Water treatment to control influent water biosecurity risk on Australian prawn farms; Effectiveness and impacts on production ponds

Abstract

The Australian prawn aquaculture industry is committed to a strategy of enhanced farm biosecurity to reduce the potential for production losses caused by disease agents. Evidence from prawn farming regions around the world indicates that source seawater is a significant route for pathogen transmission into the farm. Further, the highest risk mechanism for disease transmission is considered to be the organisms suspended in the water that without treatment of the influent water will be directly transferred into the farm. All prawn farms in Australia use seawater sourced from adjacent waterways to fill production ponds and exchange water throughout the production season.

In consultation with local and international experts, the Australian prawn aquaculture industry has identified that influent seawater filtration and chemical disinfection, either alone or combined, are key measures for enhancing biosecurity on prawn grow-out farms. These water treatment approaches can remove potential disease vectors present in the farm source water. Given the large investment required to implement seawater treatment systems, and the critical role it can have for farm biosecurity, prawn farms need information regarding practical design parameters, effectiveness of different treatment intensities and relative risk reductions of different options. This project was initiated to address the general lack of technical information on the application of water treatment systems and their impact on pond dynamics under Australian prawn farming conditions. It assessed the performance and impacts of mechanical filtration of influent seawater in an experimental tankbased system, and at a large operational farm growing black tiger prawns (Penaeus monodon) in Southeast Queensland. The technical details provided by this project directly informs the design and operation of farm biosecurity facilities, as well as the refinement of biosecurity operating standards for industry.