Chesapeake Bay Introduced Species Database

Crassostrea gigas

Common name(s):
Pacific Oyster
The Pacific Oyster is native to the Indo-West Pacific and is the most widely transplanted shellfish in the world, introduced to at least 42 countries. Incredibly there are no established populations in western Atlantic waters, in spite of illegal or unofficial introductions in Atlantic waters near Chesapeake Bay and Delaware Bay. But the introduction of Pacific Oysters was considered as a possible means of replacing or supplementing native stocks of the Eastern Oyster (Crassostrea virginica), which has been devastated by disease and overharvest. Both the Pacific Oyster and the Chinese River Oyster (C. ariakensis) were investigated for possible introduction until 1998 following research in the Bay, which including the stocking of sterile oysters. But initial studies found that the Chinese River Oyster had better growth and survival under East Coast conditions than the Pacific Oyster, and so further research and political interest shifted to the Chinese River Oyster. Ironically, early plantings of the Pacific Oyster in the 1950s in Delaware Bay are one of the possible means of introduction of MSX (Haplosporidium nelsoni), one of the diseases that lead to the decline of Eastern Oysters. The Pacific Oyster was, however, successfully introduced to Puget Sound WA in 1902 to replace the Olympic Oyster (Ostreola conchaphila), which was devastated by overfishing.
Image courtesy of Paul Fofonoff.


Crassostrea gigas


Ostrea gigas; Crassostrea angulata

Potentially Misidentified As:

Crassostrea virginica; Crassostrea ariakensis

Common Names:

Pacific Oyster; Japanese Oyster


Synonymy - Crassostrea angulata, the Portuguese Oyster, found in waters of southern Europe has been considered either a distinct species, or by many recent investigators, a population of C. gigas brought from Asian waters ~300-400 years ago (Carriker and Gaffney 1996). Currently, C. angulata is considered to be a separate but closely related species, and has been found in China (O'Foighil et al. 1998; Lapegue et al. 2004

Other Taxonomic Groupings - Several varieties (races, forms) are known, with different growth and breeding characteristics. The 'Miyagi' form is the one most often reared outside Japan, and is the strain being most heavily studied for possible planting in Chesapeake Bay and elsewhere on the Atlantic coast (DeBrosse and Allen 1996; Mann et al. 1991; Quayle 1969).

This data was last modified on Wednesday, July 17th, 2013.
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