In addition exported to Hong Kong and Japan (Murthy et al. to live clams, shell deposits (commonly referred 1979). Other important centres are Poshetra in to as subfossil deposits) are mined for industrial Pindara Bay in the Gulf of Kutch, where annual use. production is 4.5 million oysters (Varghese 1976), Alagarswami and Narasimham (1973) have and N aukim Bay in Goa, where 8000-10000 oys­ reviewed clam resources and their exploitation. ters are harvested almost daily for human con­ The coastal states of Maharashtra, Goa, Karnat­ sumption (Kutty et al. 1979). aka, and Kerala have abundant clam resources in The pearl-oyster species of most commercial estuaries. Meretrix meretrix, K. opima, K. mar­ importance is Pinctadafucata, although several morata, and P. laterisulca are the major species other species occur along the Indian coast (Rao along the Maharashtra coast, and annual pro­ 1970). The pearl fisheries of the gulfs of Mannar duction is about I. I X 103 t (Ranade 1964). The and Kutch are well known for production of clams in the estuaries of Goa are M. meretrix and orient pearls. Resources fluctuate widely. In the V. cyprinoides; total production has been esti­ Gulf of Mannar, the natural beds (known locally mated at 887 t and that of V. cyprinoides alone at as paars) are found on the rocky or coralline 500 t (Parulekar et al. 1973; Ansari et al. 1981). substrata at depths of 15-25 m. Fisheries were The estuaries of Karnataka have M. meretrix and conducted annually during 1955-61, but this P. malabarica in northern areas and M. case a and activity was preceded by a nonproductive period V. cyprinoides in the south. Ulla! near Mangalore of 27 years and has been succeeded by nonpro­ is an important lime-producing centre, and about ductivity. During 1955-61, annual (restricted 3.0 X 103 t of shell lime is produced annually, season) production of pearl oysters ranged from mainly from clam shells of the Tadri River. Ker­ 1.18 million ( 1957) to 21.48 million ( 1958), the ala has immense clam resources (both living and average being 10.85 million oysters per fishery subsoil shell deposits), but exploitation is mostly (Mahadevan and Nayar 1973). In the Gulf of for industrial production of white and grey Kutch, where pearl oysters occur in intertidal INDIA 37 beds called khaddas, the fisheries used to be con­ oysters are exposed during low tides - a condi­ ducted every 3 or 4 years, with an average annual tion that helps to control fouling. Experimental production of about 19000 oysters for the seven and production-oriented oyster farming is being fisheries between 1950 and 1967 (Easwaran et al. carried out only at Tuticorin Bay (Mahadevan et 1969). Since 1967, there has been no pearl fishery. al. 1980). At the Vaigai estuary near Mandapam, The culture of pearl oysters is limited to exper­ a 2-year experiment proved successful in terms of imental spat collection. Moderate spatfall is growth of oysters, but freshwater conditions pre­ obtained in Vizhinjam Bay on the southwest vailed in the estuary during the monsoons coast where the spat are collected on fibrillated (November-December) and resulted in high nylon ropes. Similarly, spatfall takes place on the mortality among the oysters (Rao et al. 1980). harbour breakwaters at Tuticorin. The pearl­ The normal annual salinity range of the Vaigai oyster populations settling in the artificially estuary is 6.94-35.53 ppt, but in certain years an enclosed inshore areas are mixed species of Pinc­ extreme range of 0.44-62.39 ppt has been tada, including P. chemnitzii and P. sugillata, recorded. Several short-term projects on various which are generally dominant, and P. fucata aspects of oyster culture have been carried out in (25% or less) (Alagarswami 1977). the Cochin backwaters in Kerala (Purushan et al. 1980), Mulki estuary in Karnataka (Dhulkhed and Ramamurthy 1980; Joseph and Joseph RESEARCH AND DEVELOPMENT 1980); and in Goa ( Parulekar et al. 1980), and the data indicate that many bays, estuaries, backwa­ The Central Marine Fisheries Research Insti­ ters, and creeks in the country are suitable for tute (CM FRI), Cochin, under the Indian Council oyster farming. The tidal amplitude is generally of Agricultural Research (!CAR), is the main within 1 m, and the rapid growth recorded in institution involved in bivalve culture at the experiments indicates there is adequate food. The national level and has developed techniques for ambient temperature is suitable, but the low the culture of various species during the last salinity during monsoons causes excessive mor­ decade (CM FRI 1978). Research on bivalves by tality. Still, one crop could be harvested between the Institute dates back to the early 1950s and is the monsoons each year. Spatfall is good in the now carried out at several regional centres. areas studied. Long-line culture of oysters in the The !CAR/United Nations Development open sea has not been investigated yet but has Programme (UNDP) Centre of Advanced potential. Studies in Mariculture at CMFRI has The rack-and-tray culture method is employed postgraduate- and doctoral-level teaching and for oysters at Tuticorin. Each rack (13.2 m X research programs on bivalve culture. The pro­ 2.0 m) comprises a series of teak poles. Two rows gress made in mussel farming was reviewed (2 m apart) of six poles are driven into the muddy recently at a workshop, and an action plan for bay, and the poles in each row are connected near research and development programs was devel­ the top by a long pole. Six short poles connect the oped (Silas and Rao 1980). two rows horizontally and are connected to each The science of spat fall forecasting is yet to be other by two long poles that run parallel to the developed. Spawning seasons of bivalves under other long poles but are inside the structure. This culture are known, and this information is used rack provides a platform for suspending oyster as a key to the laying of spat collectors. For cages during the nursery stage or for supporting oysters, culturists monitor the stage of maturity the oyster trays during the grow-out phase. The and the appearance of straight-hinge larvae in oyster cage is 40 cm X 40 cm X 10 cm, with a lid, plankton of the bay to determine when to place and is made of 6-mm steel rods covered with the spat collectors. Once spat are collected and nylon webbing (12-mm mesh). The tray is 90cm seeded on the sites, they remain within the area X 60 cm X 15 cm, without a lid, and is constructed until harvest. the same way as the cage except that the webbing is 22-mm mesh (Mahadevan et al. 1980). An experimental hatchery for oysters has been 0 YSTER FARMING set up at Tuticorin (Nayar and Easters on 1980). Crassostrea madrasensis has been spawned by Oysters are cultured in intertidal regions, bays, thermal stimulation and the larvae have been and estuaries. In Tuticorin Bay, the tidal range is reared to a 250 µm size. Spat settlement has not 0. 3-1. 3 m. The bottom - fine sand and mud - is been achieved so far. Spat is collected on semicy­ firm. The annual range in seawater temperature lindrical roofing tiles in the natural grounds at is 23.0-30.2° C and in salinity 26.1-34.4 ppt. The Tuticorin. The tiles, which are 24.5 cm long and 38 BIVALVE CULTURE

17.5 cm in diameter, are dipped in a solution of25 dry-flesh weight/ volume of shell cavity) of Tuti­ kg lime in 50 L of seawater (which can treat 1000 corin farm oysters varies from 40 during May­ tiles). After drying, they are coated with a mix­ June and November (postspawning period) to ture of 60 kg lime, I 00 kg river sand, and 80 L of 170 during February-March and July-August water. The lime-coated tiles are placed in iron (prespawning period). cages (JOO cm X 90 cm X 15 cm), 50 to a cage. Several other materials, such as oyster and mus­ sel shells and coconut shells, have been tried but MUSSEL FARMING did not prove as effective as the tiles. Crassostrea madrasensis has two spawning seasons, April­ There are no protected bays on the Indian May and August-September. At the beginning of mainland, but there are lagoons and bays suitable the season, the cages with tiles are laid on racks in for mussel culture in the oceanic islands. Mussel the oyster farm at Tuticorin and in the adjoining farming on the mainland is done in the open sea, creek. The average number of spat was 33.5 (with in water up to IO m deep. The southwest mon­ a maximum of97 and minimum of 11) per tile in soon in the Arabian Sea and the northeast mon­ April-May 1979 (Mahadevan et al. 1980). The soon in the Bay of Bengal create unfavourable August-September season was less productive, conditions for mussel culture for 4-5 months, with an average of 5 spat/ tile. More spat (5: I) but, because mussels reach harvestable size in 5-6 settle on the concave surface than on the convex months, there is one harvest a year. When sub­ surface of the tile. At Vaigai estuary, near Man­ merged raft culture is developed, two crops will dapam, an average 2.35 spat/ m2 settle in Febru­ be possible. ary and 11.69 spat/ m2 in March - about 2 spat/ Mussel culture has been carried out in the open tile (Rao et al. 1980). sea off Calicut (Kuriakose I 980b), in Vizhinjam Oyster spat are allowed to grow on the collec­ Bay (Achari and Thangavelu 1980; Appukuttan tors for 2 months until they reach a mean size of et al. 1980), in Dona Paula Bay of Goa (Qasim et 36 mm and are then detached from the tiles with al. 1977), in Ratnagiri (Ranade and Ranade an iron scraper. They (150-200) are placed in 1980), off Madras (Rajan 1980; Rangarajan and rearing cages (40 cm X 40 cm X IO cm) and Narasimham 1980), and in Karwar Bay. Easter­ suspended from the poles of the rack. The oyster­ son and Mahadevan ( 1980) reviewed environ­ lings reach a mean size of 52 mm in about 3 mental conditions in the open sea with reference months and are then transferred to trays (90 cm X to mussel culture, and the coastline between 60 cm X 15 cm) on racks for grow out. The trays Karwar and Kanniyakumari, with an abundant hold 150-200 oysters and are positioned so that supply of seed, seems particularly suitable for the oysters are only exposed during the lowest production. Appukuttan's (I 980a) report of pre­ tide. Each rack occupies 26.5 m2 and holds 20 dation by fish (Rhabdosargus sarba) and lobsters trays. Average annual production is 0.48 t/rack, indicates that effective measures to prevent pre­ about 135 t (whole weight)/ ha (Mahadevan et al. dation are essential. No work has so far been 1980). done on mussel culture in typical estuarine condi­ The predatory gastropod Cymatium cingu/a­ tions. An attempt at pole culture of green mussels tum is found in the farm during July-December at Kovalam near Madras failed because the poles and preys on oysterlings 35-45 mm long. They were washed away by strong currents. caused 15% mortality of the stock. in 1979 Hatchery technology has not been developed ( Mahadevan et al. 1980). The gastropods are for mussel-seed production. Rao et al. (1976) located, handpicked, and destroyed. have done experimental work on spawning and At Tuticorin farm, C. madrasensis attains 36 larval rearing of P. viridis and Kuriakose (I 980c) mm 2 months after spatfall. At 3 months, mean on P. indica. Alagarswami (1980) reviewed size is 52 mm; at 8 months, 60 mm; at IO months, mussel-seed production. Spawning occurs in 74 mm; and at I year 90 mm. In the Vaigai May-September, and seed mussels are collected estuary, at I year, the same species attains a mean from natural beds during October-December for of 86.7 mm and a maximum of I IO mm (Rao et farming along the west coast. Spatfall takes place al. 1980). The size attained after I year is the in the farm itself. Seed are collected on frilled marketable size, and the oysters are harvested. At nylon ropes at Vizhinjam. In the mussel-culture M ulki, Joseph and Madhystha ( 1980) observed a farm at Kovalam, near Madras, spatfall is some­ mean shell height of 9. 15 cm and 14. 20 cm at the times good. end of the I st and 2nd years, respectively. For The spat are collected on tiles suspended from I-year-old oysters, the wet-flesh weight is 8-10% rafts (Rangarajan and Narasimham 1980). The of total weight. The condition factor ( 1000 X rafts range in size from 5 m X 5 m to 8 m X 8 m INDIA 39 and, like the racks for oysters, are a series of teak Table I. Mean size of green mussels (P. viridis) poles. The frame is mounted on 4-5 cylindrical, under raft culture at Calicut at seeding in 200-L metal barrels for buoyancy. Each raft is November 1978 and at harvest in April 1979 moored by two anchors connected to the raft by (Kuriakose I 980b). chains. Seed mussels are attached to ropes sus­ Weight (g) pended from rafts. The ropes are either nylon Flesh (12 mm) or coir (14 or 20 mm) (Kuriakose and Length (as% (mm) Total Flesh total) Appukuttan 1980). These surface rafts cannot withstand monsoons. Experimental work on November 1978 23.6 I.IO 0.40 38.0 submerged rafts for all weather conditions has April 1979 88.2 37.50 15.18 40.5 been partially successful (Rajan 1980). Green-mussel seeds (20-30 mm) are trans­ planted, and 500-700 g of seed are used per metre weight forms 41.31 % of total weight in the bay of rope at Calicut (Kuriakose 1980b). The juve­ and 43.33% in the open sea in May. The average nile mussels are secured with a knitted cotton weight of mussel seed per metre of rope ranged cloth 25 cm wide. The seeded portions of the from 1.4 to 2.0 kg, and, at harvest, the final ropes range from 5 m to 8 m, and the ropes are weight of mussels was 10-15 kg/m rope after 7 suspended from the raft 0.5-1.0 m apart, the months in the Bay and 15 kg/ m after 5 months in lower, free end being about 2 m above the bot­ the open sea. An estimated yield of 150 t/ ha is tom. The mussels attach to the rope within 2-3 possible inside the bay. Achari and Thangavelu days, and the cloth cover disintegrates in about (1980) reported production rates of 10.16 kg, 10 days. Brown-mussel seeds are 25-29 mm when 15.81 kg, and 22.69 kg/min 7, 9, and 12 months, transplanted, and the seeding technique is the respectively, in Vizhinjam Bay. same. Old cotton fishing net, cheap bandage cloth, or mosquito netting is used for wrapping COCKLE FARMING the seed on the ropes. Wooden pegs are inserted in the ropes at fixed intervals to prevent slippage The cockle A. granosa is cultured in the subti­ during the initial stage of growth (Appukuttan et dal area of Kakinada Bay, where the site is al. l 980b). enclosed by split-bamboo screens (Narasimham For the grow-out period, some of the mussels 1980). It is also grown in unenclosed areas, poles are transplanted to new ropes. Under these con­ being used to mark the site. ditions, mussel growth is good. From November The natural distribution of A. granosa is 1978 (seeding) to April 1979 (harvest), green limited. In Kakinada Bay, the species is cultured mussels grew from an initial weight of 0.57 kg to a in a subtidal region that has a minimum of 25 cm final weight of 12.3kg/mrope(Table1). In Dona of water during low tides. The bottom is mud, Paula Bay in Goa, Qasim et al. ( 1977) found that composed of clay (64%), silt (25%), sand, and the green mussel attained the average marketable dead shells. The monthly average water tempera­ size of 62 mm in 5 months, during which time the ture is 28.9-33.5°C, salinity 22.29-34.4 ppt, and average production was 6 kg/ m of rope. The dissolved oxygen 4.98-7.00 ml/L (Narasimham ratio of shell weight to wet-flesh weight was 1: 1 1980). The Anadara bed in Kakinada Bay is and that of wet flesh to dry flesh 4: 1. about 44 km 2, much of which is also suitable for Average production of green mussels at Cali­ clam farming. cut in open-sea culture ranged from 4.4 kg/ m Anadara granosa spawns during January­ rope in 1976-77 to 12.3 kg/ m rope in 1978-79 April, and heavy settlement of seed on natural when conditions remained favourable during the beds takes place from February to May in 5-month season (Kuriakose l 980b). An esti­ Kakinada Bay (Narasimham 1980). Seed is col­ mated 12 000 seeded ropes can be cultured in 1 lected from the bed with a scoop net at low tide ( 1 ha. Rope length depends on depth: off Calicut m). 6-7 m seeded ropes can be used. Qasim et al. Seed clams of A. granosa 19-29 mm in size ( 1977) projected a yield of 480 t/ ha for the green (mean length 24.3 mm; mean weight 6. 7 g) were mussel in Dona Paula Bay. experimentally stocked at densities of 140/ ml In Vizhinjam Bay, the brown mussel P. indica and 175/m2 (Narasimham 1980). In April 1981, reaches the modal size of 55-60 mm in 8 months, smaller seed (mean length 17.8 mm and weight an average growth of 2.94 mm/month. In the 2. 74 g) was used, and stocking rate was nearly adjoining open sea, growth is faster, and the doubled (300/ m2). The baby clams are dispersed modal size of 60-65 mm is attained in 5 months, a evenly on the area from a boat at high tide. Dur­ growth rate of 5 mm/ month. The wet-flesh ing culture, no maintenance is necessary. The 40 BIVALVE CULTURE species grows in 5 months to 40.6 mm and 31.06 g Pearl oysters reared temporarily in the har­ at harvest (Narasimham 1980). The survival rate bour basin at Tuticorin gave particularly good is 88.6%. Flesh weight is about 20% of total results. An intertidal pearl-oyster farm has been weight. established at Sikka near Jamnagar in the Gulf of In Kakinada Bay, the production of A. gra­ Kutch, whereas a farm in Vizhinjam Bay had to nosa was 0.39 t/ 100 m2 in 5 months, 2.6 t/ 625 m2 be abandoned because of heavy silting and other in 5.5 months, and 6.1 t/0.16 ha in 7 months problems. Several potential sites for pearl-oyster (Narasimham 1980). These figures represent farming exist in the Andaman and Nicobar production rates per hectare of 39 t, 41.6 t, and islands. Water depth and clarity as well as relative 38.1 t, respectively. It is remarkable that, despite freedom from biofouling and boring organisms different stocking densities ( 140, 175, and 300 are important in site selection. seed clams/ ml) in the three experiments, the pro­ In experiments with pearl-oyster culture, Ala­ duction results are consistent. garswami et al. ( l 980a) used thermal stimulation, salinity variation, and chemical control (using NaOH, NH 0H, Tris-buffer, and H 0 ) in con­ OTHER BIVALVES 4 2 2 trolled breeding. They found that increasing the pH and raising the temperature of the water Other bivalves with potential in India include encouraged spawning of P.fucata. They (1980b) clams and pearl oysters; windowpane oysters are reared the larvae to straight-hinge veliger and, in not cultured at present, but techniques are being October 1981, succeeded in bringing larvae to investigated and possible culture sites are Kakin­ spat setting. The flagellate /sochrysis galbana ada Bay, Nauxim Bay in Goa, and Balapur and was used as food. Spat setting takes place 22 days Rann bays in the Gulf of Kutch. after fertilization. Thousands of spat have been Experiments on clam culture have been obtained and are being reared in the farm. At limited. In the Mulki estuary near Mangalore, setting, the mean size of the plantigrade stage is culture of M. casta has been attempted in the 300 µm X 330 µm. Spat settlement takes place on channel leading to the state fish farm. Bottom frosted and clear glass plates, split-bamboo pie­ culture was used. During the February-June cul­ ces, and on the sides of fiberglass tanks and glass ture period, the salinity range was 15.10-34.62 beakers. ppt and the temperature 28.7-33.4°C (K.S. Rao, personal communication). Experimental Although hatchery-reared oysters will be used transplantations of M. casta were done in Vellar for cultured pearl production in future, mother estuary near Porto Novo (Sreenivasan 1980), and oysters were previously obtained from natural the species has been observed (at Mandapam and beds. In Vizhinjam Bay, spat were collected, Kakinada) to colonize fish/ prawn farms. Clam mainly within 1 m of the surface, on frilled nylon resources in India are great, and the preparation ropes. of sites, seed collection, and transplantation of Raft culture is the standard method employed clams should be considered for vast areas of for pearls (Alagarswami and Qasim 1973; Ala­ backwaters and estuaries. garswami l 974a), although farming has also suc­ In Mulki estuary, M. casta grows from an ceeded on the slopes of harbour breakwaters at initial mean length of 17.9 mm to 31.5 mm in 4 Tuticorin. months, and the survival rate is48.2% (K.S. Rao, The hatchery-reared spat are transferred at an personal communication). In Vellar estuary early stage (about 4 mm) to boxes covered with (Tamil Nadu), it grew from a mean 7.3 mm, 0.25 g nylon mesh and lined on the inside with a fine­ in September 1976 to 41.5 mm and 31.34 g the mesh synthetic fabric. Here they are kept until next September (P. V. Sreenivasan, personal they can be transferred to plastic baskets with communication). rigid mesh. Spat from natural grounds are The Gulf of Mannar has already proved to removed from collectors and, like the hatchery­ have potential for pearl-oyster farming (Ala­ produced spat, are placed in plastic baskets. garswami and Qasim 1973; Alagarswami 1974 When they measure 25-30 mm dorsoventrally, a,b). Unlike pearl culture elsewhere, the practice they are grown in iron cages (40 cm X 40 cm in India is in open-sea areas. The experimental XlOcm) covered with 20-mm mesh nylon web­ farm at Veppalodai near Tuticorin has been suc­ bing. cessful, and rafts have been maintained in the The number of cultured pearls as a percentage open sea for nearly a decade. The ecological con­ of total numbers of oysters is 62.8% after single ditions at the Veppalodai farm have been dealt implantation and 180.6% after multiple implan­ with by Victor ( 1980). tation, and these rates could be improved (Ala- INDIA 41 garswami l 974b). Pearl growth in the Gulf of need to be developed along with production. Mannar has been found to be 2-3 times as fast as Venkataraman and Sreenivasan ( 1955) investi­ that in temperate waters (Alagarswami 1975). gated pollution at Korapuzha estuary near Cali­ cut and found that the P. viridis beds in shallow coastal areas were continually polluted and con­ tained Escherichia coli, type I, throughout the PROBLEMS AND CONSTRAINTS year. Pollution peaked immediately after the beginning of the southwest monsoon. Although Silas ( 1980) discussed the constraints and the Salmonella-Shigella group as well as Cholera prospects for mussel culture in India, and these vibrios were absent, Paracoli, Proteus, and £. generally hold true for all bivalves. Interest in coli, which cause infectious gastroenteritis, were bivalve culture is quite recent, and, although present. After the monsoon abated, there production-oriented techniques have been appeared to be a recovery, and coliform developed, commercial culture has not begun. numbers, as well as total counts, were low. Mus­ The major constraint is the lack of a properly sel pollution has been attributed to the storm­ organized development effort despite the high water carrying town refuse during the monsoon. priority given to aquaculture in India. The eating People in the Calicut area used to believe that of bivalves is popular only in a few pockets along mussels were poisonous or unwholesome during the coast. Consumers in India prefer other foods, the monsoon (Jones and Alagarswami 1973). and even oysters are not widely consumed. The They attributed this to water turbidity, presence low demand results in a low price, and, in some of sand and mud in the mantle cavity, lowered instances, adequate economic returns on invest­ salinity, and increased numbers of the peacrab ment cannot be ensured except at a price slightly Pinnotheres sp. in the mussels. Pillai ( 1980) higher than that for noncultured bivalves. The found that the bacterial load of the brown mussel integrated development of increased production, cultured at Vizhinjam was relatively higher (I 06) increased consumer demand, and a marketing than that of mussels in the natural beds (I 05) and strategy for molluscan products is required. that the occurrence of coliforms, E. coli, fecal Extension is badly needed. CMFRI has organ­ streptococci, and coagulase-positive staphylo­ ized several training programs in bivalve culture cocci was almost steady both in the mussels and (CMFRI 1977). Direct transfer of technology is in the seawater. Pseudomonas, Vibrio, and effected through the Lab-to-Land program in Micrococcus were seen as normal flora in mussels which scientists help local people to adopt the and seawater. techniques of mussel farming and oyster culture In August 1981, a case of shellfish poisoning (CMFRI 1979). However, these extension efforts was reported from Vayalur village in Tamil are localized and are not sufficient. Nadu. Three children died, and 82 others had Development of bivalve culture will depend on neurotoxic symptoms. Investigations conducted means to ensure seed availability for large-scale by the National Institute of Nutrition, Hyde­ production. Although mussel-seed abundance in rabad, showed that the clam M. casta, consumed the wild is adequate for culture operations, its by those affected, was contaminated with toxins collection conflicts with the interests of tradi­ secreted by dinoflagellates. Because of isolated tional mussel producers. The natural beds of oys­ cases of contaminated bivalves in the coastal ters are limited, and the paucity of pearl oysters waters, estuaries, and canals, appropriate depu­ has prevented commercial projects. Hatchery ration and other sanitary measures should be production of seed is necessary to reduce depen­ taken to make the bivalves safe for human con­ dence on nature. The technology for artificial sumption before they are marketed. production of pearl oysters has already been Bacteriological and toxicological analysis at developed and will be applied to other species. the Inspection Laboratory of the Marine Prod­ This development will necessitate mass produc­ ucts Development Export Authority, Cochin, tion of algae as food for the larval stages. showed that E. coli, Staphylococcus, and Salmo­ At present, the costs of farming are too high, nella were absent from the oyster flesh from Tuti­ and efforts need to be devoted to finding low-cost corin farm. The heavy metal contents (mercury, methods and to developing the means to cultivate copper, and cadmium) were well within admissi­ bivalves year round in the open sea. The Indian ble limits. experience is unique because the farming systems Bivalves collected from the wild are not cur­ must be developed under unfavourable sea con­ rently depurated: they are sold fresh immediately ditions caused by monsoons. after collection. However, cultured bivalves and Postharvest technology and quality control those meant for export are depurated. CMFRI 42 BIVALVE CULTURE has constructed depuration tanks at Tuticorin Table 2. The proximate composition(%) of mussel and Calicut (Nayar et al. 1980). Balachandran (P. viridis) and clam ( V. cornucopia) following and Nair ( 1975) found that mussels kept alive in preservation in ice in organoleptically acceptable seawater for 24 hand then in chlorinated water (5 conditions for up to 8 and 9 days (Chinnamma et al. 1970). ppm) for 2 h had reduced sand content (0.02% on a dry-weight basis of the flesh) and no fecal or Mussel Clam pathogenic bacteria. 8 days 9 days 8 days 9 days Protein 12.13 13.82 7.63 11.05 Fat 2.24 2.55 0.91 2.17 STORAGE, NUTRITIONAL DATA, Glycogen 8.31 10.58 1.31 7.91 AND PROCESSING Inorganic phosphorus 15.10 43.18 22.16 29.40 The Central Institute of Fisheries Technology Ash 4.50 4.70 (CIFT), Cochin, leads research on postharvest technology for bivalves, as well as for finfishes and crustaceans. Balachandran and Prabhu cucullata in several media; and the Integrated ( l 980a) have summarized developments in post­ Fisheries Project, Cochin, is working on product harvest techniques for mussels in India. Chin­ diversification with edible oysters from the Tuti­ namma et al. (1970) observed that mussels (P. corin farm. Live oysters can be kept out of sea­ viridis) and clams ( Villorita cornucopia) pre­ water for up to 30 h without mortality and can served in ice for up to 9 days were acceptable withstand transport over long distances. Canned, organoleptically (Table 2). smoked and canned, and frozen products have Chinnamma (1974) reported that whole mus­ been developed. sels (P. viridis ), removed from the shell, stored on Bivalves have been exported on a trial basis ice for 8 days, and then frozen, remained in since 1970 when 6.0 X J03 kg of frozen mussel acceptable condition for only 15 weeks, whereas flesh was sent to the Federal Republic of Ger­ fresh-frozen flesh remained acceptable for 40 many. Canned mussel flesh has been exported to weeks. Fresh-frozen clam ( Villorita sp.) Muscat and Saudi Arabia, and exports of mussel remained acceptable for 35 weeks, and the shell pickle to the Middle East are increasing. In 1981, life of material iced for 8 days and then frozen 6 t of frozen clam flesh was exported to Japan. was only 4 weeks. Some work has been done on bivalve-product development. M uraleedharan et al. (1979) devel­ FUTURE PLANS oped the smoke-curing of mussels. After the smoked product was either sun or mechanically An economic data base for bivalve culture, dried to 10% moisture level, it could be stored based on pilot-scale operations, is yet to be devel­ without spoilage for more than 6 months. The oped. The technical feasibility of culture systems yield was 22%, and the product included total for oysters, mussels, blood clams, and pearls has nitrogen, 8. 765%; glycogen, 22.15%; and fat, been established through experiments and small­ 11.51%. scale field trials. Fisheries development depart­ Balachandran and Nair (1975) developed a ments should initiate pilot projects to demon­ process for canning clams and mussels in hot, strate the economic feasibility of bivalve culture. refined groundnut oil, and Balachandran and A cost-benefit study of oyster culture by the Prabhu (l 980b) found that a canned product rack-and-tray method on 0.25 ha, producing 3 t prepared from ice-stored whole mussel or fresh of oyster flesh annually, has been made. With an shucked flesh had good organoleptic characteris­ investment of Rs 19.00/kg flesh, and at a selling tics for up to 2 days of storage. The products had price of Rs 28. 00 /kg, the net income before tax better colour, flavour, and juiciness than a would be Rs 27000 - about a 30% return on the canned product from boiled flesh. Balachandran investment. For mussel culture, several projec­ and Prabhu (l 980b) also reported a method for tions have been made. Qasim et al. ( 1977) have preparing mussel pickle having a shelf life of up given the rates of return on investment as 181 % to 6 months. for the green mussel in Goa; Ranade and Ranade Other work is under way. For example, (1980) have visualized a return of 168% on CMFRI and CIFT are cooperating in a project investment for the same species in Ratnagiri; and for product development and quality control; Achari ( 1980) has projected a return of76. 71 % on Badonia ( 1980) has canned the rock oyster C. capital for single-raft production of brown mus- INDIA 43 sels in Vizhinjam Bay. Appukuttan (1980b) has commercial culture system has yet been estab­ given a net profit rate of Rs 1480-2680 from a lished, financing agencies are hesitant and need single raft for the same species. However, these encouragement. projections must be tested in commercial Marketing as well is vital to the development of operations. bivalve culture. Traditional local markets are re­ The national policy for bivalve culture should stricted and efforts to explore new markets within be to: and outside the country have only just started. • Promote molluscs as a valuable food Mussels and clams should cater largely to inter­ resource and show that their proper utiliza­ nal markets to improve the nutrition of the poor, tion would contribute substantially to the whereas oysters, because of high production nutrition of the people (public education to costs, could be considered an export commodity. promote a wider consumption of bivalves, Cultured pearls are in great demand domesti­ even in the coastal areas, is perhaps the most cally, but they also have export potential. needed strategy from the point of view of Training is essential and should be initiated for production and nutrition); and different cadres of personnel. The present ad-hoc • Promote the potential of bivalve culture in training programs should be strengthened and augmenting production. Research and linked with development programs. development programs should derive Technological improvement is also necessary. strength and support from such a national The foremost need is for development of hatcher­ policy. ies for the low-cost production of quality seed. In the current phase of bivalve development, Natural seed grounds, seasons, magnitude, and state support is necessary to demonstrate the quality should be assessed properly. techniques and to prove the potential. Present Farming technology is an area requiring con­ programs are inadequate: extension programs siderable improvement, and engineering should should be organized on a large scale. become an essential component. As well as Bivalve resources are rich, but the present level improving efficiency and reducing costs, of utilization is not based on any rational pro­ researchers should develop systems suitable for gram. Exploitation is random and is generally by the diverse ecological conditions of different an open-entry system. At the existing level of regions of the country. demand, exploitation has not shown signs of The present production-oriented technologies depleting resources, thanks to the prolific breed­ should be adequately backed by fundamental ing of bivalves. However, any sizable increase in and applied research on ecological adaptations, demand - for example the opening of a steady reproduction, nutrition, growth promotion, export market - could change this situation. As genetic improvement of stocks, improvement of bivalves are sedentary, they can be overexploited. flesh quality, and disease diagnosis and control. Strategies for their judicious exploitation and Product diversification and quality control utilization should be developed. must be developed, and standards prescribed and Clams of all species are exploited for industrial enforced. Depuration should be mandatory for purposes, and little use is made of the flesh for all bivalves intended for human consumption, human consumption. Estuarine shell deposits are and pollution levels in production areas should considered a mineral resource and are mined be monitored and controlled. under licence. However, live clams usually occur Interest in bivalve culture among the govern­ at shell deposits, and mining activities pose a ments of South and Southeast Asia is relatively threat to them as well as to the livelihood of the recent, compared with that in the developed people who collect them. Policies must ensure the countries where oysters, mussels, and clams have protection of the living resources. been commercially farmed for several centuries. Leasing of brackish-water and coastal areas Whereas production in the West has been declin­ for bivalve culture needs immediate considera­ ing, there is great potential for increased bivalve tion; however, the requirements for the culture of production in Asia and the Pacific. A common other organisms such as finfish, crustaceans, and strategy is needed to promote bivalve culture in algae must also be taken into account so that the region and to realize the potential. priorities can be set and areas assigned. Exchange of information and interaction Financial assistance is also needed. Pearl cul­ between the scientists and development person­ ture requires the highest investment, followed by nel involved in bivalve culture in the region mussel, oyster, and clam culture. Because no should be encouraged. /NDONESJAI

