1. Potential to use passive acoustics to monitor the invasion of the Hudson River by freshwater drum.
RODNEY A. ROUNTREE – The Fish Listener, East Falmouth, MA 02536, USA
FRANCIS JUANES - Biology Department, University of Victoria, Victoria, BC, Canada V8W 3N5
Sounds were monitored in real time with amplified headphones while simultaneously recording all data at selected sites with a Cetacean Research Technology (Seattle, WA) SQ26-H1 recorder system with a SQ26-08 Hydrophone (Sensitivity = re. 1V/µPa rms). Voice notes and ambient aerial sounds were recorded to a second channel from a high definition omnidirectional measurement microphone (Earthworks, Inc., Milford, NH).
Monitoring drum in the Seneca Canal Lock No. 4 in Waterloo, New York
Results
Freshwater drum calls are composed of highly variable trains of 1 to 119 knocks/call (mean = 25 knocks/call), a mean knock period of 33 knocks/s, mean peak frequency of 400 Hz, and mean duration of 0.8 s.
Despite the limited sampling effort, drum sounds were detected at 17 of 27 sites (63%) visited during the roving surveys including 8 of 8 (100%) Champlain canal, 3 of 5 (60 %) Erie Canal, 1 of 3 (33 %) Seneca canal, and 1 of 3 (33%) Oswego canal sites, respectively. Drum sounds were heard at 3 of 4 (75%), 0 of 1 (0%), and 1 of 3 (33%) locations for Lake Champlain, Lake Ontario, and the Hudson River, respectively.
Conclusions
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 suggest that freshwater drum most likely also invaded Lakes Oneida, Onandaga, Cayuga and Seneca through the NYSCS.
Passive acoustics can be a valuable tool for invasive species studies, and will be particularly useful for monitoring of freshwater drum.
Native
Invasive
Invasive?
Introduction
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.
Methods
To examine freshwater drum calls within the NYSCS we conducted roving surveys on July and 1-2 August from the shoreline of Lakes Champlain (4 sites) and Ontario (1 site) , in the Hudson River between Troy and Stuyvesant, New York (3 sites), and along the Champlain (8 sites), Erie Canal (5 sites), Oswego (3 sites) and Seneca (3 sites) canals.
Aerial view of Champlain canal lock C7 in Fort Edwards, NY lock connecting the canal with the Hudson River. Drum can be heard on both sides of the lock (designated by red stars).
Hudson River
Champlain canal
Lock
The Fish Listener
Special thanks to: Kieran Cox, Katie Burchard (nee Anderson), Sara Rountree, Douglas Carlson and fishermen Chris Paddock and Ralph Sandfer.