(Not controled OCR) In recent years, scallop production throughout the world has been expanding at a fast rate, due to developments in aquaculture. Hanging as well as sea bed cultures produced good results in some countries. This latter method has been successful for Patinopeeten ye.ssoen.sis and Pecien novaezelandiae in Japan and New Zealand respectively. In Europe, only Peeten ma.ximus as a local species seems appropriate for development by a sea ranching production: the market demand is strong, the fisheries are closed due to over exploitation and hanging cultures are not economically feasible. Experiments in sea bed cultures started in the 1980s in France and extended to Ireland, Scotland and Norway. The technique involves the production of juveniles by spat collection and in hatcheries, and on-growing on the sea bed, on the natural scallop ground or in equivalent sites. Animals are then released at the minimum size at which they are capable of surviving. Only France has a full set of results suitable for analysis to determine the main factors affecting sea ranching.These results are not sufficient for the study of stock enhancement, which requires a longer term approach.This is because the species are very fragile and slow growing. In the Bay of Brest (France), hatchery production and intermediate hanging cultures are controlled and more than 3 million spat are released into the fishing grounds. Recapture rates have reached 25%, but depend on the seeding season and the vitality of the animals. In 1997, the population was composed of three animals from aquaculture for every one from the natural population. Production costs, recapture rates and market prices are encouraging. The management of the fishing grounds and the regulation of the resource access are key factors. However, results have proved the major role of the ecosystem.