Comparison of three portable volumetric arrays to localize and identify fish sounds in the wild

We describe three portable volumetric audio/video arrays capable of identifying species-specific fish sounds in the wild. Each array can record fish sounds, acoustically localize the fish in three-dimensions (using linearized or fully non-linear inversion), and record video to identify the species and observe their behavior. The design of each array accommodates specific logistical and financial constraints, covering a range of nearshore habitats and applications. The first platform is composed of six hydrophones, an acoustic recorder, and two video cameras secured to a 2 × 2 × 3 m PVC frame. Hydrophone placement is defined using simulated annealing to maximize localization accuracy. The second platform uses a single video camera, four hydrophones, and an acoustic recorder on a one cubic meter PVC frame. It can be deployed on heterogeneous substrates but has lower localization capabilities. The third platform consists of four hydrophones connected to an acoustic recorder mounted on a tethered underwater drone with built-in video. It allows remote control and real-time positioning in response to observed fish presence but with reduced localization capabilities. The three platforms were deployed off British Columbia, Canada, and used to identify and characterize new sounds from quillback rockfish, copper rockfish, and lingcod.