History, Status and Future of Oyster Culture in France
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No.20 The 1st International Oyster Symposium Proceedings History, Status and Future of Oyster Culture in France D. Buestel Ifremer Pacifi c Center-Tahiti B.P. 7004, 98719-Taravao-Tahiti-French Polynesia SUMMARY small family fi rms. There is a young, well educated The history of oyster culture in France consists population of farmers, with technical expertise and of a succession of development phases with dif- “savoir faire”. Careful monitoring of water quality ferent species, followed by collapses caused by assures good consumer protection, and research is diseases. The indigenous species Ostrea edulis making innovative contributions (selection, poly- was replaced fi rst with Crassostrea angulata, then ploids etc.). These points, and opportunities to ex- Crassostrea gigas. France is now the top producer pand the market, should ensure that this industry is and consumer of oysters in Europe, producing well maintained in the future although the problem around 130,000 tonnes of the cupped oyster C. gi- of toxic algae, probably linked to global warming, gas annually and a remaining 1,500 tonnes of the and the threat of new diseases are vital questions fl at oyster O. edulis. Cupped oysters are produced for future research. all along the French coast from natural (80%) and Key words: Aquaculture, French oyster produc- hatchery spat. Various structures are used to collect tion, Crassostrea gigas, Ostrea edulis, fl at oyster, spat from the wild. After a growing-on period, oys- cupped oyster. ters can be cultivated by three main methods: (i) on-bottom culture in the intertidal zone or in deep INTRODUCTION water; (ii) off-bottom culture in plastic mesh bags The French coastline, which is around 500 km in the intertidal zone; or (iii) suspended culture on long, provides favourable environments for mol- ropes in the open sea. The principal development lusc development, particularly oysters which have that has taken place in culture techniques is the use always been much appreciated by the French. The of oysters produced in hatcheries, especially trip- north coast on the English Channel and west coast loids. Almost all French oyster production is sold on the Atlantic Ocean are subject to tidal effects fresh and eaten raw straight from the shell. There with mean tidal ranges varying from 10 m in the is a strong seasonality in sales, with the most being north to 4 m in the south. Water temperature fl uc- made during the Christmas and New Year period. tuates from 6°C to 17°C in the north but can reach The abundant production and the lack of market over 20°C on the Atlantic and salinity fluctuates organisation induce strong competition between from 20 g/l in winter to 30-35 g/l in summer. These the different production areas, causing prices to conditions, added to a great diversity of coast types fall. In order to overcome this difficulty, oyster with numerous highly rich estuaries, favoured the farmers have developed strategies of sales promo- development of natural beds and later rearing ar- tion and regional quality labelling. The hazards eas. On the Mediterranean coast, although the con- of production are numerous: environmental crises ditions are quite different (lagoons with almost no (microbiological pollution, toxic microalgae), un- tide, higher salinity (30 to 40 g/l) and warmer wa- explained mortality, overstocking etc. Recently, ter in summer (up to 27°C)), the sites are suited to new problems with toxic algae have disrupted oys- oyster farming owing to very high phytoplankton ter sales. However, French oyster culture has many productivity. Oyster culture began in the middle of assets. These include a coastal environment offer- the 19th century and has remained very traditional ing favourable sites for mollusc growth and repro- in France, which remains the principal producer duction. Oysters have been consumed in France and consumer of oysters in Europe. since ancient times and their culture is now well established with a concession system that favours Oyster Research Institute News No.20 HISTORY OF OYSTER PRODUCTION IN from the Arcachon and Marennes regions. How- FRANCE. THE EUROPIAN FLAT OYSTER ever, spat capture picked up again some time later OSTREA EDULIS AND THE CUPPED OYS- in southern Brittany where flat oyster production TERS CRASSOSTREA ANGULATA AND has continued, reaching a maximum of 28,000 t CRASSOSTREA GIGAS (metric tons) in 1960. The Mediterranean also pro- The history of mollusc culture in France is very duced fl at oysters until 1950 when high mortalities informative. Fig. 1 shows the evolution of oyster occurred there also, inexplicably putting an end to production over the last century (Héral, 1989, production in the area (Fauvel, 1985). In Brittany, a Héral and Deslous-Paoli, 1991). Production recent- disease caused by Marteilia refringens broke out in ly stabilised at a high level, a situation not seen in 1968 followed by another disease