A Study on the Reproduction of the Green Snail, Turbo marmoratus in the Ryukyu Islands, Southern Japan.

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The green snail, Turbo marmoratus had sex ratios of 1: 1 both in Tokunoshima Island and the Yaeyama Island Group, the northern and southern Ryukyu Islands, Japan. No significant differences were found in mean oocyte sizes either between different sections in an ovary or between ovaries with different gonad bulk indices (GI: percentage gonad area to the total crosssectional area of the gonad-digestive gland) when GI exceeded 50%. The number of oocytes per unit weight was significantly different among different portions in an ovary, and this could be attributed to the difference in the specific gravity of oocytes. The maximum number of oocytes in an ovary was estimated between 1.279×106 and 7.523×106 for females of 12.5-19.3 cm in shell width. The main spawning season was August-November in Tokunoshima I, and July-November in the Yaeyama Island Group. Mature individuals were found during all seasons in both localities. The relationship between the spawning activity and the lunar cycle was examined for T. marmoratus from Tokunoshima I., but the relationship was not found.
日本水産増殖学会の論文