TRIAL RESULTS IN PL TRANSPORTATION SYSTEMS

Green vibrio colonies, such as Vibrio harveyi and Vibrio parahaemolyticus, are a major pathogen challenge to shrimp post larvae.

When a green vibrio colony’s concentration level reaches 2.2 x 10^3 CFU/ml in the water in which post larvae are being cultured or transported, it will ultimately cause them stress, weakening their immune systems, and making them more susceptible to infection. Thus it is very important to manage green vibrio colonies below 2.2 x 10^3 CFU/ml during the post larvae culturing process, and during transportation to farm sites.

LANXESS established a trial at a shrimp production hatchery to demonstrate the effectiveness of Virkon™ DTOX in  reducing pathogen pressure towards shrimp post larvae during transportation journeys, from hatchery to farm, of more than 6 hours. Thus, providing evidence that using Virkon™ DTOX helps to improve, not change, water quality (salinity, alkalinity, temperature, dissolved oxygen) and reduce stress and mortality in shrimp PL.

The trial protocol directly compared the pathogen load level profiles (green vibrio colonies) of two shrimp post larvae transportation bags, one filled with water disinfected with Virkon™ DTOX, and one filled with just normal water. The study was carried out over a 9-hour period with each transportation bag containing post larvae.

VIBRIO GREEN COLONY

The graph below indicates a 63% average reduction in green vibrio colonisation in over 9 hours in shrimp PL transportation water disinfected with Virkon™ DTOX treated water.

Conclusion – Virkon™ DTOX helped to manage the pathogen pressure of Green Vibrio colonies in the post larvae transportation bags over a 9-hour time period, sustaining water quality and reducing the stress the PL would have been subjected to.

Result – Reducing the stress the shrimp post larvae face during the transportation period results in less mortality and better quality PL being delivered to the farm site.

• Trial condition : salinity 30ppt.
• Red = control (normal water transportation)
• Blue = treatment (5ppm Virkon™ DTOX)

GREEN VIBRIO COLONY