However, the recovery of these fish stocks is at least partially dependent on the Hudson's ability to produce future generations. Fisheries management experts have identified several potential causes for the decline of migratory fish such as river herring and shad, and have sought to protect spawning fish by taking management actions to reduce commercial and sport fishing mortality. Within the past 70 years, the populations of many estuarine and coastal migratory fish that spawn in the Hudson, including American shad (Alosa sapidissima), have declined dramatically. These actions resulted in loss of nearly 4,000 acres of shallow water habitat including the near complete elimination of side channels in the upper third of the estuary.

Later projects included dredging the main channel, then depositing the dredged material in the shallows behind the dikes to eliminate side channels, connect islands, and further constrict the flow of water to inside the main channel. Hudson River habitats have been lost due to several large and small scale development projects including construction of the federal navigation channel and the railroads, as well as thousands of smaller developments that took place over hundreds of years.Įarly attempts to 'improve' the Hudson's navigation channel included construction of dikes along the length of the upper third of the estuary in an attempt to constrict the main channel and increase flow. The Hudson River Estuary has been transformed by human actions, significantly altering and reducing habitats critical to supporting a productive, diverse and resilient ecosystem. Areas of land inside the historic shoreline thatĪre not historic islands are areas that were filled when the Shoreline (red lines), historic islands (orange) and dikes The Hudson River near Castleton, showing the historic

Small scale dredging habitat project