Investigating the reproductive cycle and some maturation indexes of clams (Tapes dorsatus) collected from Thi Nai lagoon, Binh Dinh province
Abstract
Clams Tapes dorsatus were collected from the coastal areas of Thi Nai lagoon to examine some reproductive parameters and conduct the maturation culture experiment . The r esults of examining the reproductive cycle showed that clam s get the highest value of condition index and gonad index from October to February of years . The gonado index GI t he trial test of maturing mangrove clam was carried out in 7 periods with different treatments: the clam s reared in the plastic baskets without sandy bottom ; the clams directly reared on the sandy bottom of sandbank covered by net ; the clam s reared in the plastic baskets with sandy bottom of 1 0-15 cm . The results of the experiment indicated that clams reared in the plastic baskets with sandy bottom of 1 0-15 cm obtained the highest weight, length and survival rate ( these values were 51.6g, 49.2 mm and 96,5% respectively after 60 days of rearing ). Similarly, CI and GI were also highest for clams cultured in this treatment. The fecundity of the clams was highest, with 3,537±1,102 eggs/g fresh muscle and number of eggs/g total weight of clams 28,339±10,556 when they were reared in the plastic baskets with sandy bottom of 1 0-15 cm .