Dredge oyster

Dredge oyster
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Subclass: Pteriomorphia
Order: Ostreoida
Family: Ostreidae
Genus: Tiostrea
Species: T. chilensis
Binomial name
Tiostrea chilensis
(Philippi, 1844)

Ostrea chilensis
Tiostrea lutaria

The dredge oyster[1] or Bluff oyster,[2] Tiostrea chilensis, known in Chile as ostra chilena, is a species of marine bivalve mollusc in the family Ostreidae.


This species is native to Chile and New Zealand.

Also, a self-sustaining population in the Menai Strait was accidentally introduced from the Fisheries Laboratory, Conwy, in 1965 or 1966 (sources disagree).


This bivalve is found from low tide to depths of up to 35 m.


Its length is up to 105 mm, width up to 70 mm, and inflation up to 33 mm.

Commercial importance

Bluff oysters at a restaurant

In New Zealand, they are a prized delicacy, and harvested from March to August from the Foveaux Strait oyster fishery, which centres on the town of Bluff (hence the local name).[2] From the early 1980s, the fishery went into serious decline, due to the outbreak of an oyster parasite, Bonamia exitiosa, with the disease killing an estimated billion oysters between 2000 and 2003.[2] The population has been recovering since 2003, with fishermen voluntarily limiting the catch to half the allowable to aid the revival.[2] [3]


Changes in river flows in Southland, due to farming and especially power generation, carrying less limestone deposits into the Strait, is therefore believed to have caused an increase in susceptibility to Bonamia, as well as lower growth rates for some seasons in the past, but little evidence supports this and it seems only coincidental.


  1. "§2 Interpretation -- Fisheries Act 1996 No 88 as at 3 January 2013 -- New Zealand Legislation". Parliamentary Counsel Office. Retrieved 9 March 2013. "dredge oyster" means the mollusc known as Tiostrea chilensis
  2. 1 2 3 4 "High demand for recession-proof oysters". New Zealand Herald. 2 March 2009. Retrieved 2009-03-02.
  3. H.J. Cranfield, A. Dunn, I.J. Doonan and K.P. Michael 2005. Bonamia exitiosa epizootic in Ostrea chilensis from Foveaux Strait, southern New Zealand between 1986 and 1992. ICES J. Mar. Sci. (2005) 62 (1): 3-13 doi:10.1016/j.icesjms.2004.06.021

External links

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