Molluscan aquaculture is an important form of mariculture globally and in India. Major mollusks farmed include oysters, mussels, pearl oysters, clams, and scallops. India farms species like the green mussel, Indian backwater oyster, and blood clam. Farming methods include bottom culture, stake/pole culture, rack/raft culture, and longline culture. Site selection factors and proper farming techniques are important for successful molluscan aquaculture. Global production of mollusks from aquaculture was over 14 million tonnes in 2006.

1. Molluscan
Aquaculture
 Submitted to  Submitted by
Prof. (Dr.) B Madhusoodana Kurup Judine John Chacko
Director, 4th Semeseter
School of Industrial Fisheries (SIF), MSc. Industrial Fisheries,
CUSAT S.I.F

2. Introduction
 Mariculture is the rearing of aquatic organisms
under controlled or semi controlled condition in
coastal and offshore waters where salinity is
maximal and not subject to significant daily or
seasonal variation.
 Mollusk farming is a type of mariculture done in
open sea water on racks, rafts or longlines.
 Oysters, calms, mussels ,scallops and abalones
are the major group of mollusks farmed.

3.  The commercial imporstance of mollusc culture
is food security, pearl production, lime
manufacture etc..
 In 1984, molluscs accounted for approximately
35% of the total production of coastal
aquaculture in terms of gross weight in the
region (Shang, 1986).

4. Global status
 In 2006, molluscs accounted for the second-
largest share, 14.1 million tonnes (27 percent of
total production), worth US$11.9 billion.
(SOFIA 2008).
 Major countries farming mollusk are China,
Indonesia, Malaysia, Philippines, Singapore,
South Korea, Sri lanka, Taiwan and Thailand.

6. Site Selection
Success of farming depends on proper site
selection.
 Area location- Cockles, Clams culture ground should
be located in areas where strong winds do not prevail.
Culture systems such as poles, racks are placed in low
tide area.
 Water depth – Water depth range from 1- 15 m as
mean tide level.
 Water movement – Water current of 0.02 -0.1 m/sec
suitable for bottom culture and stronger for
hanging methods.
 Turbidity – Minimum sechhi disc reading 15cm.

7.  Salinity – 24-31 ppt
 Bottom slope – 5-15 ˚ seaward slope is
preferred for bottom culture.Muddy bottom for
mussels and rocky or coralline substrate for
oyester.
 Food availability – Phytoplankton availability.
 Pollution – Toxic waste can contaminate
mollusk meat so pollution free areas should be
selected.

8. Cultured Species
Perna viridis
Crassostrea madrasensis

9. Pinctada fucata
Haliotis variata

10. Anadra granosa

11. Species description
 Oysters
 Oysters are one of the most valued seafoods and are farmed
extensively.Nearly 12 species are commercially popular. In
India , Crassostrea madrasensis , C gryphoides, C, rivularis
and Saccostrea cucullata are the main species and
C .madrasensis is the most preffered for farming.
 Racks and rens are used for farming and culture period is 7-
10 months
 C.gryphoides- 17cm ; Saccostrea cucculata -20cm
 Estimated average production 2.5 tonnes from 500 rens.
(BFFDA)

12.  Mussels
 Mussel farming is the one of the popular mariculture
operation in the temperate countries.
 Cultured 9 different species belonging to genus Perna and
Mytilus.
 In India 2 species Perna viridis and P. indica are extensively
farmed.
 Culture practice – Pole culture, Rack culture and raft culture
 Farming up to 4-8 months.
 P. indica and P . viridis reach about 63cm and 54cm length in
one year.
 Estimated average production is 15kg/m rope/5 months.

13.  Pearl Oyster
 The pearl oyster belong to the genus Pinctada.
 Six species are found in India; Pinctada margeritifera,
P.chenanitzii, P.sugillata, P.anomioides and P.atropurpurea.
 The pearl oyster are reared for production of cultured pearls.
 The nucleues implanted oysters grow in the farm and secrete
the mother of pearl around the nucleus.
 Prevailing culture methods are Raft culture and on bottom
culture and cages are used to protect oyster.

14. Pearl implantation
1. Selection and conditioning
 1.5 to 2 yr old oyster with not less than 25gm are selected for
implantation.
 Oysters are arranged in a container with its hinge point
downwards.
 Narcotization of selected oyster by sprinkling menthol in the
seawater.
 Insertion of a small wooden peg between the 2 valves to
facilitate nucleus implantation.
2. Preparation of graft tissue
 Select healthy non narcotizd oyster and cut the mantle strip into
5 cm length and 0.5cm width.
 Remove mucous and mussel from the mantle and cut the
mantle strip into 20 – 25 pieces of 2-3 mm squares
 Keep cell live by adding azumin/eosin solution in sterilised sea
water

15. Implantation
3. Implantation
 The graft mantle piece is placed in th gonad near the
intestinal loop through an incision and placing the
sterilized nucleus on the graft mantl piece.
4. Convalescence
 Placing the implanted oyster in fresh seawater with mild
circulation for 2-3days.
 Maintaining water quality by water exchange.
 Removing dead oysters and shifting the healthy
implanted oysters to the natural environment.

