Wednesday, July 31, 2013

Technic

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Tuesday, June 4, 2013

Semi-intensive culture of Penaeus monodon in closed system

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Scientific classification 
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Subclass: Eumalacostraca
Superorder: Eucarida
Order: Decapoda
Suborder: Dendrobranchiata
Superfamily: Penaeoidea
Family: Penaeidae
Genus: Penaeus
Species: monodon
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



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.

2.Pon peparation
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


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