Assessing the impact of toothed whale depredation on socio-ecosystems and fishery management in wide-ranging subantarctic fisheries

• Published in: Reviews in Fish Biology and Fisheries
• Main Authors: Tixier, Paul, Burch, Paul, Massiot-Granier, Félix, Ziegler, Philippe, Welsford, Dirk, Lea, Mary-Anne, Hindell, Mark, Guinet, Christophe, Wotherspoon, Simon, Gasco, Nicolas, Péron, Clara, Duhamel, Guy, Arangio, Rhys, Tascheri, Renzo, Somhlaba, Sobahle, Arnould, John
• Other Authors: Deakin University Burwood, Commonwealth Scientific and Industrial Research Organisation Canberra (CSIRO), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Australian Antarctic Division (AAD), Australian Government, Department of the Environment and Energy, Institute for Marine and Antarctic Studies Horbat (IMAS), University of Tasmania Hobart, Australia (UTAS), Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Département Milieux et Peuplements Aquatiques, Muséum national d'Histoire naturelle (MNHN), Coalition of Legal Toothfish Operators Australia (COLTO), Instituto de Fomento Pesquero Chili (IFOP), Department of Agriculture, Forestry and Fisheries Cape Town, Afrique du Sud (DAFF)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: Patagonian toothfish; Subantarctic; Depredation; Fisheries interactions; Killer whales; Sperm whales; [SDE]Environmental Sciences; Indian; Southern Ocean; Orca; Orcinus orca; Patagonian Toothfish; Physeter macrocephalus; toothed whale
• Online Access: https://hal.archives-ouvertes.fr/hal-02480925; https://doi.org/10.1007/s11160-020-09597-w

International audience Marine predators feeding on fisheries catches directly on the fishing gear, a behaviour termed “depredation”, has emerged as a major human-wildlife conflict globally, often resulting in substantial socio-economic and ecological impacts. This study investigated the extent of this conflict in commercial Patagonian toothfish (Dissostichus eleginoides) fisheries across subantarctic waters where both killer whales (Orcinus orca) and sperm whales (Physeter macrocephalus) feed on toothfish caught on longline hooks. Using long-term datasets from six major fishing areas, from southern Chile to the Indian Ocean sector of the Southern Ocean, statistical models were developed to quantify the catch removals due to whale depredation interactions. The results indicated that these removals were large, totalling more than 6600 t of toothfish between 2009 and 2016 with an annual mean of 837 t [95% CI 480–1195 t], comprised of 317 t [232–403 t] and 518 t [247–790 t] removed by killer whales and sperm whales, respectively. Catch removals greatly varied between areas, with the largest estimates found at Crozet, where on average 279 t [179–379 t] of toothfish per year, equivalent to 30% [21–37%] of the total catches. Together, these findings provide metrics to assess the impacts of depredation interactions on the fishing industry, whale populations, fish stocks and associated ecosystems. With an estimated $15 M USD worth of fish depredated every year, this study highlights the large geographic scale and economic significance of the depredation issue and its potential to compromise the viability of some toothfish fisheries which are the primary socio-economic activity in subantarctic regions.