Just like Salmon is special to the United States, Hilsa fish is special to Indians. Its declining rapidly. Causes of this decline are well know. Hilsa is anadromous fish and needs to complete its lifecycle from sea to river, which is now impossibles through the hurdle of dams. This article highlights the facts well, however, its sad to see that institutions like CIFRI and ICAR are still not ready or brave enough to tackle the main issue of dams. They are busy funding more research projects about Hilsa. The gap between research and burning reality is widening..
SANDRP worked on a report which uniequivocally proved that large dams and infrastaturye projects have been behind fishery collpases in many Indian Rivers: http://sandrp.in/dams/Impacts_of_Dams_on_Riverine_Fisheries_in_India_ParineetaDandekar_Sept2012.pdf