Larval rearing, spat production and juvenile growth of the blood clam Anadara granosa

Abstract

The blood clam A d r u gmtwsa spawned in the Shdl6lsh Hatchery Laboratory, Tuf icorin on two occasions. The fertilised eggs measured 50-60~in diameter, morula larvae developed in 3 4h m and the trochophorc stage was reached in 5 hrs. The straigb t hinge stage was attained in 20-26 hrs after fertilimtion and these larvae measured 8 3I~en ah and 65.5~h eight. Advanced umbo stage was reached on day 12 (size 155.3 x 140.5~) and on day 16, majority of the larvae were in pedivcliger stage with an average size of 182.7 x 162.9~. SettIement began on day 16 and majority of the larvae were set on day 18. The growth of the spat in the hatchery is described by the exponential equation L - 0.0002739 D - where L is length in mm and D. days. On day 59, tbe spat attained an average size of 2.42 x 1.70 mm. A total of 8090 spat were produced. During tha nursery rearing in the field, the seed clam attained 20 mm average length in the following 5 months. In India, A.grund~llsecd were grodwdfor the Arst time. The significance of this study forthe mass production of the blood clam seed in the bat~herya nd its relevma to undertake blood clam culture are highlighted.