“…Their presence is commonly observed using passive acoustics for vocalizing cetaceans [54,55], active acoustics such as imaging sonars [56][57][58], underwater optical cameras (still or video) [59,60], and observations made from vessels, aircraft, or land [61]. Fish are commonly assessed as individuals or schools (depending on the species) using various active acoustic instruments like single beam or split beam echosounders [62][63][64], multibeam acoustic cameras [32,65,66] and multibeam imaging sonars [26,67], acoustic telemetry [41,42,68], and with underwater optical cameras [25,69]. Other marine animals such as sea turtles and diving sea birds may be assessed in conjunction with marine mammal surveys, or from other dedicated monitoring campaigns [70] using some of the approaches mentioned above.…”