Tetraploid Pacific Oysters for "All-Triploid" Production

In the last decade, triploid Pacific oysters (Crassostrea gigas) have become an important component of the oyster culture industry in the Pacific Northwest. Because of their reduced gonadal development, triploid oysters provide a high quality product which can be marketed year-round. Currently, triploid Pacific oysters are induced primarily by inhibiting the second polar body with cytochalasin B. There are major limitations to the use of CB, but these limitations would be eliminated if triploid oysters could be produced by crossing diploids and tetraploids. After more than a decade of attempts to produce tetraploid oysters, success was finally achieved in 1993. This novel technique, in retrospect, is quite simple and success depends on a number of variables, almost none of them explored in any systematic way. For commercial production of triploids using tetraploids as brood stock, the rate limiting process is obtaining the tetraploids in the first place, but we do not know whether the tetraploid induction technique, developed in the lab, is transferable to a commercial hatchery. The proposed project is designed to test the repeatability of the tetraploid induction process in a commercial setting, and to explore variables in the induction process that might improve yields of tetraploids.