Estuaries are known for high productivity sustained by high input of nutrients and freshwater inflow. Increased nutrient loading stimulates phytoplankton production, enriches supply of energy and organic carbon to open waters, and facilitates rapid development into zooplankton-rich ecosystem.
The resultant food web dynamics paves the way to increased fish yield. The abundance, distribution and diversity of finfish and shell fish are, therefore, significantly high raising the value of fisheries resources of estuaries. A number of environmental attributes contribute to the population response in the estuary.
The response mechanisms are strongly influenced by physical variability like changes in hydrodynamic environment (flow pattern, flooding of fringe areas, tide, salinity regime, flushing time, turbidity, nutrient level etc.) as well as the chemical and biological conditions of the estuary.
In addition to providing feeding ground and general living space to for many fish species, the estuaries play the most vital role in nursery function and recruitment and therefore considered as critical habitats for fish productivity. From the ecological perspective, abundant supply of forage fishes is a significant component of estuarine function correlated to important habitat variables favouring prey-predatory distributions in enhancing productivity through the food web.
The knowledge of juvenile habitats and the environmental requirements of different fishes at various life history stages met from a combination of estuarine habitats are essential to fisheries production management.
The fishes found in estuaries may comprise a range of species of commercial importance, while there are vastly large number of ecologically prominent species in terms of biomass and abundance.
The species specific habitat information is grossly inadequate for most of them.
