The Sydney rock oyster Saccostrea glomerata (Gould 1850) breeding programme: progress and goals.
A mass selection programme was initiated in 1990 in New South Wales, Australia, with the aim of breeding faster growing Saccostrea glomerata. After 2 generations of selection, an average weight for age advantage of 18% (range 14-23% per breeding line) was achieved which equates to a reduction of 3 months in the time taken to reach market size. 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 an outbreak of QX disease (caused by Marteilia sydneyi) in 1994. In 1997, the breeding programme was reorganized and expanded, and new lines were bred from oysters that had survived both QX and winter mortality. After one generation, a small improvement in resistance to QX was recorded; however, the exposure of further generations to M. sydneyi will be required to confirm an increase in resistance.