M. Unar, M. Fatuchri, and Retno tured, but on a limited scale, at Kanyan (Bangka­ Andamari Research Institute for lan) in Madura Island, East Java. Its culture at Marunda, in the eastern part of Jakarta, has Marine Fisheries, Jakarta, Indonesia ceased because the sand has been taken away for Indonesia has about 5.8 X J06 km2 marine construction material. coastal waters and is richly endowed with shell­ Recently, the experimental culture of green fish (molluscs) of economic importance. Shellfish mussels (Perna viridis) has begun at Ancol production was 5.1 X 104 tin 1979, and the total (Jakarta Bay), Mauk-Tangerang (West Jakarta), marine-fisheries production was 1.3 X J06t. Shell­ and Banten Bay. Production at Ancol, with the fish are gathered mostly from natural beds, and bamboo-stake method, is 100 t/ ha in 6 months, mariculture production is negligible. Blood cock­ whereas, with the hanging method, yields of 200 les (Anadara spp., kerang darah) are most impor­ t/ ha and 578 t/ ha have been obtained at Mauk­ tant, followed by clams (various species, remis), Tangerang and Banten Bay, respectively. oysters (tiram), and scallops (simping) - all The culture of blood cockles (A. granosa), harvested from wild stocks (Table 1). practiced by local people at Mauk from 1950 to The Malacca strait of North Sumatra and the 1969, consisted only of gathering seed and waters north of Java, especially in the northeast, spreading it in beds. Production was 5 t/ ha. are important sources of blood cockles. In 1979, Unfortunately, this activity was halted in 1975 2.8 X 104 t of blood cockles were taken from the because of lack of seed. Malacca strait and 2.1 X J03 t from the area north of Java. Asian moon scallops are caught by shrimp trawlers using Danish seines (dogol) in INSTITUTIONS INVOLVED JN Central Java, and production was 377 tin 1979. BIVALVE WORK Clams were gathered mainly from the Malacca Straits, and production was 2.0 X J03 tin 1979. Institutions involved in bivalve work include The small venerid-clam (Gafrarium tumidum) is research establishments, management authori­ reportedly common in Teluk Bintan, Bintan ties, and teaching institutions: the Research Insti­ Island. tute for Marine Fisheries (Balai Penelitian Perik­ Bivalve culture in Indonesia is largely experi­ anan Laut, BPPL); National Institute of mental at present, although five companies in Oceanology (Lembaga Oceanologi Nasional, eastern Indonesia are in the business of produc­ LON); Muzeum Zoologi Bogor (MZB); Gelang­ ing pearl oysters, using Japanese technology. The gang Samudera Ancol (GSA, an oceanarium); native rock or mangrove oyster is also being cul- Directorate General of Fisheries; and Faculty of Fisheries of the Bogor Agricultural University. 'Paper presented by Retno Andamari. All, except GSA, are government institutions.

Table I. Commercial landings of molluscs in Indonesia (Direktorat Jendral Perikanan 198 I).

Landings (I OJ t) Name Species 1976 1977 1978 1979 Cupped oyster Crassostrea spp. 0.62 1.27 0.19 0.91 Asian moon scallop Amusium sp. 0.08 0.08 0.45 0.48 Clams Various 1.17 2.70 4.32 2.56 Blood cockles Anadara spp. 22.98 31.36 40.98 32.18

44 INDONESIA 45

BPPL is under the Agency for Agricultural August-November have proved to be peak times Research and Development of the Ministry of for shellfish larvae in Banten Bay. This finding is Agriculture and has two branches involved with supported by observations of gonad maturity of bivalve culture: Sub BPPL Ancol and Sub BPPL oysters. Serang-Banten. It is also the implementing Experiments have been conducted on inducing agency for a mariculture research and develop­ the spawning of the green mussel and on its egg ment project based in Banten Bay, which receives development as a basis for methods of artificial technical assistance from the Japan International seed production. It has been found that one can Cooperation Agency. easily induce P. viridis to spawn by adding sperm LON and MZB are under the Indonesian Insti­ media to the water and raising the water tempera­ tute of Sciences (UPI). Experimental programs ture from 27° to 35° C. on bivalve culture are conducted by LON, and As there is no commercial farming of bivalves the study of bivalve distribution, classification, near Jakarta and the Riau Islands, there is no and ecology is done by MZB. LON and UPI practical experience to provide a basis for selec­ have successfully cooperated with GSA, with tion of culture methods. Bivalve-culture trials are support from the government of Jakarta, in the needed to determine site selection and the best experimental culture of green mussels. The methods of spat collection and growing. Some Faculty of Fisheries, Bogor Agricultural Univer­ trials have already begun in Ancol (Jakarta Bay), sity, has a department of aquaculture that is Mauk-Tangerang, and Banten Bay. In Riau engaged in bivalve work. The Directorate Gen­ Island, trials are needed to establish oyster cul­ eral of Fisheries under the Ministry of Agricul­ ture and introduce mussels. ture is the management authority and has If the trials confirm the potential for sea farm­ emphasized the development of sea farming in ing, the government should: Indonesia. • Establish a demonstration farm and a national shellfish sanitation program; • Develop a legal framework for aquaculture; CULTURE PRACTICES • Invest in the training of aquaculture special­ ists and sea farmers; and • Provide an extension service for sea farmers. Several methods of culture are being explored in Indonesia. In 1973-76, a raft or floating Several kinds of cultch are used for the collec­ method of oyster culture was tried in Banten Bay, tion of spat. For example, the fishermen at and the rack method was used in estuarine waters Marunda use oyster shells, which are a tradi­ of Pamanukan. At Marunda, Jakarta, fishermen tional collector. Collectors made from cement­ collected seed on shell cultch in February­ coated tiles are effective and have been reported March, grew the oysters in beds, and harvested to be better than plain tiles for oyster-spat collec­ after 6 months. tion. Bamboo cultch was successfully used to Green mussels are grown either on bamboo collect green-mussel spat at Ancol-Jakarta and stakes (6-8 m long) or on ropes. The first system Banten Bay, and a net-type collector has been has been used mainly by GSA with the coopera­ used at Ketapang Bay. tion of LON-UPI in Jakarta Bay and the second BPPL has identified Banten Bay as a grow-out by BPPL at Mauk-Tangerang and Banten Bay. ground and Mauk-Tangerang, which is becom­ Also, the mussels attach to bamboo bagans ing increasingly polluted, as a spat-collection (light, bamboo fishing traps used by local people) ground; some experiments applying this concept and are gathered as a subsistence food, especially to green mussels have been carried out. Mussel during the west-monsoon season. seed (I cm long), gathered from bagans or net A bivalve-culture experiment is being con­ collectors hung from rafts in Mauk, were trans­ ducted in Banten Bay by BPPL. This bay, about planted to Banten Bay, bundled to ropes by a fine 90 km2, has potential for shellfish culture and is net and hung from a raft. Preliminary observa­ far from sources of pollution. Perna viridis, tions indicate that the mussels grow to 8 cm long Anadara spp., Pinctada vulgaris (pearl oyster), within IO months in this bay and that the oyster Musculita arcuatula (kupang), and Crassostrea Saccostrea cucul/ata can reach 5 cm in length sp. (oyster) are found in the bay. within 12 months. However, there is a species of Bivalve spat are collected when their numbers oyster in Pamanukan that reaches a shell length are judged to be at a peak. To determine the best of 7.7 cm within 6-7 months. time and place for collection, researchers rely on Along the shore of Ketapang Bay, clumps of surveys of planktonic larvae; April-May and young seed mussels are gathered from the bagans 46 BIVALVE CULTURE and attached to grow-out ropes, with a bamboo • Instituting extension programs for sea dowel (30 cm long and 2 cm in diameter) being farmers; and inserted every 50 cm to prevent the growing • Beginning now to plan shellfish sanitation column of mussels from sliding off. programs - for example, certifying clean areas as suitable for harvesting of shellfish and prohibiting harvests from polluted PROBLEMS AND CONSTRAINTS waters.

Many of the constraints to bivalve culture in Indonesia derive from the fact that it is still in the FUTURE PLANS preliminary stages of development within the country. Statistics, knowledgeable personnel, Projecting the profitability of bivalve culture market demand, and sanitary regulations are in Indonesia is difficult because figures on pro­ limited if they exist at all. Some steps to relieve duction and marketing are not available. Never­ the constraints include: theless, several factors suggest a focus for pro­ • Collecting statistics on bivalve landings so duction. For example, Singapore reportedly that potential areas for bivalve production could absorb all the oysters produced from sev­ can be identified; eral 100-ha farms (Glude et al. 1981), so the • Hiring, or providing current, government development of bivalve culture in the Riau employees with special knowledge and expe­ Archipelago might well be economically feasible. rience in mariculture so that they can formu­ Jakarta consumed 0.5 t of bivalves/ day in 1971. late plans for mariculture development as As consumption has probably increased since, well as carry out government programs. small-scale bivalve farming near Jakarta (Banten • Promoting bivalves and their products as Bay) would also probably be economically feasi­ nutritious and palatable food items; ble, at least in terms of demand. MALAYSIA'

Ng Fong Oon, Josephine Pang, and Fisheries and Aquaculture Branch, Department Tang Twen Poh Fisheries Research of Agriculture, Sarawak, are involved in studies Institute, Gelugor, Pu/au Pinang; on the biology and culture of cockles, oysters, and mussels. The Fisheries Authority of Malay­ Inland Fisheries and Aquaculture sia (Majuikan) is now actively involved in organ­ Branch, Department of Agriculture, ized culture of cockles in Peninsular Malaysia. Kuching, Sarawak; and Department of Fisheries, Kata Kinabalu, Sabah, Malaysia CULTURE PRACTICES Total production of molluscs in Peninsular No organized oyster culture was carried out Malaysia in 1979 was about 7.7 X 104 t, which until very recently. The earliest record of oyster constituted approximately 11 % of the overall culture was the experimental raft-culture studies fisheries production that year. Of the total mol­ carried out by Okada from 1960 to 1963 (Okada lusc production, 6.3 X 104 twas cockles (Anadara 1963). Oysters are now being propagated on a granosa) and the rest was other molluscs (oysters, part-time basis in the Muar River, Johore, with mussels, and clams). The production of molluscs on-bottom culture methods, oyster shells being from the eastern states (Sabah and Sarawak) in used as collectors. The Fisheries Research Insti­ 1979 was low. In Sabah, about 0.17 t of oysters tute is presently carrying out research on raft were produced for export (the majority from wild culture of a flat oyster (Ostrea fo/ium) using stocks), and, in Sarawak, about 4 t of razor clams polyethylene nets and ropes as collectors at Pulau (Solen sp.) were sold in the local market. Langkawi, Kedah (Ng 1979). Although production of oysters and mussels in In Sabah, experimental oyster culture was Peninsular Malaysia was not precisely docu­ started in 1970 in Sandakan and later in Tawau mented in the annual fisheries statistics for 1979, and Labuan. Two species of oysters have been it was estimated that about 13 t of oysters (Cr as-. used: C. be/cheri and Saccostrea cucul/ata. In sostrea be/cheri) were taken from the Muar addition, an experimental station for cockles (A. River, Johore (Ng 1979), and that about 198 t of granosa) is being set up. The initial stocking seed mussels were taken from around the Johore will be from a commercial source in Peninsular region (Choo 1979). No figures are available for Malaysia. Experiments on the artificial estab­ the production of other bivalves (P/acuna sp., lishment of brown-mussel ( Modio/us philippina­ Gafrarium sp., Ge/oina sp., Pinna sp., Paphia rum) beds were carried out in 1973 along with the undu/ata, Modio/us sp., etc.), although they are oyster-culture project. There were no further sold in local markets. trials on mussels because of the lack of technical personnel and funding, but the mussel project is INSTITUTIONS INVOLVED IN BIVALVE expected to be revived in the Fourth Malaysia Plan. WORK Oyster culture is carried out experimentally in The Fisheries Research Institute, Penang, the Sarawak by the Department of Agriculture. Department of Fisheries, Sabah, and the Inland Three culture methods are used. The raft or float­ ing method is employed for oysters grown in riverine conditions where siltation is compara­ 1This paper is an edited compilation based on three separate papers presented by the individual authors tively heavy and the tidal range is often as high as during the workshop. The cooperation of the authors in 5.5 m. The raft method is also suitable in areas preparing this country paper is gratefully where the water level remains high during low acknowledged. tide. The pole and rack methods are intertidal,

47 48 BIVALVECULTURE fixed-culture methods used in both spat collec­ found to be best. In Pulau Langkawi, polyethyl­ tion and grow out, generally in places where the ene ropes and nets were found to be the best gradient is gradual, siltation less serious, and the collectors for Ostrea folium. For the culture of time that oysters will be exposed minimal. A mussels in the Straits of Johore, polypropylene com bi nation of pole or rack and raft methods has ropes have proved to be the most effective cultch. proved most effective: the spat are transferred, Forecasting the best time to set out the cultch either together with the collectors or detached for oysters and mussels depends on meteorologi­ from them, and grown in boxes or trays sus­ cal conditions and confirmation by quantitative pended from the raft. analysis, from plankton hauls, of the numbers of The Fisheries Research Institute has success­ oyster and mussel larvae in the water. fully demonstrated the culturing of mussels in the In Malaysia, oyster and mussel spatfalls occur J oho re Straits using the raft-culture method, throughout the year, but there are two main with polypropylene ropes as collectors (Choo peaks. In Pulau Langkawi, in the northwestern 1979). part of Peninsular Malaysia, the first peak for Cockle culture first began about 1948 by a oysters is in March-May and the second in village leader in Bagan Panchor, Perak; since September-December. In Sarawak, the first then, it has spread rapidly and developed into the peak is also in March-May but the second is in most important aquaculture industry in Malay­ November-December. In Sabah, the first is in sia. Today, it is the most organized culture system April-June and the second in October­ developed in Peninsular Malaysia. Currently, November. Heaviest spatfall occurs 2-3 weeks mass culture of cockles is being practiced by after a sudden, heavy rainfall and lasts 2-3 days. Majuikan or through cooperatives along the west The first peak for mussel spatfall in Selat Tebrau, coast of Peninsular Malaysia, and, on the east Johore, is in November-February and the second coast, some small areas (lagoons) have been util­ in May-June. Cockle spatfall occurs in definite ized by Majuikan for the culture of cockles. areas and seasons, generally from late June to In Sarawak, wild-seed cockles are sown in pre­ late November with a peak in September and pared coastal mud flats. From 1954 to 1967, there October. was considerable cockle farming at the delta of major rivers in southwest Sarawak (Harrisson GROW-OUT ASPECTS 1970). Most plots were bounded by natural landmarks, but, where these were lacking, the The bottom-culture method practiced for oys­ boundaries were marked by other means. The ters in the Muar River requires no special grow­ sowing density was between 2 kg and 6.5 kg of out grounds. The same ground is used for collec­ tion and grow out. The raft-culture method for seed/m2• Sites suitable for oyster and mussel culture 0.folium using polyethylene materials as collec­ need to be sheltered from strong winds and wave tors also requires no grow-out grounds, and spat action, free from predators and fouling organ­ are left on the collectors to grow to marketable isms, accessible to nearby populations because size. Thinning is only carried out when the oys­ local participation is required, and free of exces­ ters become too crowded. In Sabah, where the sive pollution. rack-and-raft-with-tray method is used, spat are Cockle culture can be carried out in coastal collected from tributaries of Cowie Bay. They mud flats with soft flocculent mud at least are retained in boxes on racks for about 4 months 45-75 cm thick. The culture area should be free and later transferred to higher intertidal racks for from predators (e.g., boring molluscs such as hardening. After hardening for 2 months, they Natica macu/osa and fish such as skates) and free (3-5 cm) are removed from the cultch and grown from excessive industrial and domestic pollu­ in trays suspended from rafts. tants; the salinity of the water should be between In Sarawak, collectors are usually transferred 18 ppt and 30 ppt. for grow out from the spat-catching ground to another area. Because the Sarawak coastline is exposed, the only suitable grow-out areas are estuaries or brackish-water mangrove swamps. NURSERY ASPECTS Not only are these areas sheltered from strong In the Muar River, Johore, oyster shells have wave action, but the lower salinity of the water proved to be the most suitable cultch for the minimizes barnacle fouling. The mussels grow on collection of spat from C. belcheri, whereas, in the cultch until they reach marketable size but are Sabah and Sarawak, various cultch materials thinned to new collectors when they become too were tested, and corrugated roofing asbestos was crowded. MALAYSIA 49

Cockle seeds taken from natural areas are introduced because of the possibility of damag­ transferred to culture areas and scattered evenly ing the oyster bed. The oysters are collected and over the culture beds. Wire scoops with long shucked, and the empty shells are immediately handles are used to gather spat and to move the thrown back into the river. Only oysters of mar­ cockles. As the spat grow, the beds are thinned, ketable size are kept; immature oysters are the cockles being transplanted to other areas. thrown back. A hard-working fisherman can get This approach results in rapid growth. an average of about 1-2 kg of oyster flesh/day. Crassostrea belcheri raised in Sabah grows to However, when oyster production is poor, the about 14 cm long, with a flesh weight of about fishermen devote more time to fishing, and this 14-21 g, after I year. The condition factor ranges allows the oyster population to recover. It is between 115 and 135 points on the standard estimated that more than 12 t of oysters (shucked)/ 50-150 condition scale for oysters. Ostreafolium year are produced from this system. cultured in Pulau Langkawi attains a length of In Pulau Langkawi, oysters 4-5 cm long are about 6-7 cm (marketable size) in 10-12 months, harvested daily during low tide by women. The with an average flesh weight of about 4-5 g. quantity taken and the number of people Mytilus viridis cultured in the Johore Straits involved are unknown. Experimental culture of reaches marketable size (7 cm) in about 5-6 oysters carried out by the Fisheries Research months. Cockles grow to more than 2.5 cm long Institute indicates that there is potential for oys­ (marketable size) in 6-8 months. ter culture, and feasibility studies are in progress. In Sarawak, the growth rates of two species of It is anticipated that raft culture of oysters on a oysters ( C. cucullata and C. rivularis) have been part-time basis can be carried out by local people. examined under experimental conditions, and C. In Sabah, oysters are being commercially cul­ cucullata, a small species, attained an average tured by cooperatives. Productivity from the size of 45 mm in I year, starting from 5-mm spat. rack-and-raft-with-tray system is estimated to be This rate is comparable with that of the same about 18 t/ha each year (Kamara et al. 1976). species found in Singapore's waters where the Fish culturists farm mussels in the ~ohore mean growth is reported to be 26. 96 mm in I 0 Straits on a part-time basis, but it is anticipated months (Tham et al. 1970); C. rivularis showed that farming will be by family units in future. much faster growth and easily attained an aver­ With raft culture, an estimated 315 t/ ha can be age length of7 .5 mm in I year. Unfortunately, the produced in a year. spat of this species are not available in sufficient Cockle culture can be carried out on a full- or quantity. part-time basis. The beds are maintained by a few The racks and rafts used for oyster culture in people working in shifts. Two full-time people Sabah and Sarawak are supported by belian (a are needed to oversee the culture beds day and heavy hardwood, Eusideroxylon zwaferi) and night throughout the culture period. Casual other suitable timber. All materials are coated workers are recruited on a part-time basis during with a layer of bituminous compound to protect sowing and harvesting. Harvesting is normally against marine borers and to prevent rusting of carried out by fishing personnel paid metal parts. Oil drums and synthetic floats pro­ $1.20-$3.00/sack of cockles collected (payment vide buoyancy for the rafts. depending on experience). An average bed of In the raft culture at Pulau Langkawi and in about an acre (0.4 ha) would produce an esti­ the Straits of Johore styrofoam blocks and plas­ mated 16 t yearly; in well-managed and fertile tic jerry cans are used for buoyancy. The rafts are beds, the yield could easily be doubled. normally made of meranti wood, coated with antifouling or tar paint.

