Soniferous Fishes in the Hudson River

Abstract

AbstractAlthough soniferous fishes have been studied in many different parts of the world, very few studies have been conducted in North American freshwater systems. The purpose of this study was to catalog and identify types of underwater sounds in the Hudson River, New York. We recorded underwater sounds with an autonomous underwater listening system consisting of a hydrophone, digital sound recorder, and weatherproof housing. Approximately 164 h of recordings were made from two sites located along the Hudson River during 2003. One site was located near the mouth of the river on Manhattan Island. The second site was located 153 km upriver within Tivoli Bays at the Hudson River National Estuarine Research Reserve. Additional manned recordings and sound auditioning of captured fishes were conducted in 2004 to identify biological and unknown sounds from Tivoli Bays. In all, we recorded 62 different sounds. Only four sounds could be identified to fish species: Oyster toadfish Opsanus tau, striped cusk‐eel Ophidion marginatum, brown bullhead Ameiurus nebulosus, and channel catfish Ictalurus punctatus. An additional 21 sounds were categorized as biological, 5 as nonbiological, and 32 as unknown. We believe that many of the sounds classified as biological and unknown are in fact produced by fishes but could not be identified due to the scarcity of studies on the sound production of freshwater and estuarine fishes of the Hudson River. Future research focused on the identification of these unknown underwater sounds will provide new insights into the ecology of the Hudson River. The diversity of underwater sounds we recorded in the Hudson River strongly suggests that sound production is an important behavior in aquatic systems and that passive acoustics can be an important new tool for the study of the river's ecology.