Studies on triploid oysters in Australia:: Farming potential of all-triploid Pacific oysters, Crassostrea gigas (Thunberg), in Port Stephens, New South Wales, Australia

Triploid Pacific oysters Crassostrea gigas farmed in Port Stephens, NSW had an exceptionally fast growth rate and reached a whole weight of 55 g in 13 months versus 20 months for diploids. Mortality of the triploids (24.5 +/- 2.94%) was significantly lower (P < 0.05) than that of the diploids (40.0 +/- 2.26%) over the duration of the experiment (July 2002-February 2004). Unfortunately, this advantage was offset by discoloration of the meats of the triploids when they were in better condition than the diploids over summer (October 2003-March 2004). However, discoloration of meat of triploids had cleared up by April 2004 and neither did they suffer this problem from April-September 2003. The triploids also had a lower peak condition than the diploids. Oysters in peak meat condition, i.e. spawning condition, are preferred for the half shell trade in Australia and in this study, there was at least a six-month period prior to discoloration, when the triploids were large enough and had sufficient meat condition for marketing on the half shell.