PROBLEMS AND CONSTRAINTS

MANAGEMENT AND PRODUCTION The main problems affecting oyster culture in Peninsular Malaysia are the fouling from other Oyster and mussel culture is currently being sedentary organisms and algae, predation by conducted on a small scale, particularly in Penin­ xanthid crabs (Myomenippe granulosa) and star­ sular Malaysia, on a part-time basis. Bottom cul­ fish, siltation, and poor spatfall. Oyster culture in ture of oysters in the Muar River involves about the Muar River is affected by poor spatfall (per­ 20 fishermen in an area of about 16 ha. The haps because of siltation) and fouling by algae. In fishermen gather the oysters by diving during low Pulau Langkawi, there has been a drastic decline tide. Mechanical devices (dredges) have not been in spatfall during the last 2 years. Predation by 50 BIVALVECULTURE

xanthid crabs and starfish and competition from These failures may have been the result of poor other sedentary organisms (bryozoans, sponges, site selection or delays in transport of seed to the and barnacles) have seriously affected culture culture beds. Other problems include the pilfer­ efforts by the Fisheries Research Institute. ing of cockles at night in Perak and the illegal In Sabah, the high cost of culture, especially culture and export of seed to Thailand. Seed collectors, may become the main constraint. In supply will likely become a problem if culture the past few years, there were two mass mortali­ increases and large quantities of seed continue to ties of oysters ( C. belcheri but not S. cucullata) at be exported. However, the most pressing prob­ the culture station. Causes of the first incident are lems in the future will be the increase in industrial not known, but sudden environmental changes and domestic pollutants, as major towns and cit­ may have caused the one, later, in May 1981. ies develop and more heavy industries locate Extensive tree cutting and burning near the cul­ along the west coast of Peninsular Malaysia. ture station, coupled with heavy rainfall, caused a In Sarawak, the main sources of pollution are sudden change of pH and temperature and heavy sawmills and woodchip and sago factories. Anti­ siltation on the site. pollution measures have already been intro­ Lack of technical personnel is affecting the duced, but many natural cockle beds may already promotion of oyster culture by the Department have been destroyed. Cockle farming has been of Fisheries, Sa bah. The basic technique of oyster going on intermittently in Sarawak since about culture has been established, but it now needs to 1954, but it has never become an established part be introduced to the interested public. To initiate of coastal life, mainly because seed are difficult to and encourage oyster farming, the agencies obtain and the harvest is inconsistent. Currently, involved need to introduce basic training on oys­ shortage of seed and difficulties in locating suit­ ter culture, ensure a supply of oyster spat, and able sites are the main constraints. At present, advise on the suitability of sites for culture. because of high market demand, the cockles are Information about general production and man­ harvested long before they reach the legal size agement skills, harvesting, and oyster handling (31.8 mm) adopted in Peninsular Malaysia. If should also be provided. Subsidies to reduce the growers can be persuaded to delay harvest until initial development cost to the individual farmer the cockles reach reproductive size, seed will be would greatly assist in establishing oyster farm­ produced. At present, seed must be imported ing. In addition, applied research must be carried from Peninsular Malaysia, and delivery from the out to improve profitability. seed bed to the culture site usually takes several In Sarawak, the main problems are a limited days, during which there is usually high supply of desirable oyster seed and difficulties in mortality. locating suitable grounds for cultivation. Although several species of oyster are found in Sarawak, only the spat of C. cucullata are abundant. Sarawak has extensive mangrove POSTHAR VEST HANDLING swamps and a long coastline that has potential for aquaculture development, but large and shel­ In many countries with oyster or mussel indus­ tered areas suitable for commercial culture of tries, sanitary and pollution surveys must be car­ oysters have not been identified. ried out before permission to cultivate in an area Most of the estuaries and rivers are subject to is granted. Fortunately, Malaysia is not affected heavy siltation and have low densities of plank­ as much by pollution as some other countries. ton -food essential to oysters. In addition, shel­ Oyster and mussel culture is still in its infancy, tered bays are lacking, and the coastline is subject and most culture areas are not affected by indus­ to strong wave action, especially during mon­ trial and domestic pollutants. Hence, sanitary soons. The excessively high tidal range (more control is not practiced at present. Likewise, than 5.5 m) is also a disadvantage. Other prob­ cockles are generally cultured in areas unaffected lems are fouling from barnacles and aquatic by pollutants. However, as industries and popu­ growths and predation from crabs and oyster lation increase, the concentration of pathogenic borers. Areas selected for small-scale oyster cul­ bacteria as well as heavy metals (copper and zinc) ture are not affected by pollution at present. will require monitoring. The Fisheries Research The main constraint affecting mussel culture in Institute has recently acquired equipment to Malaysia is poor consumer acceptability. monitor heavy metals and in future may be able Cockle culture in Peninsular Malaysia is not to undertake regular surveillance of coastal affected by serious problems, although failures in waters. culture beds have been recorded occasionally. Oysters harvested from the Muar River are MALAYSIA 51 shucked by hand. They are usually opened with a logical and ecological conditions in the Johore knife. The shucked oysters are weighed and sold Straits are very favourable for mussel culture, to intermediaries who sell to retailers or to oyster­ and, if IO ha of the Tebrau or Johore Straits sauce factories. Oysters produced in this region could be developed for mussel culture in the com­ are intended for local consumption, but some are ing decade, the production of minced flesh would sent to Singapore. Refrigeration is not necessary, amount to about 3.0 X JOJ t/year (Ong 1981). but crushed ice is normally used to keep the flesh Cockle culture is already established and is fresh. Likewise, oyster flesh harvested by local rapidly expanding in Peninsular Malaysia. Cur­ people in the Pulau Langkawi region is sold rently, about 1.6 X I QJ ha of mud flats along the directly in open markets or dispatched by boat to west coast are used for cockle culture. The poten­ the mainland. tial area is probably at least double this amount. Mussels are sold in the shell in the open market Production could be increased not only by the in Johore Baru. opening of new sites or the introduction of new Processing of mussels and oysters by drying or systems for mollusc culture but also by the con­ canning is not carried out yet in Peninsular trol, on existing sites, of pests, predators, and Malaysia, but cockles are processed in soybean diseases. With the existing potential for cockles, sauce and canned by factories for export. Cockles mussels, and possibly oysters, production of mol­ harvested from culture beds are sold locally in luscs in Malaysia could be doubled within the gunny sacks or exported to Thailand. next few years. The Fisheries Division of Malay­ sia is currently promoting aquaculture develop­ ment through research and extension. Already FUTURE PLANS major research findings on the biology and cul­ ture of cockles in Malaysia have helped the Quayle (1975) asserted that the biological cockle industry. Although the larvae of cockles problems of oyster culture in the tropics are more have been identified ( Pathansali 1963), only complex than those associated with culture in recently has any attempt been made to breed cooler waters (temperate countries), and, there­ cockles and raise larvae to spat. This has been fore, quick solutions are unlikely. The high cost carried out in the Fisheries Research Institute, involved in the production of oysters in Pulau which is also intensifying its efforts to identify Langkawi and the poor market price do not jus­ new culture sites for cockles, mussels, and oysters tify commercial production at present. Oyster and to upgrade existing culture techniques. culture in Pulau Langkawi would require consid­ Moreover, the Institute is providing training and erable financial and labour inputs and the advan­ technical advice to culturists on mollusc-culture tages over collecting oysters from the natural techniques. environment are not great enough to warrant the To date, the Department of Fisheries, Sabah, investment. has been providing advice on the suitability of The Fisheries Research Institute is carrying sites for oyster culture, information on basic pro­ out research to improve the culture techniques, to duction techniques, and free oyster spat for the solve problems like predation by crabs and star­ initiation of such ventures. The Department fish, and to locate suitable areas - areas with hopes to increase oyster production by encourag­ little predation and competition from other sed­ ing small-scale, family-run oyster farming, which entary organisms. would benefit coastal inhabitants in rural areas. The Institute has already demonstrated that Initially, these ventures would be practiced pre­ mussel culture in Malaysia has good potential as dominantly part time, but, when sufficient skill a low-cost source of protein. Raft culture is very and experience have been acquired, the farmers productive in the Straits of J ohore, and possibly would be encouraged to expand into full-time other suitable areas could be found along the operations. This strategy is in line with the objec­ coast. The poor market for this bivalve is a con­ tives of the Fourth Malaysia Plan to increase straint, but, as the prices of fish, prawns, and food production and to raise living standards in meat continue to increase, there may be an rural sectors. Although the long-term strategy increase in demand for mussels. Therefore, the would aim toward an export-oriented industry, rate at which mussel culture develops will depend small-scale, family-run farming operations must largely on demand and the market price. It is first be promoted. anticipated that both the demand and the price In Sarawak, studies are currently concentrated for mussels can be raised ifthe culture techniques on further development of culture techniques and are given wide publicity through the media. Bio- on the economic aspects of oyster culture. The 52 BIVALVE CULTURE

Department of Agriculture assists interested ture potential of C. cucul/ata. With regard to coastal people to establish oyster plots through cockle culture, the Department plans to continue an oyster-subsidy scheme. In view of the difficul­ its restocking program, which is aimed at produc­ ties in obtaining large species of oysters, however, ing seed locally. attention will be directed to determining the cul- PAPUA NEW GUINEA

J.M. Lock Department of Fisheries, adjacent to a number of villages. In 1975, 15 Konedobu, Papua New Guinea farms handling a total 20 cultivating rafts had been established on four islands. The farmers Bivalve culture has been relatively unimpor­ formed the Milne Bay Pearl Farmers Associa­ tant in fisheries development in Papua New Gui­ tion, with 250 active members. A school was nea. At present, only the culture of pearl oysters established to train personnel in pearl farming. is under way, and it is confined to a few small, The course included such subjects as establish­ village farms - remnants of a larger pearl­ ment and management of pearl farms, pearl­ farming operation that existed in the early 1970s. cultivation techniques, and the processing and Plans have been proposed to revitalize the handling of pearls. All village production was pearl fishery, mainly among village artisans, and based on half pearls. Nuclei and glue were sup­ a program may soon be implemented. The plied by the expert culturist, and pearls were sent government is emphasizing development of arti­ to him for processing. Pearl buttons, rings, ear­ sanal and subsistence fisheries, and, as pearl rings, pendants, and other costume jewelry were farming has been successfully run at the village made on Pearl Island and later also by jewelers in level, it is a logical choice for future development Port Moresby. of the inshore fishery. Unfortunately, because of financial and other problems, the activities of the Pearl Farmers Association have now virtually ceased; only a PAST DEVELOPMENTS AND small number of farmers and the expert are still FUTURE PROSPECTS producing. Nevertheless, the experience pointed the way for future programs, and, given adequate In the early 1970s, two centres of pearl farming financial backing, pearl cultivation on an arti­ existed - the only commercial attempts at sanal level is considered feasible. The villagers are bivalve culture. In Fairfax Harbour, Port enthusiastic about reestablishing pearl culture Moresby, an Australian-Japanese enterprise because it provides a source of cash without sub­ operated from 1965 to 1975 and produced some stantially altering their way of life. 40 000 pieces/ year from gold-lip oysters (Pinc­ tada maxima). It imported seeds from Kuri Bay Experiments on the exploitation of edible oys­ in Western Australia because local supplies were ters (Ostreidae) have been done, but no commer­ not considered sufficient. High mortality among cial production has yet been undertaken. At least the stocks, possibly resulting from pollution in eight oyster species or varieties occur around the the harbour, forced the shutdown of operations. Papua New Guinea coastline. Of these, the large Of more interest to Papua New Guinea's future black-lip (Crassostrea amasa) and the milky oys­ plans was the development of a pearl-culture cen­ ter ( C. echinata) could be considered for farming. tre in the Milne Bay area at the eastern end of the Both form dense clusters in intertidal zones in country. Here, in 1966, an experienced pearl cul­ harbours and bays. Studies of settlement and turist selected a site on Dagadaga Island (later gonad condition indicate that, in the Port renamed Pearl Island) as the centre of a private Moresby area, they do not possess a clearly farm. By 1972, the farm was operating on a tech­ defined reproductive cycle and probably spawn nically sound basis. Both black-lip (P. margari­ sporadically throughout most of the year. The tifera) and gold-lip oysters were bred, and spat fact that gonad condition appears to vary may collection of black-lip oysters on plain nylon rope make the rock oysters unreliable for some over­ was extremely successful. The next step was to seas markets. A further constraint to the devel­ involve local islanders by setting up small farms opment of an oyster industry is the occurrence of

53 54 BIVALVECULTURE seasonal red tides (Pyrodinium bahamense) and Australia from Milne was found to be acceptable. the associated risk of paralytic shellfish poison­ Research relevant to bivalve culture has been ing in many areas. To overcome this, it would be undertaken by the Zoology Department of the necessary to ban sales of oyster for specified peri­ University of Papua New Guinea. Tridacnid ods during and after red-tide seasons or to locate clams have been studied for a number of years, oyster farms in red-tide-free zones. The latter and findings indicate that Tridacna gigas is suita­ would restrict oyster farming to the mainland ble for mariculture. Weights of 29 kg can be west of Port Moresby on the south coast and west attained in 6 years, and, although mature clams of Lae on the north coast. exhibit a high degree of autotrophy, the juveniles The possibility of spat collection as a first step may filter-feed to meet their nutritional require­ to initiating commercial edible-oyster culture has ments. Induced spawning and mass culture of been investigated. As early as 1955, mangrove larvae and juveniles of T. gigas have not been poles were set out in Port Moresby Harbour and achieved in Papua New Guinea but are not con­ nearby sites, but the results were not encourag­ sidered major obstacles because they have been ing. Around Port Moresby, silt caused mortality done elsewhere (Beck var 1981 ). From about 1 cm among spat, and the experiments at other sites, long, juveniles could probably be reared in float­ such as Yule Island in the Gulf of Papua, also ing trays until large enough to be reared in suit­ failed. In 1960-63, extensive experimentation able habitats. As there is a high demand for dried took place in Milne Bay, and spat were plentiful. adductor muscles, and, as the flesh of the mantle Although the project was discontinued, it indi­ and internal organs is eaten by coastal peoples in cated that the coast is capable of providing oys­ many parts of the Pacific, marketing should not ters in sufficient quantities for commercial be a problem. Thus, there is potential for cultur­ bivalve culture. The warm water around Papua ing tridacnid clams in Papua New Guinea, and, New Guinea ensures rapid growth rates, and oys­ after research is completed, a pilot mariculture ters could well reach marketable size within 18 project should be launched to investigate the months. In addition, the quality of oysters sent to commercial potential. PHIL/PPINESl

Adam Young and Evelyn Serna Aqua­ PRODUCTION culture Department, Southeast Asian In 1979, bivalves produced for food comprised Fisheries Development Center, l/oi/o green mussels (Perna viridis) 2.95 X 10 3 t; blood City; and Department of Natural clams (Anadara sp. and Arca sp.) I. 95 X 103 t; Resources, Bureau of Fisheries and oysters (Crassostrea iredalei and Saccostrea sp.) Aquatic Resources, Quezon City, 799 t; scallops (Amusium pleuronectes) 62 t; and Philippines clams (Paphia spp.) 47 t. Total production had increased from 5.9 X 10 3 tin 1976 to 9.0 X 10 3 t (Table 1). Natural populations of oysters and mussels There are 22 commercially important species have long been gathered for food by coastal in the country (Table 2), but, of the species mar­ communities in the Philippines, and bivalve keted domestically, only the green mussel (P. farming began in early 1900. The first farms were viridis) and the slipper oyster (C. ireda/ei) are no more than a series of bamboo poles inserted in farmed commercially. Nevertheless, commercial the muddy bottom of Manila Bay in Bacoor farms - ranging from 100 m2 to 2 ha in size Cavite. In May 1934, the Bureau of Fisheries and -account for 75% of green-mussel production Aquatic Resources (BFAR) established a pilot and 60% of oyster production. Most other oyster farm in Binakayan, Cavite Province, bivalves are collected from the wild. Pearl oysters Luzon, and a lucrative industry soon grew up. By are collected more for their shell and pearls than 1950, about 200 ha of private farms existed in for food. The nutrient composition of green mus­ Bacoor Bay, but, in the late 1950s, mussels sel, slipper oyster, and windowpane oyster has appeared on the farms and threatened the indus­ been investigated (Table 3). try. The response of BFAR was to initiate farms Present culture practices are traditional but for mussels, and the results prompted the estab­ appropriate for local conditions. Bamboo poles lishment of a mussel industry that proved to be at serve both as substrates for mussels and oysters least as lucrative as the oyster industry. and as racks for suspension of other substrates. Farming of windowpane oysters (Placuna pla­ Bottom culture of oysters on rocks is practiced centa) began in the late 1940s in the tide flats of Bacoor Bay, the delicate, translucent Placuna Table l. Bivalve production (t) in the Philippines, shells being used for window glazing and shell­ 1976- 79. craft. In the early 1970s, however, the bay became increasingly polluted, the stocks could not sur­ 1976 1977 1978 1979 vive, and they are still not found in the waters of the bay. Oysters 33 84 799 Mussels Brown 21 17 Green 415 1697 3220 2952 1This country report is an edited version based on 4894 4 68 62 two separate papers presented by the authors during the Scallops Clams and shells workshop. The general introduction was drawn from Hammer oysters both papers; the sections on mussels, windowpane oys­ 105 243 2861 ters, and other bivalves were written by Adam Young, Giant clams 664 1635 171 1947 and Evelyn Serna wrote the sections on oysters, the Blood cockles 201 209 l 37 1134 47 economics of shellfish farming, and future prospects Marine clams 81 1635 581 221 and recommendations. The cooperation of the authors Placuna 457 53 in preparing this country report is gratefully P1eria 485 63 acknowledged. Pinciada

55 56 BIVALVE CULTURE

Table 2. Commercially important species of bivalve molluscs found in the Philippines.

Species Local name English name Perna viridis Tahong, amahong Green mussel (Mytilus viridis; M. smaragdinus) Modiolus metcalfei Abahong Brown mussel Crassostrea iredalei Talaba, talabang, sinelas Slipper oyster C. malabonensis Kukong kabayo Saccostrea echinata Sisi Denticulated oyster, S. cucullata horse's hoof oyster, palm­ root oyster Placuna placenta Kapis, lampirong Windowpane shell Pinctada margaritifera Black-lip pearl shell P. maxima Mother-of-pearl Gold lip Pteria sp. Wing shell Amusium p/euronectes Lampirong, Asian moon scallop, Lupad-lupad sun and moon scallop Cyrtop/eura costata Diwal Angel wings, piddock (Pho/as orient a/is) Anadara granosa Batotoy, imbow Blood clam, cockle, Arca sp. litab, hungkay­ Ark shell hungkay Protapes; Katelysia Halaan Sand clam (Paphia spp.) Atrina sp. Pen shell Pharel/a acutidens Tikhan Razor clam Geloina striata Tu way Mud clam Circe gibba Saropsaropan, Venerid clam bugaton Mactra mera Katakao, punaw Hen clam, mactrid clam M. maculata Kagaykay Surf clam Donax radians Alamis, polopatani Bean clam Corbicu/a fluminea Tulya Little-neck clam (freshwater)

Table 3. Nutrient composition of the green mussel, extensively, although the species caught are not slipper oyster, and windowpane oyster by weight/ 100 g always those desired. Blood clams are harvested of flesh (edible portion).' wherever they occur. Obviously, there is much Fresh flesh room for improvement, both in seed collection and in farming methods, and current research P. viridis C. iredalei P. placenta efforts are directed toward this goal. Moisture (%) 40.8 85.5 70.2 Food energy (cal) 300 62 126 INSTITUTIONS /NVOL VED IN Protein (g) 21.9 5.9 23.3 Fat (g) 14.5 1.7 1.4 BIVALVE RESEARCH Carbohydrate (g) 18.5 5.2 3.3 Ash (g) 4.3 1.7 1.8 The institutions involved in research on Calcium (mg) 151 147 110 bivalve culture and utilization are: the Aquacul­ Phosphorus (mg) 199 77 257 ture Department, Southeast Asian Fisheries Iron (mg) 24.8 5.9 17.3 Development Center - larval biology of Sodium (mg) 882 Potassium (mg) 237 bivalves, spatfall forecasting, bivalve-culture Vitamin A (JU) 365 technology, depuration, and sanitation aspects; Thiamine (mg) 0.5 0.21 0.02 the Marine Science Center, University of the Phi­ Riboflavin (mg) 1.28 0.2 0.11 lippines - larval biology of bivalves and culture Niacin (mg) 3.1 I. 7 1.4 technology; the Biology and Zoology Depart­ Ascorbic acid (mg) 5 ment, University of the Philippines - depuration 'Source: Food Composition Table, FNRC-NSDB and uptake of mercury; the National Institute of Handbook (4th Revision) 1968, Manila, Philippines. Science and Technology (National Science PHILIPPINES 57

Development Board)- microbiology of bivalves Several smaller species of oysters - all called and utilization; the Bureau of Fisheries and sisi locally - are found in various locations and Aquatic Resources - culture technology and are utilized as food. However, because they are utilization; the Philippines Atomic Energy only 3-4 cm long, they are difficult to shuck - Commission - heavy metals in shellfish; the the task usually being undertaken by the grower's International Center for Living Aquatic Re­ family before the flesh is sold to consumers or sources Management - transplantation of mus­ wholesalers. sels in areas where they are not indigenous; the Crassostrea iredalei and C. malabonensis Freshwater Aquaculture Center, Central Luzon occur in bays on the islands of Luzon, Panay, State University, Munoz, Nueva Ecija - fresh­ Negros, Cebu, Bohol, Leyte, Samar, and perhaps water bivalves; the Binmaley School of Fisheries, others. However, there are extensive coastal Pangasinan - oyster culture; and Bicol State areas where natural populations oftalaba oysters University - general biology of bivalves. are not found and where they could probably be introduced (Table 4). Many areas in the Philippines are well suited OYSTERS for oyster culture. Water temperature is ideal throughout the year (26-30° C), nutrients in the Oysters are widely distributed in the Philip­ costal bays and estuaries are adequate, and food pines in bays and estuaries that have some runoff (phytoplankton) is abundant. The growth rate of from the land and, therefore, somewhat lower oysters is excellent, and a marketable crop of sallnity than the open sea. They filter food from medium-sized C. iredalei can be produced in 6-8 the water and grow best in areas that have mod­ months. Large oysters take about 1 year, where­ erate to high concentrations of phytoplankton. as, in many places in the temperate zone, 2-5 The most desirable species for culture are the years are required. Thus, annual production in large C. iredalei, which are usually about 6-9 cm the Philippines is better than that in the temper­ long when marketed and the moderately sized C. ate zone. malabonensis, which are usually 4-5 cm long. Rainfall, although seasonal, is sufficient to Both have excellent appearance and flavour and maintain the flow of the rivers that provide suit­ are accepted equally in the market. The two spe­ able salinity for growth and reproduction. There cies have similar environmental requirements are many unused, shallow bays protected from and often occur together. surf and storms that would be excellent for oyster culture, especially by the stake or hanging Table 4. Estimated potential for expansion of method. In some locations, the sediment in shal­ oyster farming in the Philippines (Glude et al. 1981). low bays is firm enough to permit bottom culture by the broadcast method. Number Area now Potential Oyster farms are located in 17 provinces, with of used area Location farms (ha) (ha) major production in Cavite, Bulacan, Pangasi­ nan, Sorsogon, Capiz, and Negros Occidental. Pangasinan 386 16.8 300-5000 Total production exceeds IO 000 t/year. La Union 39 3.7 200-1000 Although farms average less than one-third hec­ Ilocos Sur II 1.3 100 Ilocos Norte 19 0.7 20 tare, oyster culture contributes significantly to Cagayan 32 9.5 28 the income of more than 1200 families in coastal Bulacan 145 18 17 villages (Glude et al. 1981 ). In areas where natu­ Cavite 300 300 2 ral populations occur, they are usually gathered Batangas 50-100 and sold by local people. Landings from wild Quezon 200-1200 stocks represent only a small portion of the total Sorsogon 32 6.6 500 oyster production, but the low cost of harvesting Capiz 160 50 500 results in a low price for the product, which re­ Aklan 9 8.3 100 duces the profitability of oyster farming in those Iloilo 14 3.3 15 Negros Occidental 48 7.8 100 areas. Cebu 100 Reproduction of oysters is generally good, Bohol 100 especially with off-bottom culture, which reduces Leyte 2000 or eliminates mortality from silt and crawling Sa mar 0.3 200 predators. Some mortality was noted at Calape, Davao Oriental 170 Bohol, and at Mona, Pangasinan, but much of Surigao Sur 2 0.5 400 this was attributed to high summer temperatures, 58 BIVALVECULTURE especially during low tide when some oysters predators such as era bs, starfish, and oyster bor­ were exposed. In some areas, 4-5 of the I 0-12 ers (snails) can crawl up the stakes and reach the spat that attach to a single oyster shell survive to oysters; bamboo is expensive if not available market size - a satisfactory survival rate. locally; bamboo usually lasts only 1-2 years; harvesting is difficult because the oysters must be CULTURE PRACTICES removed from the stakes; the surface available for attachment of oysters is small in relation to Four principal methods of oyster culture are costs; and bamboo collects fewer spat per unit used in the Philippines: lattice, broadcast area than do oyster shells. (sabog), stake (tulos), and hanging (bitin or The hanging method uses empty oyster or inhitin, sampayan or long line, horizontal, or coconut shells as collectors. These are hung on bangsal) methods. synthetic twine or heavy, monofilament nylon The broadcasting method is the most primitive line, held IO cm apart by spacers - bamboo and is used where the bottom is firm enough to tubes or knots in the twine. In some places, the support the collectors. Old oyster shells, stones, shells are strung without spacers for spat collec­ rocks (paringit), and tin cans are scattered on the tion and then restrung with spacers for the grow­ bay bottom in areas where natural setting occurs. out phase. In Tinagong-dagat, Capiz, blocks, boulders, or Variations of the hanging method include: logs are used as collectors. Areas without natural • Bitin or inhitin, in which empty oyster shells setting can also be used, collectors with attached are threaded on polyethylene rope (no. 4) spat or juvenile oysters being transplanted from and are hung on a bamboo platform or fence areas where setting occurs. The oyster spat are with bamboo posts attached horizontally left in place, attached to the collectors, for 8-12 near the high-tide level. The strings of oyster months or until large enough to be harvested. or coconut shells are spaced about 25 cm Gathering is usually done by divers. apart. String length depends on the depth of The principal advantage of the broadcast the water, but, if the lower end is allowed to method is low-investment cost; the disadvantages touch the bottom, some of the oysters will are that it can only be used in shallow waters with die from siltation and predation. a firm bottom; the production per unit of area is • Sampayan or long line, in which the cultch less than for off-bottom methods; mortality of consists of a long line of threaded oyster­ oysters is higher than for off-bottom methods shell valves held apart by tubes 12-15 cm because of silt and predation; harvest is difficult, long. Four parallel lines, approximately 20 especially if stones are used as collectors, unless m long and 20 cm apart, are strung between the beds are exposed at low tides. two bamboo posts. Oysters grown by the The stake method is used in areas where the line method are not crowded and, thus, can bottom is too soft for the broadcast method (the grow fatter and larger in IO months than water is usually not more than I m deep at lowest those grown by other methods. tide); stakes, 5-9 cm in diameter, made of bam­ • Horizontal, in which horizontal pieces of boo or other rigid materials are driven into the barn boo are replaced with synthetic rope or, bottom. Usually, they are placed in rows and in deep water, the barn boo fence or platform placed about 0.5 m apart during the April-July is replaced by an anchored raft. The frame­ spawning season. The tip of the stake extends to work, which is usually I m X IO m, consists the high-tide level because oysters, unlike mus­ of heavy bamboo horizontal stringers and 20 sels, can survive and grow in the intertidal zone. small-diameter bamboo cross pieces 0.3-0. 7 The stakes provide clean surfaces to which the m apart. The whole frame is driven 1.0-1.3 oyster larvae attach after their pelagic stage. In m into the bottom. It is partly submerged some cases, culturists increase the attachment during low tide. The cultch of threaded surface available by adding horizontal bamboo shells is prepared in June and July. In Pan­ pieces or by attaching empty oyster shells or gasinan Province, round strips of rubber other hard materials to the stakes. This method is tires are used as collectors and are hung from commonly used in Binakayan in Cavite, Binloc in horizontal poles. Dagupan, Binmaley in Pangasinan, Sto. Tomas • Tray, which is practical in still waters with in La Union, and Abucay in Bataan. firm bottoms where silt is minimal. A bam­ The advantages of the stake method over the boo tray ( 1.5 m X I m) with 15-cm sides is broadcast method are that mortality from setting used to hold the collectors. These trays rest is eliminated, growth rate is increased as is pro­ on horizontal supports, and oyster seedlings duction per unit area. The disadvantages are that are left in them to grow to marketable size. PHILIPPINES 59

