The Sydney rock oyster Saccostrea glomerata (Gould 1850) breeding programme: progress and goals

In 1990, NSW Fisheries initiated a mass selection programme in Port Stephen s, NSW, with the aim of breeding faster growing Sydney rock oysters Saccost rea glomerata (Gould 1850). After two generations of selection, an average weight for age advantage of 18% (range 14-23% per breeding line) was achiev ed. This equates to a reduction of 3 months in the time taken to reach mark et size. Experiments are planned to determine how much of this 3 months adv antage is additive to the 6 months advantage this laboratory has already ob tained using triploid S. glomerata. A parallel set of S. glomerata breeding lines was established on the Georges River, NSW, to include selection for resistance to the protistan parasite Mikrocytos roughleyi, the causal agent of winter mortality. The programme was disrupted by the outbreak of QX dis ease Marteilia sydneyi, another protistan parasite, in 1994. In 1997, the b reeding programme was reorganized and expanded. New lines were bred from oy sters that had survived both QX and winter mortality. After one generation, a small improvement in resistance to QX has been recorded; however, the ex posure of further generations to M. sydneyi will be required to confirm an increase in resistance.