Hudson River Park's estuarine sanctuary is stopping point or home to more than 200 fish species. The most frequently observed are the striped bass, winter flounder, American eel, white perch, Atlantic silverside, Atlantic menhaden, hake, hogchoker, and bay anchovy. The Hudson River Estuary provides vital habitat to the endangered short nose and Atlantic sturgeon, as well as the American eel. The eel has seen population drops throughout its natural habitat in past decades. Studies conducted in the Hudson River though the NYS Department of Environmental Conservation have focused on answering questions about possible reasons for this population decline. Aside from providing habitat for threatened and endangered species, the estuary also hosts numerous plankton species that are an important food source for fish and other organisms.
Hudson River Park is part of the Lower Hudson River Significant Coastal Fish and Wildlife Habitat, as designated by New York State Department of State in 1992. While the designation report recognizes that most of the shoreline along this reach of habitat has been disturbed through historical filling, bulkheading, and development, this ecosystem is considered one of only a few large tidal river systems in the northeastern United States and provides important ecological features. For example, as stated in the designation report, the Lower Hudson River provides wintering habitat for large numbers of striped bass between mid-November and mid-April, and may be critical habitat in the life cycle of the striped bass by providing a sheltered environment with abundant food sources associated with the winter position of the river’s salt front.