Nursery operations (creating shrimp nursery ponds) are carried out due to the occurrence of damaging viral and bacterial diseases in the shrimp farming industry. In recent years, more biosecurity plans have been implemented to prevent disease damage and sustainable development of shrimp farming activities.
The reason for the construction of the shrimp nursery pond
The shrimp nursery pond is a part of the shrimp cultivation process. By using this system the biological safety of production increases and subsequently the incidence of diseases decreases. As a result, the profitability of production is done in a more favorable way.
Achievements of nursery operations
In this system, by using the control and monitoring of environmental factors such as temperature, water, feed, light, oxygen, etc., it is possible to provide high-quality, healthy, uniform post larvae. as a result, explosive growth in shrimp farms is created.
nursery in Iran
This system is in the beginning in Iran and many other countries. To fight EMS disease (early death), the nursery system is used up to 45 days. The location of the nursery system is in the shrimp farming area, at the beginning of the farm and near the ponds. These tanks are made of concrete, fiberglass or earthen with geomembrane cover, and are made in different geometric shapes.
The purpose of nursery operations
- Biosafety to prevent all kinds of hazards
- Easier diagnosis of diseases, rapid elimination of the cycle of pathogenic agents in the infant phase and preventing the spread of contamination in the farm
- The possibility of optimal management of inputs, water, environmental and economic parameters, etc.
- Making it possible to increase the number of cultivating courses per year
- Increasing the resistance of shrimps against diseases with increasing age
- Easier management of annihilation and disease prevention
Necessities in building a nursery system
- Access to water with the suitable quality and quantity
- The irrigation of the farm should not interfere with the irrigation of the nursery pond
- The discharge of the effluent from the nursery should be in the field drain
- It is possible to access emergency power facilities or generators
- The construction of the greenhouse system should be planned according to the climatic conditions of the place of operation
- Access to permanent and reliable electricity is important
Know before doing the nursery operation
Before storing post-larvae in nursery ponds, it is necessary to disinfect all surfaces, equipment and nursery tanks. Car wash, fresh water and chlorine with appropriate dosage (as disinfectants), are used to wash and disinfect ponds. For washing, first the floor and walls are washed with a high-pressure water hose to completely remove the sludge from the floor t is better to wash with fresh water Disinfection of the floor and walls of the pond is done with a calcium hypochlorite solution with a concentration of 200 mg/liter. The final washing of the nursery pond should be with clean and disinfected water, and then the ponds should be allowed to dry.
In nursery operations, the initial water intake depth is 50-70% of the useful depth of the ponds during storage, Then the work of completing the dewatering will be done. A 577 micron filter is used for dewatering tanks. A 377 micron filter is recommended for changing the water in the central outlet.
The optimal amount of physical and chemical factors
Water salinity: from 13 to 45 ppm, depending on the location of the project
Water temperature: minimum 20 to maximum 33 degrees Celsius (optimum temperature 28 degrees Celsius)
Dissolved oxygen in water: at least 4 mg/l
pH level: maintaining the Ph level of water in the range of 7.5 to 8.25
Transparency: 35 to 45 cm with secchi disk
NH4 content: less than 1 ppm
NO2 content: less than 0.5 ppm
NO3 content: less than 1 ppm
Lighting hours: 12 hours of light, 12 hours of darkness, and if possible, preferably 13 hours of darkness and 11 hours of light.
Executive stages of nursery operations
Nursery systems must have a disinfection and filtration system approved by the veterinary organization in the water path of the pond. If the dissolved oxygen decreases from 4 mg/liter, it is recommended to change the water, remove the sludge from the bed, use probiotics and even use pure oxygen. Central drainage is required for water change and final harvesting. The amount of daily water change depends on the quality of the water, at least 35%.
The central discharge will be done by means of a central vertical pipe with a protective pipe around it, a safety pipe, a suction and a hose. It is recommended to aerate nursery tanks continuously 24 hours a day, and reduce the aeration pressure during water analysis and feeding. It is necessary to use various aerators in nursery tanks, such as floor aeration as well as rotating airlift. Monitoring of dissolved oxygen is done every 2 hours.
The food used must be factory-made and of good quality. Due to the lack of biological production of food in tanks, access to sufficient food at the right time is mandatory. For the first 3 to 4 days, Napulius Artemia should be used for the consumption of larvae, and then the special nursery concentrate food should be gradually replaced.
10-12-day-old shrimps are kept in nursery ponds for at least 30-45 days and then transferred to rearing ponds. The recommended weight of transferable larvae is 0.5 to 1 gram.
The process of adaptation of post larvae takes place in rearing ponds and in large tanks of 500 to 1000 liters. In this method, the bags containing post larvae and water are emptied into the tanks that are located next to the ponds, and then the pond water is gradually added until the temperature, salinity and Ph of the water in the containers are almost like pond water. the post larvaes are ready to be released in the shrimp cultivation ponds The transfer of post larvae from the nursery to the rearing ponds is the bottleneck of nursery operations. If it is possible to transfer by gravity from the nursery to the rearing ponds, it is better to use this method, but if this is not possible, it is necessary to transfer the post larvae to the rearing ponds within 20 minutes at most. Also, it is necessary to transfer the post larvae from nursery to rearing ponds in the coolest hours of the day.