.
Scientific classification
2.Pon peparation
2.2.Topography of Pond
Scientific classification
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| common name:Giant tiger prawn | . | ||||||||||||||||||||||||
| Local name:Bagda chingri.See more | |||||||||||||||||||||||||
| Description | |||||||||||||||||||||||||
| Females can reach approximately 33 centimetres (13 in) long, but are typically 25–30 cm (10–12 in) long and weight 200–320 grams (7–11 oz); males are slightly smaller at 20–25 cm (8–10 in) long and weighing 100–170 g (3.5–6.0 oz).See more | |||||||||||||||||||||||||
| Culture method | |||||||||||||||||||||||||
In
generally, Penaeus monodon is
cultured in the coastal areas in our country and have a great value because of
its high market demand, high nutritional value, fast growth rate and
availability of fry or post larvae in natural resource.There are some important steps of culturing penaeus monodon.
1.Site selection
2.Pon peparation
Site selection
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The
selection of a suitable site always plays a major role in shrimp farming. The
selection is made on the basis of information on topography, ecosystem, and
meteorological and socio-economic conditions of the people in relation to farm
design, species computability and overall economic viability of the envisaged
activities. A few important criteria are here in suggested:
1.
For shrimp culture the soil type should be clay loam,
silty-clay, sandy-clay, or silty-loam because they hold water.
2.
Site should be such area where sunlight is available.
3.
The pond should
be free from flood area.
4.
Fertilizers and supplementary food should available.
5.
The pond should near at the road, market and home.
6.
Draining system should be ensured.
7.
Fry supply should be ensure.
Site should be free from industrial domestic or pesticide
pollution.
|
In any earthen pond culture system, the bottom soil
play a major role in pond yield. High organic matter content
in neutral soil often promotes higher primary productivity
and hence higher fish yield. Natural food organisms are
one of the most important food sources in ponds. It is
rich in protein, vitamins, minerals and other essential
growth elements that simple supplementary feed cannot
complete. Fish yield in pond can also be affected by the
presence of predators, deteriorating water quality and
improper pond management. Hence, pond preparation is a
first step towards ensuring a better pond production. See more
2.1. Pond Drying
2.1. Pond Drying
The drying
of the pond bottom is the most practical, easy and effective method of
eliminating undesirable species, organisms and materials in grow out ponds prior
to the culture operation.Pond drying process should apply in those areas where
there is an available source of water.
Pond should
dry the end of the dry season.
Pump
machine can be used for drying the pond.
If there is
no facilities of using pump machine, there will need physical labour.
There is another process of draining system by
which pond can also be dried. 2.2.Topography of Pond
Coastal
sites where the slopes run gently towards the sea are easier for pond
development requiring less financial inputs since excavation cost is minimal.
Filling and draining of water likewise is
easily facilitated by gravity. In areas where the above conditions are absent,
the use of mechanical pumps are required which again is uneconomic.
In Bangladesh, it has been observed in
polders in Satkhira, Khulna, that the surface level inside some of Ghers has
become higher than the outside due to heavy sediment deposition and this has
caused a failure for further shrimp culture in the area.
2.3.Soils of the grow out ponds
The types and texture of the soil of the chosen site should
be analyzed before setting on a site for shrimp farming.
Soil simples must be taken at random location, preferably
upto a depth of 0.5—. I m and subjected to physical and chemical tests to
measure the acidity, amount of organic load, level of fertility and physical
composition
The soil should have enough clay content
to ensure holding water in the ponds.
Good
quality dikes are usually built from sandy clay or sandy loam materials, which
harden, and compacted easily, clay loam or silty clay loam at pond bottom
promotes growth of natural food organisms i.e., planktons.
.
2.4.Tilling
Tilling
or ploughing of bottom soil improves soil quality by exposing subsoil to the
atmosphere. Thereby speeding up the oxidation process and the release of
nutrients are enhanced and are known as an desirable substances that are
already locked up in the soil, which is released through ploughing the soil and
make them available for primary productivity.
2.5.Leaching
When the pond soil is found to be acidic, it is normally leached. Flushing does this and washing the pond bottom with water to leach away undesirable metallic compounds like aluminium, iron and excess sulphur ions, which cause negative output in shrimp production.
