Some Aspects of Biology of Bivalves from Kakinada Bay, East Coast of India

Biological aspects such as maturation, size at first maturity, spawning season, sex ratio, length – weight relationship, age and growth studies of Perna viridis, Crassostrea madrasensis, and Meretrix casta have been carried out during June 2013- May 2015 from Kakinada Bay. A scale of four stages of maturity i.e. maturing, matured, spent and recovery was noticed in the present study. The size at first maturity in females was reported at 7.2 cm, 7.2 cm, and 4 cm length, whereas in males it was reported at 7.2 cm, 8.7 cm, and 4 cm length for P. viridis, C. madrasensis, and M. casta respectively. These bivalves spawn throughout the year with peak spawning season during pre-monsoon in P. viridis, C. madrasensis and M. casta. Females were dominant in the catches of bivalves during the study period. The growth pattern in bivalves indicated that P. viridis and C. madrasensis showed negative allometric growth, while M. casta showed isometric growth. The growth parameters noted were L∞ = 22.4 cm, K= 0.31, to = -0.34 in P. viridis; L∞ = 22.6, K = 0.40, to = -0.43 in C. madrasensis; and L∞ = 7.7, K = 0.20, to = -0.35 in M. casta. The growth rate was high in young bivalves and decreased subsequently towards advancement of age.