Prepared for the
Pearl Oyster Farming and
Pearl Culture Training Course
conducted by the
Central Marine Fisheries Research Institute
at Tuticorin, India
and organized by the
Regional Seafarming Development and
Demonstration Project (RAS/90/002)

February 1991

Training Manual 8


Pearls, one of the highly esteemed gems, are very valuable due to the high demand and prices for them. Several countries bordering the Indian and Pacific Oceans and some countries along the Eastern Atlantic Ocean have pearl oyster resources. Many of these countries, particularly those in Asia, are very much interested in pearl oyster farming and pearl culture. Japan stands foremost in the two fields having developed technologies and innovations in the field.

The techniques of pearl oyster farming and pearl culture are not widely known. There is a need to promote more widely the techniques and relevant information on the bionomics of pearl oysters.

In India, interest in pearl culture began at the start of this century. Several studies have been conducted by the Madras Fisheries Department in the 1930s. In 1972, the Central Marine Fisheries Research Institute (CMFRI) took up intensive research on pearl culture at Tuticorin achieving a breakthrough in July 1973 when it produced free spherical cultured pearls by employing the mantle graft implementation technique. Since then intensive research has been carried out by the Institute on pearl formation, pearl oyster biology and ecology, and hatchery techniques for production of pearl oyster seed. Considerable information of applied value has been obtained.

The development of the pearl oyster hatchery technology in India in 1981 opened the way for large and commercial scale culture of this bivalve species. Based on the technical know-how provided by the CMFRI, a company has been established at Tuticorin to produce cultured pearls.

In view of the keen-interest shown by countries in the region, the FAO/UNDP Regional Seafarming Development and Demonstration Project (RAS/90/002) requested the Indian Council of Agricultural Research (ICAR), New Delhi to conduct a training programme on "Pearl Oyster Farming and Pearl Culture" at the Central Marine Fisheries Research Institute in Tuticorin, to train personnel from different countries. In line with this training course, this training manual was prepared. This manual deals with various aspects of pearl oysters, pearl oyster farming, pearl production technology, etc. The Manual is designed for technicians as well as entrepreneurs.

The effort by Mr. A. Chellam, Dr. A.C.C. Victor, Mr. S. Dharmaraj, Mr. T.S. Velayudhan and Dr. K. Satyanaryana Rao in preparing and editing the manual is acknowledged. I would like to thank Mr. Chen Foo Yan, Coordinator of the Seafarming Development and Demonstration Project, and his staff, particularly Mr. Pedro Bueno, Mr. Alessandro Lovatelli and Prof. H.P.C. Shetty for further editing and publishing the manual.

Dr. P.S.B.R. James
Central Marine Fisheries Research
Institute, Cochin, India

National Coordinator
Regional Seafarming Development and
Demonstration Project (RAS/90/002)

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Pearl culture in India

1.1 Introduction


Taxonomy and distribution

2.1 Taxonomy
2.2 Distribution


Morphology and anatomy

3.1 Morphology

3.1.1 Shell features
3.1.2 Shell structure

3.2 Anatomy

3.2.1 Mantle
3.2.2 Foot
3.2.3 Byssal gland
3.2.4 Muscular system
3.2.5 Digestive system
3.2.6 Respiratory system
3.2.7 Circulatory system
3.2.8 Excretory system
3.2.9 Nervous system
3.2.10 Reproductive system