The hanging method, which was patterned Paralytic shellfish poisoning evidently does after Japanese techniques, has several advan­ not occur in the Philippine islands. However, tages over other methods: high productivity per research is needed to verify this, especially in unit area; no mortality from silt; no mortality areas where red tide has been observed. The from crawling predators; the oysters grow major deterrent to wider use and increased rapidly with thin shells; the quality of flesh from demand for Philippine oysters is the fact that the mature oysters is excellent; the method can be most are grown in waters contaminated by used in shallow water where the sediment is too domestic wastes. Although this kind of pollution soft for culture by the broadcast system as well as usually does not adversely affect the growth rate areas where the oysters do not occur naturally; or survival of oysters, the product must be and harvesting is easy and economical. Disad­ cooked thoroughly to avoid the transmission of vantages include: cost of materials, including diseases and cannot be exported as it does not ropes, strings, and bamboo (although less bam­ meet the sanitary standards of most countries. boo is needed than for stake culture); and the Harvesting procedures vary with the culture requirement of floats, anchors, and anchor line, method. In the stake method, the bamboo stakes and weights in the raft-culture system. are usually lifted from the water, the oysters In the lattice method, bamboo trunk splits are removed on shore or in the boat, and the stakes woven into a lattice and tied with galvanized wire discarded. If the stakes are strong enough to be (no. 14) or monofilament nylon twine. The splits used again, the oysters are scraped or pulled off are spaced about 15-30 cm apart, and, on aver­ by divers, put into the boat, and brought ashore age, a lattice comprises 10-16 splits, which can be for separation of clusters. When grown by the handled easily by an individual. hanging method, oysters are lifted from the water The lattice can be positioned horizontally or on the strings and brought ashore where they are vertically; the setups include: fence style - either removed. When stones or logs are used, the oys­ stuck on the bottom or supported by bamboo ters are usually removed at low tide and the posts; tent formation in rows; mounted on rocks; stones or logs left on the bottom. flotation style (mounted on long bamboos and Although oysters may be harvested at the empty drums); suspended (three pieces of lattice grower's convenience, the quality is best when the assembled in a triangle and supported by long glycogen content of the oysters is high, usually bamboos and empty drums); etc. just before or 3-4 months after the peak of The advantages of the lattice method are that spawning. If spawning is continuous, with no the device is usable alone or in groups; losses of clearly defined peak, the grower must experiment collectors are eliminated; harvesting is simple; to determine the best time. the oysters do not touch the bottom; the method Most oysters are transported in the shell; they is practical for collecting, growing, and fattening are put into loosely woven plastic-coated sacks oysters; production is increased per unit area, that hold about 37 kg. They withstand shipping especially in three-dimensional setups; and the well because their shells are tight enough to retain placement of oysters can be controlled for moisture. However, when they are shipped in the abundant food, favourable water temperature shell, they are bulky and are more expensive to and salinity, etc., and, hence, maximal oyster transport than are shucked oysters. They are sent growth. to market in jeepneys, trucks, tricycles, buses, boats, etc. If the growing area is close to the market, intermediaries or even retailers provide POSTHARVEST HANDLING their own transportation as well as containers - The flesh of C. iredalei and C. malabonensis is often 5-gallon (~20-L) vegetable oil or kerosine excellent. Both species reach prime condition cans. When markets are nearby, shucked oysters shortly before spawning, and the yield (weight of are packed (with or without fresh water) in flesh compared with live weight in the shell) is polyethylene bags, bottles, or in evaporated milk highest at that time. Both species recover rapidly cans. after spawning, reaching marketable condition Oysters, as filter-feeders, extract microscopic within about 1 month. The flavour is also excel­ food particles from the water they inhabit. In lent, at least as good as, and perhaps better than, sewage-contaminated areas, they digest, retain, temperate-zone oysters. Although the oysters and discharge sewage bacteria. To be purified, harvested at 6-8 months are small for consump­ they must be placed in clean water for 7 days, tion raw on a half shell, they are ideal baked, where they rid themselves of impurities naturally smoked, or in stew or soup. before being marketed fresh. 60 BIVALVE CULTURE

Oysters are usually retailed in the shell; how­ Luzon, growers get only 30-40 centavos/ kg. ever, if they have been transported for some dis­ Retail prices of oysters in the shell in Manila tance, they are shucked at the market in an effort vary between 4 and 5 pesos/ kg, and markups in to avoid discarding the weak ones. The flesh is other cities are also about twice the price to the packed in polyethylene bags, fresh water is producer. The retail price includes transporta­ added, and the bags are iced until sold. Also, live tion costs, and, in some cases, the cost of contain­ oysters are shucked and sold at roadside stalls ers. There is no transport equipment designed close to or at the growing sites. and built to deliver perishable products while Oyster flesh, which spoils quickly, can be pre­ maintaining quality. served simply if packed in bottles with salt As there is little oyster processing in the Phi­ (bagoong, or salted oyster). Other methods of lippines, distribution channels from producer to preservation include pickling, smoking, canning, consumer are relatively simple. Some conve­ freezing, and cold storage. Storing the flesh at niently located producers attempt to sell as much -23° C for 7 days has been found effective in limit­ of their production as possible directly, through ing contamination. roadside stands or wholesale-retail booths at Oysters in the shell are protected naturally landing sites. Most of the production, however, is from external contamination as long as the valves sold at landing points to wholesalers who trans­ are tightly closed. However, the growth of bacte­ port the product to markets and sell it to other ria in the liquid within the shells is enhanced ifthe wholesaler-retailers and institutional (hotel and oysters are kept alive in ambient temperature. restaurant) buyers or sell it wholesale-retail Shucking under unsanitary conditions at the themselves in one or more urban markets. market adds to the bacterial load of the product, Prices are monitored weekly by the statistical and, although the bags of flesh and water are division of BFAR through representatives in usually put into pans of ice while being offered producing and marketing centres throughout the for sale, the pans are shallow and the ice level Philippines. In April-May 1981, oysters in the rarely rises to the warm water in which the flesh is shell were selling wholesale at about 3 pesos/ kg bathed. Oysters shucked and stored in this way and retail at 4 pesos/ kg in Manila markets. Thus, have a shelf life of about 1 day. when the local demand is satisfied, wholesalers Shucking at the growing sites is even more must buy at a price that includes the cost of contaminating. It is usually done over a wet cloth transportation to another market. on the ground, often by children who interrupt Oyster exports are small, but, in 1980, some their work to play and then resume shucking with 1. 8 X 105 kg of frozen oyster flesh was shipped to dirty hands. The flesh is deposited in a pan on the Singapore. The value to the shipper was 2.5 mil­ ground and is, thus, exposed to dust, dirt, and lion pesos. Singapore is the only significant insects. importer of Philippine oyster products, and The best initial means of retarding bacterial export data show fairly regular increases since spoilage and avoiding associated dangers is to 1976. From 1976 to 1980, oyster flesh was trans­ maintain careful sanitation during processing ported by air as chilled (iced) products; however, and preparation. Cooking is indispensable, as it outbreaks of gastroenteritis in Singapore in 1979 minimizes bacterial growth. Rapid cooling, and were reportedly traced to Philippine oysters, and, storage as close to 32° F (0° C) as possible, also subsequently, Singapore authorities have prolongs storage life. Spoiled, uncooked oysters required that the bacterial levels of imports be develop a sour odour. If they are cooked long certified and that products be frozen during enough for the enzymes to get hot, a rancid odour transportation. prevails. Wholesalers prefer the Manila market to other areas because it absorbs large quantities of oys­ MUSSELS ters at prices higher than smaller markets. The price to growers from sales to wholesalers is gen­ Mussel culture occurs mainly in Bacoor Bay, erally related to the distance between growing Cavite (about 134 farms, Glude et al. 1981); areas and Manila and to the complexity of trans­ Sapian Bay, Capiz (about 300 farms); and portation. In the Cavite area, close to Manila, the Maqueda Bay, Samar (250 farms) (Table 5). growers get 2-2.5 pesos/ kg and in Sorsogon, Mussel farms range in size from 0.025 ha to Luzon, and Jiabong, Samar, about 1 peso/ kg; nearly 1 ha, and their productivity is generally oysters from Tinagong Dagat, Capiz, destined higher than that of oyster farms, ranging from for Panay markets are sold to wholesalers for 20-68 t/ ha from stake culture to about 300 t/ ha 60-70 centavos/ kg. In some parts of Pangasinan, from the hanging method. PHILIPPINES 61

Table 5. Estimated potential for expansion of currents better than do single stakes and, thus, is mussel farming in the Philippines (Glude et al. 1981). used in deeper waters and where currents are too strong for single stakes. Number Area now Potential of used area The bamboo poles serve as cultch for the set­ Location farms (ha) (ha) tling mussel larvae, and no thinning or trans­ planting is done during the grow-out phase. Zam bales 23 Bulacan 10 In Bacoor Bay, Cavite, the spatfall seasons are Mindoro Oriental 10 March-May and August-November, and the Pala wan 25 bamboo stakes are put out during these periods. Quezon 200-1200 If they acquire a lot of barnacles (Ba/anus sp.), a Capiz 300 15 200 good set of mussels may be expected. Similarly, Iloilo 10 in Europe, mussel larvae like to settle on Aklan 100 hydroids, which in turn like to settle on the cal­ Negros Occidental 6 2 100 Cebu 50 careous shells of barnacles. A catch of 2000-3000 Bohol 50 spat Im of pole is considered good. Poles staked Leyte 100 in 12 feet ( 4 m) of water usually yield the most Sa mar 250 200 5000 spat 4-7 feet ( 1.2-2.1 m) from the surface, with at least 600-1000 spat/foot (0.3 m). In the hanging method, cultch made of empty oyster shells or coconut shells strung on wire or Not all areas in which green mussels occur are twine is hung on bamboo-pole racks. The cultch suitable for commercial farming; factors affect­ materials are kept about IO cm apart by knots or ing site selection include: loops on the wire. Recently, the Southeast Asian • Availability of spat in the area; Fisheries Development Center (SEAFDEC) • Protection from strong winds; found that pieces of coconut husk could be used • Availability of natural food in the water; and as cultch in the hanging method. These are • Adequate tidal exchange. inserted into polyethylene or polypropylene ropes (12-20 mm in diameter) at 50-60-mm CULTURE PRACTICES intervals. Bamboo pegs 1.5 cm wide and 15 cm Philippine mussel farmers generally grow the long are inserted into the rope between husk seg­ spat to marketable size on the same materials and ments to prevent clusters of mussels from slip­ site that are used for collection. Farming is com­ ping off the ropes during bad weather or when the monly done with either the stake method or the ropes are lifted for inspection. Such collector hanging method, although recently the rope-web ropes are also hung on barn boo racks or rafts and method was tried in Capiz Province. spaced 0.5 m apart. The average farm using this In the stake method, bamboo (Bambusa blu­ method is JOO m X 25 m and has about 20 mussel meana) poles are sharpened at the base and plots. Each plot spans the width of the farm and driven into the muddy bottoms of bays and estu­ consists of five parallel pairs of stakes spaced 5 m aries at water depths of 2-10 m. In shallower apart, with 2 m between parallel rows. The space areas, a shorter variety of bamboo (Schizosta­ between plots is 3 m for navigation purposes. chyum lumampao) known locally as buho is A new method using rope web was introduced used, and, in areas where bamboo is in short in Sapian Bay, Capiz Province, by Bruce French, supply, trunks from mangrove and palm trees are American Peace Corps. One unit of rope web used. The stakes are spaced 0.5-1.5 m apart, with consists of a parallel pair of 5-m ropes, positioned some lanes left open for regular inspection. A 2 m apart, and connected at intervals of 40 cm, in 0.25-ha farm would normally comprise about a zigzag pattern, by a 40 m rope. Bamboo pegs 5000 stakes, and, if the current is strong in the are inserted into the rope at 40-cm intervals. Each area, each row of stakes would be connected and unit is strung across a pair of bamboo stakes reinforced by horizontal poles. The lower half of spaced 5 m apart, parallel to the current and the poles are drilled full of holes so that water can positioned 2 m deep at low tide. The rough, enter and prevent the poles from floating. fibrous rope serves as cultch, and the mussel spat A variation of the staking method is the wig­ that settle on the ropes are left to grow to market­ wam method, where 7-10 poles are staked in a able size. Farms using the rope-web method have 2-m radius from a central pole; then the upper the same layout as those using the hanging ends of the poles are tied to the central pole to method, with the rope webs spaced 5 m apart. form a wigwam, which withstands waves and Usually, the whole length of the farm faces the 62 BIVALVE CULTURE current; however, in narrow tidal rivers, the On farms using the rope-web method, the farms are laid out across the current so that navi­ farmer inspects the rope web under water because gation lanes are kept open. Rope webs are usually the laden ropes are too heavy to lift; repairs of parallel with the current. ropes and bamboo pegs are made under water. In the Sapian Bay region, the peak spawning Where settlement of spat is heavy, additional seasons are February-March and September, bamboo posts are added. with peaks in February and in March. Peaks Harvesting and selling begin when the mussels probably differ in other areas of the country. are 5 cm long, rather than at a fixed time. The quantity harvested depends on buyers' orders, the prevailing market price, and the monetary GROWTH AND CONDITION needs of the farmer. Philippine green mussels grow an average 10 In the stake method, harvesting is done when mm/ month and are marketed after 4-6 months the sea is calm. The farmer usually hires 3-5 when they are 40-60 mm long. After they reach divers, depending on the size of the farm. Divers 60 mm, they grow more slowly. wear goggles or face masks and improvised They are ideal for harvest when they are in the flippers. The mussel-laden stakes are pulled on resting phase of their reproductive cycle, when board a small boat (banca), and other hired large amounts of glycogen are stored in the meso­ workers strip the mussel clusters off the stakes soma and mantle lobes. Condition-index studies with iron bars. The mussels are separated, sorted, on mussels grown in Himamaylan, Negros and cleaned (placed in a nylon-net bag and Occidental, from 1977 to 1978 indicated two shaken in the water until the dirt is removed). periods when the mussels were in prime condi­ Stakes with more undersized than marketable­ tion: July-September and January-March. Raw sized mussels are not completely harvested, but flesh constitutes about 55% of the total shell-on partial harvesting can be accomplished by the weight, and cooked flesh constitutes from 12% to divers, the large mussels being stripped from the 33% of the total shell-on weight, depending on stakes under water and deposited in a nylon the condition (gonadal) of the mussel. basket tied around the diver's waist. After the harvest, the poles that are still sturdy are res­ FARM MANAGEMENT AND PRODUCTION taked. Mussel yields vary from 2.5 kg to 15 kg/ m of pole. A 0.25-ha farm using the stake method On farms using the stake method, after spat can produce annually about 12-13 t of whole have settled, little is done until harvest. If there is mussels; deeper, more productive farms in heavy settlement of spat on the poles, farmers Sapian Bay, Capiz, produce as much as 5 t / 250- sometimes dive and tie thin ropes or plastic straw m2 plot each year. In good growing areas with around the mussel clusters to prevent the over­ regular spat fall seasons, two main harvests a year sized clusters from falling. Regular management are possible. practices include inspection of the farm area so In the rope-web method, the rope-web units that floating debris can be removed and weak or are untied from the bamboo poles and hauled on rotten poles can be replaced or reinforced. a small boat or an improvised raft made from 9-m On most farms, whatever the culture method, bamboo poles. Mussel clusters are detached, there is a 24-h guard who lives in a small hut at the sorted, and cleaned as in the stake method. The farm and who serves as farm caretaker. Near rope-web units are cleaned offoulers and dried in harvest, more guards are posted to prevent the sun for a few days before they are restrung on poaching. The stake method of culture on small the vertical poles for a new set of spat. farms (<600 m2) requires about 54 work days (one work day is one person working 8 h) from In Sapian Bay, mussels harvested from rope­ farm layout to harvest. The figure for bigger web units are not always transported imme­ farms is about 71 work days. diately to markets. Instead, the improvised rafts On farms using the hanging method, the grow­ containing the mussels (sometimes packed in ing ropes are lifted weekly for inspection. Poorly polyethylene sacks) are sunk (weighted down settled collectors are replaced with new ones to with rocks, water-filled barrels, and other heavy catch new sets of spat. During inspection, foulers objects) and kept under water until needed. are scraped from the ropes and loose or rotten With the rope-web method, a unit with a good bamboo pegs are replaced. If there are excep­ catch of mussels produces an average 200 kg tionally large clusters, additional pegs are pro­ whole mussels. If the spatfall is heavy, the annual vided as support. yield can be up to 300 t/ha. PHILIPPINES 63

PROBLEMS AND CONSTRAINTS POSTHARVEST OPERA TJONS The major problems in the mussel industry and Little or no processing is involved after green the constraints to its expansion are: mussels have been harvested. They are trans­ ported to market where they are cleaned, • Irregular spatfall and lack of spatfall­ trimmed of their byssal threads, and sold live and forecasting services. Except in a few tradi­ unopened. The only processed mussel product is tional culture grounds, spatfall seasons are brined mussels (locally called bagoong), made of generally irregular, and spatfall may occur flesh of oversized mussels or of mussels that have in March and November one year and a died or weakened during transport. month earlier or later the next year. The intensity of spatfall also varies from year to year, perhaps because of total harvesting by WINDOWPANE OYSTERS mussel farmers and harvesting regardless of gonadal stage. The Seafarming Project of the Aquaculture Department of SEAFDEC The adult Placuna or windowpane is up to is initiating spatfall-forecasting programs in 16 cm in diameter and can be found in waters Himamaylan and Batan Bay; however, as from 0.5 m to I 00 m deep. If undisturbed, it forecasting schemes are geared toward the prefers to live under a thin layer of mud that hanging method of culture, farmers who use camouflages it from predators. Juveniles have the stake method might not benefit. been observed to dive into the mud by repeated (every 4-8 seconds), sharp contractions of the • Deterioration of prime farming areas. Rec­ adductor muscle. lamation of areas for housing and industry Unlike mussels or oysters, the windowpane has has been detrimental to some culture an extended reproductive cycle; at 8-12 months, grounds. Even more devastating than rec­ it is sexually mature (about 70 mm diameter). lamation is the increase in siltation caused Spawning usually occurs from February to May. by bamboo stakes being placed too close When viewed against the light, the male Placuna together and rotted poles being left to decay is a dull, dirty-yellow hue, whereas the female is on the bottom. Putting new poles beside generally orange-yellow. Females release eggs these rotting stumps results in slowed tidal with a sudden contraction of the adductor mus­ currents, reduced mussel growth, increased cle, which forcefully expels the eggs through the mortality, and thin, brittle shells. In addition posteroventral margin. Males release sperm in to biological deterioration, pollution from steady streams. Eggs are golden yellow and mea­ industrial wastes and heavy metals has sure about 45 µmin diameter. Fertilization takes increased and has adversely affected many place in the water. mussel-culture areas. Developing larvae are planktonic for only about 10 days. Pediveligers settle at a size of • Lack of consumer demand because of unsanitary measures in the culture and har­ 220-230 µm. Settling larvae either sink directly to the bottom or drift with the currents. Juveniles vesting of mussels and because of variable up to 8 mm long are capable of crawling on clean, quality from year-round harvesting, regard­ hard surfaces (e.g., glass) and have been observed less of how plump or thin the mussels are. At to float either horizontally or vertically on or present, there are no sanitation programs for near the water surface. They are capable of secret­ shellfish-growing waters or for shellfish. Many mussel-culture areas are heavily pol­ ing thin byssal threads while floating or crawling. The environmental limits of tolerance of the luted with coliforms, and the mussels are not windowpane are (Rosell 1981 ): temperature depurated before being sold. As mussels are generally eaten without much cooking, the 24.5-30°C; salinity 18-38 ppt; pH 6.4-7.7; and consumers all suffer gastrointestinal dis­ dissolved oxygen 2.65-6.06 m I/ L. Placuna thrives in soft muddy or sandy­ orders at some time or other. muddy bottoms. Notable Placuna beds are Another factor contributing to the lack of located along eastern Manila Bay; Capiz; Iloilo; popularity is the poor condition of mussels sold Talibon, Bohol; Hinigaran and Valladolid, in the markets. Spent mussels shrink during Negros Occidental; Sama!, Batan; Labrador, cooking much more than do plump mussels and Pangasinan; San Jose, Mindoro Occidental; leave homemakers feeling short-changed. Low Misamis Oriental; and Sulu. In the late 1970s, the demand is the main constraint to the growth and main collection grounds for the fishery were in expansion of the mussel industry. Western Visayas, notably Leganes, Miag-ao, 64 BIVALVECULTURE

