Bluff (Dredge) oysters
Māori Name: Tio paruparu
Name Scientific: Tiostrea chilensis
Availability: March to August
Attributes Length: 6–8cm, reaching 10cm
They are endemic to New Zealand, where they are widely distributed around the coast, and form dense beds in gravel or coarse sand bottoms from 25 to 50 metres deep.
Shell of varied colours from white to a dull purple-brown. The left shell is ridged and cupped while the right shell lies flat and has scaly layers. Inside, the shell is luminous, and the flesh has shades of white, grey, gold, and black. The creamy coloured meat is delicate and succulent, with a medium oil content.
Bluff oysters, also known as Dredge oysters, belong to the Ostreidae family (oysters). There is a similar species in Chile.
Bluff/Dredge oysters are hermaphrodites, and they spawn in summer. Larvae have a brief free-swimming stage before they settle on the sea floor.
Bluff oysters have been commercially fished in the Foveaux Strait since the late 1880s. Over that time, total landings of oysters have varied from 7.5 to 77 million oysters annually. Bonamia exitiosa, a parasite identified in 1986 and found globally, caused high mortality in the oyster population. In response, reduced catch limits were put in place, including a period of closure from 1993-1996. The fishery has since recovered and catch limits are now being increased. Regular monitoring for disease outbreaks is in place.
The fishery is strictly controlled and only open from March to August when the oysters are in the best condition. They are harvested principally in Foveaux Strait and, in much smaller commercial quantities, in Tasman Bay and Golden Bay.
Did You Know
Bluff/Dredge oysters have an almost fanatical following among oyster fanciers. There is an annual Bluff Oyster and Food Festival to coincide with the catch.
Bluff oyster flesh has shades of white, grey, gold and black. The meat is delicate and succulent, with a medium oil content. They are arguably best eaten fresh, raw and straight from the shell, however they can also be baked, barbequed, fried, poached, smoked, steamed, or used in a soup/chowder.
The majority of Bluff oysters available in shops are in pottles, keeping the oyster meat fresh and tasty. If you purchase live Bluff oysters, their shells should be tightly closed or close slowly when tapped. Live Bluff oysters should be stored in an open container with a damp cloth over them, in the fridge, and served within 48 hours of purchase.