Fig. 2: Ultrasonic antifouling signal.

Long-term spectral average (top), spectrogram (middle), and spectrum (bottom) recorded on the seafloor-mounted acoustic recorder within Bahía Norte of tourist boats equipped with UA systems a transiting over the recorder and b anchored near the coastline ~2 km away. A shipboard echosounder operating at 88 kHz by the transiting boat is also present in a.