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The dredge oyster, bluff oyster or Chilean oyster (''Ostrea chilensis''), is also known in
Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
as ''ostra verde'', is a
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of bivalve mollusc in the
family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Ostreidae The Ostreidae, the true oysters, include most species of molluscs commonly consumed as oysters. Pearl oysters are not true oysters, and belong to the order Pteriida. Like scallops, true oysters have a central adductor muscle, which means the ...
. This species of flat oyster is a marine bivalve mollusc of the
family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Ostreidae The Ostreidae, the true oysters, include most species of molluscs commonly consumed as oysters. Pearl oysters are not true oysters, and belong to the order Pteriida. Like scallops, true oysters have a central adductor muscle, which means the ...
.


Distribution

This species is
native Native may refer to: People * Jus soli, citizenship by right of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Native Americans (disambiguation) In arts and entert ...
to
Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
and
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
. 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 ''Ostrea edulis'', commonly known as the European flat oyster, is a species of oyster native to Europe. In Britain and Ireland, regional names include Colchester native oyster, mud oyster, or edible oyster. In France, ''Ostrea edulis'' are known ...
'' 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. Whereas in Chile, its range limit is from
Chiloé Island Chiloé Island ( es, Isla de Chiloé, , ) also known as Greater Island of Chiloé (''Isla Grande de Chiloé''), is the largest island of the Chiloé Archipelago off the west coast of Chile, in the Pacific Ocean. The island is located in southern ...
, Los Lagos region to Guaitecas Islands, Aysén region. Practically, nowadays it only exists in the wild in one natural bank, Pullinque, a sector located in the Quetalmahue Gulf of Ancud which was declared a genetic reserve in 1982, and as a marine reserve in 2003.


Habitat

This bivalve is found from low tide to depths of up to 35 m. In Chile it lives attached to hard rocky or muddy bottoms, from intertidal to about 8 meters deep, in enclosed bays or areas protected from strong waves.


Description

Its length is up to 105 mm, width up to 70 mm, and inflation up to 33 mm. In Chile its maximum controlled length is 87 mm.


Commercial importance

In New Zealand, they are a prized delicacy, and harvested from March to August from the
Foveaux Strait The Foveaux Strait, (, or , ) separates Stewart Island, New Zealand's third largest island, from the South Island. The strait is about 130 km long (from Ruapuke Island to Little Solander Island), and it widens (from 14 km at Ruapuke ...
oyster fishery, which centres on the town of
Bluff Bluff or The Bluff may refer to: Places Australia * Bluff, Queensland, Australia, a town * The Bluff, Queensland (Ipswich), a rural locality in the city of Ipswich * The Bluff, Queensland (Toowoomba Region), a rural locality * Bluff River (New ...
(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. In Chile, it has been harvested by the fishermen of Chiloé Island since ancient times, but the written and photographic information dates back to the mid-1800s. As Chile is th
longest country in the world
the transportation of the harvested oysters by wooden-made ships, or b

to the port of
Valparaíso Valparaíso (; ) is a major city, seaport, naval base, and educational centre in the commune of Valparaíso, Chile. "Greater Valparaíso" is the second largest metropolitan area in the country. Valparaíso is located about northwest of Santiago ...
, and then to the capital,
Santiago Santiago (, ; ), also known as Santiago de Chile, is the capital and largest city of Chile as well as one of the largest cities in the Americas. It is the center of Chile's most densely populated region, the Santiago Metropolitan Region, whos ...
, was complex; however, it got solved when the oysters were placed in barrels that were grated and jointed by quila, a kind of bamboo, and then filled with seawater. The trip lasted half a month. In the city of
Ancud Ancud () is a city in southern Chile located in the northernmost part of the island and province of Chiloé, in Los Lagos Region. It is the second largest city of Chiloé Archipelago after Castro. The city was established in 1768 to function as ...
, Chiloé Island, the extraction of the oyster was banned even at that time (as in 1869 and then in 1874) due to its overexploitation, on the other hand its sale brought thousands of barrels, boxes and sacks of oysters to the capital to supply its great demand. The oysters was even kept in ponds for growing by Frenchmen, first b
Mr. Choloux
in Lechagua, Ancud, 1874 and later by the Solminihac family, formally with a concession in Quetalmahue, city of Ancud, in 1915. A couple of years later, in 1935, the Pullinque Oyster Station was built in Pullinque to try to cultivate the Chilean oyster, initiative that proved to be successful because it could provide with seeds for growth to other aquaculture centers that emerged during the agrarian reform period. The economy of Chilean oysters was severely hurt when the most powerful earthquake recorded happened in Valdivia, 1960 because the Pullinque Oyster Station was destroyed by it. Hence, the Corfo institution tried to bring-in the
Pacific oyster The Pacific oyster, Japanese oyster, or Miyagi oyster (''Magallana gigas''), is an oyster native to the Pacific coast of Asia. It has become an introduced species in North America, Australia, Europe, and New Zealand. Etymology The genus ''Mag ...
, but the intention was not recommended by the consulted experts, a decision that was respected by the national government. After the agrarian reform the commercial aquaculture started in the 80s, during the Civic-military dictatorship of Chile, according to
FAO The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...
, since producers that were state-managed passed to be privately regulated, and also because many exotic species were tentative to introduce as culture options. Nowadays, its culture is successful in Chile with considerable tons exported, and consumed in some places and restaurants.


Other

Changes in river flows in
Southland Southland may refer to: Places Canada * Dunbar–Southlands, Vancouver, British Columbia New Zealand * Southland Region, a region of New Zealand * Southland County, a former New Zealand county * Southland District, part of the wider Southland Re ...
, 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. Flawed discards practices in Chile during the 1890s of the small oysters ended up killing some oyster banks in Ancud. Particularly i
Corona lighthouse
and Quetalmahue Gulf; as the turbulence generated by the falling oysters resuspended the bottom sand, creating hypoxia conditions that did not allow to breath the bivalve.


References


External links


The National Centre for Fisheries & Aquaculture's page on Bluff oysters (''Tiostrea chilensis'')

JNCC: ''Tiostrea chilensis''
{{Taxonbar, from1=Q7808747, from2=Q14651290 Ostrea Molluscs of the Pacific Ocean Molluscs of Chile Bivalves of New Zealand Commercial molluscs New Zealand seafood Foveaux Strait Bivalves described in 1844