Performances de croissance de l'huître creuse, Crassostrea gigas (Thunberg) dans le bassin d'élevage de Marennes-Oléron entre 1979 & 1982

Growth of the japanese oyster, Crassostrea gigas was monitored during 4 years, by following the recruitment of the year 1978, held in rearing conditions. After three and half years, the average length was la cm and the average total weight was 80 g. Clear seasonal changes were observed on the growth in length and weight. An important loss in dry weight occured in July, during the release of gametes. Such losses constituted 29 %, 43 % and 60 % of the dry weight, respectively for individuals which were 2 years, 3 years and 4 years old. The higher instantaneous growth rates (G) were observed during spring and at the beginning of summer. Growth model of Von Bertalanffy, gave the best estimate for the length growth of the species. During the 1979-1982 period, growth was clearly slower then that was observed in the early seventies, when the species was introduced in the area. It was also slower, if compared with other rearing areas or with experiments reproducing the field environment. Such a decrease in the growth performance was related with the high level of the reared stock in the Marennes-Oleron area.