Shell fisheries

1. SHELL FISHERIES
Lecture-26

2. SHELL FISHERIES
1. Crustacean Fisheries
2. Source of Foreign Exchange
3. Prawn (Fresh Water Forms)
4. Shrimps (Marine Species)
5. 150 species of freshwater prawns
6. Most of them belongs to Genus
Macrobrachium
7. Most Common Giant Freshwater
Prawn , Macrobrachium rosenbergii

3. Giant Freshwater Prawn
(Macrobrachium rosenbergii)
 Found in rivers where there is tidal influence
 Brackish water
 Size (15cm female-25 cm male)
 Feed (Omnivorous) Insect larvae,small
worms, Molluscs, crustaceans,detritus
 Life Cycle(Four Phases)egg, larvae,post
larvae and adults
 Breeding (Natural in rainy season)In
captivity through out the year
 Fecundity (80,000-100,000 eggs ,Bright
orange in colour)
 Larvae require brackish water

4. Prawn Farming
1. Collection of seed from wild or collection
of ripe females
2. Larvel Tanks Rectangular concrete 5x2x1
with brackish water (initially 5ppt salinity
increased to 12ppt after hatching)
Larvae hatch 3–4 days
3. Change of water after 10 days, Feeding
with Artemia, Hen Egg and fish flash 28-
30 days to complete metamorphosis

5.  Nursery Ponds (2 kanal) Stocking @ 5000/m
sq when size becomes 2-4 cm shift to Grow-out
ponds
 Grow-out Ponds (4-20 kanals), Depth
(1m)Stocking 20,000/Acer, Salinity not more
then 4ppt
 Pond preparation same as fish pond,liming, cow
dung, fertilizers
 Culture Period (4-5 months) Marketable Size
(30-40 gm) Production 200-1200kg/ac/year
 Artificial Feeding 75% Animal and 25% Palnt
origin @ 5% of body wt. Poultry Feed may be
used.

6. Culture of
Marine Shrimp

7. Major Culture Species
Pacific white shrimp
Peneaus vannamei
Pacific tiger shrimp
Peneaus monodon

8. Native Range
P. vannamei
P. monodon

9. Pacific white shrimp biology
Food habits – benthic organizms, detritus
Preferred water temperatures – 25 to 30o C
Preferred salinity – 15 to 25 ppt
Sexual maturity - 1 year

10. Life Cycle
Adults spawn at
sea, the eggs and
larvae drift to
inshore estuaries
where the
juveniles grow.
Adults move back
to sea to spawn.

11. Marine shrimp have
been harvested from
coastal waters,
processed and
shipped as frozen
product for many
years. Shrimp
farmers took
advantage of the
infrastructure to
market cultured
shrimp.

12. Shrimp postlarvae can be
captured from the wild
Push nets

13. Shrimp postlarvae can be produced in
hatcheries Nauplii stage
Zoea stage
Mysis
stage

14. Mature adults for spawning
in hatcheries are captured
from the ocean or raised in
captivity.
Ocean
captivity broodstock

15. Wild and hatchery
produced postlarvae
are stocked into
earthen ponds for
grow-out

16. Ponds should be
built on salt
flats, which are
covered during
high tide twice a
month.
Mangrove forest
should be
preserved.
Mangroves are
flooded daily by the
high tides

17. Ponds are 5 to 10 ha in area, water depth
averages 1 m and bottoms are flat and slope
to a drain to aid shrimp harvest.

18. Ponds are
filled with
saltwater
pumped from
estuaries into
canals that
distribute
water to every
pond.
diesel pumps

19. Drain
structures are
“monks” or
sluice gates
which control
water level, top
or bottom water
release and
keep shrimp
from escaping
the pond.

20. Shrimp can be cultured:
1.Extensively
2.Semi-intensively
3.Intensively

21. Postlarvae enter
the pond with the
tide or are stocked
at < 4/m3.
Sometimes the
pond entrance is
screened to limit
entrance of
predators. Water is
not fertilized and
shrimp are not fed.
Extensive
culture

22. Semi-intensive culture
Postlarvae are stocked into ponds at 15
to 25/m3 and are fed daily. Some water
exchange is practiced to maintain water
quality.

23. Shrimp are fed sinking
pellets which are
distributed over the
pond surface. Feeding
trays are sometimes
used to help determine
shrimp appetite.

24. Intensive Culture
Shrimp are
stocked at 35 -
250/m2 in tanks
and small ponds
with heavy
aeration and
water exchange.

25. Ponds are fed daily
Shrimp are
sampled weekly
to check growth
rate
Intensive Culture

26. Expansion of
pond area leads to
poor water quality
and high shrimp
mortality
Water intake pipes
and effluent
release in Taiwan

27. Diseases have reduced the shrimp
harvest in many countries.
Black-spot disease
Taura virus

28. Shrimp are benthic animals and live on the
pond bottom. Pond bottoms should be dried
to oxidize organic matter in pond mud before
stocking shrimp. Reducing organic material
improves water quality.

29. Shrimp are harvested as they pass through
the sluice gate during pond draining.

30. Yields are:
1.Extensive – 500 kg/ha/crop
2. Semi-intensive – 1,000 to 1,500
kg/ha/crop
3. Intensive – 10,000 to 20,000
kg/ha/crop

31. Shrimp are transported to processors
that freeze the whole or deheaded
shrimp in blocks of water by size.

32. Most cultured shrimp is exported to the
U. S., Europe and Japan.

33. capture
74%
aquaculture
26%
3,081 mmt
1,087 mmt
The harvest of marine shrimp by wild
capture and aquaculture in 2000

34. World harvest of farmed marine
shrimp in 2000 was 1,087,111 MT
Ecuador
81000 MT
India
73,000 MT
China
114,000 MT
Thailand
204,000 MT
Indonesia
98,000 MT

35. The East produced 90% of the
world farmed marine shrimp
while the West produced 10 %.

36. Harvest of marine shrimp in the U. S.
in 2000 was 4,782 MT, less than 0.2 %
of world harvest.

37. Excellent markets and
ease of culture has made
shrimp one of the fastest
growing aquaculture
industries during the
past 20 years. THE END