Research: A catalogue of aquatic sounds

The sounds presented are shown in two sections (click to listen):
  1) Biological sounds (fish and unknown, but possibly biological origin)
  2) Non-biological sounds (anthropogenic and environmental) 

The River Project has long sought to educate professionals and the public about the importance of New York Harbor’s soundscape to its ecosystem. Staff and visiting scientists working with The River Project were the first to use passive acoustic technology to document the underwater soundscape of the estuary surrounding New York City. Visiting scientists completed a piolet study that went on to publication and then seminars around the world. They returned to The River Project for a follow up program that was later incorporated into TRP’s projects to educate the public about the harbor soundscape. The use of underwater technology to listen to sounds in the aquatic environment is a growing field in fisheries science and marine biology (Anderson et al 2008). 

The River Project documented natural sounds such as waves and rain, man-made noise (boats, wakes, traffic, sonar, etc), and biological sounds (fish, unknowns). Passive acoustics can not only be used to listen for fish, invertebrates and even marine mammals that may come into the harbor at night, but can also be an important step in understanding the impact of human activity on the marine acoustic environment. 

The River Project captured the sounds of the lower Hudson River using a drop hydrophone at various locations around the edge of Pier 26 and Pier 40. The audio feed was observed live through a set of earphones, recorded digitally, and then uploaded for further analysis. This study created a general catalogue of sounds—biological and non-biological—to help build an online library of identifiable noise producers in New York waters. 

The most recognizable fish to produce sound at our locations are the oyster toadfish, Opsanus tau and the cusk eel, Ophidium marginatum. Anthropogenic sources include noise generated by boating and shipping activity, sonar and construction activities. Each sound file catalogued is accompanied with a photograph when possible, along with a spectrogram and waveform. The spectrogram depicts a given sound recorded by hydrophone by showing the intensity of different frequencies in the sound over time.  Intensity is indicated by color.  The waveform plots amplitude against time. 

This study made two important discoveries. It demonstrated that anthropogenic noise levels decrease dramatically at night, and biological sounds are common. The study also recorded a wide range of previously unknown and unidentified sounds from biological sources. The wildlife in the Hudson River produces sounds, relying on a mostly unstudied soundscape to survive. There is an almost completely unknown frontier in science in the heart of densely populated New York City. 

This research was conducted with the help of Dr. Rodney Rountree. For more great underwater sounds and information visit his website at He has also written "Listening to Fish: New Discoveries in Science", available for download

For more information on The River Project's bioacoustic research please email Nina Hitchings at

Cited here:
Anderson, K. A, Rountree, R. A, Juanes, F. 2008. Soniferous fishes in the Hudson River. American Fisheries Society 137: 616-626.