Potential of passive acoustic recording for monitoring invasive species: freshwater drum invasion of the Hudson River via the New York canal system

Abstract

We conducted a preliminary passive acoustic survey of the occurrence of freshwater drum, Aplodinotus grunniens, in the New York State Canal System (NYSCS) to demonstrate the usefulness of underwater sound monitoring in invasive species studies. Data from known populations of freshwater drum in Dale Hollow Reservoir and J. Percy Priest Lake in Tennessee and Lake Champlain in New York were used to validate freshwater drum call characteristics. Similar to more well studied marine members of the Sciaenidae, freshwater drum calls are composed of highly variable trains of 1–119 knocks call−1 (mean = 25 knocks call−1), a mean knock period of 33 knocks s−1, mean peak frequency of 400 Hz, and mean duration of 0.8 s. The occurrence of drum chorus calls at many locations within the NYSCS indicates likely spawning throughout the system, and suggests the possibility that individuals have invaded the Hudson River from native populations of Lake Champlain, Lake Erie, and Lake Ontario. We point out that the species has been excluded from the east coast of North America throughout history by geographic barriers, and it would have been impossible for the species to gain entrance to the Hudson without the NYSCS, or direct introduction, and thus it is a true invasive which will likely have a dramatic impact on the Hudson River ecosystem. We suggest that freshwater drum most likely also invaded Lakes Oneida, Onondaga, Cayuga and Seneca through the NYSCS. We conclude that passive acoustic surveys are a highly effective non-invasive tool to monitor the distribution of soniferous invasive organisms in aquatic systems, and promise to be especially useful in documenting the future spread of freshwater drum in the Hudson River system.