In Iloilo, the NSB-NB5 farm is adopting science-based protocols for sustainable production
By Mary Ann C. Solis, Leobert de la Pena, Cary P. Andigan and Ryan Joseph Zamora
Application of probiotics for pond water to maintain good water quality and reduce Vibrio levels in pond water and in shrimp
Shrimp farming in the Philippines has never been more challenging than it is today; producers encounter many issues, from environmental degradation, climate change, emerging diseases, lower demand and lower market prices due to the current global economic situation.
Among these, diseases have been the most challenging, owing to the evolving nature of pathogens affecting shrimp stock. Disease-related crop failures have prompted shrimp farms to adapt to the changing culture environment and develop with strategies and protocols to improve shrimp survival rate and boost production. These strategies include adopting innovative technologies suited for site-specific farm conditions.
In this article, we describe how one such farm in central Philippines has succeeded in making Penaeus vannamei shrimp production profitable and sustainable despite these challenges.
Facing shrimp farming challenges
Similar to most farms, NSB-NB5 in Iloilo province has to deal with the prevalence of diseases and high shrimp mortalities. It faces high Vibrio levels as well as the white spot syndrome virus (WSSV), Enterocytozoon hepatopenaei (EHP) and acute hepatopancreatic necrosis disease (AHPND).
Biosolutions International Corporation, an aquaculture solutions company providing shrimp health products and equipment, was called in to provide technical solutions to the recurring problems encountered by the farm. With this assistance, NSB-NB5 has managed to develop proactive culture techniques to address specific issues and problems in shrimp culture. While diseases present a major risk in shrimp farming, it was even more so in this farm, where multiple disease infections occurred simultaneously during the same cycle.
Co-infections by WSSV and vibriosis caused mass mortalities among cultured shrimp in past culture cycles resulting in crop failures. One key strategy adopted by the farm is to minimise and control the presence of Vibrio bacteria in the pond water and, subsequently, in shrimp stocks to protect shrimp gut and hepatopancreas from damage.
During periods with high levels of Vibrios (3.1×106 CFU/mL), the farm will implement remedial measures by applying an organic acid-based disinfectant in the pond water to reduce Vibrio levels. Highly concentrated probiotics are then applied to the pond water regularly High concentrations of probiotics are specifically used as they have been proven that higher numbers of good bacteria are more effective in reducing Vibrio levels through competitive exclusion and direct inhibition. Feeds are also supplemented with high concentrations of probiotics to minimise the Vibrio population in the shrimp gut; immune boosters and vitamins are used as well to help improve disease resistance and overall health condition and immune response of the shrimp.
Another key issue in high-density shrimp farming is organic waste accumulation and high toxic ammonia levels as more feed is being used in such culture systems. Feed is one of the most important inputs in shrimp production, providing the necessary nutrients for growth and survival. Since feed comprises 50-60% of the total production cost in shrimp culture, it is crucial that feed is administered as efficiently as possible. Shrimp that are stressed from the presence of high organic waste and toxic ammonia, even under sub-lethal levels, can experience slow growth, resulting in high feed conversion ratios (FCR), thereby increasing the cost of shrimp production. Finding the right balance between proper nutrition with adequate amount of feed while maintaining good water quality is also among the farm’s key success factors.
A practical and site-specific approach
We recommend a science-based and practical approach to address shrimp culture issues and challenges faced by the farm; together with farm management, we derive a proactive and site-specific approach in farm operations. This combination specifically addresses shrimp health issues and the deteriorating pond culture environment. In addition, we enlist an in-house technician to help monitor the overall condition of shrimp stocks and the proper application of health products and proactive culture methods. This innovative approach has been adopted at the farm’s 11 culture ponds and 4 reservoirs, spanning 10 ha. These strategies adopted by the farm resulted in a significant increase in production through better growth rates, higher survival and a more efficient FCR.
Fry quality screening and handling
Only healthy post larvae from SPF (specific pathogen free) broodstock from accredited hatcheries are used in stocking culture ponds. Post larvae samples of PL7-PL8 are screened by the Southeast Asian Fisheries Development Center, Aquaculture Department (SEAFDEC-AQD) to test for potential diseases, such as WSSV, Infectious hypodermal and hematopoietic necrosis (IHHNV) and the microsporidian EHP. Tests are also carried out for total Vibrio counts and AHPND-causing pathogens. Only clean and healthy post larvae (PL9-PL10) with less than 1 x 102 CFU/mL Vibrio count that pass this stringent testing process are delivered to the farm for stocking directly into culture ponds.
Strict biosecurity
Biosecurity measures are strictly implemented, including the movement of personnel and vehicles, to minimise and prevent the entry of pathogens into the farm. Water in the reservoir and culture ponds undergo disinfection prior to stocking of post larvae. Disinfection is correctly applied to all materials used in the ponds. Personnel working at the farm use rubber boots that are regularly disinfected, Foot baths are located at the entrances of all ponds. Net and crab fences are installed around each pond to prevent potential disease-carrying organisms from entering the pond area. Regular disinfection is done in the culture ponds before stocking and during the culture phase to control pathogenic bacteria build-up inside the pond environment. Prevention is the key to minimising the risk of diseases.
Proper pond preparation
Before the start of each crop, technicians carry out the necessary pond and farm preparations. Water samples from the seawater source are tested for Vibrio and AHPND. Crustaceans such as crabs in the pond vicinity are tested in the laboratory for WSSV as these are major carriers of viral disease in shrimp farms. Pond liners are also cleaned and disinfected, as well as equipment to be used during the culture cycle, such as paddlewheels, root blowers, aerator hoses and diffusers. When everything has been cleaned and prepared, the reservoir is filled with seawater and disinfected using 30ppm chlorine. This treated water is then pumped to the disinfected culture ponds. The pond water is then treated with probiotics, as well as silicate-based mineral fertilisers to allow plankton to bloom with natural food and to stabilise the water in preparation for stocking.
