1. Presented by
Satyaveer
Department of Fisheries Resources & Management
College of Fisheries Mangalore

2. • Introduction
• Status of molluscans production
• Culture of oysters
• Culture of clams
• Culture of Scallops
• Conclusion
OVERVIEW

3. Introduction
• Molluscs, bivalves
• Sedentary nature
• High nutritive profile

4. Oyster
• 11 species commercially popular
• Most important -Crassostrea gigas

5. Oyster farming in India
• Available oyster species - crassostrea madrasensis
-crassostrea gryphoides
-crossostrea rivularis
-saccostrea cucullata
• Preferable -crassostrea madrasensis

6. Crassostrea madrasensis

7. Crassostrea gryphoides Saccostrea cucullata

8. • Salinity- 15-35 ppt
• Free form pollution
• Depth -1.5-3 meters
• Mild current
• pH >7 & <8.5
• D.O ->3.5ml/L
• Access to market
REQUIREMENTS
Seed (Spat)
Site selection
natural hatchery

9. Spat collection
• Prerequisite for success of oyster farming
• Temperate and Subtropical countries spat is hatchery
reared.
• Tropical courtiers - wild.

10. Conti…..
• Branches of mangrove vegetation
• Coconut shelves
• Spilt bamboo poles
• Cement coated plywood
• Asbestas sheets
• Pvc tubes
• Bivalve shells- commonest,earlist.

11. Seed production
Brood stock
E.g. Narikal at sattar island (kerala)-CMFRI
2–3 years old
collected from natural bed
conditioning room with the temperature is low.
After 3or 4 weeks brood stock shift to the spawning tank

12. • Fed with mixed algae
• After 2 weeks they are induced spawn by slowly raising
the temperature.
• Gametes released into water & fertilization .
• Pedi veliger.
• Settle on the cultch.
• Grow one month (2-25mm length)in the hatchery &
then transfer to the farm.

13. Bottom Off bottom
Raft culture
stake culture
Rack culture
Long line
culture
Lattice method
Age-old practice
Sites where silting is low
Sea floor is firm
Grow -out period generally is 9-14 months.
Harvest sizes of 8-10 cm shell height.
E.g. Beach culture
In Mexico & along the gulf coast-C.virginica
Culture
Techniques

14. Beach culture

15. Raft culture
• Dimension -5 x 5 or 6 x 6 or 8 x 8 meter
• Stocking density -1st phase-3x104 /m2
- 2nd phase-275/m2

17. Rack culture
• Erecting vertical poles(2.4 m length ) at intervals of 2 m in two rows.
• Interconnected by cross poles of 2m length.
• 8 poles of length 5.5 -6.5 m are arranged to form a platform .
• Each rack is about 25 m2 .
• Accommodates 20 rectangular trays holding 3000-4000 oysters
• species - C.rhizophorae,C.madrasensis, C.echinata, C.belcheri and
S.cucullata.

18. Rack & Ren method
• Shell strings /Ren are suspended from the racks
• Rens are grown for period of 5-8 moths & harvest
• Avg production-2.5 tonnes/500 rens

19. Rack & tray method
• 25 mm spat transferred to trays (40x40x10cm).
• Stocking density -150-200 spat/tray.
• Spats have grown to a size 50 mm spats segregated &
transferred to -90x60x1cm tray.
• Estimated production-120 tonnes/tray.
• Culture period -5-8 months

20. Long line
• Dimension-20 meters
• Stocking density-1st phase-2x104 /meter
-2nd phase-200/meter

21. Bag culture
Large mesh bags containing oyster spat.
Attached to lines that are in turn staked to the beach in
the intertidal zone.
 more protected than those that are beach cultured

23. • Phylum: Molluscs,
• Class: bivalve
• Burrowing
• Shallow coastal waters
• Kerala clam production -72.5% ,Karnataka 12.5%.
Clam culture

25. clams mussels oysters
94.39 %
5.5%
0.3%

26. Cultivable clam species
• Families:
Arcidae,
Veneridae,
Corbiculidae
Tridacnidae

27. GAINT CLAM
Tridacna gigas
Length->1.3m
Weight-100kg
Life spawn->50 yrs.

28. Seed collection
• From the natural bed ,
• Hatcheries .
• Hand picking-low tide
• scoop net or a dredge - 2-5 mm mesh

