Using hanging plastic trays for three-dimensional collection of antique mactra (Mactra antiquata) spat

This paper describes the first case of using hanging plastic tray for three-dimensional collection of the spat in the hatchery production of antique mactra. Different numbers of clusters (72, 90, 108) of plastic trays loaded with fine sand were hung in three tanks for three-dimensional collection of antique mactra, while the other two tanks without hanging plastic trays were controls. There was a higher survival rate in the tanks with hanging plastic trays than the controls and there was significantly increasing the survival rate of the spat as the numbers of clusters of plastic trays increased. At the end of the experiment, in the tank with most numbers of clusters of hanging plastic trays the survival spats was almost 2.6 times of that in the controls. In the early stage of the experiment there was significantly faster growth of the spat in the tank with hanging plastic trays than the controls. However, at the end of the experiment, there was significantly shorter shell length of the spat in the tank with most numbers of clusters of hanging plastic trays, and there was no significant difference in the shell length of the spat among the others tank.