島根県隠岐島島前湾における垂下養殖イワガキの成長

抄録

Growth of hatchery-produced Iwagaki-oyster Crassostrea nippona suspended at a mean depth of 7 m at Dozen Bay, the Oki Islands, Shimane Prefecture, Japan was examined over 23 months. Means of shell height, weight of whole body, and volume of whole body after hatching, respectively attained 52.2 mm, 25.6 g and 19 cm^3 after 12 months and 106.2 mm, 183.9 g, and 126.9 cm^3 after 23 months. The growth of Iwagaki oysters was affected by spawning, gonad development, low water temperature and possibly food availability inferred from the abundance of phytoplankton. Eleven shell characters : Total shell height, shell height, shell length, shell width, weight of whole body, soft tissue weight, weight of right valve, weight of left valve, volume of valves, volume of whole body, and volume of inner space were measured, and analysis was carried out to determine which characters best represent growth in whole body volume. The results showed that weight of the whole body and weight of the left valve were the most representative, but suggested that shell height was the most convenient for practical use.