29. Production of seed
CMFRI
• A.granosa,
• P .malabarica,
• Meretrix meretrix
• M.casta

30. A.granosa,

31. Meretrix meretrix

32. Meretrix casta

33. P .malabarica

35. Brooder
• 1-2 years
• About 30 adult clams - brood stock.
• Clean and remove contaminants from the surface
• Conditioning the clam

36. Conditioning- Out door FRP tank
Salinity25-30 ppt,
Temp 22-24oC
Feed-microalgae
Static water Flow throwgh

37. Spawning tank
Spawning induced by thermal stimulation (32oc ) or buffer
solution of 9.0 pH for 1-2 hours
After about 3 weeks of conditioning, the clams attain full
gonad development.
•Fertilization & veliger larvae

38. Larval rearing
larvae are reared at a
density of 5 larvae/ml of
seawater.
Stocking FRP tank
Fed with
unicellular microalga,
Isochrysis ,galbana is given
as food to the larvae from
day 2.

39. • Spat (2-5mm length)are transferred to 40x40x10 cm
cages,
• Stocking density-600spat/cage
• covered with fine velon screen mesh .
• cages are suspended from racks in shallow calm waters.
• In about 6 weeks the spat attain 10-15 mm length and
are ready for planting on the grow-out grounds.
Nursery rearing

40. • On the bottom –coastal waters
• 1-2 hours tidal exposure at low tide is desirable
• Substratum-M.casta on sandy bottom
-A.granosa- mud flats with greater proportion of
silt & clay.
• Pollution free
Selection of site

41. Farming in open coastal waters
• The ground is levelled and cleared of predators
• Fencing , Synthetic fibre net pens -hold the clams ,
predators away
e.g. Kakinada bay, split bamboo Screens of 0.3m
height

42. A. granosa
Malaysia
Seed -10-25mm length
Stocking density- 1000 to 2000/m2
- 300 seed of 20- 25mm/m2 optimum
Synthetic netting (10mm)
Culture period -5-6 months
Harvest- hand picking, hand operate
dredge.

43. Cont…
India
Kakinada Bay
Seed -21.8-25.1mm length,5.53-7.08 g
Stocking density- 140 to 175/m2
Synthetic netting (10mm)
Culture period -5-6 months
-weight 25.5 to 32.9g
-length 39.2 to 42.7mm
Harvest - hand picking, hand operate
dredge.
Craft -plank -built non- powered craft.

44. Farming in coastal ponds
Taiwan
Shrimp culture ponds are used for farming the dam Meretrix lusoria.
Thailand:
A. granosa is grown along with the shrimp in the shrimp culture ponds.
seeds are planted in the central elevated areas of the shrimp ponds .
Harveste after 5-6 months along with the shrimp.

45. Cont..
India:
P. malabarica
A. granosa - integrating clam farming with shrimp culture.
clams purity the water by reducing the sediment load.

46. Scallops Culture
• Scallop aquaculture is the commercial activity of cultivating (farming) scallops until
they reach a marketable size and can be sold as a consumer product.
• Wild juvenile scallops, or spat, were collected for growing in Japan as early as 1934.
• The first attempts to fully cultivate scallops in farm environments were not recorded
until the 1950s and 1960s.
• Traditionally, fishing for wild scallops has been the preferred practice, since farming
can be expensive.
• China and Japan account for about 90% of the reported production.

47. Cultured species
• Established commercial operations.
• Aequipecten opercularis (United Kingdom, northern France and Spain,
Norway)
• Argopecten irradians (China)
• Sub species A. irradians irradians (eastern USA)
• Sub species A. irradians concentricus (eastern USA)
• Argopecten purpuratus (Chile)

48. • Early commercial operations
• Argopecten ventricosus (Mexico)
• Chlamys islandica (Norway)
• Crassadoma gigantea (western North America)

49. Method of culture
• Spat collection
• Collection of wild spat has historically been the most common way
obtaining young scallops to seed aquaculture operations.
• There are a variety of ways in which spat can be collected. Most methods
involve a series of mesh spat bags suspended in the water column on a line
which is anchored to the seafloor.
• Spat bags are filled with a suitable cultch (usually filamentous fibers) onto
which scallop larvae will settle. Here larvae will
undergo metamorphosis into post-larvae (spat). Spat can then be collected
and transferred to a farm site for on-growing.

50. Hanging culture

51. Rope culture
• Rope culture is very similar in principle to ear hanging with the only
difference being the method of attachment.
• In rope culture, instead of scallops being attached by an ear hanging,
they are cemented by their flat valve to a hanging rope.
• This method results in a similar growth and mortality rates as ear
hanging but has the advantage of being able to set scallops from a small
size.

