Gametogenesis and somatic versus gonadal growth in the oyster <i>Crassostrea madrasensis</i> (Preston)

Abstract

Histological changes in gonad during the breeding season, gametogenic pattern, gonadal and somatic growth and factors affecting gonadal cycle of <i>C. madrasensis</i> inhabiting a tropical estuary, were studied for 2 yr. Gametogenic activity was noticed twice in a breeding season (October and February - March). Increase in ambient salinity from 0.3 to 17% induced gametogenesis in oysters which has stock piled reserve carbohydrates. Relationship between gonad thickness and gonadal cycle was distinct and the indeterminate gonads were the thickest. Development of testis was faster than of the ovary in oysters &lt; 105 mm shell-height. Spawning was slow but nearly complete in females while in males it was rapid and incomplete. Temporal variations in wet weights of tissue in different sexes indicated that the bulkiest oysters were the indeterminates. Which constituted as much as 100% of the population during southwest monsoon (July-September) period when the salinity was 1%.