The Latin name for The Pacific Oyster is Crassostrea gigas

Other common names: Pacific king oyster, Pacific rock oyster

Pacific oysters are endemic to Japan, but have been introduced into a number of other countries including Australia. Most of these introductions have been for the purposes of aquaculture, with Pacific oysters the most widely cultured shellfish species worldwide.

Pacific oysters were first introduced into south-eastern and western Australian waters for aquaculture. They later found their way into NSW waters, where they have spread and invaded intertidal habitats of many waterways.

Pacific oysters are a hardy species with fast growth and high reproductive rates. This has allowed them to establish dense populations in some areas, often displacing native intertidal species.

Although Pacific oysters are the basis of an important aquaculture industry in Port Stephens, elsewhere they have caused significant problems for oyster farmers who culture native Sydney rock oysters (Saccostrea glomerata). As the two species live and spawn in the same locations, Pacific oysters can settle on and (due to their faster growth rate) smother farmed Sydney rock oysters.

NATURAL DISTRIBUTION AND BIOLOGY OF THE PACIFIC OYSTER (Crassostrea gigas)

Pacific oysters are bivalve molluscs belonging to the family Ostreidae. They are native to northeast Asia (including Japan), but have been translocated and spread widely throughout many countries (including the UK, France, USA, Canada, Korea, China and New Zealand) for the purpose of aquaculture.

Pacific oysters have a fairly thin shell with no hinge teeth on the inner, upper shell (unlike Sydney rock oysters). The adductor muscle (which holds the two shells together) is purple or brown in colour, whilst the edges of the mantle (the tissue which secretes and lines the shell) are black.

Adult Pacific oysters are sessile and will settle on any hard substrate in the inter-tidal and shallow subtidal zones, to a depth of about 3 metres. They favour brackish waters in sheltered estuaries, although they tolerate a wide range of salinities and water quality and can also occur offshore.

Pacific oysters have very high growth rates (they can grow to over 75 mm in their first 18 months) and high rates of reproduction.

Like most oyster species, Pacific oysters change sex during their life, usually spawning first as a male and subsequently as a female. Spawning is temperature dependent and occurs in the summer months. Pacific oyster females can produce between 30 to 40 million eggs per spawning, often giving the surrounding water a milky appearance. Fertilisation takes place in the water column.

The larvae are planktonic and free swimming, developing for three to four weeks before finding a suitable clean hard surface to settle on. Although they usually attach to rocks, they can also settle in muddy or sandy areas (where they attach to small stones, shell fragments or other debris) or on top of other adult oysters. A very small percentage of oysters survive this phase; those that do are called "spat".

Pacific oysters can live up to 10 years and reach an average size of 150-200 mm.

Pacific oysters are plankton feeders that filter minute marine algae and other microorganisms out of the water.

Pacific Oyster Shell Top	Pacific Oyster Opened
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Pacific Oyster Meats	Pasteurised Pacific Oysters in Juice