Fisheries Infosite

Dredge Oyster Part Central (East) (OYS2A)
Maori name
Tio (general name for all Oysters (Ngai Tahu))
Scientific name
Ostrea chilensis

Physical characteristics

Dredge Oysters have a minimum legal harvesting shell length of 57 mm, but can grow to a length of at least 75 mm.

Life cycle

Dredge Oysters have a maximum age of 33 years. They are thought to reach maturity at 3 years for males and 4 years for females. Spat settlement occurs in December-February.


Dredge Oysters are found around New Zealand waters from shoreline to depths of 60 m. They are most abundant in Foveaux Strait at depths from 20-48 m.

Key statistics
Recreational significance Low
Customary significance Low
Reported commercial catch1 (tonnes)
Quota value estimate2 (NZ$m)
Exports estimate2 (NZ$m)
1 Reported commercial catch is calculated for the 12 month period to 30/09/2025
2 Quota value and exports are calculated pro-rata to reported commercial catch for the 12 month period to 30/09/2025