Biology and ecology

4.1 Biology

4.1.1 Food and feeding habits
4.1.2 Age and growth
4.1.3 Reproduction

4.2 Ecology


Hatchery techniques for seed production

5.1 Artificially reared spat

5.1.1 Hatchery building
5.1.2 Seawater management
5.1.3 Aeration

5.2 Live food production

5.2.1 Phytoplankton

5.3 Broodstock handling and spawning

5.3.1 Broodstock maintenance
5.3.2 Spawning
5.3.3 Fertilization
5.3.4 Early development and larval rearing

5.4 Larvae and spat handling

5.4.1 Larval rearing conditions
5.4.2 Spat production
5.4.3 Feeding
5.4.4 Transplantation
5.4.5 Survival


Pearl oyster farming

6.1 Selection of culture sites

6.2 Environmental conditions

6.2.1 Temperature
6.2.2 Salinity
6.2.3 Bottom
6.2.4 Depth
6.2.5 Silt load
6.2.6 Water current
6.2.7 Primary productivity

6.3 Supply of oysters

6.4 Rearing methods

6.4.1 Raft culture
6.4.2 On-bottom culture

6.5 Rearing containers

6.5.1 Culture of mother oysters
6.5.2 Juvenile rearing


Biofouling and predation

7.1 Biofouling organisms

7.1.1 Barnacles
7.1.2 Ascidians
7.1.3 Bryozoans
7.1.4 Molluscs
7.1.5 Sponges
7.1.6 Other organisms

7.2 Boring organisms

7.3 Predator organisms

7.4 Control measures

7.4.1 Fouling
7.4.2 Boring
7.4.3 Predation


Culture system

8.1 Culture operations


The mantle

9.1 Mantle structure

9.1.1 Marginal mantle
9.1.2 Mantle isthmus
9.1.3 Pallial mantle
9.1.4 Central mantle


The surgery

10.1 Surgical instruments
10.2 Nucleus
10.3 Selection of oysters
10.4 Graft tissue preparation
10.5 Conditioning for surgery
10.6 Surgery


Pearl formation

11.1 Natural pearl formation
11.2 Cultured pearl formation


Post-operation culture

12.1 Culture conditions


Production of cultured pearls

13.1 Development of implantation technique

13.2 Nucleus retention and pearl production

13.3 Pearl harvesting


Improvement of pearl quality

14.1 Measures for enhancing pearl quality

14.1.1 Oyster selection
14.1.2 Narcotization of oyster
14.1.3 Graft tissue preparation
14.1.4 Implantation
14.1.5 Oyster convalescence
14.1.6 Tool maintenance

14.2 Colour of pearls




Figure No.

  1. World distribution of pearl oysters.

  2. Section of the shell of Pinctada fucata. C.L.= conchiolin layer; P.L.= prismatic layer; and N.L.= nacreous layer.

  3. Anatomy of Pinctada fucata. 1) Mouth; 2) oesophagus; 3) stomach; 4) left labial palp; 5) left inner labial palp; 6) crystalline style; 7) liver; 8) digestive diverticula; 9) descending intestine; 10) ascending intestine; 11) rectum; 12) anal papilla; 13) byssal gland; 14) nucleus implanted in the gonad.

  4. (A) Culture raft constructed with teak poles; (B) A FRP styrofoam buoy; (C) A mild steel buoy, and (D) Oyster long-line culture system.

  5. Section of oyster mantle. (1) Central mantle; (2) Pallial mantle; (3) Marginal mantle. I.F.= inner fold; M.F.= middle fold; S.F.= shell fold; P.G.= periostracal groove; and P.S.= periostracal secretion.

  6. Steps in graft tissue preparation. (A) mantle tissue when removed from an oyster (p.m.= pallial mantle and m.m.= marginal mantle); (B) trimming of the margins to remove marginal mantle and inner muscular tissue; (C) further trimming to obtain ribbons of pallial mantle; and (D) cutting of the ribbon into small sections.

  7. Process of pearl formation. (A) round and half natural pearls; (B) half cultured pearl; and (C) round cultured pearl with an artificially implanted nucleus.


Plate No.

  1. (A) Pinctada fucata and (B) Pinctada margaritifera.

    Cont'd. (C) Pinctada chemnitzii and (D) Pinctada sugillata.

    Cont'd. (E) Pinctada anomioides and (F) Pinctada atropurpurea.

  2. (A) Inside view of the C.M.F.R.I. pearl oyster hatchery in Tuticorin, (B) Male oyster while spawning and (C) Pyriform oocytes.

    Cont'd. (D) Fertilized oocytes, (E) Early cleavage and (F) Morula stage.

    Cont'd. (G) Trochophore larvae and (H) Straight-hinge larvae.

  3. (A) Umbo larvae, (B) Eye-spot larvae and (C) Transitional stage.

    Cont'd. (D) Pediveliger larvae, (E) Plantigrade larvae and (F) spat.

  4. (A) A scuba diver diving to collect pearl oysters and (B) A culture raft floated with mild steel barrels.

    Cont'd. (C) A culture raft with FRP styrofoam buoys and (D) Oyster long-line culture.

  5. (A) A box-cage containing pearl oysters and (B) A frame netcage with oysters.

    Cont'd. (C) A netcage for rearing oyster spat of 3–10 mm in size and (D) Rearing netcage covered with velon screen.

  6. (A) Fouling organisms on adult oysters and rearing cage and (B) Oysters heavily encrusted with barnacles.

    Cont'd. (C) Damage caused by a boring sponge and (D) Cymatium cingulatum, a major pearl oyster predator.

  7. Pearl oyster surgical instruments.

  8. Implantation of a pearl oyster. (A) Opening of the oyster valves and (B) Insertion of the graft tissue.

    Cont'd. Implantation of a pearl oyster. (C) Implantation of the nucleus, and (D) General view of oyster surgery.