Larval rearing and spat production of Marcia opima (Gmelin)

The ‘baby clam’ Marcia opima (Gmelin) was spawned on seven occasions in the shellfish hatchery at the Tuticorin Research Centre, India. The fertilized eggs measured 47.8 μm in diameter and the straight hinged larvae attained at 20 h were 87 μm in length and 71 μm in height. Settlement occurred on day 9 at 273 μm. The percentage of settlement varied from 13.9% to 56.2%. The growth of post-set clam spat has been described by the equation of L=0.0086x1.4672, where L is the length in mm and x is the number of days. The clam seed reached a size of 11.5 mm at 4 months. The significance of this study is to standardize the techniques for hatchery production of the seeds of M. opima