The Role of the Soundscape in the Behavioral Ecology of Stream-Dwelling Salmonids

Stream salmonids inhabit areas impacted by aerial, terrestrial, and underwater sounds which make up the holo-soundscape. Components of the holo-soundscape include sounds from biological sources (biophony), natural sources (geophony), and human activities (anthropophony). Here we review and synthesize the limited research on freshwater soundscapes as they pertain to stream-dwelling salmonids and suggest that holo-soundscape characteristic differences among habitats and along stream-order gradients likely play a role in salmonid ecology. We suggest that the holo-soundscape interacts with other biotic and abiotic attributes of habitats and has the potential for both indirect and direct effects. Direct effects occur when sounds are perceived by, or have a physiological impact on a given species, while indirect effects impact a species by affecting other species, or other components of its habitat. The role of the holo-soundscape in the ecology of salmonids and the potential for direct and indirect impacts of anthropophony have rarely been considered and represent an area for future research. To do this, simultaneous aerial and underwater recording should be incorporated in research programs. Finally, there is a critical need for documentation of salmonid hearing ability and sound production at all ontogenetic stages.