16. Clams
 Clams or cockles for a valued item of food in many countries.
 Clams under commercial production are Venerupsis sp., Meretrix sp. ,
Mercentrica sp. and Anadra sp. And in India the important species are
Villorita cyprinoids, Paphia malabarica, Meritrix casta and Anadra
granosa.
 Simplest system of culture is the transplantation of seed growing beds
with sandy bottom in the shallow intertidal areas.Pens are also used.
 Experimental culture of Anadara granosa , Villorita cyprinoids and
Meretrix meritrix were done in Kakinada, Karnataka and Kerala
respectively.
 Average production rate is 39-41.6 tonnes/ ha/ 5.5months for the blood
clam culture.

17. Scallops
 Commercial scale production is limited mainly to China and
Japan.
 The major species cultured are Chlamys barrei, C.nobills,
Placopecten magellanicus and Argopecten irradians.
 Grow out is by planting in suitable beds and spats are released
during summer months.
 Stocking density – 5-6nos./m2.
 In longline and raft system stocking density is 20
nos./compartment.
 Thy reach marketable size in 1.5-2 yrs.

18. Abalones (Gastropod)
 Abalones have soft meat and are capable of producing good
quality rainbow colour pearls.
 USA , Mexico , South Africa, Australia , China, Taiwan,
Ireland etc are the major abalone farming countries. India has
not yet started farming abalones commercially.
 Babylonia spirata(whelk) is a common species cultured.
 Bottom culture with cages are used for farming.
 Stocking density is 150 larvae /litre and growth of juvniles is
0.06mm/day
 Culture period is 18 months were the organism attain 1010g
weight.

19. Farming methods
 Basic method
 Bottom culture or broadcast technique
 Off bottom culture technique
 Stake or pole method
 Rack
 Raft
 Longline

20. Bottom culture
 Mainly done in Phillipines, USA, Holland and
France.
 Simplest way of farming Oyster and Clam.
 Oyster shells and bamboo splits are used as spat
collectors or clutches.
 Clams are protected from the predators through
the use of screned boxes and trays with net
coverings.

21. Bottom culture

22. Pole or Stake culture
 France and Philippines are the major countries doing
pole or stake culture.
 Oak or bamboo poles are used for stake culture.
 Poles with 3 m length and 20cm diameter are driven
into the sea bed with 1-2 m exposed above the ground
and spaced 1 m apart.
 Seed or spats are wrapped around the poles.
 Harvesting is done after 5-7months by pulling up the
pole and the mussels are striped off using an iron rod.

23. Rack or Ren method
Rack and string method
 The racks are constructed at 1-1.25m depth.
 Rack is a fixed structure comprising several wooden poles
vertically driven into the substratum over which a wooden frame
is made at a height of 0.5m above the water level.
 Nylon ropes or strings with cocofibres or empty oyster shells
attached at 10 cm interval.
 The spat will attach the substrate and grows.
Rack and tray
 Cultch free spat are transferred to 40x40x10cm size trays at a
density of 150-200 seed /tray.
 The tray is suspended from rack.

24. Suspended rack culture

26. Raft method
 In raft mthod, frames are floated using any
floating structures or rafts and are held in a tray
or stringed.
 Raft can be of any shape or material , usually oil
drums are used as floats.
 Rafts are anchored to the bottom and each raft
carries 200-300 hanged ropes.
 Harvesting is done by pulling up the ropes and
giving a vigorous shake to remove the oysters.

28. Long line method
 Long line culture is an alternative to raft culture
where areas less protected from wave action.
 A long line is supported by a series of small
floats joined by a cable or chain and anchored at
the bottom on both end is employed.
 Spats collected are suspended on ropes or
strings on the line.

29. Longline culture

30. Depuration
 The process of purification by which the
mussels are rendered free of harmful materials
or to remove toxic metals is called depuration.
 Depuration can be done simply by starving the
bivalves in clean and filtered sea water for a
certain period of time.

32. References
 Agarval, V.P, 2000. Aquaculture Science, S.R Scientific
Publication, Agra , 321-341 p.
 Narasimham, K.A, Molluscan fisheries of India, B.R
Publishing Corporation, Delhi, 56- 98 p.
 John, S.L, 1998. Aquaculture, Farming aquatic plants
and animals, Blacwell publishing ,USA, 443-465 p.
 Handbook of fisheries and aquaculture , 2006 ,ICAR,
New Delhi, 406-422 p.
 www.fao.org Molluscan aquaculture practices.