Guimbal, Tigbauan, Oton, Zarraga, La Paz, and are again rinsed and then soaked in a solution of Guimaras in Iloilo; Valladolid and Pontevedra in hydrogen peroxide to soften them so that they Negros Occidental; at the mouth of the Visayan can be moulded into various shapes. Two layers Sea channel in northern Capiz; and Batan, of shells are used in the making of trays or plates Aklan. These beds range from 4 m to 20 m deep. so that only the smooth, lustrous shell interior is seen on each side. CULTURE METHODS Some shells are placed on a grill and exposed briefly to heated charcoal, which gives them a The usual gathering season in Panay and golden, mother-of-pearl lustre. The products are Negros islands is summer (February-May), when all coated with a layer of fiberglass to give them the water is clear enough for diving. Divers use strength. goggles, improvised flippers, and stone weights. Processing is labour-intensive, providing Instead of using standard scuba tanks, however, employment and income for entire coastal vil­ they breathe air from a thin rubber hose con­ lages. Processors who have enough capital pur­ nected to an ordinary air compressor mounted on chase boats and hire divers to gather shells at the a nearby service boat. This hose is usually 20-30 natural beds. Others, particularly the children m long to allow the diver to move around. At the and women, shuck, clean, cut, sort, soak, and sea bottom, the divers grope for shells with shape the Placuna shells into various shellcraft gloved hands and place the shells in net bags that items. are later pulled on board. Divers generally gather about 6000 pieces a day, diving eight times and PROBLEMS remaining under water for up to 1.5 hours/dive. Placuna farms consist of mud flats in protected In 1977-78, 42.5 billion Placuna bivalves, bays or lagoons that the farmers enclose with valued at 850 million pesos, were gathered in fences made of bamboo poles and barbed wire. Capiz Province alone. Total production of Plac­ Placuna seed, 25-40 mm in diameter, are una shells in 1979 was 221 t, only 14% of 1977's gathered from wherever they occur and stocked production of 1635 t. in these farms. In Bacoor Bay, stocking rate is As Placuna shells become increasingly opaque 100-200 seeds/m2; thus, a I-ha farm is usually with age and, thus, decreasingly desirable for planted with I million pieces of seed. In Capiz shellcraft (for which translucent shells are Province, seeds, 30-35 mm in diameter, are required), they are harvested early. Because of stocked at a rate of 80 000-120 000 /ha. Seeds this conflict between the demand for young, planted in October-November are harvested in translucent shells and the need for maintaining April-June the following year at an average older, sexually mature shells to replenish the length of 90 mm, whereas those planted in April stocks, the occurrence and yield of Placuna are become 80-100 mm long after 4 months, with a very erratic. survival rate of 80-90%. As Placuna shells more than 90 mm long become increasingly opaque and cannot be used for shellcraft purposes, most shells are harvested OTHER BIVALVES as early as possible after they reach this size, usually before they have had a chance to mature Bivalves other than oysters, green mussels, and and spawn. windowpanes are not farmed; they are simply collected wherever they occur. Modiolus spp., Paphia spp., Arca and Anadara spp. are gathered PROCESS/NG by divers using bare hands or simple digging The shells are shucked on shore and then blades. In some areas, blood clams or cockles are cleaned (soaked overnight in fresh water and then harvested in mud flats at low tide. Paphia is brushed vigorously). They are then cut into usually gathered by divers, but, in some places, rounded shells by a shell cutter that operates like people can gather it by wading through shallow a paper punch with hollow plungers. The shell­ waters and feeling for the clams with bare feet. cutting machine cuts away the soft fragile edges, M odiolus occurs in mats or carpets, composed of leaving a firm, translucent piece of shell. Cut intertwined byssal threads, found on the bottom shells are sorted by size and then rinsed in fresh of many shallow bays, and is easily collected by water. A weak solution of acid (HCI) is applied divers. to the adductor-muscle scar with a piece of soft The angel's wings shell Crytopleura costata of rubber to remove the scar impression. The shells Negros Occidental Province lives in burrows up PHILIPPINES 65 to 50 cm deep in sticky, soft sandy-muddy bot­ than for oysters because mussel farms have toms rich in silt and detritus. It displays a general higher productivity. If fully utilized, this addi­ tendency toward gregariousness. Natural beds of tional area could provide sea-farming opportuni­ C. cost at a average 5-10 min depth. Divers use an ties for nearly 20% of the municipal fishermen in iron or wooden paddle-shaped implement or the Philippines. bare hands to dig the animal from its burrow. Although Philippine oyster and mussel farms Crytopleura costata does not burrow again if average less than 4 ha, they are profitable, earn­ taken from its original spot (Ablan 1938). ings being dependent upon the culture methods Pearl oysters, Pinctada margaritifera, P. max­ and on the size of the farms. Some culture ima, and Pteria spp., occur in clear waters up to methods are more productive than others. In a 40 m deep where the current is strong and the study conducted by Ordona and Librero (1976), bottom sandy or gravelly. Juveniles and young total farm receipts for oyster culture were found adults up to 10 cm long attach themselves with to be P 19001 /ha for the lattice method, byssal threads to rocks and other objects; how­ Pl8 394/ha for the hanging method, P8942/ha ever, when they become heavy enough to with­ for the stake method, and Pl556/ha for the stand the currents, they detach and live un­ broadcast method (Table 6). Earnings for mussel attached or weakly attached on the sea bottom. farms were 76% of sales/ ha for long line, 74% of The pearl shells are usually gathered by expe­ sales/ha for rope web, and 53% of sales/ha for rienced divers. the stake-culture method (Table 7). The expansion of oyster and mussel farming has been precluded in many areas by limited demand, low prices, the high cost of transporting ECONOMICS OF SHELLFISH FARMING the product, the uncertain sanitary quality of the oysters and mussels, and lack of capital. At present, there are 1200 oyster farms and 700 mussel farms operating in the Philippines. The oyster farms occupy 500 ha of coastal waters and the mussel farms 300 ha. In 1980, the estimated FUTURE PROSPECTS AND combined annual production of these farms was RECOMMENDATIONS 1.4 X J04 t: 1.0 X 104 t from oyster farms and 4.0X 103 t from mussel farms. Recent studies The shellfish farms in Bacoor Bay, the first reveal that 9.0 X 103 ha of coastal waters are farms to be established in the Philippines, subse­ suitable for expansion of oyster culture and 5.0 X quently became the most productive. From 1935 J03 ha for expansion of mussel culture. A total to 1955, the farms produced an abundance of 86 000 additional farms have been identified as oysters and mussels in an environment relatively suitable coastal areas for bivalve culture: 45 000 free from human and industrial wastes. The prox­ for oyster farms and 41 000 for mussel far:ms. For imity of the farms to Manila and outlying urban these additional farms, the projected average areas made possible the distribution of fresh oys­ area per farm is 0.1 ha for mussels and 0.2 ha ters and mussels to markets at low transport cost. oysters. The projected area for mussels is smaller These factors increased the area of shellfish farms

Table 6. Receipts, expenses, and measures of profitability for various methods of oyster and mussel culture (based on Librero et al. 1976).

Mussel-culture Oyster-culture method method Item Stake Hanging Lattice Broadcast Stake Average farm size (m2) 1603 5968 472 3678 3242 Capital investment (P/farm) 400 800 203 Ill (P/ha) 2495 1340 4301 302 Total annual receipts (P /ha) 8942 18934 19001 1556 12975 Total annual expenses (P/ha) 5711 4975 9559 1408 5765 Net annual earnings' (P/ha) 3231 13419 9442 148 7210 Earnings on sales (%) 36 73 50 10 56 'Includes unpaid family labour. 66 BIVALVE CULTURE

Table 7. Projected costs of, and income from, mussel farming at Samar by long-line, rope-web, and stake methods. Culture method Item Long-line Rope-web Stake Investment cost (P/ha) 64663' 31618 1617 Annual operating cost ( P /ha) 28560 37808 102086 Annual interestb (P/ha) 33948 16600 849 Total annual expenses ( P /ha) 127171 86026 104552 Total annual receipts (P/ha) 528840' 333450d 222300' Net annual earnings (P/ha) 401669 247424 117748 Earnings on sales (%) 76 74 53 'Amortized over 5 years. bBased on 14% of 75% of the total investment. '476 t/ha less 5% losses X 1.17 P/kg. d300 t/ ha less 5% losses X 1.17 P /kg. '200 t/ ha less 5% losses X 1.17 P /kg. to 200 ha, with some of the farms producing as health through sanitary regulations; increase the much as 50 t/ ha annually. After 1960, demand demand for oysters and mussels through promo­ and production declined because the water tional measures; increase production through became contaminated by human and industrial innovations in existing techniques and incentives wastes. Now, there are about 70 ha of shellfish for expansion of farming. farms left, and their output is steadily declining. It is expected that, within the next few years, PROTECTING PUBLIC HEALTH shellfish farms in the area will disappear. The growth and the decline of shellfish farming Philippine oysters and mussels are harvested in Bacoor Bay indicate that the potential for from waters of unknown sanitary quality, trans­ bivalve farming depends crucially on some fac­ ported and processed under conditions that may tors affecting demand for, and supply of, oysters be unsanitary, and stored at temperatures that and mussels. The factors affecting demand encourage the growth of bacteria. There is, at include: the nearness of the farms to the markets; present, little or no effective control by govern­ the cost of transporting the product from the ment. The government must protect the health of farms to the markets; the palatability and clean­ its citizens, visitors from other countries, and liness of the product; the price; the existence of residents of other countries who consume Philip­ consumers who have the income to buy the prod­ pine products. ucts, and the presence of good market outlets Shellfish, and other foods, should be pro­ for the product. Major factors affecting supply duced, processed, and transported under condi­ include farm productivity; production and oper­ tions that ensure safe products. Achieving this ating costs; prices; availability of suitable (unpol­ goal will require a series of actions over several luted) culture areas; and government support. years, including: These factors should be considered when plans • Sanitary surveys of areas for oysters and are made to develop potential oyster and mussel mussels. BFAR or other appropriate seeding, culture, and cleansing areas. The oppor­ government agencies should conduct or tunity for developing a potentially profitable bus­ commission sanitary surveys of all waters iness must be demonstrated so that the municipal that are sources for bivalves used as food; fishing families can be convinced that integrating the surveys should include periodic determi­ culture fishing with their capture fishing will nation of total and fecal coliforms in waters make them economically productive members of and in shellfish from productive waters for their community. at least 1 year and from waters proposed for expansion of oyster and mussel farming. • A shellfish sanitation and health program. RECOMMENDED ACTION BFAR should design and implement a sys­ tem for approving areas and methods To expand oyster and mussel farming, the (including depuration where necessary) for government must intervene to protect the public shellfish harvest as well as the means for PHILIPPINES 67

enforcing the regulations. Control proce­ approved shellfish-sanitation and health dures should be consistent with the require­ program providing an acceptable certifica­ ments of countries that might import Phi­ tion of wholesomeness precludes even the lippine molluscs - for example, the USA, sale of processed shellfish in most world whose Food and Drug Administration has markets. laid down requirements for imported • Develop better systems for packing and shellfish. shipping to improve product quality. Shell­ • A system for natural cleansing of shellfish fish from outlying areas such as Capiz, grown in contaminated waters. A series of Samar, Negros, and Pangasinan require shellfish-cleansing stations should be estab­ 6-24 hours to reach Manila, the principal lished in clean areas near contaminated market. Oysters in the shell can live about 3 growing areas, beginning with three sta­ days out of water but a significant portion of tions, probably at Pangasinan, Capiz, and green mussels die within a day. Therefore, Quezon. Shellfish would be held for 1-3 the product reaching the Manila market weeks at stations before being marketed. It is may already be in poor condition, leaving an recommended that these stations be oper­ extremely short time for distribution to ated by BFAR in conjunction with other retailers, sale, and consumption. It is appropriate government agencies. recommended, therefore, that BF AR evalu­ • A pilot-scale, shellfish-depuration plant. A ate the existing methods of packing and plant for depuration should be located near shipping and develop systems that will Manila and operated by BF AR to develop reduce mortality en route and extend the and test procedures for cleansing shellfish in safe marketing time in Manila. These sys­ areas where no uncontaminated waters are tems should be tested and demonstrated to available for natural cleansing. If practica­ industry. ble, depuration plants could be established in several areas and operated by government • Introduce processing, for items that must be or by private industry under government shipped, to reduce bulk and ensure quality. supervision. Oysters shucked under sanitary conditions • A pilot-scale, shellfish-processing plant. and marketed in sealed containers kept on ice retain high quality for up to 10 days and BF AR should also operate a plant to dem­ are only 8-18% of the weight of oysters in the onstrate sanitary methods for shucking shell­ shell. A system based on this observation fish; for processing, packaging, storing, and would provide employment in local process­ shipping shucked flesh; and for the training ing plants and would retain oyster shells of plant operators. Such a plant should be near the farms where they are needed as located in an area where production out­ collectors. Likewise, mussels should be strips local demand and where transport opened by steam and the flesh frozen for costs preclude shipment in the shell. Possible shipment to population centres in the Phi­ sites are Roxas (Capiz), Bacolod (Negros lippines and to export markets. Other prod­ Occidental), and Dagupan (Pangasinan). ucts that might be processed and packed at Another possibility is the Manila area, in various places in the Philippines include combination with a government-operated shucked or steamed oysters or mussel flesh shellfish-depuration plant. In this case, shell­ frozen in blocks and packed in various-sized fish from a variety of sources could be containers for shipment to world markets. cleansed, shucked, and processed at a single Canned products include smoked or boiled location. oysters and mussels, and oyster or mussel stew or soup; dried products are also a pos­ sibility. Government efforts should intensify INCREASING DEMAND the development and testing of procedures Limited demand is frequently cited as a major for preparing products in various forms for reason for the failure of oyster and mussel farm­ domestic use and for export, training indus­ ing to expand rapidly, and it is an area in which try personnel in their use. government can intervene effectively to: • Ensure continuity of supply. Because oysters • Ensure the availability of clean, safe prod­ and mussels are grown on farms, it should be ucts. The lack of assurance that shellfish possible to schedule harvests so that fresh produced in the Philippines are safe to eat oysters and mussels are available to con­ limits sales in major markets. The lack of an sumers throughout the year. BFAR should 68 BIVALVE CULTURE

assist the sea farmers with analysis of the in Samar, 50% in Pangasinan, and more market and advise them on the best time to than 5% in Quezon - the priority provinces. harvest their crops. Government actions to encourage municipal part- or full-time farming might include allocating space for oyster and mussel cul­ INCREASING PRODUCTION ture (restricting plots to a size large enough There are good opportunities for expanding to provide substantial increases in the production: more than 9.0 X J03 ha in shallow income of municipal fishing families but bays are suitable for oyster culture, although small enough to make them unattractive to fewer than 500 ha are now in use. Likewise, wealthy individuals or corporations); estab­ nearly 5.0 X J03 ha are suitable for mussel culture, lishing training programs and expanding and fewer than 300 ha are now being used. To sea-farming extension services through increase production, the government should: BFAR in cooperation with other appro­ priate government agencies, universities, or • Evaluate and modify high-productivity methods used elsewhere. organizations; providing funding to fishing families who wish to become sea farmers • Establish training programs, expand sea­ through assistance programs like Biyayang farming extension services, and operate Dagat; operating and making available, demonstration farms to encourage expan­ without charge, shellfish-cleansing services; sion of oyster and mussel farming. and offering business-management services • Contract or conduct research to solve bio­ for sea farmers. BFAR-operated cleansing logical problems (uncertainty in spatfall stations and demonstration farms should forecasting, predator attacks and other perform the management functions of coop­ causes of mortality, etc.) limiting oyster or eratives until the sea farmers are able to mussel farming. operate without government assistance. The • Help municipal fishing families to become services should include assistance in market­ sea farmers. There are enough suitable areas ing and bulk purchasing of supplies and in the Philippines to provide space for more equipment. The BFAR cleansing stations than 45 000 additional oyster farms and would receive payment from buyers of about 41 000 additional mussel farms. Such cleansed shellfish, so loan payments could expansion could benefit nearly 20% of the be deducted from returns due the sea municipal fishing families, including 100% farmers. SJNGAPORE1

Leslie Cheong Aquaculture Unit, Pri­ Spain is used (Cheong and Lee 1982, unpub­ mary Production Department, Changi lished), and mussels grow on culture ropes sus­ pended from rafts. The rafts are basically wooden Point, Singapore pontoons with cross beams for culture ropes. They are anchored parallel to the flow of the tides The green mussel (Perna viridis) is cultured in so that wave resistance is minimized, and they are Singapore; however, other bivalves, such as oys­ arranged in rows to maximize utilization of water ters (Saccostrea cucullata) and brown mussels space and to reduce the problem of rope entan­ (Glauconome rugosa), are collected mainly from glement, which is often encountered with indi­ the wild. Mussel production is derived from arti­ vidually anchored rafts. The minimum plot area sanal fishermen who harvest from fishing stakes is 0.5 ha, and the effective culture area is about during low tide or from farmers operating raft 20-30% of this, the remaining space being used culture in coastal areas. Annual production is for anchoring purposes. estimated at 500 t, with half derived from the wild and half from culture. NURSERY ASPECTS Basic research on bivalves is conducted by the National University of Singapore, and, in late In early studies at the Primary Production 1975, the Primary Production Department of the Department, ropes used for spat collection Ministry of National Development initiated stu­ (Cheong and Chen 1980) were 4 m long and dies on the intensive culture of mussels in Singa­ 40 mm in diameter, were made of unoiled pore's coastal waters. coconut-coir fibres, and were different from those used in the grow-out phase. However, later, studies showed that spat-catching and grow-out CULTURE PRACTICES phases could both be done on a polycoco rope (FOR GREEN MUSSELS) (Cheong and Lee 1981) consisting of a main, 14-mm diameter, polyethylene rope with pieces Grounds suitable for mussel culture (in both of 40-mm coconut-coir rope attached at the mid­ the nursery and the grow-out phases) are those dle of each metre of the main rope. Farmers also with phytoplankton concentrations ranging from use polyethylene netting for spat collection and 17 µg to 40 µg Chi.a/ L seawater, currents rang­ grow out. ing from 0.17 m to 0.25 m/second at flood tide About 2 weeks after the rope has been and 0.25 m to 0.35 m/ second at ebb tide, and immersed, the spat settle, usually first along the primary hourly productivity ranging from 73 µg lay of the rope and later along the entire rope to 100 µg carbon/m3. The estuaries of Sungei surface. On an ordinary 4-m coconut-coir rope, Serangoon, Sungei Ponggol, and Sungei Seletar spat tend to settle more densely on the upper 2 m at the East Johore Strait and Sungei Kranji and of rope, whereas, on polycoco ropes, settlement is Sungei Sarimbun at the West Johore Strait have more uniform. natural stocks of mussel beds and are suitable for A simple and effective technique for inducing farming. spawning of mussels is to raise the water tempera­ A modification of the raft method employed in ture rapidly; this method has been tested by Lim et al. ( 1982, unpublished) and has proved better for mussels conditioned in tanks for a few days 11n total, five presentations were made during the workshop on aspects of bivalve culture in Singapore. than for freshly collected ones. These contributions are listed in appendix 2. The coop­ In spatfall forecasting, test ropes are moni­ eration of the individual authors in agreeing to a single tored once every fortnight, and the appearance of country report is gratefully acknowledged. spat, 0.5 mm long, on them signals the time to

69 70 BIVALVE CULTURE

immerse more culture ropes. Farmers sometimes that shading is not necessary for the nursery or use the colour of the mantle to ascertain the onset the grow-out phase. of spawning. When the majority of the mussels The mussels are harvested after 6 months. have a reddish-coloured mantle, the mussels are From a 4-m polyethylene production rope, a considered ready for spawning, and spat settle­ yield of 40 kg of mussels can be expected. The ment will occur in 1-2 weeks. Spatfalls occur 2-m and 4-m polycoco ropes yield 25 kg and 42 kg throughout the year, with peaks (seasons) about respectively. In other words, based on a stocking February-May and October-November in the density of 4 ropes/ m2, production, every 6 East and June-August and November­ months, from polycoco ropes would range from December in the West Johore Straits. However, 100 kg to 160 kg/ m2. the seasons vary from year to year and have been observed to occur as often as once every 2 PROBLEMS AND CONSTRAINTS months. Each spatfall within the season normally lasts 2-3 weeks. Usually, if 5000 spat/ m2 are col­ To date, sea farmers in Singapore have not lected at any one time, the resource is considered reported major problems in the culture of mus­ sufficient for commercial farming. (The com­ sels. Constraints lie in the handling of the large bined surface area of the culture portion of the quantity of fresh shell-on mussels that are har­ polycoco rope is 0.164 m2 for the 2-m rope and vested at any one time. The current method is 0.328 m2 for the 4-m rope.) time-consuming and labour-intensive, and the Primary Production Department is looking into GROW-OUT ASPECTS the possibility of mechanizing the operation. Mussels collected in the nursery ground either remain there for grow out or are transferred to POSTHARVEST HANDLING areas that do not have broodstock. In areas where only grow out is possible, i.e., where spat Acceptable bacteriological limits for imports are not found, the current can be slightly faster of frozen, shucked oysters in Singapore are: than in the nursery ground. aerobic plate count, ~ 500000 M PN / g; Escheri­ Monthly growth increments for shell length chia coli, ~ 20 M PN / g; Vibrio parahaemolyti­ average 1.06 cm and for shell width, 0.4 cm. cus, ~ 100 M PN / g; Salmonella, Shigella, and V. Mussels attain a marketable size of 6-7 cm after 6 cholera, nil in 25 g. months when the flesh-condition index is about The Primary Production Department moni­ 80. tors the heavy metal and bacteria levels in the For nursery ropes made entirely of coconut water and mussels of the farm areas and, to date, coir, thinning is necessary prior to grow out. This has found that the levels fall within acceptable is done 2 months after the spat have collected on limits. the nursery ropes and involves binding the spat Studies have been conducted on the use of an on production ropes made of polyethylene. Each ultraviolet, recirculating seawater system for rope is 14 mm in diameter and 4 m long. The high-density depuration of bivalves, and the find­ operation is time-cons urning and laborious and is ings are that highly polluted mussels (>2400 E. one ofthe major constraints to large-scale mussel coli/ m2) can be depurated to acceptable limits production. (~20 MPN E. coli/ g flesh) within 48 h. The Farmers using polycoco ropes don't need to system uses a stocking density of 100 kg shell-on thin because the spat that have settled on the mussels/ mJ of water at a water flow of 6 m3 / h coconut-coir rope pieces of the polycoco rope (Cheong and Syed 1982). The mussels are placed distribute themselves naturally along the entire in shallow trays that are stacked in tiers and rope length during grow out. Where polyethylene hosed down every 24 h. The water is drained, and nets are used as culture materials, thinning is also fresh, sterilized seawater is then added for a unnecessary. further 24 h depuration. This method is feasible Ropes are immersed at 8 ropes/ m2 for spat for both small- and large-scale operations and collection and spread to 4 ropes/ m2for grow out. could be used to improve the quality of live mus­ They are checked occasionally in case they have sels when they are to be eaten raw or semicooked. become tangled. Double immersion, i.e., immer­ Postharvest processing machines for decluster­ sion of new spat-collecting ropes between grow­ ing, washing, debearding, and deshelling mussels out ropes, would help increase production as well have been made locally under the joint supervi­ as stagger harvesting time. Studies have shown sion of the department and a quasi-government SINGAPORE 71 engineering firm, the M/ S Applied Research before being cooked, the flesh tears and becomes Corporation. Designs based on those developed unsightly. Cooked flesh can be brined or smoked, by farmers in Holland were modified to suit local and the product canned, as is done in Europe. conditions. The declusterer-cum-washer separ­ The protein composition of local mussel flesh ates the mussels from each other and can handle averages 67.8 g/ 100 g dry weight. This value approximately I t/h, with about 10% breakage compares favourably with beef, pork, mutton, and 80% efficiency. The debearder removes the chicken, and eggs. The amino-acid composition byssal threads from individual mussels and can is comparable with that of high-quality fish meal handle I t/ h, with about 15% breakage and 30% and shrimps, as it is fairly rich in essential com­ efficiency. The desheller dislodges the flesh from ponents. The flesh also contains minerals such as the shell and handles cooked mussels - again calcium, phosphorus, iron, iodine, copper, and about I t/h - with almost no breakage and small amounts of thiamine, riboflavin, and nia­ about 60% efficiency. The mussels have to be cin. The shell contains 90% calcium, which could cooked under pressure for the flesh to be dis­ be directly incorporated into feed suitable for lodged. productive hens. Also, it has been reported from Because these machines are still being tested, overseas that the flesh of green mussels has an farmers currently enlist their families to carry out antiarthritic effect. the operations: the mussels are usually cooked in There is no industry involved in mussel pro­ a metal drum, shucked by hand, and sauteed on a cessing in Singapore. However, there is a local metal plate. They are then sun dried and sold. cannery that cans samba) (curry) cockles. Studies About 5 persons can handle 300 kg of fresh mus­ have been conducted by the department on block sels in a 6-h day, i.e., 10 kg shell-on/ person-hour. freezing of cooked-mussel flesh; glazing and The shelf life of the mussel depends on the state quick freezing of individual mussels; and smok­ in which it is sold. Fresh, shell-on mussels can ing, brining, and drying of mussel flesh. stay alive for only 2 days under normal room conditions. They should be kept in a wet gunny sack but not immersed in stagnant water. Studies FUTURE PLANS have shown that shelf life can be increased to as much as 4 days if the mussels are placed in shal­ The economics of farming green mussels in low trays supplied with a flow of sterilized water. Singapore with various culture methods (raft, Processed mussels have longer shelf lives. long line, pole, and bouchot) were examined by Cooked mussels can be kept in a refrigerator for the department, based on extrapolations from 1-2 weeks and in a freezer for as long as 2-3 research findings, and raft culture was found to months. If blast frozen, they can be stored for as be the most feasible. Operations that don't long as I or 2 years, and the texture of the flesh is involve thinning and that use 4-m polycoco ropes still comparable with that of freshly cooked mus­ suspended either from a single 150 m2 raft or a sels. Glazing of individually frozen mussels helps group of rafts located in a farm (0.5 or 0.75 ha) to retain their shape so that they can be easily are economically feasible. Better profits are pos­ handled during thawing. The shelf life of dried­ sible, however, through highly mechanized, mussel flesh depends on moisture content. After large-scale operations. sun drying, the moisture composition is usually There is a need to ensure that bivalves are about I 0% of the dried-flesh weight, and the flesh available in Singapore and that they are whole­ can be stored for 4 months if kept in air-tight some and of good quality. Further studies on a containers. high-density depuration system suitable for other Shell-on mussels can be frozen whole for stor­ bivalves, especially oysters and cockles, are age and plunged directly into boiling water needed, and studies to improve machines used in before being eaten. If they are allowed to thaw postharvest operations should continue. SRI LANKA

D.H. Sadacharan Ministry ofFisheries, sun dried, are occasionally sold in the markets Galle Face, Colombo 3, Sri Lanka1 during and immediately after the monsoon period. Clam shells are used for the manufacture Bivalve resources are considerable in Sri Lan­ of lime on the west coast. With the recent increase kan waters, and some have been described by of tourism in the coastal areas, utilization of wild Fernando ( 1977) and Pinto and Wignarajah stocks of oysters has increased considerably at ( 1980). Present exploitation is far below the level some locations. of natural production and is confined to wild stocks, as bivalve culture is not practiced in the country. FUTURE PROSPECTS Bivalve species commonly found in Sri Lanka are: oysters - Crassostrea belcheri and Saccos­ The rich resources of bivalves, especially oys­ trea cucullata; mussels - Perna perna, P. viridis, ters and mussels in certain coastal areas and and Modiolus auriculatus; cockles - Anadara lagoons, indicate suitable environmental condi­ antiquata and Larkinia rhombea; and others - tions for culture, although studies on chemical, Pinctada vulgaris, Pinna bico!or, Ge!oina coax­ physical, and biological parameters in these areas ans, Gafrarium tumidum, Meretrix meretrix, are a prerequisite for culture projects. A low tidal Marcia opima, and Donaxfaba. range (on average, < 0.5 m) and heavy barnacle infestations are common in these areas. As well, most of the large lagoons support heavy fishing PRESENT UT/LIZA T/ON activity and have dense populations and heavy boat traffic. Therefore, decisions on, and selec­ To date, the demand for bivalves has been tion of, sites, methods, and times of spat collec­ limited, being confined to subsistence purposes in tion will have to be carefully made. areas where the resources are plentiful. Local Preliminary studies on oyster culture will begin fishing families turn to bivalves during the mon­ next year in Putlam lagoon on the west coast. soon seasons when they are unable to go out to Currently, trained personnel and technical sea and when fish are scarce. knowledge are lacking because mariculture is not Fresh clams and cockles are cooked with con­ traditional in Sri Lanka, as it is in many South­ diments and made into curries; small quantities, east Asian countries.

