The s hell colour is vvaried and is usually pale white or off-white. Adults can vary in size from 8 cm to 40 cm in length. Pacific oysters will attach to almost any hard surface in sheltered waters. They will also settle on adult oysters of the same or other species. The oysters prefer sheltered waters in estuaries where they are found in the intertidal and shallow subtidal zones, to a depth of about three metres. Pacific oysters are filter feeders. They grow quickly and and havehigh reproductive rates.
Where did they come from?
This oyster is native to the Pacific coast of Asia. It has been farmed for hundreds of years in Japan.
Where are they found in Australia?
It has become an introduced species in Australia and the United Kingdom, France, America, Canada, Korea, China and New Zealand.
How was it introduced?
In Australia, the Pacific oyster was deliberately introduced into Tasmania, Victoria, WA and South Australia for use in aquaculture, and has spread to New South Wales and southern Queensland. Fortunately, its introduction into WA in 1947 was unsuccessful.
What is its impact?
The greatest impact of the Pacific oyster is its competition with native oyster species. They have the ability to develop high density populations within the intertidal zone.The spread of this introduced species has been harmful to some long-standing and valuable fisheries based on local rock oysters. The Pacific oyster competes with native oyster species for space and food and may even smother them. This potential change in the species balance also has the potential to impact on non-oyster species, through a modification of their habitat. They can also spread parasites or diseases that are harmful to native species of molluscs.
How is it controlled?
To minimise the spread of Pacific oysters in NSW, NSW DPI has implemented a Pacific oyster closure which includes strict criteria for the movement of oysters between estuaries, with movement of oysters into some areas prohibited.