Potential of Passive Acoustic Monitoring for Diadromous Fishes.

Rountree, Rodney, The Fish Listener, Waquoit, MA, Biology Dept., University of Victoria, Victoria, B.C., Canada

Passive acoustic monitoring (PAM) has become an important tool in marine fisheries research but has only recently taken on importance in freshwater habitats. The technique involves deploying hand-held, tethered, or autonomous hydrophones and digital recorders to listen to the sounds that fishes and other organisms produce. Sound can be purposeful, as in those used in inter- and intra-specific communication, or incidental (produced as a byproduct of some physiological or mechanical activity. As long as the sound is a reliable marker of species identity and/or behavior, it does not matter how or why the sound is produced to be useful in PAM studies. In the New England region sounds of several diadromous fishes have been documented, including alewife, Atlantic salmon, and Atlantic sturgeon. Sounds of brook and rainbow trout, which in some populations can include sea-run forms, have also been documented. Although these sounds are not likely to be useful in census, they can be useful in documenting presence/absence at night and in turbid conditions. More research is needed to document sound production by other diadromous fishes, especially within the clupeids. Even if sound production of these species is not found to be sufficient for PAM, information on sound production does provide useful insight into behavior and some physiological processes.