The Spawnless Oyster

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Spawnless (Triploid) Oysters

Prof. Standish Allen, a professor of Marine Science, Aquaculture Genetics in the United States is considered a leader in the field of the development of the Spawnless (Triploid) Oyster.

The Spawnless (Triploid) Oyster has three sets of chromosomes, whereas the naturally occuring Diploid Oyster  has only two sets.

In 1979, and using the oyster species Crassostrea virginica, Prof. Allen developed  the first Triploid Oyster. Further research lead to the development of the PacificTriploid  (Crassostrea gigas) oyster in 1984.   In 1985 the production of the Pacific Triploid in the US became commercially viable.

The Triploid strain of the Pacific oyster with its three sets of chromosomes is reproductively inactive — in other words, virtually sterile. Generally speaking,  they grow in the same way as the Diploid oyster, with the difference primarily being that they have poorly developed male sex organs, and therefore do not divert much of their energy into reproduction. The result is a fast-growing, generally larger, firmer and more palatable oyster.

In their overall appearance, and for the untrained eye, the Diploid and Triploid Pacific oyster look basically the same. For the 'non expert', the most obvious difference is the size of the abductor muscle (the part of the oyster that adheres the animal to its shell). The abductor muscle of a Triploid Pacific oyster is considerably larger than that of the Diploid Pacific.

 

                            

                                                                      The Spawnless (Triploid) Oyster

Diploid oysters spawn during the warmer summer months and lose much of their condition. They also tend to become "mushy" during this reproductive phase, and somewhat unpalatable.  Because triploids do not undergo the transformations associated with the reproduction cycle they can be marketed all year round.

The development and introduction of the Triploid oyster into Australia has provided Marine Culture with the ability to supply the Australian and International market with oysters year-round.