Aquaculture Research Institute III has just sent a document to the Ministry of Fisheries (MARD); The ministries of agriculture and rural development of Da Nang, Quang Nam, Quang Ngai, Binh Dinh, Phu Yen, Khanh Hoa, Ninh Thuan, Binh Thuan, Lam Dong, Dak Lak, Dak Nong, Gia Lai and Kon Tum provinces have warned of hot weather in the region. Flooding in the South Central Coast and Central Highlands aquaculture region in 2023.

According to the document, the monitoring results for the first 6 months of 2023 in the south-central provinces and central highlands show that the water fed to the brackish water shrimp farming and hatchery areas with 7/14 periodic monitoring parameters has values ​​outside the allowable limits, including salinity, alkalinity, ammonia, COD, phosphate, vibrio sp., E. coli.

In addition, the results of monitoring white leg shrimp in Binh Dinh showed a positive sample for whistling substances (EHP) accounting for 18.2%; Water in caged lobster farming area with 50% of parameters outside acceptable limits including temperature, DO, ammonia, COD, vibrio spp., coliform bacteria; Cold water fish farming area with 25% of regular monitoring parameters outside acceptable limits including temperature, pH, ammonia and parasite detection Gyrodactyl sp. (single-host tapeworm) on the skin and gills of salmon was monitored at Klong Klang (Lac Duong, Lam Dong).

According to the National Center for Hydro-Meteorological Forecasting, hot weather is expected to continue in the central-central region in July through August of 2023, with a higher number of hot days than the average for many years over the same period.

In the central highlands in particular, the overall rainfall from July to September 2023, the peak of the rainy season, is about the average of many years in the same period. % compared to the average of many years in the same period.

According to the forecast of the National Center for Hydro-Meteorological Forecasting, there will be about 6-8 storms and tropical depressions in the East Sea area from July to September 2023, of which about 2-4 storms tropical depressions are likely to directly affect the mainland of our country.

Forecasting weather developments in the coming period will continue to be complicated, especially during the period when the south-central region changes from dry season to rainy season, weather changes, temperature changes, precipitation changes and a number of water environmental factors such as temperature, pH, salinity decrease, nutrient dissolved salts (ammonium, lobster phosphate, etc.), TSS, increased clarity in feed water and water in agricultural area change. This is a favorable condition for the development of pathogens on farmed shrimp, especially EHP, WSSV, AHPND and powdery mildew on brackish shrimp; Milk sickness, black gills and local sweetening of caged lobsters; Parasites, bleeding, cold water sores.

In order to limit the negative effects caused by weather fluctuations, the Research Institute of Aquaculture III, at the request of the Ministry of Fisheries, issued warnings and proposed some solutions to overcome them.

Statistics show that the average temperature at water monitoring points in brackish water shrimp farming areas in the south-central region in the first six months of 2023 is 29.6 degrees Celsius, 1.3 degrees Celsius higher than the average temperature of the same period in 2022 (28.3 degrees Celsius) and the water in lobster farming areas is 29.1 degrees Celsius, 0.8 degrees Celsius higher than the same period (28.3 degrees Celsius).

Measures to reduce heat impact in agricultural areas in the south-central provinces

– For brackish water farmed shrimp (Black Tiger shrimp, Vannamei shrimp): Farmers need to increase the depth of pond water (>1.4m), prepare sufficient oxygen tanks, aerators, lime and orchid nets, strengthen water fans to stabilize pond water temperature, and avoid pond water temperature change. Changes in temperature factors, sudden dense algae affect the health of farmed shrimp. The water should be supplied cool (treated water in settling tanks) and add minerals to the pond water to avoid mineral deficiencies.

The weather prevails in hot sunny areas, there are places where the sun is hot, so it is necessary to check the basic environmental indicators in the ponds (temperature, pH, algae color…) and abnormal activities of the farmed shrimp (eating ) to monitor. (falling down, run over, surfacing, etc.) to take timely action.

Persistently hot weather causes shrimp to eat less, so farmers need to pay close attention to the amount of feed given to shrimp. It is recommended to feed about 70-80% of the daily feed amount, early morning or evening feed, the feed is of good quality. Increase the siphon after the shrimp have finished eating (in the case of tarpaulin ponds).

Install the water fan in the right position to concentrate the waste when operating. Increase the time of fanning, especially between 10:00 p.m. and 5:00 a.m. the next morning, to increase dissolved oxygen, especially soil oxygen, thereby creating conditions for the growth of aerobic microorganisms and reducing toxic gases in the pond.

– For caged lobsters: Prepare oxygen tanks and backup aerators if farmed lobsters are overwhelmed by local low oxygen levels; Shade the cage/raft with a double layer of black orchid netting.

Take measures to improve water circulation, such as B. reducing the density of farmed shrimp, cleaning cage nets, adherent organisms and collecting waste.

Pay attention to the phenomenon of abnormal water color change, stratification of water temperature and current in the breeding area to promptly take appropriate adjustment measures (increase/decrease cage depth, reduce feeding, etc.).

In hot and sunny weather, reduce the amount of food you put in the cage by 20-30% compared to normal. When it is hot and windy, it is necessary to provide dissolved oxygen in time to avoid local hypoxia in farmed shrimp.

Choose fresh food, disinfect the food (with potassium permanganate, dose 1 g/100 liters of water), soak fresh food in potassium permanganate for about 15 minutes before feeding shrimp, combine with vitamin C, minerals and preparations for Improving the resistance of farmed shrimp.

Actively prevent shrimp diseases against some diseases that thrive in the hot season, such as: B. milk disease, red body disease, etc. in farmed lobsters.

Farmers must follow the local government stocking plan and production guidelines.

Measures to reduce the impact of flooding on agricultural areas in the Central Highlands provinces

Use nets with appropriate meshes to block all types of debris (shells, leaves, plastic wrap, etc.) upstream. It is necessary to let the water flow through the coarse filter (coarse sand, fine sand…) to limit the high levels of TSS and COD in the pond/aquarium.

Dose with Calcium Carbonate CaCO3/Dolomite in ponds/tanks, dosage of 30-50kg/1000m3 to reduce aeration, TSS and pH increase of pond water. Strengthening feed control, feeding regime, supplementation with vitamin C, minerals, preparations to improve resistance of farmed fish.

Actively prevent fish diseases when the region is at its peak rainy season. Proactively prevent landslides in areas with ponds/tanks near slopes and foothills.

The Local Competent Authority distributes heat and rain alerts to the local aquaculture community.