52. • Pocket nets
• Hog rigging
• Plastic trays

53. Bottom culture
• Methods of bottom culture can be used in conjunction with or as an
alternative to hanging culture.
• The main advantage of using methods of bottom culture is in the lower
cost of reduced buoyancy needs as equipment is supported by the
seabed. However, growing times have been noted as being longer in
some cases due to the loss of use of mid-water plankton.

54. Plastic bottom trays
• Plastic trays such as oyster cages can again be utilized in
bottom culture techniques.
• They provide simple and easy to use system. Plastic trays are
effective in large numbers but their size is limited by the growth
rates of scallops near the centre of cages due to reduced water
and food flow rates.

55. Wild ranching
• Wild ranching is by far the cheapest of all forms of scallop farming and
can be very effective when large areas of seabed can be utilized.
• However, there can often be problems with predators such
as crabs and starfish so areas must be cleared and then fenced to some
degree. However, clearing and fencing will not prevent settlement of
larvae of predators.
• Harvesting is usually done by dredge further reducing costs. On smaller
farms, however, divers may be employed to harvest

56. Fedding
• Scallops are filter feeders that are capable of ingesting living and inert
particles suspended in the water column. In culture, scallop diets contain
primarily phytoplankton that occur either naturally at a site or are
produced artificially in culture. Much research has been conducted into
what species of phytoplankton are most effective for inducing growth
(and particularly growth of the adductor muscle). Such research has
shown that of the species commonly used
in bivalve aquaculture, Isochrysis aff. galbana (clone T-Iso)
and Chaetoceros neogracile are the most effective.

57. Research paper 1

58. Summary
• Pearl oyster culture is unique because the product is gem not flesh and one
of the species that produce pearl is Pinctada maxima (Silver or Gold lip
pearl oyster). Stock for pearl oyster production can be collected from the
wild or hatchery. However, hatchery production is a better solution to
supply P.maxima for pearl production rather than just depend on wild
stocks. Spat from the wild or hatchery will be grown-out for pearl
production by longline or raft culture system method in ocean. Raft culture
provide a work platform to repair, clean and store culture tools, while,
longline culture has better design to deal with wave or wind exposure.

59. Conti ……
• There are identified different culture systems according different species
(for example between P.maxima and P.fucata) and locations. Several
constraints on P. maxima culture also identify such as biofouling
organisms, predations and diseases that can reduce productivity and pearl
quality. For example, mass mortalities of P.maxima occurred in Western
Australia due to viral infection and it disrupted the pearl oyster industry.
Therefore, several strategies are needed to mitigate those problems to
achieve maximal productivity by using good management culture practice.

60. Research paper 2

61. Summary
• We examined the impact of wave induced movement on two species of scallops
in suspended culture in the Golfo of Cariaco, Venezuela, by comparing growth of
juveniles in cages suspended at 6.5 m in depth using two methods. In one case
movement from wave action was transmitted to the cages from supporting buoys at
the surface, and in the other the supporting buoys were in deeper water, just above the
cages, so that the cages were only slightly affected by wave action. For the
scallop Euvola ziczac, which is normally found on sandy bottoms, the suspension
methods markedly affected growth. After a 31-day growout period, all measured body
parameters were markedly smaller for the scallops strongly affected by wave action
than for those less exposed to wave action.

62. Conti ……
• The differences were 27.0% for muscle mass, 28.7% for digestive gland mass, 24.6%
for the mass of remaining somatic tissues, 29.4% for gonadal mass, 13.1% for shell
mass and 8.4% for shell height. Survival was 72–75% for the scallops more strongly
affected by wave action compared to 94–100% for those less affected by wave action.
In contrast, parallel observations on Lyropecten nodosus, which is normally found on
rock and coral bottoms, showed no evidence of an effect of wave action on either
growth or survival. L. nodosus was probably less affected by wave action than E.
ziczac because its movement in the cages was likely reduced by its byssal attachment
and by its rugose and more flattened valves. For species such as E. ziczac, wave
induced movement of culture enclosures should be minimized either by choosing
protected sites or by using techniques that reduce the impact of waves.

63. Conclusion
• Different types culture techniques promoting and
increasing the molluscans production.
• oysters, clams and scallops are contributing great
portion to the molluscans production.
• Livelihood for many self help groups.

64. References
• Aquaculture :principles and practices.2nd edition black well
• Hand book of fisheries and aquaculture.ICAR.Pillay TVR