Must follow correct shrimp farming techniques

(Baonghean) -To prepare for the 2012 shrimp farming season, on December 22, 2011, the Department of Agriculture and Rural Development announced the seasonal schedule, according to which shrimp farming households in the province are allowed to release shrimp seeds for the main farming season of 2012 from March 20 to June 30 for white-leg shrimp and April 15 for black tiger shrimp, so at this time shrimp farming households are urgently renovating ponds, taking water and finding quality shrimp seeds to release in time for the season. Compliance with regulations and recommendations of the authorities as well as technical processes is the decisive factor for the success of shrimp farmers in 2012.

Specifically, farmers should only stock one crop per year for black tiger shrimp, and white-leg shrimp after the main crop. In farming areas with good infrastructure conditions and a stable water environment, the second crop can be stocked from September 20 to November 5.

Regarding technical requirements, farmers need to dredge the pond, remove the black mud layer from the pond (for old ponds), carry out mechanized renovation (applicable to old and new ponds) to ensure the following criteria: suitable pond area from 0.3 - 0.5 ha, water depth reaching 1.2 - 1.5 m, apply lime CaO or CaCO3 with recommended dosage from 700 - 1,000 kg/ha (soil pH > 6), dry the pond for 7 - 10 days with the aim of destroying all pathogens of the previous crop.

For water collection and treatment, farmers need to have a settling pond with a ratio of about 30% of the total area to actively supply water to the pond. In addition, farmers must regularly monitor the results of environmental monitoring when needing to take water into the pond. Water supplied to the pond needs to be passed through a filter bag and treated through a settling pond by leaving the water for 3-5 days combined with a water fan so that the crustacean eggs can hatch completely. Then farmers proceed to kill miscellaneous organisms with saponin at a dose of 15-20 kg/1000 m3, or some chemicals permitted by the Ministry of Agriculture and Rural Development; kill bacteria and viruses in the pond with Chlorine at a dose of 25-30 kg/1,000 m3, Formalin at a dose of 20-30 liters/1000 m3, or potassium permanganate (KMnO4) at a dose of 5-8 kg/1000 m3.

For water coloring, farmers can use products containing key ingredients such as beneficial microorganisms (Bacillus subtilis, Lactobacillus groups...), vitamins, essential amino acids according to the manufacturer's instructions. For ponds that are difficult to color, farmers can use biological products combined with urea fertilizer (2 - 3 kg/1000 m3), fish meal (0.5 - 1 kg/1000 m3) continuously for several days until the pond meets standards such as: clarity (30 - 40 cm), pH (7.5 - 8.5), alkalinity (80 - 120 ppm), toxic gas (< 0.1 ppm)... to create a green, yellow color in the pond, then they can proceed to release shrimp larvae.

When choosing shrimp seeds, it is necessary to choose seeds that meet Post 15 standards for black tiger shrimp and Post 12 standards for white-leg shrimp. Observe and test the quality by sensory inspection with criteria such as uniform size, large intestine, standard intestine/muscle ratio of 1/4, and flexible swimming.

Next, shock by suddenly lowering the salinity to only 50% (for example from 20 parts per thousand to 10 parts per thousand), or shock with Formalin at a dose of 2 liters/10 liters of water for 1 hour, if the shrimp survival rate is above 90%, it is satisfactory. Then quarantine the shrimp larvae by PCR method at the aquatic quarantine agencies of the provinces/cities to ensure that the shrimp larvae are healthy and do not carry pathogens; for white-leg shrimp, the shrimp larvae in the herd must be highly uniform, and the same shrimp selection methods as for black tiger shrimp are applied.

Regarding seed release, farmers should ask the hatcheries to acclimatize the salinity between the hatcheries to the salinity in the pond. When releasing shrimp seeds, choose a cool time (morning, evening) and soak the shrimp bags in water for about 30 minutes to balance the temperature between the shrimp water in the bag and the pond before releasing.

The stocking density should be from 15 - 20 shrimp/m2 for intensive and semi-intensive black tiger shrimp farming and from less than 6 shrimp/m2 for improved extensive farming. For white leg shrimp, stocking density should be from 80 - 100 shrimp/m2; do not stock too densely as it will be difficult to manage, prone to disease, and high risk.

Tran Trung Thanh