OPTIMIZATION OF TRIPLOID INDUCTION FOR THE OYSTER CRASSOSTREA-VIRGINICA (GMELIN)

Standard techniques developed for producing triploid oysters (Crassostrea gigas) in the northwestern United States cause > 90% mortality of Crassostrea virginica, which is unacceptably high considering the scale of most east coast hatcheries. We examined the effect of cytochalasin B (CB) concentration, timing of treatment after fertilization, and duration of treatment on survival and triploid induction of C. virginica embryos. Survival to D-stage was inversely related to CB concentration and length of treatment. Induction of triploidy was CB-dose dependent. Optimal treatment of 0.25 mg/l CB for 10-15 min beginning when half the embryos were observed to be undergoing meiosis-I yielded mean survival to D-stage of 84% of control values with a mean of 96% triploid production.