In order to study individual growth variability and its relationship with survival in juvenile Crassostrea gigas, parental oysters were sampled at four sites located along the French Atlantic coast and bred under controlled hatchery conditions. Fourgroups of larvaewere obtained by crossing fivemales and five females fromeach of the four sites, and a fifth group by crossing these 20 males and 20 females together in a pool. Larvae were reared under conditions allowing the maintenance of a maximum variability of size and gave five experimental groups. Oysters were individually monitored for growth and survival from 3 to 10 months after fertilization. The individual growth performances were relatively stable over time and no noticeable compensation for growth occurred.Early growth ratewas a very good predictor of size later in life: 66% of variation in the live weight at 10 months could be explained by variation in the initial growth rate calculated between 3 and 4 months. A significant group effect was observed on survival and on growth rate. Mortality mostly occurred between 3 and 5 months and appeared to affect the slow-growing animals more. However, two groups can be distinguishedamong thosewhich died during the experimental period, onewhich showed a decrease in weight and the other whose growth was similar to surviving oysters. These results are discussed in the light of usual oyster farming practices and selective breeding.
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