In the present paper population structure of four commercially important fishes were studied, namely Tenualosa ilisha, Pampus argenteus, Scomberomorus guttatus and Osteogeneiosus militaris, in the Sundarban Estuary of the northern Bay of Bengal from June 2011 to March 2012. However, a thorough understanding of life history based on length and weight data of these four fishes (617 T. ilisha, 485 P. argenteus, 351 S. guttatus and 416 O. militaris) would be immensely important. Results of such studies would be important for sustainable management of these highly economic biological resources. The analysis of life history parameters of these four species, such as growth, exploitation, mortality, etc. showed that their stocks in coastal waters off West Bengal were overexploited during the study period as exploitation rate of T. ilisha, P. argenteus, S. guttatus and O. militaris were 0. 78, 0. 62, 0. 75 and 0. 54 respectively. Widespread fishing of juvenile and growing fish declined the population considerably losing the economic advantage. Good governance, strong law enforcement and effective management system should be sure for actual benefit from the fish resources and improving livelihoods of dependent communities.