the PowerPoints are useful for fish farmers fishery, lectures, interested personnel and aquaculture students

1. Presented by
Magoti Ernest Ndaro
Dept. Of Animal, Aquaculture and Range Science

2. INTRODUCTION
• Mollusks are an important
source of food for human
consumption
• Contributed 14 MT in 2018,
27% of the total world
aquaculture production
• intensive and extensive
aquaculture scallop has been
reported since 1960s

3. Cultured species
• 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)
• Patinopecten yessoensis (Japan)

4. Habitat and biology
•scallops occur in
sheltered, shallow bays(30-
40m) and inlets adjacent
to rocky shores
•Protandrous
hermaphrodites maturing
initially as males and
changing sex to female as
they age

5. GLOBAL PRODUCTION
TREND OF SCALLOPS
•China account for 85%
of the world production
•Africa contributes less
than 2% globally
•In other continents, the
production is stabilizing
or decreasing (Europe)

6. TANZANIA PRODUCTION TREND OF
SCALLOPS
• scallop farming is not a major industry in Tanzania,
however there is less information about marketing of
scallops.
• Tanzania marketed frozen scallops (queen scallop), in
2022. United Arab Emirates was primary destination,
accounting for approximately 90% of total exports

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

8. PRODUCTION CYCLE OF SCALLOPS

9. Wild spat collection
• Branches of mangrove vegetation
• Coconut shelves
• Spilt bamboo poles
• Cement coated plywood
• Pvc tubes
• Bivalve shells- commonest,earlist.

10. Hatchery seed source
• Scallops 5–6 cm in shell
height are selected as breeders
• Fouling organisms attached
to the shells are removed and
cleaned by brushing
• If the ligament is damaged,
both shells of the scallop
would never close as usual and
the scallop soon dies.

11. Breeders
Culture Density
• A density of 80–100/m3
• water in tanks should be
renewed every day with pre-
heated water and sediment on
the bottom of tanks must be
removed and cleaned
• Dead scallops must be
removed in order to prevent
the rest from being infected
with disease

12. Food source for parent
Phaeodactylum tricornutum,
Isochysis galbana and
Thalassiosira pseudonana
Unicellular algae
early stage of rearing
P. tricornutum

13. Observation of Gonad
•gonadal index: G=(gw/sw)
100 %
•When reaches about 16 %
and the black film on the
surface of the gonad region
disappears, it means scallops
are about to spawn

14. Checking on Spawning
• appearance of bubbles on the water surface and
examine water under a microscope for the presence
of gametes.
• After spawning feeding must be stopped and aeration
increased, when the density of eggs reaches 30
eggs/ml, aeration must be stopped and the parent
scallops taken away from the tanks

15. Hatching
• water in the hatching tanks are
stirred with the swing boards for
30 minutes to prevent the eggs
from sinking to the bottom.
• The fertilized eggs can be normally
hatched in a salinity range of 17–
35 ppt.
• fertilized eggs develop into D-
shaped after22 hours swimming in
the water column

16. Larval
Cultivation
• The rearing density ranges from
5–15 larvae/ml.
• (16–21, 22–23 and 27–25°C),
300–800 lux, 18–36 ppt
• Isochrysis galbana, Dicrateria sp.,
Phaeodactylum tricornutum,
Platymonas sp. and Chlorella sp.
are the main food

17. daily feeding rate Where:
V1: volume of water containing unicellular
algae
V2: total volume of water in the rearing tank
C1: concentration of unicellular algae
C2: desired concentration of unicellular algae
in the rearing tank

18. Spat
Collection
• eye spot is an indication
for settling stage, once
appears larvae are sieved
and transferred into
another tank.
• The spat collectors are
then put into the tank for
larvae to settle on.

19. NURSERY
• 20 days after fertilization shell
height reaches 4–6 mm, spats can
be transferred to the sea.
• When spats have settled, the
rearing water temperature should
be lowered by 1–2 °C every day to
approximate the temperature of
the sea (acclimatization).
• The water temperature of the sea
area must be higher than 10 °C
when the spats are transferred

20. GROW-OUT CULTURE
OF SCALLOP
• the juvenile scallops are reared to
marketable size, takes about six
months
• Epiphytes and epi-commensal
animals affect growth of the scallop,
Silt is deadly to juveniles with shell
height <1 cm. The scallop grows faster
in slow current(velocity is 1–5 cm per
second).
• mortality ranges 20–30 and 5–10%
in early nursery and grow out.

21. CULTURE SYSTEM
Bottom
cages
Pearl nets Pearl
Lantern nets

22. Cont.…
Suspension cages Ear hanging

23. CHALLENGES AND
RECOMENDATIONS FOR SCALLOPS
FARMING
Biotoxins
Sea Scallop Farming Financials
Awareness in developing countries like Tanzania
Government

24. Thank
you