Do whales really care about conventional fisheries acoustics?

• Main Authors: Nøttestad, Leif, Brehmer, Patrice, Josse, Erwan, Doksæter, Lise, Pavan, Gianni, Sancho, Gorka, Lebourges-Dhaussy, Anne, Georgakarakos, Stratis, Aumeeruddy, Riaz, Dalen, John
• Other Authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), European Commission, Arthur N Popper, Anthony Hawkins
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2007
• Subjects: Fisheries acoustics; underwater sound; conventional sounder; Sonar; Underwater Noise Tolerance Threshold; [SDV]Life Sciences [q-bio]; Norwegian Sea; Indian; Sei Whale
• Online Access: https://hal.science/hal-03224799; https://hal.science/hal-03224799/document; https://hal.science/hal-03224799/file/Poster%20Nyborg%20Do%20whales%20care1.pdf

International audience Acoustic monitoring is considered essential for the modern exploration and understanding of marine communities and ecosystems. Nevertheless,underwater noise pollution may have potentially negative effects, particularly on marine mammal and fish physiology and behaviour. This study aim toquantify how offshore whales and dolphins react on conventional fisheries acoustics from both a stationary and moving research vessel. An acoustic monitoring methodology was applied with conventional fisheries acoustic instrumentation. A three-frequency echosounder (38, 70 and 120 kHz)and an omnidirectional multibeam sonar (24 kHz) were connected to artificial drifting Fish Aggregating Devices (FADs) during an international scientificcruise (February 2004) in the western Indian Ocean. A moving vessel equipped with multi-frequency echosounders (18, 38, 70, 120 and 200 kHz) andmultibeam (20-30, 110-120 kHz) sonars was also used during an ecosystem survey in the Norwegian Sea. Digital filming and ping-to-ping sonar tracking of animals were used to study marine mammal behaviour and possible reaction patterns to emitted sound from hydro-acoustic instrumentation.When using conventional fisheries acoustics in the Indian Ocean, a group of sei whale approached a stationary vessel, providing some evidence that the acoustic signals did not cause a measurable avoidance response by the whales. Similarly, large whales (fin, humpback and sperm whales), and dolphins (pilot and killer whales) did not show measurable behavioural responses and avoidance reactions towards a moving vessel. Groups of whales and dolphins were actively feeding on herring, mackerel and krill for 10-40 minutes simultaneously as the vessel was within 50-800 meters distance at different speed (2-12 knots). Our results suggest that many marine mammals in open oceans do not actively avoid stationary or moving vessels applying fisheries acoustics. Further studies are needed to find operational hydro-acoustic thresholds (intensity, time and frequency), ...