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Dredge oyster facts for kids

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Dredge oyster
Naturalis Biodiversity Center - ZMA.MOLL.415097 - Ostrea chilensis Philippi, 1846 - Ostreidae - Mollusc shell.jpeg
Museum specimen of the shell of Ostrea chilensis
Scientific classification
  • Crassostrea discoidea (Gould, 1850)
  • Crassostrea nelsoniana (Zittel, 1865)
  • Ostrea callichroa Hanley, 1846
  • Ostrea charlottae Finlay, 1928
  • Ostrea chiloensis G. B. Sowerby II, 1871
  • Ostrea cibialis Hupé in Gay, 1854
  • Ostrea corrugata Hutton, 1873
  • Ostrea discoidea Gould, 1850
  • Ostrea fococarens Finlay, 1928
  • Ostrea heffordi Finlay, 1928
  • Ostrea huttoni Lamy, 1929
  • Ostrea longiuscula Hupé in Gay, 1854
  • Ostrea lutaria Hutton, 1873
  • Ostrea nelsoniana Zittel, 1865
  • Ostrea vinolenta Hupé in Gay, 1854
  • Tiostrea chilensis (Philippi, 1844)
  • Tiostrea lutaria (Hutton, 1873)

The dredge oyster or Bluff oyster, Ostrea chilensis, known in Chile as ostra chilena, the Chilean oyster, 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 deliberately introduced from the Fisheries Laboratory, Conwy, during the 1960s as an experiment to establish if they could form an alternative to the native oysters Ostrea edulis in fisheries, when the species was shown to be unsuitable because of low recruitment and vulnerability to parasites and pathogens the experiment was abandoned. O. chilensis has now spread to other areas of the Menai Strait and is regarded as an invasive species.


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 on ice
Bluff oysters served on ice
New Zealand bluff oysters
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). 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. The population has been recovering since 2003, with fishermen voluntarily limiting the catch to half the allowable to aid the revival.


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.[opinion]

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