2008/757 Commercial production of all-female reproductively sterile Giant Tiger Prawns: Assessing their commercial performance in ponds

By Melony J Sellars

Several Australian companies currently have breeding programs producing domesticated and selective-bred Penaeus monodon lines. The most advanced of these lines have demonstrated high commercial pond performance over several generations. However, there is a risk for the breeding program companies, due to on-sale or on-rearing of their selected postlarvae. To avoid this problem, genetic protection for the selectively bred prawns is required; however, to-date there is no commercial method for fail-proof genetic protection of prawns. Triploid induction is the only methodology that has been trialled experimentally that shows promise of genetic protection in prawns. However, there are limited reports of triploid induction in Black Tiger Prawns and no studies have reared the larvae through to harvest age and conducted rigorous performance measurements for this species.

This project aimed to develop a technique that would be suitable for commercial triploid induction (which gives each individual an extra set of their own chromosomes; a process that occurs sporadically in nature) of whole spawnings of the Giant Tiger Prawn. A methodology was developed to induce whole spawn triploidy with temperature and chemical shocks. However, hatch rates from this system were consistently low. Despite this a chemical induced triploid family with a high induction rate and reasonable larval survival was produced at a commercial hatchery, allowing rigorous tank-based performance assessments to be carried out.

The overall performance of triploids was comparable to other penaeid prawn species with some exceptions. In triploids, survival was lower, and females were significantly larger. Furthermore, there were more males than females with a 1:1.625 sex ratio and reproductive age triploids were unable to produce viable offspring. This demonstrates that triploidy would provide the industry with a method of genetic protection for Black Tiger Prawns, however significant challenges in maintaining high hatch rates, survival rates and induction rates of the triploids when inducing whole spawnings on a commercial scale still remain.