Acoustics and photo-identification provide new insights on killer whale presence and movements when interacting with longline fisheries in South East Australia

• Published in: Fisheries Research
• Main Authors: Cieslak, Matthew, Tixier, Paul, Richard, Gaétan, Hindell, Mark, Arnould, John P.Y., Lea, Mary-Anne
• Other Authors: University of Tasmania Hobart, Australia (UTAS), Deakin University, Burwood, Australia, Deakin University Burwood, Equipe Observations Signal & Environnement (Lab-STICC_OSE), Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom Paris (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom Paris (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom Paris (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom Paris (IMT), École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: Fisheries interactions; Mitigation; Marine mammals; Longlining; Depredation; [SDV.BA]Life Sciences [q-bio]/Animal biology; [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing; Antarc*; Antarctica; Killer Whale; Orca; Orcinus orca; Killer whale
• Online Access: https://ensta-bretagne.hal.science/hal-03104264; https://doi.org/10.1016/j.fishres.2020.105748

International audience Removal of target catch from longlines by marine mammals, known as depredation, is a global issue creating animal welfare, socioeconomic and management concerns. The killer whale (Orcinus orca) is a key species of concern for longline depredation due to their global presence and ability to remove large quantities of caught fish. Currently, data on whale behaviours around fishing vessels, including timing of depredation and ability to follow vessels, is not completely understood. This lack of knowledge prevents a complete assessment of depredation both spatially and temporally, which is important to reduce the chance of underestimating depredation events. Our study utilised both photo-identification and acoustics as complementary approaches to investigate depredation on the blue-eye trevalla (Hyperoglyphe antarctica) demersal longline fishery in Australia. Of the 14 d when depredations were recorded acoustic detection of killer whales prior to visual confirmations occurred in 13 (93 %). Photo-identification revealed individuals repeatedly interacting with the vessel, sometimes over long distances (>1000 km), with increasing inter-depredation times as the vessel travelled further. These findings suggest that killer whales move to known fishing areas well before detection from surface monitoring occurs. While this study has revealed aspects of killer whale behaviours when encountering and interacting with longline fisheries, it has highlighted how traditional monitoring methods underestimate depredation and that this aspect needs to be further investigated.