A day before stocking, the pond water is again disinfected using organic-based disinfectants to control pathogenic bacteria. Culture ponds of 4,000-5,000m2 are then stocked with 120-140PL/m2.
Water and waste management
Water parameters are regularly measured to keep track of water quality and organic waste levels. Suspended solids settling at the centre of ponds are removed by pumping after every feeding and placed at the central sludge collection pit. These procedures prevent the abnormal and drastic increase in levels of toxic ammonia, nitrite, and hydrogen sulphide in water and remove organic waste from uneaten feed, decaying plankton, shrimp faeces and moulted shells.
The wastes from the central sludge pit are pumped out and passed through a sludge collection pond where the organic waste is allowed to settle while only clear and treated wastewater is drained back to the sea. This ensures that the immediate coastal environment is not polluted by the farm. During the culture cycle, water parameters, particularly pH, salinity, temperature and dissolved oxygen (DO) are strictly monitored to minimise stress to the shrimp due to sudden changes in these parameters.
As part of its environmentally-friendly approach to water management, the farm uses only organic-based treatments for the pond water during the culture phase; these include organic-based disinfectants for water treatment and probiotics for bioaugmentation. The periodic treatment of pond water is done by applying disinfectants in the morning, after which probiotics are introduced 6 hours later to allow beneficial bacteria to multiply and proliferate in the pond environment and become one of the dominant species.
This combination treatment of pond water is highly efficient in controlling the levels of pathogenic Vibrio in the pond water and shrimp, thus, controlling the occurrence of AHPND brought about by Vibrio parahaemolyticus.
Feed supplementation
Proper feeding ensures that the feed is evenly distributed throughout the pond in adequate amounts. Good quality feed that provides the correct nutritional requirement results in good growth and survival. Good feed management and feed consumption monitoring result in better feed conversion, thus, lowering the overall cost of production and increasing profitability and cost efficiency.
Early in the culture phase, feeds are supplemented with probiotics, immune enhancers and vitamins by top-dressing the feeds to boost shrimp immune response to stress and disease. This is an important part of the proactive protocol in shrimp farming – not just to focus on maintaining a better pond water environment, but also to prioritise shrimp health and nutrition. A strong and healthy shrimp is a resilient shrimp that will survive challenges.
Disease surveillance and shrimp health management
As mentioned earlier, the farm has had its fair share of disease outbreaks, particularly WSSV, AHPND, and EHP. Due to the presence of these widespread diseases, proactive and close monitoring of shrimp stocks must be done throughout each crop cycle. During culture, pond water and shrimp samples are regularly sent to SEAFDEC’s Fish Health Laboratory for testing. This proactive approach to disease monitoring helps the farm detect the presence of pathogens at the onset of a disease outbreak. Early detection allows for the prompt implementation of remedial measures to prevent mortalities and crop losses.
During multiple disease outbreaks a more aggressive remedial measure will be adopted. Water in the culture pond is treated in the morning with 1ppm of an organic acid-based disinfectant. After 6 hours a double dose of concentrated probiotics will be applied and thereafter on the following days until Vibrio levels drop. Feeds are mixed with a double dose of probiotics, together with vitamins as immune enhancers.
A more intensified disinfection process is employed to prevent further contamination that may affect other ponds with healthy stocks and shrimp post larvae to be stocked in the next cycle. After harvest and full draining, the pond liners are cleaned and disinfected with 1ppm an organic acid-based disinfectant. Then chlorine is used at 60ppm; it is injected below the pond liner to disinfect the underside portion of the plastic liners.
Improved production with innovative strategies
The above measures are key to the farm’s success in production, and are defined by the following:
• Improved survival rates of 87%-96%
• Better growth rates – the farm is now able to harvest larger-size shrimp 32 to 51g (ABW) in 92 days and 121 days, respectively
• Lower FCR at 1.15 to 1.25
• Improved production/ha to 31 tonnes/ha compared to previous crops (Table 1)
These science-based and proactive approaches resulted in a healthy pond environment, with pathogens under control and shrimp with enhanced overall health and nutrition, profitability and sustainability.
Wealth in learning and sharing knowledge
Since 2018 with the full application of the Biosolutions Technology, this farm despite facing numerous challenges not merely survived but experienced superior shrimp production performance. Today, NSB-NB5 is not deterred from finding aquaculture solutions for a more sustainable and profitable shrimp production.
This innovative shrimp aquaculture approach was shared with many other shrimp farmers in Cagayan Valley (North Luzon), Mindoro (South Luzon), Negros Occidental (Visayas), South Cotabato (Mindanao), and Sarangani (Mindanao). These farmers have seen for themselves the advantage of using quality health products, innovative technology and best aquaculture practices to achieve better growth and survival. As a result, they have since adopted the Biosolutions methodology.
In fact, NSB-NB5 Farm owner Nestor Bretaña said,
“Our collaboration with Biosolutions enables us to respond holistically and overcome the threat of emerging diseases in our farm. Using evidence-based monitoring together with high quality products that work, allows us to have a consistently healthy and optimal harvest yield.â€
The key factors contributing to the successful application of this technology involve the selection of high-quality health products and their proper and timely application customised to the culture circumstances unique to the farm. It also includes the stringent screening process for post larvae, regular laboratory testing during the culture period, and the presence of competent and trained farm personnel.
The article was published in issue November/December 2022 AQUA Culture Asia Pacific, p24-28. Download pdf here.
