MEIOSIS IN TETRAPLOID PACIFIC OYSTERS, THEIR TRIPLOID MOTHERS, AND DIPLOID GRANDMOTHERS
The Pacific oyster occurs on all continents but Antarctica (Mann 1979) and for the past several years has had the highest annual production of any freshwater or marine organism (4.2 million metric tons in 2002, worth $3.5 billion; FAO 2004). About 92 million pounds of Pacific oyster meat were produced on the West Coast in 2000, with a farm-gate value of nearly $70 million (Toba and Chew 1999). West Coast production exceeds the harvest of Eastern oysters on either the Gulf or Atlantic Coasts, primarily because diseases have wiped out those natural stocks. As the Pacific oyster does not naturally reproduce along much of the West Coast, seed was imported from Japan for decades (Chew 1984). In the early 1980s, however, the industry adopted hatchery techniques and now relies mainly on hatchery seed. This sets the stage not only for commercial breeding programs, which industry identifies as a top priority (Pacific Shellfish Institute 1999), but also for development in the future of a mature seed industry servicing global markets.