Construction of dams and barrages over the rivers has created obstructions in migration of Hilsa resulting in sharp decline in the number of the delicious fish in Odisha, West Bengal and other States, said Dr Utpal Bhaumik, former head of Riverine Ecology and Fisheries Division of Central Inland Fisheries Research Institute (CIFRI), Barrackpore. Hilsa is mostly found in the rivers Bhagirathi-Hooghly, Godavari, Mahanadi and Chilika Lake. There is huge demand for Hilsa. Hydro-ecological barrier on the passage connecting Daya river has been preventing freshwater migration and production sustenance of the species. The catchment areas of Chilika Lake have rock, sand and mud substratum. Around 1.6 million tonne sediment is deposited every year in Chilika Lake through river Daya and several streams, he added. Bhaumik said the barrages and dams block the flow of water which in turn affects the migration of Hilsa. The peak upstream migration of Hilsa in most of the rivers generally begins with the onset of south-west monsoon and continues till October. However, other factors such as rainfall, current velocity and temperature, low salinity, turbidity, primary productivity and availability of planktonic food cannot be ignored, Bhaumik added.Recently, in Dhaka, the fishery officials of Bangladesh, India and Myanmar shared plan for sustainable management of Hilsa as these three countries net around 90 per cent of the delicious fish worldwide, he said.
2016, The New Indian Express