We experimentally played back tones and sweeps to captive herring (Clupea harengus) in a net pen and measured the collective response of a large and a small group of fish using a camera, echo sounder, and multibeam sonar. The playbacks ranged in frequency from 160 to 500 Hz and 131 to 147 dB re 1 μPa in received sound pressure level. Herring behavior was scored by a team that blindly evaluated the observations. Overall, the responses were modest. Stronger reactions were observed at higher source levels, lower frequencies, and smaller school sizes, but there was no effect on signal rise time.
Keywords: Collective response; Group size; Herring; Playback.