The Pacific Oyster, Crassostrea Gigas (Thunberg, 1793), in New Zealand

The Japanese or Pacific oyster, Crassostrea gigas , grows to large size, and specimens up to 300 mm have been recorded. Growth squamae are conspicuous in the right ventricle, particularly in spat and young oysters. Pacific oysters have been recorded at some sites at the top of the South Island. The oyster farming industry has been fortunate that, from its inception in the early 1900s, there have been no mass mortalities, disease, or pollution problems; the country continues to enjoy a high reputation for quality oysters produced in fairly clean waters. Crassostrea gigas is farmed in all the east coast and a few west coast harbors of the northern peninsula of the North Island and in Coromandel and Ohiwa Harbor to the east. The shoreline of inlets and coast where oysters occur intertidally is hard bottom, generally consisting of “greywacke” formations on the east coast and of typically hydraulic limestone made up of calcareous mud and sand on the west coast.