Growth and age determination of an intertidal cupped oyster Crassostrea madrasensis (Preston) (Bivalvia: Ostreidae) around Moheshkhali Channel, Bay of Bengal

The age of C. madrasensis from the Moheshkhali Channel was determined by counting thc growth rings in the umbonal region and the growth rate is compared with analyses the length-frequency data usin g FiSAT software. The estimates of von Bertalanffy growth paramete.s, L~ and K were found 116 mm and 1.9 yea(1 respectively. The annual growth ring formed during monsoon (May-Aug) period. The cupped oyster Crassostrea madrasensis was reported by Sarkar & Alam' from Cox's Bazar, Bangladesh. Shell size, morphological ratio and growth rings are used as indicator for age and growth determination of oyster species 2 . Outs ide Bangladesh Paul 3 , Ra0 4 , Reuban et al. 5 and Nair 6 have made investigations on the growth of C. madras ens is. Length-frequency method is used to find out the growth rate of oyster popUlation in different months of the year6. The growth of oysters are intluenced by variGlus factors of the environment. Korringa 7 observed differences in growth rate of oysters from the same brood in the same locality owing to the variation in the nature of substratum, salinity and temperature. Rao & Nayar8 reported pronounced growth of Ostrea madrasensis in brackish waters than the oysters inhabiting typical marine habit of the harbour 3 . Results of age and growth rate studies are used to identify the best criteria for commercial cultivation . Growth rates are also useful as indicator of oyster fitness. Faster growth reduces the lengthy growout