'Present address: National Aquatic Resources Agency, Fisheries Complex, Crow Island, Colombo 15, Sri Lanka.

72 THAILAND 1

Anant Saraya Department of Fisheries, total area of intertidal flats, based on 2 km width Ministry of Agriculture and Coopera­ from the shoreline, is about 3.25 X J06 rai (5.2 X J05 ha). The intertidal flat can be utilized for tives, Bangkok, Thailand mollusc culture, fish-cage culture, and shrimp­ pen culture. In addition, the use of some deterio­ Thailand ranks among the top 10 fishing rated mangrove areas would provide about 3.0 X nations of the world, with a reported production 10 5 ha of coastal land for development as shrimp of about 2.0 X J06 t. Marine products account for and fish ponds. The shellfisheries of Thailand more than 90% of this figure and include a mod­ have been reviewed by Rabanal et al. (1977). est production of molluscs. There is potential for even greater production, and the Government of Thailand, through the Department of Fisheries, PRESENT PRODUCTION is emphasizing coastal aquaculture development as one component of the Fifth National Eco­ Bivalves have been captured and cultured in nomic and Social Development Plan (1982-86). Thailand for several decades. The people of the This development activity is the responsibility of maritime provinces have traditionally collected the Brackishwater Fisheries Division (BFD) of edible molluscs and have been increasingly turn­ the Department of Fisheries, which is assisted by ing to mollusc culture as the deterioration of the several foreign agencies including the Food and coastal environment has reduced production Agriculture Organization of the United Nations from natural beds. (FAO), the UN Development Programme Oysters (Crassostrea commercialis, C. lugu­ (UNDP), the Japan International Cooperation bris)2, mussels (Mytilus smaragdinus), and cock­ Agency (JICA), the Asian Development Bank les (Anadara granosa) are cultured for human (ADB), and the World Bank. consumption; species collected as food from nat­ Thailand has 2.6 X 103 km of coastline on the ural beds include horse mussel (Modiolus sen­ Gulf of Thailand and the Andaman Sea. The hausenii), carpet shell or short-necked clam (Paphia undulata), piddock (Pho/as spp.), razor 1This report includes some information on the repro­ clam (Solen abbreviatus), Jackknife clam (Ensis ductive cycle of mussels from a paper presented by malaccensis), surf clam (Mactra spp.), wedge Tanittha Chongpeepien, who is also with the Depart­ ment of Fisheries. The cooperation of the authors in 2 Editor's note: C. /ugubris may be a similar species to agreeing to the publication of a single country paper is C. belcheri found in Malaysia; C. commercialis may gratefully acknowledged. likewise be similar to C. cucullata.

Table 1. Present and potential production of cultivable shellfish in Thailand (Rabanal et al. 1977).'

Production Estimated potential Area Unit Total Area Productionb (ha) (t/ha) (t/year) (ha) (t/year) Mussels 2626 39.5 103727 34994 1382263 Horse mussels 300 40.6 12180 4600 186760 Ark shells (cockles) 500 8.9 4450 11300 100570 Oysters 1430 13.4 19162 13190 176746 'Based on estimates by the Brackishwater Fisheries Division, Department of Fisheries, 1970. •Based on present rates of production. Another way to increase production is to improve techniques, a possibility not considered here.

73 74 BIVALVE CULTURE

Table 2. Catch (t) of economic mollusc species, 1974~79.

1974 1975 1976 1977 1978 1979 Blood cockle 3130 6201 12729 16646 16326 19263 Green mussel 13478 46916 72542 81855 49868 48266 Oyster 4398 5456 6963 15889 14594 9832 Horse mussel 12887 29681 43233 15711 17313 12553 Short-necked clam 13806 14307 23275 17360 10654 21098 Hoi tok 4320 2532 600 420 225 75 Jackknife clam 36 270 326 336 360 108 Hoi-lod 40 I I 4 86 158 Venus shell 648 255 90 491 550 Other shell 13 58 12 32 shell (Donaxfaba), and top shell (Trochus sp.). structed where the mangrove forest has been de­ The shells of some species are used for decora­ stroyed, whereas mollusc culture is usually prac­ tions. These include top shell (Trochus sp.), tur­ ticed on muddy or sandy mud flats. In some ban shell (Turbo sp.), windowpane oysters (Plac­ places, floating-cage culture is also practiced. una placenta), and Mytilus. Species cultured for Other government agencies directly concerned pearls are Pinctada margaritifera, P. maxima, with mollusc fisheries include six Brackishwater and Pteria penguin. Fisheries stations and the Songkhla Coastal Thailand has substantial areas available for Aquaculture Center. They are responsible for mollusc culture. In 1976, the activity occupied 4. 9 management and development of both fisheries X I OJ ha, but the potential area is 6.0 X I 04 ha and shellfish. Several universities also work (Table I), according to a field study by the BFD. closely with the staff of the Department of Fisher­ Mollusc production has fluctuated widely. It ies (DOF) in research and training. At present, gradually increased from 5.0 X 10 4 tin 1958 to a the Faculty of Fisheries, Kasetsart University, peak 2. 9 X I 05 t in 1971, and then abruptly and the Department of Marine Science, Chula­ declined. It increased again from 5.0 X 104 t in longkorn, are working on bivalves and related 1974 to more than 1.0 X 10s tin 1979 (Table 2). fields. Other universities, including Sri Nakha­ The total value in 1977 was 264 million baht rinwirot and Songkhla, participate to some (US$1 =22.5 baht) and in 1978, 342 million baht extent. (Table 3). In 1982, the International Center for Living Aquatic Resources Management (ICLARM) began to support a project on technical assistance INSTITUTIONS INVOLVED IN for applied research on coastal aquaculture. This BIVALVE WORK agency will implement the project by means of a special agreement between the Government of Coastal land in Thailand is composed of the Thailand and the German agency for technical mangrove forest zone and the muddy or sandy cooperation (GTZ). mud flats off the mangrove forest. Coastal aqua­ It is not known when bivalve culture started in culture on these areas is the responsibility of Thailand; however, the present systems have BFD. Generally, shrimp and fish ponds are con- been operating for several decades.

Table 3. Catch and value of mollusc production for Thailand (1977, 1978).

1977 1978 Quantity Value Quantity Value (t) ( 1000 baht)' (t) (1000 baht) Blood cockle 16646 47135 16326 59666 Green mussel 81855 90041 49868 69815 Oyster 15889 88978 14594 154113 Horse mussel 15711 15711 17313 19044 Short-necked clam 17360 19096 10654 31962 Other shellfish 976 2928 2670 7120 '22.5 baht = US$!. THAILAND 75

OYSTERS that there is space for passage and for manage­ ment of the farms. The shallow-bottom-tray method is used for Oyster culture was first attempted in Chanta­ parent oysters transplanted to new areas or for buri province about 35 years ago and has, since, young, small oysters. Young oysters, approxi­ been introduced to other sandy mud intertidal, mately 2-4 cm, are put in a shallow-bottom tray, flats, mostly on the east side of the Gulf of Thai­ consisting of a wooden frame with a nylon-net land, particularly in Cholburi Province. Traad, bottom. The trays may be covered with small­ Chantaburi, and Rayong on the east coast and mesh nylon net to prevent losses caused by the Chumporn and Surajthani on the west coast also waves. The trays are held above the bottom by have moderate amounts of oyster production posts. from farms. Two species of oyster can be cap­ Oyster farmers need a simple way to determine tured from natural beds and cultured: C. com­ the best time to place collectors, avoiding attach­ mercia/is and C. /ugubris. The first, a small spe­ ment of barnacles and maximizing spat collec­ cies, is commonly cultured along the east coast. tion. BFD staff suggest placing a few collectors On the west coast, the larger C. lugubris is pro­ several months before spatting season and moni­ duced naturally and on farms in Surajthani Prov­ toring them for occurrence of oyster spat, espe­ ince; it is more expensive than C. commercialis cially in relation to barnacles, which are mostly and is in great demand for consumption fresh. found before spatfall, gradually decreasing with The spat have been observed along the east and increasing oyster spat. When suitable numbers of west coasts as well as on the Andaman Sea coast. spat are found on the test collectors, the Spawning peaks in May-July and October­ remainder of the collectors can be placed. November. Sites for oyster culture are usually on the hard, stable bottom of intertidal flats, which will sup­ port heavy collectors such as cement blocks, MUSSELS stones, or rocks for spat attachment. The collec­ tors should not be exposed for more than 3-4 Mussels are a popular and inexpensive protein hours during low tide and should be submerged source for Thai people as well as a feed for poul­ during high tide so the oysters can feed. Sufficient try, shrimp, and fish. The history of mussel cul­ plankton, provided by mild water movement, in ture in Thailand is not documented, but, at one moderately clear water is essential for oyster time, fishing families harvested mussels from growth. fishing gear such as bamboo-stake traps and Methods of culture in Thailand range from from rocks or stones in natural beds. As the traditional to semitraditional, and the most suit­ human population increased, so did the demand able for a particular area depends on bottom for mussel products. Therefore, several culture conditions. There are basically four types: those methods are being investigated, although the that use stones or rocks as the substratum, those ones in common use employ rocks or stakes as that use wooden stakes, those that rely on con­ spat collectors. Bamboo or date-palm stakes are crete blocks, and those incorporating trays. The driven into the intertidal muddy area along the first method used in Thailand was large stones or Thai coast, especially in Chachoengsao Province. rocks, placed on hard, sandy or sandy-mud bot­ Hanging ropes and long lines, which have toms. The spat attaching to these materials would proved successful in Spain and in Singapore for be left for I-I. 5 years before being harvested. mussel culture have recently been tried in Thai­ Date-palm and bamboo stakes are also used as land, Manila rope being used as a collector collectors, in certain areas of Rayong, Ranong, (Choncheunchop 1979). After 8 months, about and Surajthani provinces. The stake method is 359 mussels were attached per metre of rope, usually practiced on soft or muddy bottoms, and whereas about 900 pieces attach to 1.4-m bam­ the stakes are pushed into the ground about 0.6 m boo stakes, according to Anant et al. ( 1980). apart. The spat settling on these collectors are Thus, the method is not practical in Thai waters allowed to grow for up to I year when they are at present, but further experiments should be harvested. carried out with different rope materials. Both Several kinds of artificially made concrete ropes and stakes have one serious drawback: blocks, such as pegs, rods, and tubes, are although attachment of mussel spat is usually employed as spat collectors. A pair of pegs is high during spatfalls, less than half of the initial pushed into the bottom to fix and hold a rod off numbers of spat are harvested because of the the bottom, with about 0.6 m between pairs so competition for space among the growing mus- 76 BIVALVECULTURE sels. Anant et al. ( 1980) reported that then umber able sites in 23 maritime provinces. At present, of mussels attached to 1.4-m bamboo stakes was several maritime provinces in the inner gulf are reduced from 4000 to 500 after 11 months of the main centres for mussel production. Chol­ growth and that on 1-m Manila rope, the number buri, Chachoengsao, and Samutprakarn prov­ was reduced from 850 to 350 after 8 months. inces on the east coast and Samutsakorn and These figures indicate that at least some of the Petchaburi provinces on the west coast of the gulf crowded, young mussels should be transplanted have suitable mud flats for mussel farms. These to new substrates for resettlement. areas are usually adjacent to dense and well­ In one experiment, young mussels, 1-2 cm developed mangroves. The bottom must be mud long, were removed from bamboo stakes and or muddy-sand and must not be exposed during placed in a 0.3-m diameter by 1-m long cylindri­ the lowest tide. The size of the farm depends on cal net. The net was stretched with iron rings so management ability and purpose. Farms range in that the mesh allowed the passage of water and size from one-third hectare to several hundred. plankton but not the mussels. After I month, all the young mussels were attached to the mesh of the net. At this time, the thread holding the net in COCKLES a cylindrical shape was removed and the net was allowed to hang in the water. This method Cockle culture in Thailand has a 70-year his­ reduced competition for space and should be tory at least (Amatayakul 1957). Fishing families studied further so that the findings can be con­ in Bangtabun district, Petchaburi Province, firmed and methods can be developed that are where natural beds exist, first practiced culture profitable for the farmers. over the intertidal flats. Since then, cockle culture Transplanting parent mussels has also been has spread along the west coast of the Gulf of attempted in areas where limited numbers of Thailand and the Andaman Sea coast. At pres­ mussels exist. Usually the spatting season occurs ent cockles on farms are said to be semicultured after the rainy season, in July-September and bedause the seeds are collected from natural spat­ October-March. However, the periods of spawn­ fall areas and then sown on prepared grounds. ing vary with locality. Detailed studies, by Tanit­ Cockle farms of maritime provinces along the tha ( 1982), of the reproductive cycle of mussels, west coast of the inner gulf depend on cockle carried out on specimens collected from mussel seeds collected from adjacent areas; however, farms at Samaekao, Chachoengsao Province, cockle farms in Satul Province on the Andaman revealed two spawning periods there: one in Sea coast depend on seeds imported from Malay­ July-September and another in November­ sia. February. The development of the mussel gonad The highest cockle production is currently in can be divided into four stages: indifferent; active; Satul Province; however, farmers in Petchaburi ripe; and spawning. This development cycle and Samutsongkarm provinces also culture cock­ requires about 1-3 months. Determining the sex les. The size of farms is generally 1-5 ha for of the mussel by the colour of the mantle can be family operations and 30-100 ha for commercial accurate if the gonad is orange or creamy white operations. but is difficult if the colour is deep yellow or Cockle culture in Thailand could be expanded between pale orange and creamy white. No her­ if the broadcast or sowing method were used maphrodite condition was found during the more widely not only on natural intertidal mud investigation (Tanittha 1982). flats but also on elevated central areas of shrimp Hatchery propagation is not practiced in Thai­ ponds. The former commonly extend along the land, so farmers depend on the availability of coastline of tropical countries, especially where wild spat. Two places are considered as nursery mangrove forests exist. The extent of intertidal grounds: culture beds where collectors are used mud flats depends on geographic conditions and for culture purposes and natural beds where mus­ sedimentation. The thicker and denser the man­ sel seeds attach to submerged rocks or stones. In grove forest, the wider the intertidal mud flats July 1979, transplanted small mussel seeds (Anant et al. 1980). The areas already under (2.4-4. I cm long) were experimentally intro­ cockle culture are fenced by the farmers with duced to Ban Koa Mak Noi, Phang Nga Prov­ 50-cm long bamboo stakes to prevent the escape ince. After 70 days, they attained a shell length of of cockles from the culture beds. A guard house is 7-8 cm. This rapid increase in size was of interest also sometimes necessary to prevent losses to to the villagers. nearshore trawling and dredging operations. Plans are to introduce mussel culture to suit- Also, shrimp ponds have an elevated central THAILAND 77

portion, surrounded by a ditch, and shrimp (2-4 cm long) for poultry feed. One diver wearing farmers can use this central area for cockle cul­ goggles or a face mask dives to the bottom and ture (Chomdej and Anant 1978). The elevated cuts the bamboo poles, leaving 1 m of pole with area is fenced with 50-cm bamboo stakes. Cockle attached mussels to reach market size. A worker seeds, 2-3 cm, are sown in the area and then in the boat lifts the upper portion, with the young harvested after 5-6 months along with the mussels attached, into the boat and removes the shrimp. This method has been practiced for mussels with a type of shovel. Mussel production about 5 years in the Klongkone district, Samut­ varies from 1.4 X J03 kg to 6.0 X J03 kg/ rai sakorn Province. The seed used is larger than that (8.6-37. 7 t/ ha) annually. The variation in pro­ for cockles cultured on natural intertidal flats duction results from differences in the depth, (usually about 300-400 pieces/ L), but yields monsoon season, and amplitude of tides, all of receive a higher price because of better consumer which affect spatfall on the poles. However, mus­ acceptance. sel production in Chumporn Province once The bottom substratum for cockle culture reached 3.1 X 10 4 kg/ rai ( 19 kg of mussels/ pole). must be muddy-silt, that is, high in organic mat­ The broadcast or sowing method is practiced ter and nutrients, and the topsoil must be soft and only for cockle culture, and the management or grey. Cockles must be able to move freely to a layout of farms has already been mentioned. deeper layer of the bottom to escape enemies, However, areas where cockle farms have long avoid desiccation during low tide, and avoid been located should be improved, as some areas unsatisfactory environmental conditions. An have had problems with increased silt and sedi­ excess of empty shells should not be left on the mentation and the accumulation of broken twigs culture grounds because these obstruct the and mangrove leaves. Moreover, after dead cock­ movement of the cockles. Cockle farms that have les rot, empty shells accumulate on the bottom. been used for a longtime have many empty shells, These should be removed. Traditional methods and these should be removed. At harvest, farmers of cockle culture yield 5.0 X J03 kg and 17.5 X J03 can gather empty shells as well as marketable­ kg/ rai ( 31 t/ ha and 109 t/ ha) annually for small­ sized cockles. Amatayakul ( 1957) described con­ scale and commercial-scale farms, respectively. ditions that indicate suitable sites for cockle cul­ ture: a layer of soft grey mud 15-30 cm thick; moderate water movement; water 2.0-2.5 m deep during high tide; and bottom exposed during low PROBLEMS AND CONSTRAINTS tide. Attention to coastal aquaculture by fishing nations, such as Thailand, has increased as cap­ MANAGEMENT ture fishing has increasingly become less feasible. The prices of oil-based fuels have risen rapidly, For each method of oyster culture, two or three and the coastal nations of the world have all workers are usually hired to remove fouling declared exclusive economic zones, charging fees animals, especially barnacles, from the collec­ for access to their waters and, in some cases, tors. Also, some sedimentation of small particles excluding other nations entirely. Development of and blue-green algae must be cleaned from the mollusc culture is one method of increasing coast­ collectors for good oyster growth. Market-sized al animal-protein production. Different tradi­ oysters are removed piece by piece at harvest. An tional methods for the culture of economic mol­ average of 3.0 X J03 kg/ rai (19 t/ ha) is harvested lusc species have been improved and developed annually. Thailand still has a large potential area by the introduction of modern techniques. How­ of intertidal flats suitable for oyster culture - ever, the most important factor is the ecology of reportedly 80 000 rai ( 1.3 X 104 ha). the area. Several culture areas are now polluted In the common stake method of mussel cul­ by industrial and domestic wastes, and, to some ture, bamboo poles are driven into the bottom extent, highly turbid waters have resulted from 0.5-1.0 m apart. On a 1-rai farm, about 1600 mining activities. Therefore, in addition to farm poles are used ( 10000 poles/ ha). When long management, government assistance is required bamboo poles are used, spaces between farms are to improve environmental conditions. needed for navigation. After the spat settle, the Intertidal zones are the only habitats suitable farmers pay little attention to management and for mollusc culture. Coastal waters are also the simply wait until harvest. However, some productive zone where nutrients, phytozoo­ farmers harvest part of the crop of mussels early plankton, and larval and juvenile stages of coas- 78 BIVALVE CULTURE ta! animals, as well as true coastal species, exist. duction. Many potential areas should be devel­ These areas - nursery grounds or natural cradle oped for coastal aquaculture to improve the soci­ for young stages of aquatic animals - are often oeconomic conditions of the fishermen. To adversely affected by human activities, which accomplish these objectives, BFD under the Min­ also affect mollusc culture. istry of Agriculture and Cooperatives was set up Except for sales under moderately hygienic with full responsibilities for promotion and conditions at the Fish Marketing Organization extension of coastal mollusc-culture develop­ (FMO), there are no mollusc markets that handle ment. the product with a high degree of sanitation. The Oyster culture is one of the inexpensive coastal molluscs from culture beds are harvested from protein sources. Annual C. commercialis produc­ the farms and then transported without ice to tion is reported to range from 16.7 t/ha to 21.5 local markets. They are only kept moist during t/ha. The annual investment in oyster culture transportation. with cement blocks is about 8000 baht/ ha, which Molluscs are sold either fresh or cooked. Mus­ could give a net income of 59000 baht to the sels and cockles are commonly sold in their shells farmer (Chomdej and Poocharoen 1979). in local markets. Shucked molluscs may be Although fishermen are interested in oyster cul­ boiled and dried for preservation. Oysters, ture, supplies from farms are still insufficient to mostly C. commercialis, are usually shucked and meet the market demand. frozen, and then sent greater distances. How ever, Among bivalve culture operations, commer­ C. lugubris is commonly sold in the shell for cial cockle culture could yield the highest income. consumption. There is little sanitary control But only certain areas far from industrial and because at present molluscs are not markedly domestic wastes, such as the intertidal flats of the affected by industrial and domestic pollutants. outer gulf and the Andaman coast, are suitable Heavy industries are starting in certain prov­ for development, and lack of cockle seeds is a inces, and, thus, monitoring of pathogens and problem. At present, cockle farmers, especially in heavy metals will be needed. Satul, must import cockle seeds from Malaysia. Mussels are consumed locally because of their low market price. The mussel farmers may har­ vest young mussels as feed for poultry and leave FUTURE PLANS some to grow to marketable size for human con­ sumption. Because of space competition between The mollusc-culture development plans of the mussels on collectors, methods should be sought Royal Thai Government aim at creating greater to maintain a proper density of mussels through­ employment opportunities and increasing pro- out the growing cycle. v . APRENDICES 1. PARTICIPANTS

Syed Ali bin Monzil, Aquaculture Unit, Pri­ Lim Lian Chuan, Aquaculture Unit, Primary mary Production Department, 300 Nicoll Drive, Production Department, 300 Nicoll Drive, Changi Point, Singapore 1749. Changi Point, Singapore 1749. W .H.L. Allsopp, Associate Director (Fisher­ J.M. Lock, Department of Fisheries, P.O. Box ies), International Development Research Cen­ 2417, Konedobu, Papua New Guinea. tre, 5990 Iona Drive, University of British C. W. MacCormac, Program Officer (Agricul­ Columbia, Vancouver, Canada V6T I L4. tural Economics), Agriculture, Food and Nutri­ Anant Saraya, Department of Fisheries, Min­ tion Sciences, International Development istry of Agriculture and Cooperatives, Raja­ Research Centre, Asia Regional Office, Tanglin damnern Road, Bangkok 2, Thailand. P.O. Box IOI, Singapore 9124. Retno Andamari, Research Institute for Masud Ahmed, Ministry of Fisheries and Marine Fisheries, Jalan Kerapu 12, Jakarta, Livestock, Government of the People's Republic Indonesia. of Bangladesh, Dacca 2, Bangladesh. Boon Boonruang, Phuket Fisheries Station, Edward McCoy, Brackishwater Division, Phuket, Thailand. Fisheries Department, Kasetsart University W.L. Chan, Senior Small-Scale Fisheries Campus, Bangkhen, Bangkok, Thailand. Adviser, FAO/UNDP South China Sea Fisher­ K.A. Narasimham, Kakinada Research Cen­ ies Development and Cooperative Programme, tre, Central Marine Fisheries Research Institute, P.O. Box 1184 MCC, Makati, Metro Manila, Kakinada 533002, Andhra Pradesh, India. Philippines. J. Navakalomana, Fisheries Division, Minis­ Leslie Cheong, Aquaculture Unit, Primary try of Agriculture and Fisheries, G.P.O. Box 358, Production Department, 300 Nicoll Drive, Suva, Fiji. Changi Point, Singapore 1749. G. Newkirk, Department of Biology, Dal­ D. Coatanea, Centre national pour l'exploita­ housie University, Halifax, Nova Scotia, Canada tion des oceans, Centre oceanologique du Paci­ B3H 4JI. fique, B.P. 7004, Toravao, Tahiti. Ng Fong Oon, Fisheries Research Institute, F. Brian Davy, Senior Program Officer Gelugor, Pulau Pinang, Malaysia. (Fisheries), Agriculture, Food and Nutrition Sciences, International Development Research Nie Zhong-Qing, National Fish Administra­ Centre, Asia Regional Office, Tanglin P.O. Box tion, Yellow Sea Fisheries Research Institute, 19 IO I, Singapore 9124. Lai Yang Road, Qing Dao, China. Michael Graham, Regional Liaison Officer, Josephine Pang, Inland Fisheries and Aqua­ Communications Division, International Devel­ culture Branch, Department of Agriculture, opment Research Centre, Asia Regional Office, Kuching, Sarawak, East Malaysia. Tanglin P.O. Box IOI, Singapore 9124. Qiu Li-Qiang, South China Sea Fisheries Yap How Keong, Sin Chew Mussels Farming Research Institute, Singanglu, Hai Zhu Qu, 2389 and Company, Block 134, 12-97, Bedok North Canton, China. Street 2, Singapore 1646. D.B. Quayle, 3560 Planta Road, Nanaimo, Lee Hoe Heng, Aquaculture Unit, Primary British Columbia, Canada V9T I L9. Production Department, 300 Nicoll Drive, D.H. Sadacharan, Ministry of Fisheries, P.O. Changi Point, Singapore 1749. Box 1707, Galle Face, Colombo 3, Sri Lanka.

