2008/756 Increasing seedstock production of domesticated Giant Tiger Prawns

By Greg Coman, Brian Paterson, Stuart Arnold, Roger Chong, David Mann, Jeff Cowley and Andrew Wood

Given the rationale that pond systems are likely the most cost-effective system for large-scale production of Giant Tiger Prawn (Penaeus monodon) broodstock, this project aimed to determine whether pond-rearing poses a significant risk for broodstock production.

The gross reproductive development of males reared in low-density broodstock ponds was found comparable to sibling males reared in controlled-environment tanks. Furthermore, none of the environmental 'stressors' and dietary manipulations examined impacted on male reproductive tract development. Thus, within the boundaries of the parameters tested, we can state that rearing of male broodstock in low-density ponds does not pose inherent risks of gross reproductive tract impairment.

The project also focused on developing an objective measure of 'male fertility' that could be used commercially; and which could be employed within a monitoring regime. None of the simpler assays, which have typically been used as 'proxy' measures of male fertility, were found to correlate with egg fertilisation rates. One assay that was tested, evaluated levels of 'activation' of 'matured sperm' exposed to 'egg water' (EW-AR assay) and this activation correlated with egg fertilisation. Therefore, this provides a reliable measure of male fertility. However, whilst providing an objective measure, this assay is not straightforward to implement commercially; and certainly the applications of this measure are likely restricted. Importantly, an overall approach to long-term monitoring of stocks is suggested; this approach incorporating application of simpler spermatophore/sperm assessments and the EW-AR assay at different points throughout broodstock rearing and at stocking of the hatchery.

During the project, a previously undescribed abnormality termed 'hollow sperm syndrome (HSS)' was observed through histology. Whether the presence/prevalence of such abnormal sperm impacts egg fertilisation rates negatively is not yet known; and further research is thus required to establish its commercial importance