triploid larvae in commercial hatcheries; triploidy induced by mating tetraploids with diploid oysters approaches 100% effectiveness, but the small percentage of diploids occurring in mated triploid offspring (0.09%) becomes a significant number in commercial-scale operations involving millions of offspring. Triploids may also revert to the diploid state as they age, but probably less than 1% of a mated triploid cohort might eventually produce normal gametes if they remain in the field more than 3 or 4 years. Triploids are not always completely sterile. Careful examination of C. gigas triploids indicates that the fecundity of triploid females averages 2% of diploids, but survival of progeny of triploid × triploid and triploid × diploid crosses is extremely small.



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