Nearshore kelp farming is a rapidly growing industry in the United States, presenting powerful opportunities for economic growth, sustainable food sources, and environmental benefits. However, her-ring spawning events can threaten to undermine the efforts of kelp farmers. A serious need exists for a singular study which would explore the relative effects of different stimuli. We chose to investigate whether certain stimuli could be used to physically contain a group of Pacific herring away from a given region of a net pen.
We subjected Pacific Herring (n ≈ 400) to six different stimuli: a bubble curtain, a 2x2 array of strobing lights (SafetyNet Technologies), an acoustic pinger (Fishtek Marine whale deterrent pinger), a 1x6 array of static fishing flashers, a 1x6 array of moving fishing flashers, and a 2x6 array of moving fishing flashers. We exposed the fish to the stimuli in blocks of 30 minutes on and then 30 minutes off. We recorded fish locations and movements using sonar (Flexview multi-beam; Fig. 1).
We measured the distance between the fish and the stimuli, comparing the distances when the stimuli were on versus off. The fish were largely unafraid or influenced by the flashing lights, acoustic pinger, or fishing flashers. Only the bubble curtain deterred the herring. Our analysis (a multiple linear regression) confirmed our observations. We hope these findings can lead future re- search and attempts to protect kelp farms.