2.6.Required Water Quality of the farm
- Water quality includes all the inherent physico-chemical and microbiological characteristics of water.
- In a selected site, pH of water preferably ranges from 7.5 to 8.5.
- Fluctuations in dissolved oxygen level should be predetermined and the oxygen level should not be lower than 4 ppm.
- The water should be turbid but not too turbid. Water with heavy silt load cause clogging of filter nets, sluice gate and increase sedimentation at the pond bottom
The water should be ideally rich in micro-organisms
(both plants and animals).
2.7.Salinity
Salinity
variation is considered as determinant fact in shrimp production in the coastal
farms. Optimum level varies from species to species. For instance, the tiger
shrimp (Penaeus rnonodon) grows
faster at 15-25 ppt. whereas white shrimp (Penaeus indicus) and (Penaeus merguensis) tolerate higher salinity ranges (24-40 ppt).
2.8.Tidal Fluctuations
Shrimp farming should have moderate tidal fluctuations
may range between 2 to 3m. In areas where the tidal range is greater than 4m,
this place may prove uneconomical to develop or operate as large and high pond
dikes will be required.
In areas where tidal range is less than one meter,
water management will be expensive requiring the use of pumps.
The knowledge of tidal range, the highest and lowest
water levels, available to farmers, they may build perimeter dike of desired
size and height to prevent flooding and even tidal bore of lower magnitudes.
The direction and strength of water current should be
known for making provisions for dike construction to reduce erosion.
The proposed site must not be adversely affected by
any industrial or agricultural pollution.
2.9
Liming Substances and liming process
The chemicals used for liming of soils
are the oxides, hydroxides and silicates of calcium or magnesium since these
are the ones capable of reducing acidity. They are given in table below
English
name
|
Local
name
|
Molecular
formula
|
Lime
stone
|
Patura
chun
|
Ca CO3
|
Slaked
lime
|
Koli chun
|
Ca(OH)2
|
Quick
lime
|
Pora chun
|
CaO
|
Dolomite
|
Dolomite
|
CaMg(CO3)2
|
Gypsum
|
Gypsum
|
CaSO4H2O
|
Doses of
lime:
The doses of liming depend upon the
pH of soil, age of pond and the type of lime. The power of quick
lime is two times than lime stone. Before use of lime the pH of soil
of the pond must be examine.
Table: Lime requirement at different pH levels of
soil
Soil pH
|
Amount of calcium oxide(Kg/ha)
|
||
Clay/loamy
|
Sandy/loamy
|
Sandy
|
|
4-4.5
|
3000
|
1500
|
1250
|
4.5-5
|
250
|
1200
|
1000
|
5-5.5
|
1500
|
1000
|
500
|
5.5-6
|
1000
|
500
|
250
|
6-6.5
|
500
|
500
|
200
|
6.5->
|
200
|
200
|
200
|
Process of use:
- During the pond preparation the solid pieces of lime should make powder in a bag.
- For wet method the lime should in a big pan of mud or alluminium pot.
- Then the required amount of lime should scatter in the whole pond including the dike equally.
It should be noticed that the whole pond is liming
equally
2.10.Control of undesirable organism and predator
The
control of undesirable organism and predator could be done by
1.
Physical method
2.
Chemical methodxz
*
Physical method*
In physical methods
¨
Drying the pond
¨
Installation of appropriate screens in the out let and
in let gates to prevent entrance of undesirable species
¨
Proper maintains of dikes
¨
Netting system: By coetaneous netting it is possible
to catch predator and undesirable species by gill net. But through the system
it should not be removed properly.
Chemical methods
By using
the chemical methods eradication of undesirable species is very effective, it
becomes less cumbersome, efficient and fast when using chemicals. In selecting
chemicals, which have in origin from plant-extracts, compounds are
biodegradable and in most cases contribute to the fertility of the pond size.
The commonly used chemicals which are-
Rotenone:
Commercial rotenone available in the
markets is in powder from containing 4-5% rotenone. Effective dosage for
commercial rotenone is-
-2g /m3 for eradicating
the common predator such as fin fishes and
-8g/m3 for eel and crabs.
Saponin:
It contains 10-15% saponin widely used to eradicate fin fishes without
toxic effect on crustaceans especially shrimp and prawn.
