MAPPING STUDIES IN PACIFIC OYSTERS, Crassostrea gigas

CSIRO Marine Research, GPO Box 1538, Hobart, Tasmania 7001, Australia

Pacific oyster growers in Tasmania became interested in applying genetics to improve their product several years ago. The industry is completely hatchery-based, so the potential for stock improvement could be considerable. Our initial studies were directed towards assessing levels of molecular variation in the Tasmanian stock, and in particular in comparison with the Japanese populations that provided the source material some 50 years ago. These studies showed levels of variation remained high in Tasmania, and the industry was keen to embark on a selection program. We have developed a three part program, based on mass selection, family selection, and the use of molecular markers. Non-amplifying alleles are quite common in the microsatellite loci, with an estimated frequency based on progeny testing of around 20% in the Tasmanian collections. Some loci experience segregation distortion. We have produced a preliminary linkage map based on microsatellites, AFLPs and allozymes for one family, and have mapped some traits including meat weight. Oyster physiology is also being examined, and we hope shortly to map some physiological parameters.