80 PARTICIPANTS 81

Evelyn Serna, Department of Natural Re­ Tanittha Chongpeepien, Department of sources, Bureau of Fisheries and Aquatic Fisheries, Ministry of Agriculture and Coopera­ Resources, 860 Quezon Avenue, Quezon City, tives, Rajadamnern Road, Bangkok 2, Thailand. Metro Manila 3008, Philippines. Soehardi P, Directorate-General of Fisheries, M. Unar, Central Research Institute for Djalan Salemba Raya No. 16, Jakarta, Fisheries, Jalan K.S. Tubun, Jakarta, Indonesia. Indonesia. Adam Young, Aquaculture Department, Swe Thwin, Department of Marine Biology, Southeast Asian Fisheries Development Center Moulmein Degree College, Moulmein, Burma. (SEA FD EC), 6th Floor, Triumph Building, 1610 Tan Wee Hin, Department of Zoology, Quezon Avenue, Quezon City, Philippines. National University of Singapore, Kent Ridge, Singapore 0511. Paciencia Young, Fish Hatchery Project, Tang Twen Poh, Department of Fisheries, Southeast Asian Fisheries Development Center Mail Bag No. 107, Kota Kinabalu, Sabah, East (SEAFDEC), P.O. Box 256, Iloilo City, Malaysia. Philippines. 2. PAPERS SUBMITTED AT THE WORKSHOP

These papers were presented for discussion Report of Trials on Culturing Green Mussels purposes. Edited versions of some of these papers (Perna viridis) in Laucala Bay near have been included in the proceedings. Where Suva Navakalomana more than one paper was presented per country, Bivalve Culture in Eastern Canada Newkirk the papers have been combined by the editors Status of the Mollusc Cultures in Malaysia Ng into a single country report. Artificial Cultivation of Bivalves in China Nie Present Status of Bivalve Production in Sarawak, Malaysia Pang Oysterculture Techniques in Guangdong Qiu Bivalve Exploitation Sadacharan Status of Bivalve Culture in Thailand Anant Bivalves in the Philippines: Oysters and High-Density Depuration Trials on Green Mus­ Mussels Serna sels Perna viridis (L) Using Ultraviolet Present Status of Marine Bivalve Culture in Radiation Cheong India Silas Bivalve Culture in Singapore Cheong The Tolerance to and Uptake of Lead in the Manual on Mussel Farming in Singa­ Green Mussel (Perna viridis) (L) Tan pore Cheong Status of the Sabah Shellfish Culture Tang Preliminary Report on the Induced Spawning of Reproductive Cycle of Mussel (Mytilus smarag­ the Green Mussel, Perna viridis (L) in dinus) at Samaekao, Chachoengsao Prov­ Singapore Lim ince Tanittha Bivalve Culture in Papua New Guinea Lock Present Status of Bivalve Culture in Indo­ Bivalves and Bivalve Fisheries in Bangladesh nesia Unar Masud Shel/fisheries of the Philippines Young

82 3. BIBLIOGRAPHY

Ablan, G. 1949. The commercial production of oysters Symposium on Coastal Aquaculture, Cochin, India, in the Philippines. Manila, Philippines, Department 12-18 January 1980. Cochin, India, Marine Biology of Agriculture and Natural Resources, Popular Bul­ Association of India, Abstract 181. letin 26. 29 p. Alagarswami, K., Kuriakose, P.S., Appukuttan, K.K., Ablan, G.J. 1938. The diwal fishery of Occidental and Rangarajan, K. 1980. Present status of exploita­ Negros. Philippine Journal of Science, 66(3), tion of mussel resources in India. Paper prepared for 379-385. the Workshop on Mussel Farming, Madras, India, Ab Ian, G. L. 1953. Lattice method of oyster culture. 25-27 September 1980 (mimeo). Philippine Journal of Fisheries, 2, 189. Alagarswami, K., and Narasimham, K.A. 1973. Clam, Abraham, K.C. 1953. Observations on the biology of cockle and oyster resources of the Indian coasts. In Meretrixcasta (Chemnitz). Journal of the Zoological CMFRI, Proceedings of the Symposium on Living Society of India, 5, 163-190. Resources in the Seas around India. Cochin, India, Achari, G. P. K. 1980. System design for mussel culture. CMFRI, Special Publication, 648-658. Paper prepared for the Workshop on Mussel Farm­ Alagarswami, K., and Qasim, S.Z. 1973. Pearl culture ing, Central Marine Fisheries Research Institute, - its potential and implications in India. Indian Madras, India, 25-27 September 1980 (mimeo). Journal of Fisheries, 20, 533-550. Achari, G. P.K., and Thangavelu, R. 1980. Mussel cul­ Amatayakul, C. 1957. Mussel. Thai Fisheries Gazette, ture - its problems and prospects. Paper prepared 10(4), 547-557. forthe Symposium on Coastal Aquaculture, Cochin, Anant Saraya et al. 1980. Physico-chemical properties India, 12-18 January 1980. Cochin, India, Marine of mussel farm at Samaekao, Chachoengsao pro­ Biology Association of India, Abstract 170. vince. Bangkok, Department of Fisheries, Brackish­ Ahmed, M. 1971. Oyster species of West Pakistan. water Fisheries Division, Coastal Aquaculture Inves­ Pakistan Journal of Zoology, 3(2), 229-236. tigation Section, Technical Report 15. 32 p. Alagarswami, K. 1974a. Development of cultured Anon. 1946. Pointers on oyster cultivation. Manila, pearls in India. Current Science (Bangalore), 43(7), Philippines, Department of Agriculture and Com­ 205-207. merce, Food Production Series Leaflet 3. 7 p. I 974b. Results of multiple implantation of nuclei 1971. Survey sea-food in Djakarta. Jakarta, in production of cultured pearls. Indian Journal of Indonesia, Marine Fisheries Research Institute. Fisheries, 21(2), 601-604. 1976. Natural-resources based investment project 1975. Preliminary study on growth of cultured profile: Tahong. Quezon City, Philippines, Depart­ pearls. Indian Journal of Fisheries, 22, 300-303. ment of Natural Resources, Industry Profile Series. 1977. Larval transport and settling of pearl oysters 33 p. (genus Pinctada) in the Gulf of Mannar. In National Ansarj, A.A., Parulekar, A.H., and Matondkar, S.G. P. Institute of Oceanography, Proceedings of the Sym­ 1981. Seasonal changes in meat weight and biochem­ posium on Warm Water Zooplankton, National ical composition in the black clam, Villorita cypri­ Institute of Oceanography, Special Publication, noides (Grey). Indian Journal of Marine Science, 678-686. 10(2), 128-131. 1980. Review on production of mussel seed. In Appukuttan, K.K. 1980a. Predation on mussels by Silas, E.G., ed., Coastal Aquaculture: Mussel Farm­ silver bream, Rhaboosargus sarba. In Silas, E.G., et ing, Progress and Prospects. Cochin, India, CMFRI, al., ed., Coastal Aquaculture: Mussel Farming Pro­ Bulletin 29, 22-26. gress and Prospects. Cochin, India, CMFRI, Bul­ Alagarswami, K., Dharmaraj, S., Velayudman, T.S., letin 29, 44-45. Cheliam, A., and Victor, A.C.C. 1980a. On con­ 1980b. Brown mussel production and economics trolled spawning in the pearl oyster Pinctadafucata at Vizhinjam. Paper prepared for the Workshop on (Gould). Paper prepared for the Symposium on Mussel Farming, Central Marine Fisheries Research Coastal Aquaculture, Cochin, India, 12-18 January Institute, Madras, India, 25-27 September 1980 1980. Cochin, India, Marine Biology Association of (mimeo). India, Abstract 64. Appukuttan, K.K., Nair, T.P., Joseph, M., and Tho­ I 980b. Larval development of the pearl oyster mas, K. T. 1980. Culture of brown mussel at Vizhin­ Pinctada fucata (Gould). Paper prepared for the jam. In Silas, E.G., et al., ed., Coastal Aquaculture:

83 84 BIVALVECULTURE

Mussel Farming Progress and Prospects. Cochin, ter farming. Quezon City, Philippines, BFAR. 54 p. India, CMFRI, Bulletin 29, 30-32. Bayne, B. L. 1976. Marine mussels: their ecology and AQUACOP. 1977. Elevage larvaire et production de physiology. Cambridge, England, Cambridge Uni­ naissain de Crassostrea gigas en milieu tropical. versity Press. 506 p. Actes de colloques du CNEXO, 4, 331-346. Beckvar, N. 1981. Cultivation, spawning, and growth 1979. Larval rearing and spat production of green of the giant clams Tridacna gigas, T. derasa, and T. mussel Perna viridis Linnaeus in French Polynesia. squamosa in Palau, Caroline Islands. Aquaculture, Proceedings of the World Mariculture Society, 10, 24, 21-30. 641-647. BFAR (Bureau of Fisheries and Aquatic Resources). 1980. Mass production of green mussel spat Perna 1979. National workshop on seafarming and special viridis in French Polynesia. Paper prepared for the aquaculture project: volume I, general report. Symposium on Coastal Aquaculture, Cochin, India, Quezon City, Philippines, BFAR. 37 p. 12-18 January 1980. Cochin, India, Marine Biology Blanco, G.J. 1956. Stake method of oyster farming in Association of India. the Dagat-dagatan lagoon, Rizal Province. Philip­ Arakawa, K. Y. 1980. Prevention and removal of foul­ pine Journal of Fisheries, 4(1), 21-32. ing on cultured oysters: a handbook for growers. 1958. Kapis farming at the tidal flats of Bacoor Walpole, Mai~e, Maine Sea Grant Publications, Bay, Luzon. Philippine Journal of Fisheries, 6( I), Marine Sea Grant Technical Report 56. 38 p. 9-15. Awati, P.R., and Rao, H.S. 1931. Ostrea cucul/ata (the Blanco, G.J., Villaluz, D.K., and Montalban, H.E. Bombay oyster). Indian Zoological Memoirs 3, 1951. Cultivation and biology of oysters at Bacoor 1-107. Bay, Luzon. Philippine Journal of Fisheries, 1(1), Ayres, A.A. 1978. Shellfish purification in installations 45-67. using ultra-violet light. Lowestoft, UK, Ministry of Breisch, L. L., and Kennedy, V.S. I 980. Selected biblio­ Agriculture, Fisheries and Food, Directorate of graphy of worldwide oyster literature. Solomons, Fisheries Research, Fisheries Research Centre Maryland, Sea Grant Publication U M-SG-TS-80-11. Laboratory Leaflet 43. 20 p. Broom, M.J. 1976. Synopsis of biological data on scal­ Badonia, M.A. 1980. Canning of edible oysters. Paper lops. Rome, Italy, FAO, Fisheries Synopsis 114. 44 prepared for the Symposium on Coastal Aquacul­ p. ture, Cochin, India, 12-18 January 1980. Cochin, Brusca, G., and Ardill, D. 1974. Growth and survival of India, Marine Biology Association of India, Abstract the oysters, C. gigas, C. virginica and 0. edu/is in 290. Mauritius. Revue agricole et sucrii:re de !'lie Mau­ Bae, G. M. 1971. Studies on the hardening of seed pro­ rice, 53, 111-131. duction for export. Pusan, Bulletin of the Fisheries Bryan, G.W. 1976. Heavy metal contamination in the Research Development Agency, 8, 55-56. sea. In Johnston, R., ed., Marine Pollution. London, Baird, R.H. 1958. Measurement of condition in mussels England, Academic Press, 185-302. and oysters. Journal du conseil international pour Cahn, A. R. 1949. Pearl culture in Japan. Washington, !'exploration de la mer, 23(2), 249-257. D.C., USA, Fish and Wildlife Service, Fishery Leaf­ Balachandran, K. K., and Nair, T.S. U. 1975. Diversifi­ let 357. 91 p. cation in canned fishery products - canning of clams 1950. Oyster culture in Japan. Washington, D.C., and mussels in oil. Paper prepared for the Sympo­ USA, Fish and Wildlife Service, Fishery Leaflet 383. sium on Fish Processing Industry in India, Mysore, 80 p. India. Mysore, India, Central Food Technology 1951. Clam culture in Japan. Washington, D.C., Research Institute. USA, Fish and Wildlife Service, Fishery Leaflet 399. Balachandran, K.K., and Prabhu, P.V. 1980a. Tech­ 103 p. nology of processing mussel meat. Paper prepared Careon, J.A. 1968. The malacology of Philippine oys­ for the Workshop on Mussel Farming, Central ters of the gen us Crassost rea and a review of their Marine Fisheries Research Institute, Madras, India, shell characters. Proceedings of the National Shell­ 25-27 September 1980 (mimeo). fish Association, 59, 104-111. I 980b. Preliminary studies on preservation and Castagna, M., and Kraeuter, J.N. 1981. Manual for transportation of green mussel Perna viridis. Paper growing the hard clam Mercenaria. Gloucester prepared for the Symposium on Coastal Aquacul­ Point, Virginia, USA, Virginia Institute of Marine ture, Cochin, India, 12-18 January 1980. Cochin, Science, Special Report in Applied Marine Science India, Marine Biology Association of India, Abstract and Ocean Engineering 249. 293. Chen, T. P. 1976. Aquaculture practices in Taiwan. Banchong Teinsongrasamee. 1974. Marine farm man­ Norwich, England, Page Brothers, Ltd. 162 p. agement. I st ed. Bangkok, Thailand, Secretary oft he Cheong, L., and Chen, F. Y. 1980. Preliminary studies Cabinet Printing Office. on raft method of culturing green mussels, Perna Bardach, J.E., Ryther, J.H., and Mclarney, Q.O. 1972. viridis (L.), in Singapore. Singapore Journal of Aquaculture. The farming and husbandry of fresh­ Primary Industries, 8(2), 119-133. water and marine organisms. New York, USA, Wiley Cheong, L., and Lee, H.B. 1981. Improvements to rope I nterscience. 868 p. design for the raft culture of green mussels, Perna Basa, S.S., Mamaril, D.A., Fadriguela, J.F., Zazarte, viridis (L.) in Singapore. Singapore Journal of Prim­ N.A., and Busque, C.M. no date. Handbook on oys- ary Industries, 9(1), 38-53. BIBLIOGRAPHY 85

Cheong, L., and Syed Ali Bin Syed Monzil. 1982. High­ tius. Revue agricole et sucriere de !'lie Maurice, density depuration trials on green mussels Perna vir­ 48(3), 216-217. idis (L.) using ultraviolet radiation. Paper prepared Cox, K. W. 1973. Seychelles, oyster development. A for the Bivalve Culture Workshop, Singapore, 16-19 report prepared for the United Nat ions Development February 1982. 18 p. Programme/ Department of Agriculture, Seychelles Chin, P.K., and Lim, A.L. 1975. Some aspects of oyster project. Rome, Italy, FAO, F AO/ Seychelles project, culture in Sabah. Kuala Lumpur, Malaysia, Ministry FAO-F I-DP/ Sey.-72/ 003/ I. 9 p. of Agriculture and Rural Development, Fisheries Curtin, L. 1971. Oyster farming in New Zealand. Wel­ Bulletin 5. 14 p. lington, New Zealand Marine Department, Fisheries 1976. Notes on the efficiency of various materials Technical Report 72. 99 p. tested as oyster spat collectors in Cowie Bay, Sa bah. Dare, P.J. 1980. Mussel cultivation in England and Malaysian Agricultural Journal, 50(4), 462-479. Wales. Lowestoft, England, Ministry of Agriculture, 1977-78. Oyster culture development in Sabah. Fisheries and Food, Directorate of Fisheries Sa bah Society Journal, 6(3), I 08-115. Research, Fisheries Research Centre, Laboratory Chinnamma, G. 1974. Technological aspects of preser­ Leaflet 50. 18 p. vation and processing of edible shellfishes: 5. Cold Davies, G. 1974. A method of monitoring the spatfall of storage changes in mussels (My ti/us edu/is) and Mussels (Mytilus edu/is L.). Journal du Conseil clams ( Villorita sp.). Fishery Technology, I !(I), international pour !'exploration de la mer, 36( l ), 22-27. 27-34. Chinnamma, P.L., Chaudhuri, D.R., and Pillai, V.K. Devlin, l.H. 1973. Operation report: oysterdepuration plant - Ladysmith, B.C. Ottawa, Canada, Envi­ 1970. Technological aspects of processing of edible ronment Canada, Fisheries and Marine Service mussels, clams and crabs: I. Spoilage during ice stor­ age. Fishery Technology, 7(2), 137-142. Industrial Development Branch, Project Report 57. !08 p. Chomdej, W., and Anant Saraya. 1978. Preliminary Devlin, l.H., Eng, P., and Neufeld, N. 1971. Oyster observation on rearing of cockles (Andara granosa) depuration plant, Ladysmith, B.C. Vancouver, Can­ (Linnaeus) on elevated area of shrimp ponds. Bang­ ada, Department of the Environment, Inspection kok, Thailand, Department of Fisheries, Brackish­ Branch, Fisheries Service, Project Report 43. water Fisheries Division, Coastal Aquaculture Inves­ Dhulkhed, M.H., and Ramamurthy, S. 1980. Experi­ tigation Section, Technical Report 5. 12 p. ments on oyster culture at Mulky, Dakshina Kan­ Chomdej, W., and Poocharoen, W. 1979. Coastal nada (Karnataka). Paper prepared for the Sympo­ aquaculture in Thailand. Bangkok, Thailand, sium on Coastal Aquaculture, Cochin, India, 12-18 Department of Fisheries, Brackishwater Fisheries January 1980. Cochin, India, Marine Biology Asso­ Division, Coastal Aquaculture Investigation Sec­ ciation of India, Abstract 177. tion, Technical Report 10. 33 p. Dinamani, P. 1977. Oyster experiments in Tongo. Choncheunchop, P. l 979. Green mussel culture by Catch 77, 4(9), 20. hanging method. Thai Fisheries Gazette, 32(3), Direktorat Jendral Perikanan. 1981. Fisheries statistics 3129-3229. of Indonesia 1979. Jakarta, Indonesia, Directorate Choo, P.S. 1979. Culture of the mussel, Mytilus viridis General Fisheries (DGF). Linnaeus, in the Straits of Johore, Malaysia. Malay­ Dover, C. 1929. Oyster culture in Malaya. Nature, 124, sian Agricultura!Journal, 52(1), 67-76. 264-265. Choo, P.S. and Speiser, G. l 979. Estimation of the Dupuy, J.L. 1977. Manual for design and operation of growth parameters and mortality of Mytilus viridis an oyster seed hatchery for the American oyster Linnaeus (Mollusca, Mytilidae) cultured in a sus­ Crassostrea virginica. Gloucester Point, Virginia, pended plastic cage in Jelutong, Penang. Malaysian USA, Virginia Institute of Marine Science, Special Agricultural Journal, 52( l ), 9-16. Report 142. 104 p. Clark, J.E., and Langmo, R.D. 1979. Oyster seed hatch­ Durve, V.S. 1965. On the seasonal gonad changes and eries on the U.S. west coast: an overview. Marine spawning in the adult oyster Crassostrea gryphoides Fisheries Review, 41, 10-16. (Schlotheim). Journal of the Marine Biology Associ­ CMFRI (Central Marine Fisheries Research Institute). ation of India, 7(2), 328-344. 1977. Pearl culture training. Cochin, India, CM FRI, Easterson, D.C.V., and Mahadevan, S. 1980. Review of Special Publication I. 39 p. open sea environmental conditions along Indian 1978. Mariculture research and developmental coast. In Silas, E.G., et al., ed., Coastal Aquaculture: activities. Cochin, India, CMFRI, Special Publica­ Mussel Farming Progress and Prospects. Cochin, tion 2. 48 p. India, CMFRI, Bulletin 29, 17-21. 1979. Proceedings of the first workshop on tech­ Easwaran, C.R., Narayanan, K.R., and Michael, M.S. nology transfer. Cochin, India, CMFRI, Special 1969. Pearl fisheries of the Gulf of Kutch. Journal of Publication 6. 96 p. the Bombay Natural History Society, 66(2), 338-344. Coatanea, D. 1982. Present status of bivalve culture in Escritor, G.L., and Padua, P.B. 1961. Culture of Myti­ French Polynesia. Paper prepared for the Bivalve lus smaragdinus edu/is, a bay mussel at Bacoor Bay, Culture Workshop, Singapore, 16-19 February Cavite. Philippine Fisheries Gazette, 2, 3. 1982. 5 p. Fatuchri, M., Wardana, I., and Wardana, W. 1975. Couacaud, L. 1969. Oyster culture on the Isle of Mauri- Study of Crassostrea cucullata born in Banten Bay, 86 BIVALVE CULTURE

in relation with its possibility for culture. Jakarta, Heslinga, G.A., and Hillmann, A. 1981. Hatchery cul­ Indonesia, Marine Fisheries Research Institute, ture of the commercial top snail Trochus niloticus in Research Report 2, 76-10 I. Palau, Caroline Islands. Aquaculture, 22, 35-43. Fernando, D.H. 1977. Lamellibranchiate fauna of the Hidu, H., Conary, C., and Chapman, S.R. 1981. Sus­ estuarine and coastal areas in Sri Lanka. Sri Lanka pended culture of oysters: biological fouling control. (Ceylon) Bulletin of the Fisheries Research Station, Aquaculture, 22 (l-2), 189-192. 27, 29-54 Hughes-Games, W.L. 1977. Growing the Japanese oys­ Fleet, G. H. l 978a. Oyster depuration -a review. Food ter ( Crassostrea gigas) in subtropical seawater fish Technology in Australia, 30(11), 444-454. ponds. Aquaculture, 11(3), 217-229. 1978b. Protecting public from micro-biological Hynes, T.F. no date. Observation and review of cultur­ pollution of oysters. Australian Fisheries, 37(12), ing methods of green mussel (Perna viridis) in the 18-21. Province of Zambales. Masinloc, Zambales, Philip­ Furfari, S.A. 1976. Shellfish purification. A review of pines, BFAR. current technology. Paper prepared for the FAO IDRC (International Development Research Centre). Technical Conference on Aquaculture. Rome, Italy, Oyster farming in the tropics. Ottawa, Canada, FAO, FAO/ AQ/CONF./76/R.ll. 16 p. Communications Division, IDRC, 16-mm colour Furukawa, A., and Hisaoka, M. 1975. Biological study film, 29 minutes. on shallow water production: 3. On the basket cul­ Ignacio, M.F. 1980. Capiz shells: gathered from the ture of the clam Venerupis japonica. N aikai-Ku Sui­ bottom of the sea. Countryside Banking, 6(3), 6-10. san Kenkyujo Kenkyu Hokoku, 10, 1-19 (in Imai, T., ed. 1978. Aquaculture in shallow seas: pro­ Japanese). gress in shallow sea culture. Rotterdam, Nether­ Glude, J.B. 1955. Tidal spat trap, a new method for lands, A.A. Balkema. 615 p. collecting seed clams. Proceedings of the National lno, T. 1970. Controlled breeding of molluscs. Paper Shellfish Association, 55, 45, I 06-115. prepared for the lndo-Pacific Fisheries Council 1979. Oyster culture - a world review. In FAO, Symposium on Coastal Aquaculture, Bangkok, Advances in Aquaculture; Papers Presented at the Thailand, 18-25 November 1970. Bangkok, Thai­ F AO Technical Conference on Aquaculture, Kyoto, land, lndo-Pacific Fisheries Council, !PFC/ Japan, 26 May-2 June 1976. West Byfleet, Surrey, C70/SYM 35. England, Fishing News (Books) Ltd. Iversen, E.S. 1968. Farming the edge of the sea. West Glude, J.B., Steinberg, M.A., and Stevens, R.C. 1981. Byfleet, Surrey, England, Fishing News (Books) Ltd. Feasibility of oyster and mussel farming by munici­ 301 p. pal fishermen. Manila, Philippines, South China Sea Jenkins, R.J. 1979. Mussel cultivation in the Marlbo­ Fisheries Development and Coordinating Pro­ rough sounds (New Zealand). Wellington, New Zea­ gramme, Working Paper, June. land Fishing Industry Board. 75 p. Goldberg, E.D., Bowen, V.T., Farrington, J. W., Har­ Jones, S., and Alagarswami, K. 1973. Mussel fishery vey, G., Martin, J.H., Parker, P.L., Risenbrough, resources of India. In CMFRI, Proceedings of the R. W., Robertson, W., Schneider, E., and Gamble, E. Symposium on Living Resources in the Seas around 1978. Mussel watch. Environmental Conservation, 5, India. Cochin, India, CMFRI, Special Publication, 101-125. 641-647. Gough, D.K. 1976. Preservative treated bamboo poles Joseph, M.M., and Joseph, S. 1980. Some aspects of for use as oyster floats. Interim report. Suva, Fiji, experimental culture of the oyster Crassostrea mad­ Ministry of Agriculture, Fisheries and Forests, Div­ rasensis (Preston). Paper prepared for the Sympo­ ision of Forests. sium on Coastal Aquaculture, Cochin, India, 12-18 Gwyther, J., and Munro, J.L. 1981. Spawning induc­ January 1980. Cochin, India, Marine Biology Asso­ tion and rearing of larvae of tridacnid clams (Bival­ ciation of India, Abstract 174. via: Tridacnidae). Aquaculture, 24, 197-217. Joseph, M.M., and Madhystha, M.N. 1980. Growth of Hallier, J.P. 1977. Oyster breeding in the New the oyster Crassostrea madrasensis (Preston) at Hebrides. South Pacific Commission Fisheries News­ Mulki estuary, Dakshina Kannada. Paper prepared letter, 15, 49-53. for the Symposium on Coastal Aquaculture, Cochin, Hancock, D.A. 1969. Oyster pests and their control. India, 12-18 January 1980. Cochin, India, Marine Lowestoft, England, Ministry of Agriculture, Fisher­ Biology Association of India, Abstract 175. ies and Food, Directorate of Fisheries Research, Joyce, E.A. Jr. 1972. Partial bibliography of oysters, Fisheries Research Centre, Laboratory Leaflet 18. 29 with annotations by Edwin A. Joyce Jr. St. Peters­ p. burg, Florida, USA, Department of Natural Re­ Harrisson, T. 1970. Malays of south-west Sarawak sources, St. Petersburg Marine Research Labora­ before Malaysia. London, England, MacMillan and tory. 846 p. Co. Ltd. 670 p. Kamara, A.B., and McNeill, K.B. 1976. Preliminary Henry,G.M.1913. Window-paneoysterinvestigations, oyster culture experiments in Sierra Leone. Free­ January and May, 1913. Spolia Zeylan (Colombo), town, Sierra Leone, Ministry of Agriculture and 9, 134-440. Natural Resources, Fisheries Division, Occasional Hershberger, W.K. 1978. Oyster breeding: where can it Paper I. 50 p. go. Proceedings of the National Shellfish Associa­ Kamara, A.B., McNeill, K.B., and Quayle, D.B. 1979. tion, 68. 90 p. Tropical mangrove oyster culture: problems and BIBLIOGRAPHY 87

