Unveiling gender-specific annual developmental, nutritional, and hormonal variations in Cyclina Sinensis: Insights for aquaculture optimization

Cyclina sinensis exhibits externally indistinguishable genders and developmental stages, which often leads to the oversight of gender-specific nutrient and flavor disparities. This study systematically collected samples of female and male clams from Lianyungang (Yellow Sea region) over one year (March 2023–January 2024), covering key developmental stages. For each stage, developmental indices, sex steroid hormone levels, and nutritional composition were analyzed. Results revealed a seasonal pattern, with gonadosomatic index (GSI) increasing and hepatosomatic index (HSI) decreasing during gonadal maturation, and reversing post-gamete emission. Estradiol and testosterone in hemolymph and gonads had triphasic annual changes, reaching their lowest values in July and August. Glycogen content peaked in May for females and June for males, while lipid content peaked in June and August, with females generally exhibiting higher lipid levels. Both genders had high EPA and DHA, but males had more polyunsaturated fatty acids (PUFAs). Protein levels in male declined; females adjusted upward from June to August, with EAA/TAA ratio peaked from May to August. Sensory evaluations found no significant difference in muscle and gonads between genders. Overall, these results suggest that the optimal harvest period is from growth to maturity ( i.e. , May to July). Furthermore, the findings offer insights into the generalizable reproductive and nutritional patterns of bivalves, contributing to sustainable harvesting and farming strategies in the aquaculture industry.