Shrimp is one of the export commodities from the fisheries sector which has the potential to be developed. According to the Director General of Fisheries Cultivation, shrimp is a leading export commodity which is expected to make a major contribution to national economic growth. This is because the shrimp export market is very large, and Indonesia is one of the 5 (five) largest shrimp producers in the world.
This is also supported by the Ministry of Maritime Affairs and Fisheries (KKP) which targets national shrimp production of two million tons per year by 2024. To achieve this, the Directorate General of Fisheries Cultivation (DJPB) has encouraged a breakthrough program to increase the productivity and sustainability of shrimp cultivation, namely through the development of sustainable vannamei shrimp cultivation.
One type of shrimp currently being developed is vannamei shrimp (Litopenaeus vannamei). This type of shrimp has several advantages compared to other types of shrimp, including the ability to adapt to high densities, resistance to disease, ability to survive in the salinity range of 5-30 ppt, survival rate (SR) and high feed conversion (Muhammad Ghufron, 2017) .
In general, vannamei shrimp cultivation activities are divided into three activity sectors, namely hatching, rearing and maintenance. In this article, we will discuss vannamei shrimp rearing activities. The vannamei shrimp rearing technique involves pond preparation, selection and planting of fry, maintaining water quality, feed management and disease control, up to harvest. The following is a complete explanation of vannamei shrimp rearing cultivation techniques, including:
- Planting fry
The size of vannamei shrimp that are ready to be planted in ponds is PL10. Before the fry are transferred from the plastic bag to the pond, they need to be acclimatized first. Acclimatization to temperature can be done by soaking a plastic bag containing shrimp fry closed until steam appears in the plastic bag. This shows that the temperature inside the plastic bag is the same as the pool water temperature. After that, acclimatization to salinity can be done by adding pond water little by little into the plastic bag containing the fry until it is full and the fry can come out by themselves.
Fry planting activities can be carried out in the morning or evening at the same time as planting Artemia as natural food for the fry. The planting location is at a point with a weak current so that the fry are not stressed, while the Artemia planting location is near the steering wheel so that the Artemia can be spread evenly.
- Feed management
The feed given during the vannamei shrimp rearing process is in the form of pellets. This is caused by the relatively small size of the vannamei shrimp's mouth. At the beginning of the first month, feeding is carried out using the blind feeding method. The blind feeding method is a method of determining shrimp feed dosage by estimating the dose required without taking shrimp weight samples. The initial amount of feed given for every 100,000 fry is three kilograms. At the age of 1-10 days, the addition of feed per day is 200 grams, for 11-20 days it is 400 grams, and for 21-30 days it is 600 grams.
After that, in the following month the feeding is adjusted to the shrimp biomass and controlled using the Anco Check Score indicator. The application of additional feed is also applied to the rearing of white vannamei shrimp. The additional feed includes vitamin C, omega protein and probiotics. Sampling is carried out once a week to determine the average weight and biomass of vannamei shrimp so that the daily amount of white vannamei shrimp feed can be determined.
- Water quality management
Pond water quality management is very important in determining the success of vannamei shrimp cultivation because the health, growth and survival of vannamei shrimp are influenced by the interaction of the environment, pathogens and living conditions. Water quality plays an important role for vannamei shrimp because water functions as a growth medium both internally and externally. As an internal medium, water functions as a raw material for body reactions, transports food throughout the body, and also functions as a temperature regulator or buffer.
On the other hand, water functions as a habitat for shrimp as an external environment. Therefore, the role of water is very important for vannamei shrimp, so the quality and quantity of water in vannamei shrimp cultivation must be maintained according to their needs (Sumarni, 2019).
Based on the period, water quality checks are divided into two, namely daily and weekly checks. Water quality parameters measured every day include temperature, brightness, salinity and pH. These parameter measurements were carried out in the morning and evening. Meanwhile, the parameters measured every week are hardness, alkalinity, nitrite, TAN (Total Ammonia Nitrogen), TOM (Total Organic Matter), and the number of plankton and bacteria.
The optimal water temperature for growth and development of vannamei shrimp is in the range of 28-32 °C (Kharisma and Manan, 2012). In this temperature range, metabolic processes can run well so that shrimp survival and growth are expected to be optimal.
Brightness in vannamei shrimp ponds ranges from 15-35 cm. According to Malik (2014), the optimal brightness of pool water is around 20-40 cm. Therefore, if the transparency of the pond water is below 20 cm, the effort that can be taken is to pour the pond water until optimal brightness is obtained to support the life of the cultivated shrimp. Rahmawati et al., (2014) stated that factors that can influence the brightness value are weather conditions, suspended solids, measurement time, and the accuracy of the person taking the measurement.
Water salinity is closely related to the osmoregulation process found in aquatic organisms. White shrimp are euryhaline organisms that are able to adapt to a very wide salinity range, namely 1-40 ppt. However, to obtain optimal growth, vannamei shrimp require a salinity of 15-25 ppt (Malik, 2014). Therefore, the salinity of pond water needs to be increased so that it does not fall below the optimal range during the cultivation process. Efforts that can be made are by adding sterilized water of a certain salinity.
The pH level must be measured regularly during cultivation activities. According to Malik (2014), the ideal pH of pond water for rearing vannamei shrimp is 7.5-8.5. In general, the pH of pool water in the afternoon is higher than in the morning. This is because in the afternoon there is absorption of carbon dioxide (CO2) by phytoplankton through the process of photosynthesis. Meanwhile, in the morning, the CO2 levels produced by the respiration of vannamei shrimp and other organisms in the water are quite high.
