Our understanding of endemic and exotic prawn pathogens in P. monodon hatchery systems remains fairly sparse,
with limited large scale studies having contributed to this topic . The hatchery phase represents a critical stage of the production cycle influencing the overall success of each farm. Furthermore, the Australian P. monodon industry is reliant on wild caught broodstock which poses a biosecurity risk when they enter a controlled environment from the uncontrolled natural environment they are caught from. The aim of the study presented here was to attain a “snap-shot” assessment of the pathogens that are present at the starting phase of prawn production, namely, the hatchery system.
This project analysed pleopod samples from 967 individual P. monodon broodstock that were sourced from four commercial hatcheries. The participating hatcheries supply over 80% of the postlarvae to the Australian prawn farming industry. The P. monodon broodstock in this study were wild-caught from East Coast Queensland and Northern Territory. Samples were analysed,
using qPCR, for the presence of WSSV, YHV-1, IHHNV, GAV, YHV-7, HDV, When-2, Pir -A as well as the P. monodon Dicer-1 gene. Details of the geographic source (East Coast Queensland or Northern Territory), health status (culled, moribund, dead, dead on arrival, jumped from the tank), production status (pre- or post-spawn) and date of sample collection were provided. This allowed comparisons in viral load between stock sources used by prawn farmers in Australia to collect their broodstock. T he effect
spawning had on viral load of broodstock was also investigated by comparing pre and post spawned broodstock. Quantification and basic statistical paramaters for each virus were
enabled through qPCR.
This study concludes Phase 1 of the NA CRC project “Improving Biosecurity in northern Australian prawn aquaculture” (Ref No. A.3.1718113). The analysis conducted in Phase 1 of the NA CRC is the most comprehensive and extensive study to date that examines endemic viruses in Australian prawn hatchery systems. This study revealed correlations between pre and post spawn viral loads as well as differences in viral load and prevalence between East coast and Northern Australian P. monodon stocks. Results reported here are beneficial to informing better management decisions in prawn hatcheries as well as improving economic sustainability by reducing the risk of disease outbreaks in broodstock and postlarvae.