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Crassostrea gigas:   (click for more)

Crassostrea gigas:   (click for more)

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  • Crassostrea angulata  Lamarck, 1818, is a name often used for this species. The question whether angulata and gigas are different species, subspecies or just forms has not yet been resolved.
    FAO Names
    En - Pacific cupped oyster, Fr - Huître creuse du Pacifique, Sp - Ostión japonés.
    3Alpha Code: OYG     Taxonomic Code: 3160700801
    Diagnostic Features
    Shell solid, inequivalve, extremely rough, extensively fluted, and laminated; left (lower) valve deeply cupped, its sides sometimes almost vertical, the right (upper) valve flat or slightly convex sitting withing left; inequilateral, beaks and umbones often overgrown; tending to be oblong in outline but often disorted and very irregular. The shape of the shell varies with the environment.  Colour usually whitish with many purple streaks and spots radiating away from the umbo. The interior of the shell is white, with a single muscle scar that is sometimes dark, but never purple or black. 
    Can be confused with: It differs from Crassostrea virginica in never having a purple or black muscle scar, and from Ostrea lurida in its extremely large size and heavy shell. In addition, the inside of an O. lurida shell is iridescent green.

    Geographical Distribution

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    Cosmopolitan. Recorded from Japan, Korea, Siberia, Australia, United States and Canada. Introduced in North America is found Southeast Alaska to Baja California. In Europe from the British Isles south to Portugal and in the Mediterranean.
    Habitat and Biology
    Is an exotic species introduced into west coast estuaries americaines from Japan. Prefer firm bottoms, and usually attach to rocks, debris or other oyster shellsat depths of between 5 and 40 m.However, they can also be found on mud or mud-sand bottoms.
    Pacific oysters are protandrous hermaphrodites. They change sex, but their timing is erratic and seasonal. Spawning depens on a rise in water temperatures above eighteen degrees Celsius. When spawning does occur, it occurs primarily in July and August; eggs (50-100 millions in single spawning) and larvae are planktonic distributed throughout the water column in estuarine waters. Later stage larvae settle out of the water column and crawl on the bottom searching for suitable habitat before settling.  Juveniles and adults are sedentary and are found in lower intertidal areas of estuaries.
    Maximum length is 30 cm (exceptional specimens can attain 40 cm), but normally the length is from 8-15 cm.
    Interest to Fisheries
    The commercial fishery for this species has grown rapidly since its introduction from Japan to the west coast of the United States in 1903. The United States now consumes almost 60 percent of the world's total oyster production. The Pacific oyster is a dominant shellfish in a growing United States aquiculture industry along the Pacific Coast. The 60-70 percent of the Pacific oyster production is marketed in the Pacific Coast States.The total catch reported for this species to FAO for 1999 was 12 271 t. The countries with the largest catches were Korea, Republic of (11 609 t) and USA (539 t).
    Local Names
    English : Giant oyster ,  Giant Pacific oyster ,  Immigrant oyster ,  Japanese Oyster ,  Miyagi oyster ,  Pacific cupped oyster .
    French : Gigas ,  Huitre géante du Pacifique .
    Spanish : Ostión ,  Ostión japonés .
    Pauley, G.B., B. Van Der Raay & D. Troutt - 1988Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Pacific Northwest) Pacific oyster. U.S. Fish and Wildl. Serv. Biol. Rep. 82 (11.85). U.S. Army Corps of Engineers, TR EL-82.4 28 pp.
    Poppe, G.T. & Y. Goto. - 1993European Seashells.Verlag Christa Hemmen, darmstadt, Germany, vol. II: 221 pp.
    Turgeon, D.D., A.E. Bogan, E.V. Coan, W.K. Emerson, W.G. Lyons, W.L. Pratt, C.F.E. Roper, A. Scheltema, F.G. Thompson & J.D. Williams - 1988Common and scientific names of aquatic invertebrates from the United States and Canada: mollusks.
    Vera, J. - 1992 Diccionario multilingüe de especies marinas para el mundo hispano.Ministerio de Agricultura, Pesca y Alimentación. Secretaria General Técnica.  1282 pp.
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