Studies on triploid oysters in Australia: evaluation of cytochalasin B and 6-dimethylaminopurine for triploidy induction in Sydney rock oysters Saccostrea commercialis (Iredale and Roughley)

Naturally spawned Sydney rock oysters Saccostrea commercialis (Iredale and Roughley), were used to determine the appropriate stage of development for inducing triploidy and to compare the effectiveness of cytochalasin B (CB) and 6-dimethylaminopurine (6-DMAP) in dose-optimization trials. Induction should commence at 50% first polar body (PB1) extrusion in eggs (approximately 17-19 min post-fertilization at 25°C). By day 5 the highest triploidy percentage and yield (number of triploid larvae per 100 fertilized eggs) were achieved in the ranges of 0.75-1.5 mg CB l-1 (1.6- 3.1 μM CB) or 200-400 μM 6-DMAP (32.6-65.3 mg 6-DMAP l-1). However, CB treatment resulted in greater survival and triploidy percentage than 6-DMAP in Sydney rock oysters.