Alkalinity is a description of the capacity of water to neutralize acids, which is known as Acid Neutralizing Capacity (ANC) or the number of anions in water that can neutralize hydrogen cations (Abidin, 2014). The optimal alkalinity value for rearing vannamei shrimp is 100-150 ppm.
In aquaculture activities, as the shrimp get older, the amount of feed also increases. This increase in the amount of feed can trigger an increase in organic matter and toxic compounds, such as nitrite NO2 and ammonia NH3. Apart from that, these compounds can also come from shrimp excretion feces. According to Kilawati and Yunita (2014), the optimal level of NO2 and NH3 for the growth of vannamei shrimp is below 0.01 ppm, while the tolerance limit for NO2 ranges from 0.01-0.1 ppm and NH3 is around 0.01-0.2 ppm.
NO2 and NH3 levels in aquaculture ponds are beyond optimal values, which can reach 0.968 ppm and 0.37 ppm, respectively. Efforts that can be made to overcome this problem are the application of probiotics containing nitrifying bacteria.
Total Organic Matter (TOM) describes the total organic matter content in water which consists of dissolved, suspended and colloidal organic matter. Excessive organic material content can cause changes in pond water quality and affect pond biota, especially shrimp cultivation. An increase in organic matter content will result in an increase in nutrients, a decrease in pH and dissolved oxygen, and an increase in biological activity.
TOM values in the pond ranged from 103.65 to 115.57. Kilawati and Yunita (2014) stated that the TOM content suitable for shrimp life is below 55 ppm. Therefore, efforts that can be made to reduce TOM content in ponds are by changing the water and siphoning regularly.
The presence of plankton in water can be used as a biological indicator to evaluate the quality and level of water fertility. Plankton is divided into two groups, namely phytoplankton and zooplankton. Plankton is natural food for aquatic organisms.
Management of water and feed quality for vannamei shrimp cultivation in Bali
4. Pests and diseases
Preventing the entry of pests and diseases into shrimp is carried out starting from the pond preparation stage. One of the steps taken is to install a Crab Safety Device (CPD) at the edge of the pond. This is done to prevent crabs from entering cultivation waters. Not only are crabs a pest that can compete with shrimp for food, dissolved oxygen, and space, but they can also spread diseases such as WSSV. White Spot Syndrome Virus (WSSV) is a virus that causes white spot disease in shrimp.
Apart from that, the type of bacteria that is susceptible to attack by shrimp during the cultivation process is Vibrio sp. The infectious disease caused by this group of bacteria is called vibriosis. Several types of bacteria from the genus Vibrio that cause vibriosis are V. harveyi, V. parahaemolyticus, V. alginolyticus, V. anguillarum, V. vulnificus, and V. splendidus.
The general bacterial density of Vibrio sp and total bacteria was 170-880 CFU/ml and 7,000-118,000 CFU/ml, respectively. This figure can still be tolerated in vannamei shrimp rearing activities. According to Kharisma and Manan (2012), the maximum threshold for the presence of Vibrio sp. in water is 104 CFU/ml while the maximum limit for general bacteria in water is 106 CFU/ml. If this threshold is exceeded, mass death of farmed shrimp in ponds can occur.
5. Shrimp harvest
Examples of success in vannamei shrimp harvesting
Shrimp can be harvested after reaching a market size of around 10-13 grams/fish or when they reach a length of around 18 cm. To get high quality shrimp, before harvest, dolomite is added to harden the shrimp shells at a dose of 6-7 ppm. Apart from dolomite, you can also use Ca(OH)2 lime or what is usually called lime water at a dose of 5–20 ppm one day before harvest to raise the pH of the water to 9 so that the shrimp do not molt (Malik, 2014).
These are the techniques for growing vannamei shrimp, starting from selecting and planting the fry, feed management, water quality management, to the harvest stage. All of these steps are important to support the sustainable growth and survival of vannamei shrimp in Indonesia.
References
Kharisma, A. and A. Manan. 2012. The abundance of vibrio sp. In rearing water for vannamei shrimp (Litopenaeus vannamei) for early detection of vibriosis attacks. Scientific Journal of Fisheries and Marine Affairs, 4 (2): 129-134.
Kilawati, Y. and Y. Maimunah. 2014. Environmental quality of intensive pondsLitopenaeus vannamei in relation to the prevalence of White Spot Disease Virus. Research Journal of Life Science, 2 (1) : 50-59
Malik, I. 2014.Vannamei shrimp cultivation: Semi-intensive ponds with waste water treatment plants (IPAL). WWF-Indonesia. Jakarta. Page 3-30
Muhammad Ghufron, M. L. P. D. W. S. H. S., 2017. Vannamei shrimp rearing techniquesTechniques for rearing Vannamei Shrimp (Litopenaeus vannamei) in the assisted ponds of PT Central Proteina Prima Tbk in Randutatah Village, Paiton District, Probolinggo, East Java. Journal of Aquaculture and Fish Health, VII(2), pp. 70 -77.
Sumarni. 2019. Water quality management in rearing vannamei shrimp (Litopenaeus vannamei) at PT. Central Proteina Prima Probolinggo, East Java.
Suwoyo, H.S. 2011. Study of water quality in grouper cultivation(Epinephelus fuscoguttatus) Intercropping system in mangrove areas. Deepwater Fisheries Journal, 39 (2) : 25-40.
