| The year 1991 is the third one of the regional network on growth assessment of Crassostrea gigas in Brittany, wearing on 9 sites and 3 stations per site. 2 bags of 210 oysters, 18 month old, were placed in each station. Comparatively to previous years, the 1991 growth was moderate, and condition index inferior. However, the survival rates were very high (above 91 %) and most of the slight mortalities occurred a short time after stocking (as revealed by the sizes of dead shells). An improvement was also observed in the infestation rate by the polychaete Polydora sp..Most of the growth differences between sites and stations are still present. An analytical study including environmental variables would be necessary for explanations and will be tempted in 1993. |
