1 Introduction
1.1 Background
Oysters have proved highly amenable to aquaculture, and today exploitation of wild populations contributes little to worldwide oyster production.
In the United States, five species of oysters are cultivated on the Pacific Coast of the United States : the native oyster Ostrea lurida, the Atlantic oyster Crassostrea
virginica, the Kumamoto oyster Crassostrea sikamea, the European flat oyster Ostrea edulis, and the Pacific oyster Crassostrea gigas. The Pacific oyster is by
far the dominant species, with a production level in the range of 5 million kg per year. The Pacific oyster has been the most important cultivated oyster since 1977.
Beside in the Pacific Coast, Pacific oyster also well developed in Washington State, Willapa Bay, Oakland Bay, and Samish Bay Lavoie, 2005.
In Asia, oysters have been traditionally appreciated as seafood. Such as
in Malaysia, they found on the market in fresh form, or as shucked meat, frozen meat, dried or canned. Three genera of commercially important oysters are found
in Malaysia, Crassostrea, Saccostrea, and Ostrea. The genus Crassostrea comprises of two species, C. iredalei and C. heicheri, whereas the genus Ostrea
has only one species O. folium. C. heicheri, C. iredalei and Saccostrea spp. are usually harvested in Malaysia for human consumption. The species most valued
for culture is C. iredalei Nawawi, 1993. In Korea, the Pacific Oyster C. gigas, Korean kang-gul C. rivularis, Korean pawit-gul C. nippona, spiny oyster C.
echinata and the densely lamellated oyster C. denselamellosa are grown, however the Pacific oyster is the main species for commercial farming Park et
al., 1988. On the other hand, in Indonesia, oysters are not famous. There aren’t many oysters farming. Even though, we have Pinctada maxima in east Indonesia
Tun, 2001. In France, oyster culture began in the middle of the 19th century. The
indigenous species Ostrea edulis was replaced first with Crassostrea angulata, then Crassostrea gigas. Right now the top producer and consumer of oysters are
1
2
in Europe, producing around 130 000 tons of the cupped oyster C. gigas annually and a remaining 1 500 tons of the flat oyster O. edulis Buestel et al., 2009.
Quiberon Bay has a large production of oyster, approximately 15 000 tons annually which contributes to oyster production in France Fleury et al., 2008.
There are 81 oyster-farmers 22 of companies in South Brittany exploit 2643 ha of marine farming in deep water or 50 of the production area in the southern
Brittany. As raw material, oyster farmer sell the oyster directly to the consumer, supermarket or export to other countries. More than 50 of the production of the
Bay is sold directly in Marennes-Oléron shippers. Pacific oyster have been cultured in several country, as a result, C. gigas
has become the leading species in world culture, with an estimated production of 4.6 million tons in 2006. Because C. gigas does not require additional food to
sustain its growth, this species is relatively inexpensive and easy to produce. Its capacity to adapt to various environmental conditions and temperature
fluctuations, coupled with its rapid growth and resistance to highly turbid areas, contributes to its success Miossec et al., 2009.
In oyster culture, there are several factors that could influence growth and mortality the oyster, such as predator, disease, parasite, and environmental
conditions such as salinity, temperature, etc. This study focus on mortality which is caused by the predator, which is regularly happened in oyster farming beside
other factors. Since the year of 2000 and especially 2006, the oyster mortality rates C.
gigas have reached quite unusual number estimated at 60 mortality in a breeding cycle ending in late 2006, according to the response of 51 companies
interviewed by the Comité Régional de la Conchyliculture de Bretagne Sud CRC. This mortality brought a great impact on Frances economy. So, in this
study, we observed the effects of oyster mortality in terms of biology and economics.
RISCO-QB Risks in shellfish farming, in Quiberon Bay is a project research which is held to analysis the phenomena and find the best solution for
3
oyster culture in Quiberon Bay. RISCO is a “Pôle Mer Bretagne” project with a collaboration between CRC Comité Régional de la Conchyliculture de Bretagne
Sud, Ifremer La Trinite sur Mer and different partners including UBS Laboratory Géoscience Marine et Géomorphologie du Littoral G.M.G.L Université de
Bretagne Sud, Vannes, Université de Nantes – Laboratoire LEMNA: Laboratoire d’Économie et Management de Nantes, Cochet Environnement and CER du
Morbihan Réseau nautile, Vannes
1.2 Objectives
Kategori