prospects. In FAO, Advances in Aquaculture; Pa­ Ling, Y.S. 1970. Preliminary studies on the collection pers Presented at the FAO Technical Conference on of oyster spat in Johore Straits. Journal of the Singa­ Aquaculture, Kyoto, Japan, 26 May-2 June 1976. pore National Academy of Science, 2(1), 14-18. West Byfleet, Surrey, England, Fishing News Loosanoff, V.L., and Davis, H.C. 1963. Rearing of (Books) Ltd, 344-348. bivalve mollusks. In Advances in Marine Biology, Korringa, P. l 976a. Farming the cupped oyster of the Volume I. London, England, Academic Press, genus Crassostrea: a multidisciplinary treatise. Am­ 1-136. sterdam, Netherlands, Elsevier Scientific Publishing Lutz, R.A. 1980. Mussel culture and harvest: a North Company. 224 p. American perspective. Amsterdam, Netherlands, l 976b. Farming marine organisms low in the food Elsevier Scientific Publishing Company. 350 p. chain. Amsterdam, Netherlands, Elsevier Scientific Magoon, C. 1979. Introduction to shellfish aquaculture Publishing Company. 264 p. in the Puget Sound region. Olympia, Washington, 1979. Economic aspects of mussel farming. In USA, State of Washington Department of Natural FAO, Advances in Aquaculture; Papers Presented at Resources. 68 p. the FAO Technical Conference on Aquaculture, Magsuci, H., Conlu, A., and Moyano-Aypa, S. 1980. Kyoto, Japan, 26 May-2 June 1976. West Byfleet, Windowpane oyster fishery of West Visayas. Fisher­ Surrey, England, Fishing News (Books) Ltd, ies Research Journal of the Philippines, 5(2), 74-80. 371-379. Mahadevan, S., and Nayar, K.N. 1973. Pearl oyster Krippine, D. 1977. Observations and notes on the cul­ resources of India. In CMFRI, Proceedings of the turing and settling characteristics of the green mussel Symposium on Living Resources in the Seas around Mytilus smaragdinus in the province of Capiz. Phi­ India. Cochin, India, CMFRI, Special Publication, lippine Journal of Fisheries, 15(1), 12-40. 659-671. Kuriakose, P.S. 1980a. Mussels (Mytilidae: genus Mahadevan, S., Nayar, K.N., and Muthiah, P. 1980. Perna) of the Indian coast. In Silas, E.G., et al., ed., Oyster farming. Cochin, India, CMFRI, Marine Coastal Aquaculture: Mussel Farming Progress and Fisheries Information Service, T and E Series, 26, Prospects. Cochin, India, CMFRI, Bulletin 29, 1-5. 1-3. l 980b. Open sea raft culture of green mussel at Mangum, D., and Mcllhenny, W. 1975. Aquatic appli­ Calicut. In CMFRI, Coastal Aquaculture: Mussel cations of ozone. Cleveland, Ohio, USA, Interna­ Farming Progress and Prospects. Cochin, India, tional Ozone Institute, 138-153. CMFRI, Bulletin 29, 33-38. Mann, R. l 979a. Exotic species in mariculture. Cam­ l 980c. Development of the brown mussel Perna bridge, Massachusetts, USA, MIT Press. indica. Paper prepared for the Symposium on Coast­ ed. l 979b. Proceedings of the symposium on al Aquaculture, Cochin, India, 12-18 January 1980. exotic species in mariculture: case histories of the Cochin, India, Marine Biology Association of India, Japanese oyster, Crassostrea gigas (Thunberg), with Abstract 169. implications for other fisheries. Woods Hole, Massa­ Kuriakose, P.S., and Appukuttan, K.K. 1980. Work chusetts, 18-20 September 1978. Cambridge, Massa­ details for rope culture of mussels. In CMFRI, Coast­ chusetts, USA, MIT Press. 363 p. al Aquaculture: Mussel Farming Progress and Pros­ Menon, N.R., Katti, R.J., and Shetty, H.P.C. 1977. pects. Cochin, India, CMFRI, Bulletin 29, 47-51. Biology of marine fouling in Mangalore waters. Kutty, C.T.A., Nair, S.R.S., and Pratap, M.M. 1979. Marine Biology, 41(2), 127-140. Pearls of the windowpane oyster, Placenta placenta. Menzel, R.W., Cake, E.W., Haines, M.L., Martin, Mahasagar, Bulletin of the National Institute of R.E., and Olen, L.A. 1976. Clam mariculture in Oceanography, 12(3), 187-189. northwest Florida: field study on predation. Pro­ Lamy, E. 1938. Huitres de l'Indochine. J. Conchology ceedings of the National Shellfish Association, 65, (England), Ser. 2, 8(5), 396-400. 59-62. Librero, A.R., Callo, R.A., Dizon, S.P.,and Pamulak­ Millaud, S. 1971. Etude sur une huitre comestible de la lakin, E. R. 1976. Socio-economic survey of the Polynesie Fram;:aise. Service de la peche, Polynesie aquaculture ind us try of the Philippines: oyster sea­ Fram;:aise, Rapport 2/02/ Peche. 19 p. farming, a socio-economic study. Singapore, South­ Millous, 0. 1980. Essais de production controlee de east Asian Fisheries Development Center, naissain d'huitre perlii:re Pinctada margaritifera en SEAFDEC-PCARR Research Paper Series 6. IOI p. laboratoire. Rapport convention CNEXO/ CIP Lim, L.C., Lee, H.B., and Heng, H.H. 1982. Prelimi­ SOC REDO, Territoire de Polynesie Fram;:aise. 32 p. nary report on the induced breeding of the green Milne, P.H. 1972. Fish and shellfish farming in coastal mussel, Perna viridis (L.) in Singapore. Paper pre­ waters. West Byfleet, Surrey, England, Fishing New pared forthe Bivalve Culture Workshop, Singapore, (Books) Ltd. 208 p. 16-19 February 1982. 12 p. Ministry of Agriculture, Malaysia. 1972-79, 1980. Lin, Y.-S., and Tang, H.C. 1980. Biological studies on Marine fisheries annual reports. Sarawak, Malaysia, cultured oysters in Penghu. Bulletin of the Institute Marine Fisheries Department. of Zoology Academia Sinica (Taipei), 19(2), 15-22. Mizuno and Coeroli, M. 1980. Document technique Ling, S.-W. 1977. Aquaculture in Southeast Asia. Seat­ nacres. Service de la peche, Polynesie Fram;:aise. 47 tle, Washington, USA, University of Washington p. Press. I 08 p. Mottet, M.G. 1979. Review of the fishery biology and 88 BJVALVECULTVRE

culture of scallops. Olympia, Washington, USA, for the millions. Australia, 14-25 October 1968. Department of Fisheries, Technical Report 39. 100 p. Paper prepared for the Indo-Pacific Fisheries Coun­ 1980. Research problems concerning the culture of cil, 13th meeting, 14-25 October. Bangkok, Thai­ clam spat and seed. Olympia, Washington, USA, land, Indo-Pacific Fisheries Council. Department of Fisheries, Technical Report 63. 106 p. Okada, H. 1963. Report on oyster culture experiment Munro, J.L., and Gwyther, J. 1981. Growth rates and in Malaysia. Kuala Lumpur, Malaysia, Ministry of maricultural potential of tridacnid clams. Paper pre­ Agriculture and Land, Fisheries Division. pared for the Fourth International Coral Reef Sym­ Ong, K.S. 1981. Aquaculture development in Malaysia posium, Manila, Philippines, May 1981. 21 p. in the eighties. Kertas Perkembangan Perikanan, Muraleedharan, V., Nair, T.S.U., and Joseph, K.G. PL/36/81(3), Bilangan 74. 1979. Smoke curing of mussels. Fishery Technology, Ordona, A.G., and Librero, A.R. 1976. A socio­ 16, 29-31. economic survey of mussel farms in Bacoor Bay. Murthy, V.S., Narasimham, K.A., and Venugopalam, Singapore, Southeast Asian Fisheries Development W. 1979. Survey of windowpane oyster (Placenta Center, SEAFDEC-PCARR research program, placenta) resources in the Kakinada Bay. Indian Research Paper Series 2. 41 p. Journal of Fisheries, 26(1-2), 125-132. Pagcatipunan, R.N. 1973. Pearl culture in the Philip­ Nagabhushanan, R.,and Mane, U.H.1975. Reproduc­ pines. Science Review, 14(5), 1-8. tion in the mussel, Mytilus viridis at Ratnagiri. In 1974. Bay mussel fisheries. Bureau of Fisheries and University of Cochin, Proceedings of the 3rd All Aquatic Resources, Fisheries Newsletter, April-June. India Symposium on Estuarine Biology, University Pang, J. 1982. Present status of bivalve production in of Cochin, Cochin, India, 4-6 February 1975. Bulle­ Sarawak, Malaysia. Paper prepared for the Bivalve tin of the Department of Marine Sciences, University Culture Workshop, Singapore, 16-19 February of Cochin, 7(2), 377-387. 1982. 13 p. Narasimham, K. A. 1973. On the molluscan fisheries of Parulekar, A.H., Dwivedi, S.N., and Dhargalkar, V.K. the Kakinada Bay. Indian Journal of Fisheries, 20, 1973. Ecology of clam beds in Mandovi, Cumbarjua 209-214. canal and Zuari estuarine system of Goa. Indian 1980. Culture of blood clam at Kakinada. Cochin, Journal of Marine Sciences, 2, 122-126. India, CMFRI, Marine Fisheries Information Ser­ Parulekar, A.H., Nair, A., Ansari, Z.A., and Harkan­ vice, T and E Series, 23, 7-9. tra, S.N. 1980. Culture of shellfish in Goa. Paper prepared for the Symposium on Coastal Aquacul­ Navakalomana, J. 1982. Report of trials on culturing ture, Cochin, India, 12-18 January 1980. Cochin, green mussels (Perna viridis) in Laucala Bay near India, Marine Biology Association oflndia, Abstract Suva. Paper prepared for the Bivalve Culture Work­ 165. shop, Singapore, 16-19 February 1982. 17 p. Pathansali, D. 1961. Notes on the biology of the cockle, Nayar, K.N., and Easterson, D.C.V. 1980. On the Anadara granosa L. Proceedings of the Indo-Pacific design of a small scale hatchery system for produc­ Fisheries Council, 11(2), 84-98. tion of oyster seed. Paper prepared for the Sympo­ 1963. Larva of the cockle, Anadara granosa L. sium on Coastal Aquaculture, Cochin, India, 12-18 Bulletin of the Singapore National Museum, 32, January 1980. Cochin, India, Marine Biology Asso­ 163-164. ciation of India, Abstract 96. 1977. Culture of cockles and other molluscs in Nayar, K.N., Mahadevan, S., Alagarswami, K., and coastal waters of Malaysia. In ASEAN (Association Meenakshisundavam, P.T. 1980. Mussel farming: of South East Asian Nations), First ASEAN Meeting progress and prospects. Cochin, India, CMFRI. 56 of Experts on Aquaculture. Jakarta, Indonesia, p. ASEAN, 77/FA.EgA/Doc. WP21, 149-155. Nayar, K.N., Rajapandian, M.E., and Easterson, Pathansali, D., and Soong, M. K. 1958. Some aspects of D.C.V. 1980. Plan for the purification system for cockle (Anadara granosa L.) culture in Malaya. Pro­ farm grown oysters before marketing. Paper pre­ ceedings of the Indo-Pacific Fisheries Council, 8(2), pared for the Symposium on Coastal Aquaculture, 26-31. Cochin, India, 12-18 January 1980. Cochin, India, PCARR (Philippine Council for Agriculture and Marine Biology Association of India, Abstract 291. Resources Research). 1977. Philippines recommends Neilson, B.J. 1978. Engineering considerations in the for mussels and oysters. Los Banos, Philippines, design of oyster depuration plants. Proceedings of PCARR. 42 p. the National Shellfish Association, 68. 84 p. Perera, M.M., and Arudpragasam, K.D. 1966. Ani­ Ng, F.O. 1979. Experimental culture of a flat oyster mals living in association with Ostrea irrginica ( Ostrea folium L.) in Malaysian waters. Malaysian (Smel) at Batticaloa. Ceylon Journal of Science, Bio­ Agricultural Journal, 52(2), 103-113. logical Section, 6(1), 20-25. 1980. Occurrence of a flat oyster Ostrea folium Phillips, D.J. H. 1977. Use of biological indicator organ­ Linnaeus in Malaysian waters. Malaysian Agricul­ isms to monitor trace metal pollution in marine and tural Journal, 52(3), 308-314. estuarine environments - a review. Environmental Nikolic, M., Bosch, A., and Alfonso, S. 1976. System Pollution, 13, 281-317. for farming the mangrove oyster ( Crassostrea rhizo­ Pillai, C.T. 1980. Microbial flora of mussels in the phorae Guilding, 1828). Aquaculture, 9, 1-18. natural beds and farms. In CM FRI, Coastal Aqua­ Obusan, R.A., and Urbano, E.E. 1968. Tahong-food culture: Mussel Farming Progress and Prospects. BIBLIOGRAPHY 89

Cochin, India, CMFRI, Bulletin 29, 41-43. Rao, K.S., Sivalingam, D., and Unnithan, K.A. 1980. Pillay, T.V.R., ed. 1972. Coastal aquaculture in the Observations on the settling of spat and growth of lndo-Pacific region. West Byfleet, Surrey, England, Crassostrea madrasensis in Vaigai estuary at Athan­ Fishing News (Books) Ltd. karai. Paper prepared for the Symposium on Coastal Pinto, L., and Wignarajah, S. 1980. Some ecological Aquaculture, Cochin, India, 12-18 January 1980. aspects of the edible oyster Crassostrea cucullata Cochin, India, Marine Biology Association of India, (Born) occurring in association with mangroves in Abstract 98. Negombo Lagoon, Sri Lanka. Hydrobiologia, Rao, K.V. 1970. Pearl oysters of the Indian region. In 69(1-2), 11-19. Marine Biology Association of India, Proceedings of Purushan, K.S., Gopalan, U.K., and Rao, T.S.S. 1980. a Symposium on Mollusca. Cochin, India, Marine Raft culture experiment on the edible oyster Crassos­ Biology Association of India, 3, 1017-1028. trea madrasensis (Preston) in Cochin backwater. Rao, K. V., Kumari, L. K., and Qasim, S.Z. 1976. Aqua­ Paper prepared for the Symposium on Coastal culture of green mussel Mytilus viridis L.: spawning, Aquaculture, Cochin, India, 12-18 January 1980. fertilisation and larval development. Indian Journal Cochin, India, Marine Biology Association of India, of Marine Sciences, 5, 113-116. Abstract 173. Rasalam, E.J., and Sebastian, M.J. 1980. Lime-shell Qasim, S.Z., Parulekar, A.H., Harkantra, S.N., fisheries of the Vembanad Lake, Kerala. Journal of Ansari, Z.A., and Nair, A. 1977. Aquaculture of the Marine Biology Association of India, 18(2), green mussel Mytilus viridis L.: cultivation on ropes 323-355. from floating rafts. Indian Journal of Marine Sci­ Rees, C.B. 1950. Identification and classification of ences, 6, 15-25. lamellibranch larvae. Hull Bulletin of Marine Ecol­ Qiu, L.-Q. 1982. Oyster culture techniques in Guang­ ogy, 3, 73-104. dong. Paper prepared for the Bivalve Culture Work­ Rho, G. Y., and Pyen, C.K. 1977. Experimental studies shop, Singapore, 16-19 February 1982. 12 p. on the seed collection of Anadara broughtoni Quayle, D.B. 1969. Pacific oyster culture in British (Schrenk). Bulletin of the Korean Fisheries Research Columbia. Ottawa, Canada, Fisheries Research and Development Agency, 16. 16 p. Board of Canada, Bulletin 169. 192 p. Rosell, N .C. 1981. Mariculture of Ka pis, Placuna pla­ 1975. Tropical oyster culture: a selected bibliog­ centa. A pilot study. Terminal report. Manila, Philip­ raphy. Ottawa, Canada, International Development pines, University of the Philippines National Science Research Centre, IDRC-052e. 40 p. Development Board Project 7609 Ag. 34 p. 1980. Tropical oysters: culture and methods. Rosenberg, E. 1975. Economic appraisal of commercial Ottawa, Canada, International Development oyster farming in Fiji. Suva, Fiji, Ministry of Agri­ Research Centre, IDRC-TS17e. 80 p. culture, Fisheries and Forests, Economic Planning Quayle, D.B., and Bernard, F.R. 1968. Oyster purifica­ and Statistics Division (manuscript). tion study: I. Incidence and enumeration of coliform Rougerie, F., and Ricard, M. 1980. Elements du regime bacteria in the Pacific oyster. Ottawa, Canada, hydrologique de la Baie de Port-Phaeton, ile de Fisheries Research Board of Canada, Manuscript Tahiti, Polynesie Fran\:aise. Dakar, Senegal, Office Report Series 973. 21 p. de la recherche scientifique et technique outre-mer 1976. Purification of basket-held Pacific oysters in (ORSTOM), Note et Documents d'Oceanographie the natural environment. Proceedings of the 1980-23. 33 p. National Shellfisheries Association, 66. 7 p. Roy, R.N. 1977. Red tide and outbreak of paralytic Rabanal, H.R., et al. 1977. Shellfisheries of Thailand. shellfish poisoning in Sabah. Medical Journal of FAO/UNDP South China Sea Fisheries Develop­ Malaysia, 31(3), 247-251. ment and Cooperative Programme, SCS/ 77 /WP/ 61. 48 p. Salafranca, E .S. 1953. Bacteriological survey of the Rajan, S.J. 1980. Experiments on submerged raft for oysters and shellfish-growing waters of the Bina­ open sea mussel culture. In CMFRI, Coastal Aqua­ kayan oyster farm of the Bureau of Fisheries. Philip­ culture: Mussel Farming Progress and Prospects. pine Journal of Fisheries, 2, 26-39. Cochin, India, CMFRI, Bulletin 29, 46-47. Silas, E.G. 1980. Mussel culture in India - constraints Ranade, M.R. 1964. Studies on the biology, ecology and prospects. In CMFRI, Coastal Aquaculture: and physiology of the marine clams. Bombay, India, Mussel Farming Progress and Prospects. Cochin, University of Bombay. 266 p. (PhD dissertation). India, CMFRI, Bulletin 29, 51-56. Ranade, M.R., and Ranade, A. 1980. Mussel produc­ Silas, E.G., et al., ed. 1980. Coastal aquaculture: mussel tion and economics at Ratnagiri. Paper prepared for farming progress and prospects. Cochin, India, the Workshop on Mussel Farming, Madras, India, CMFRI, Bulletin 29. 56 p. 25-27 September 1980 (mimeo). Silas, E.G., and Rao, P. V. 1980. Workshop on mussel Rangarajan, K., and Narasimham, K.A. 1980. Mussel farming - an action plan for R & D programmes. farming on the east coast of India. In CMFRI, Coastal Cochin, India, Central Marine Fisheries Information Aquaculture: Mussel Farming Progress and Pros­ Service, T and E Series 23, 10-13. pects. Cochin, India, CMFRI, Bulletin 29, 39-41. Sindermann, C.J., ed. 1977. Disease diagnosis and con­ Rao, K.S. 1974. Edible bivalves: mussels and oysters. In trol in North American marine aquaculture. New Nair, R. V., and Rao, K.S., ed., Commercial Mol­ York, USA, Elsevier. 329 p. luscs of India. Cochin, India, CMFRI, Bulletin 25. Singh, S.M., and Zouros, E. 1981. Genetics of growth 90 BIVALVECULTURE

rate in oysters and its implications for aquaculture. land, Colonial Office, Fisheries Publication 14. 36 p. Canadian Journal of Genetic Cytology, 23(1), Varghese, M.A. 1976. Windowpane oyster (Placenta 119-130. placenta (Linn.)) of the Gulf of Kutch. Seafood Sivalingam, S. 1962. Bibliography on pearl oysters. Export Journal, 8(5), 25-28. Colombo, Sri Lanka (Ceylon), Department of Velez, A., and Epifanio, C.E. 198 l. Effects of tempera­ Fisheries, Fisheries Research Station, Bulletin 13. ture and ration on gametogenesis and growth in the 21 p. tropical mussel, Perna perna (L.). Aquaculture, Sivalingan, P.M. 1977. Aquaculture of the green mus­ 22(1-2), 22-26. sel, Mytilus viridis Linnaeus, in Malaysia. Aqua­ Venkataraman, R., and Sreenivasan, A. 1955. Mussel culture, 11, 297-312. pollution at Korapuzha estuary (Malabar), with an Souness, R., Bowrey, R.G., and Fleet, G. H. 1979. account of certain coliform types. Indian Journal of Commercial depuration of the Sydney rock oyster, Fisheries, 2(2), 314-324. Crassostrea commercialis. Food Technology in Aus­ Victor, A.C.C. 1980. Ecological conditions of the pearl tralia, December, 531-537. culture farm off Veppalodai in the Gulf of Mannar. Sreenivasan, P. V. 1980. Growth of clam Meretrix casta Paper prepared for the Symposium on Coastal (Chemnitz) transplanted in the Vellar estuary. Paper Aquaculture, Cochin, India, 12-18 January 1980. prepared for the Symposium on Coastal Aquaculture, Cochin, India, Marine Biology Association of India, Cochin, India, 12-18 January 1980. Cochin, India, Abstract 28. Marine Biology Association of India, Abstract 100. Wade, B., Brown, R., Hanson, C., Alexander, L., Hub­ Stickney, R.R. 1979. Principles ofwarmwater aquacul­ bard, R., and Lopez, B. 1980. Development of a ture. New York, USA, John Wiley and Sons. 375 p. low-technology oysterculture industry in Jamaica. Tan, W. H. l 975a. Effects of exposure and crawling Gulf and Caribbean Fisheries Institute Proceedings, behaviour on the survival of recently settled green 33,6-18. mussels (Mytilus viridis L.). Aquaculture, 6, Walker, N. P., and Gates, J.M. 198 l. Financial feasibil­ 357-368. ity of high density oyster culture in saltmarsh ponds l 975b. Egg and larval development in the green with artificially prolonged tidal flows. Aquaculture, mussel, Mytilus viridis Linnaeus. Veliger, 18(2), 22(1-2), l l-20. 151-155. Watne, P.R. 1974. Culture of bivalve molluscs: 50 years 1977. Note on the taxonomy of the edible green experience at Conwy. West Byfleet, Surrey, England, mussel Mytilus viridis Linnaeus= Perna viridis Fishing News (Books) Ltd. 173 p. (Linnaeus) (Mollusca: Bivalvia): abstract. Journal of Webber, H.H., and Riordan, P.F. 1976. Criteria for the Singapore National Academy of Science, 6(1), candidate species for aquaculture. Aquaculture, 7, 13-14. 107-123. Tan, W. H., and Lim, L. H. 1982. Tolerance to and Wood, P.C. 196 l. Principles of water sterilisation by uptake of lead in the green mussel Perna viridis (L.). ultraviolet light and their application in the purifica­ Paper prepared for the Bivalve Culture Workshop, tion of oysters. Fishery Investigations, Series l, Sal­ Singapore, 16-19 February 1982. 29 p. mon and Freshwater Fisheries, Great Britain Minis­ Tang, T. P. 1982. Status of the Sa bah shellfish culture. try of Agriculture, Fisheries and Food, 23(6). 48 p. Paper prepared for the Bivalve Culture Workshop, Worth, G.K., Maclean, J.L., and Price, M.J. 1975. Singapore, 16-19 February 1982. 5 p. Paralytic shellfish poisoning in Papua New Guinea, Tanittha Chongpeepien. 1982. Reproductive cycle of 1972. Pacific Science, 29(1), 1-5. mussel (Mytilus smaragdinus) at Samaekao, Cha­ choengsao Province. Paper prepared for the Bivalve Yamamoto, G. 1964. Studies on the propagation of the Culture Workshop, Singapore, 16-19 February scallop, Patinopecter yessoensis (Jay), in Mutsu Bay, 1982. 11 p. Japan. Ottawa, Canada, Fisheries Research Board of Tham, A.K., Yang, S.L.,and Tan, W.H. 1972. Experi­ Canada, Marine Resources Protection Association, ments in coastal aquaculture in Singapore. In FAO, Booklet 6. 77 p. Coastal Aquaculture in the lnd'o-Pacific Region. Yap, W.G. 1978. Settlement preference of the brown West Byfleet, Surrey, England, Fishing News mussel Modiolus metcalfei and its implication on the (Books) Ltd, 375-383. aquaculture potential of the species. Fisheries Thomson, J.M. l 954a. Genera of oysters and the Aus­ Research Journal of the Philippines, 3(1), 65-70. tralian species. Australian Journal of Marine and Yap, W.G., et al. 1979. Manual on mussel farming. Freshwater Research, 5(1 ), 132-168. Tigbauan, lloilo, Philippines, Southeast Asian l 954a. Handbook for oyster farmers. Australia Fisheries Development Center, Aquaculture Commonwealth Scientific and Industrial Research Department, Aquaculture Extension Manual, 6. Organization, Division of Fisheries and Oceano­ 17 p. graphy, Circular 3. 21 p. Young, A. L. 1980. Larval and postlarval development Van Someren, V.D., and Whitehead, P.J. 1961. Inves­ of the windowpane shell, Placuna placenta Linnaeus tigation of the biology and culture of an East African (Bivalvia: Placunidae), with a discussion on its natu­ oyster Crassostrea cucullata (Born). London, Eng- ral settlement. Veliger, 23(2), 141-148.