Reproductive potential and histological profiling of the wild female anadromous shad (Tenualosa ilisha) in lower Meghna Estuary, Bangladesh

Hilsha shad (Tenualosa ilisha, Hamilton 1822) is the most commercially important and national fish of Bangladesh, belongs to the family of Clupeidae of the Clupeiformes. The study was conducted to identify the seasonal gonadal cycles through histological study and the peak breeding season combining histological and Gonado Somatic Index (GSI). One hundred and twenty fish samples with an average weight of 756.75±6.25 g was collected from the Tentulia river for the study throughout the year. Monthly mean GSI values of females ranged from 6.36±0.69 to 15.02±1.33. The lowest mean GSI value was found in December and the highest GSI value was in October. From the histological observation of the ovary, early perinucleolar stage, late perinucleolar stage, yolk vesicle stage, yolk granule stage, pre-mature and mature stages were identified. The highest percentage (75%) of mature oocytes and peak breeding season were observed in October and the breeding season continues from October to November. These results will be helpful for fishery managers to impose adequate regulations for sustainable fishery management in Bangladesh