The effectiveness of saponin decreases with
the rate of decreasing salinity. Then the suggested dose is
-12 and 20g/m3 for
salinity above 15 ppt.
Calcium carbide: It is applied to control crabs and pour into the
crab hole along with water so that it activates calcium carbide to kill the
crab effectively.
Tobacco
dust: A dosage of 200 kg/ha
could be used to kill undesirable predators especially snails and ceephalopods,
it also kills mankind.
Amonium
sulphate: it is used as fertilizer and to eradicate undesirable predators
while used in combination with lime at dosage to 1 part of amonium sulphate to
5 parts of lime
2.11.Fertilization
The pond is fertilized to
promote and maintain the growth of phytoplankton
Two types
of fertilizer can be used. These are
1. Organic fertilizers:
a. Cowdung- 5 Kg/ha/day
b. Compost (Green manure)- 5 Kg/ha/day
2. In- organic fertilizers: a.
Urea-5-10 Kg/ha/day
b. TSP-5-10 Kg/ha/day
3.Identification
of Post-larvae (fry)
It has been observed that fry collectors sometimes mistakenly
identify the postlarvae of Panaeus
monodon.
However, identification of the
postlarvae can be made based on their morphological characteristics such as
shape of rostrum, number of rostral
teeth, relative length of anternnular flagelle, antennal spine, and presence of
dorsal spinules on the 6th abdominal segment.
The chrometophore
patterns on the 6th abdominal segment and on the telson and uropods are also
useful criteria to identify them.
The identifying points of shrimp are given below:
P. monodon
¨
A long blackish red or brown line present on the
ventral side of the fry.
¨
14-19 spot found just below the abdomin.
¨
8 pairs spine found at the edge of the telson.
¨
spinules on the 6th abdominal segment,
¨
antennal spine prominently present,
M. rosenbergii
¨
In front of the chephalothorax looks like
branches.
¨
At the joined point of abdomine found blue line.
¨
carapace longer than 6th abdominal segment.
¨
Inner antennular flagellum more than 2 times the outer
one, exceeding the latter by 3 distal segments.
¨
Chromatophores are thickly covered on the 6th
abdominal segment.
4.Seed Supply
Shrimp fry are generally collected from the wild sources.
However, substantial number should be supplied through shrimp hatcheries.
At present all of the shrimp farmers still
depend on wild fry for culture. PL are collected through trapping from natural
fry grounds.
5.Stocking
Stocking time:
The farmers stock shrimp in
the ghers in the month of Frebuary to March and the stocking is done in the morning
or late in the afternoon because shrimp fry are highly sensitive to abrupt
changes of water parameters and exposure to sunlight.
Stocking rate:
Stocking rate varies from area to
area. Stocking rate depends on the types of culture system.
Extensive shrimp culture: 1-2 pcs/m2
Improve extensive shrimp culture: 3-6 pcs/m2
Semi-
intensive shrimp culture: 7-15
pcs/m2
Intensive
shrimp culture: above 15
pcs/m2
6.Feeds and Feeding
In Semi-intensive culture operation,
supplementary feeds are given while natural food organisms remain the major
food source. In intensive culture operation, shrimp growth is completely
dependent on artificial diet
Application
of natural food in the pond
Chicken manure is broadcast at a rate of 600 kg/ha throughout
the pond water, then allowed to enter the pond to a depth of 8—10 cm while the
pond is further enriched with inorganic fertilizers such as ammonium phosphate
(35 kg/ha) and urea (12 kg/ha).
Liming the pond alone can produce a luxurious growth of
natural food.
Application both inorganic and organic fertilizers is useful.
Supplementary Feeding
With
stocking densities of 3-5 shrimp/rn2 and a properly maintained
fertilization regime, supplementary feeding is not necessary.
If higher
stocking densities are used, distribute supplementary feed as evenly as
possible throughout the entire pond.
Table:
Percentage of supplementary food by body weight
Supplementary
food
|
Percentage
of body weight
|
fresh
trash fish,
shrimp heads and
other
animal protein sources
|
approximately
5-10 % /day
|
rice
bran,
mustard
oil cake and wheat bran
along
with powdered or crashed shell of snails and pila
|
approximately
5%/day
|
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