in 1979 caused the past as production was highly variable. Twice by the parasite Bonamia ostreae. Production in the past, culture developed around a single spe- dropped from 20,000 to 2,000 t. Despite numerous cies followed by a population collapse and recon- efforts to relaunch fl at oyster production, it remains struction of the industry based on a different spe- very low to this day. cies. The first species, which has been fished from time immemorial by dredging natural beds, is the native Ostrea edulis. The oyster beds were overex- ploited from the 18th century, especially along the Atlantic coast (Goulletquer & Héral, 1997), and in spite of a long series of restrictive regulations the landings became poor and irregular during the 19th century. Culture of this species began in the 17th century with the use of former evaporation ponds for salt production in the Marennes region (Grelon, 1978). Juvenile oysters were fished and placed in these ponds and then left for 4 or 5 years before sale. Fig.1. Historical trends of French oyster These ponds became known as “claires”, or salt production (from Héral, 1989) water ponds. However this activity, which depend- ed greatly on fishing, was only marginal. Oyster Flat oyster culture was developed at the turn of culture really took off following several large inno- the 19th century, especially in the bay of Arcachon vations, the fi rst of which were technical. Between where a yield of around 15 to 20,000 t per year 1853 and 1859 Coste and De Bon started collecting was reached between 1908 and 1912 (Bouchet et spat from the wild (Coste, 1861). The technique al, 1997). of liming tiles was discovered in 1865, making it The first imports of the Portuguese cupped possible to obtain an abundant and regular spat oyster Crassostrea angulata into Arcachon date supply without fi shing. On-growing techniques for from 1860 and were made to compensate for the spat were then set up using special trays (Marteil, scarcity of the fl at oyster. The species then spread 1979). Another major innovation was administra- along the Atlantic coast and both species, O. edulis tive. In 1852, a law was passed in order to regulate and C. angulata, were produced at the same time. the exploitation of public maritime areas so that Following the large-scale fl at oyster mortalities in land for oyster production was leased to farmers by 1920, the Portuguese cupped oyster replaced the the state. This law was modifi ed in 1983 but is still flat oyster in the main culture sites of Marennes- in force. The precise criteria for allocating conces- Oléron and Arcachon. Production increased rapidly sions favours those already on the “maritime reg- and extended widely after World War II, reaching ister” (a register system of sailors from the navy, 90,000 t after 1950. From then onwards, oyster set up by Colbert). This system encourages small growth began to decrease and mortalities began family businesses. to increase, indicating overstocking of production A crisis hit fl at oyster culture throughout Europe units (Héral & Deslous Paoli, 1991). Production after 1920 when massive unexplained mortalities gradually decreased until the outbreak of the “gill were reported and the fl at oyster then disappeared disease” in 1966 (Comps and Duthoit, 1976), later No.20 identifi ed as a viral disease caused by an iridovirus business, situation of the culture site, number of (Comps et al., 1976). This disease spread through- employees, plurality of activity etc. Moreover, as out all culture zones causing massive mortalities French oyster farmers are very individualistic it between 1970 and 1973 and leading to the total can be said that each one has his particular manner extinction of C. angulata in France. of working. The oyster industry reacted quickly to this alarming situation with the “Resur” plan which Total production consisted of introducing a new species, Crassostrea Oyster production statistics, which are often gigas, from the Pacific. Following some small- imprecise, come from various sources: Ministry of scale trials conducted between 1966 and 1970, sev- Fisheries (DPMA), producer’s organisations (CNC: eral hundred tons of C. gigas cupped oysters were National Mollusc Production Committee), Ifre- imported from Canada between 1971 and 1973 mer Maritime Economics Service (SEM), Ofimer (Grizel and Héral, 1991) to form broodstock. This (National inter-profession bureau for sea and aqua- operation was successful and from the fi rst year in culture produce). These statistics are summarised Marennes-Oléron abundant capture of spat allowed annually by Ifremer (Kalaydjan, 2004). healthy, fast-growing oysters to be produced. At the same time, 10,000 t of spat were imported from Japan and distributed to all the other production sites. The result was a great commercial success and production increased quickly. Spat capture developed rapidly in Arcachon and Marennes, pro- ducing enough spat to supply all the production sites, so that further spat imports became unneces- sary.