Summary
Acoustic studies of salmon farm net-pen (floating cages) shows these salmon communicate at a peak sound level of 400 Hz and surface sounds decreased at 3 meters below the surface. Importantly, salmon make different involuntary sounds when they are hungry compared to when they are satiated. A limitation is the control data for the net-pen audio of the environment was from a different location then where the recorded the experimental audio, which may result in environmental noises being mistaken for salmon noises. A strength of this study is it was conducted in a naturalistic setting. This study suggests that acoustic studies can be conducted as a noninvasive way to monitor fish hunger on a larger scale and potentially improve welfare and reduce food waste by providing information needed to meet, and not exceed, fishes’ dietary needs.
Continuous data on the condition of fish is necessary to monitor, control and document biological processes in fish farms in real-time, yet acquiring it from a large net-pen environment is challenging. Tools to rapidly detect change in the entire net-pen population are lacking. Automated passive acoustic monitoring is emerging as an effective monitoring tool in wildlife monitoring but has not before been tested in an aquaculture setting. Here, we explore the possibilities for passive acoustic monitoring in an aquaculture perspective. We investigated whether the soundscape of a net-pen could infer information on the condition of the whole net-pen population. In three cases, conducted at two different fish farms, we tested whether Atlantic salmon (Salmo salar) influence the soundscape of the net-pen. We provide evidence that Atlantic salmon alter the acoustic environment when compared to an empty net-pen. We observe from a 24-h recording that the acoustic fingerprint of the net-pen varies over time and mirrors the feeding status of the fish. Our results demonstrate the potential for passive acoustic monitoring in fish farms and provide a new direction for data-driven management in aquaculture to improve fish welfare and operational feeding routines.