Sound emissions from Ultrasonic Antifouling equipment (PDF)

Martin, S.B., A.O. MacGillivray, J.D. Wood, K.B. Trounce, D.J. Tollit, K. Angadi

The Effects of Noise on Aquatic Life (2024)

DOI: 10.1007/978-3-031-50256-9_102

The Vancouver-Fraser Port Authority-led Enhanced Cetacean Habitat and Observation (ECHO) Program has managed underwater listening stations (ULSs) on the approach to the Port of Vancouver since 2015, measuring the sound levels generated by thousands of vessels. Since 2017, these systems have measured at or above a 128 kHz sampling rate. Anomalously high sound levels were observed in 212 of the measured ships signatures at frequencies typically associated with navigational, fisheries, and scientific sonars. Sixty-one of these detections were found to originate from a novel continuous sound source in the 20–30 kHz frequency range. During a separate underwater noise monitoring program, a similar high-frequency continuous sound source was identified proximate to a berthed vessel. The vessel engineer identified it as an ultrasonic antifouling system. The sounds from these systems are detectable at 4–6 km from the vessels in deep water. The measurements indicate that echolocation by lower-frequency delphinids, such as killer whales, may be completely masked when a ship is 3 km away and that porpoises flee from the source at distances of 1.5 km. In shallow waters, a porpoise 70 m from the source is predicted to experience temporary threshold shift (TTS) after 1–2 s, and permanent threshold shift (PTS) after 200 s. It is recommended that use of these systems be restricted or prohibited when there is a possibility of exposing marine mammals to potentially harmful sound levels.