Do commercial fisheries display optimal foraging? The case of longline fishers in competition with odontocetes

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Richard, Gaëtan, Guinet, Christophe, Bonnel, Julien, Gasco, Nicolas, Tixier, Paul
• Other Authors: Lab-STICC_ENSTAB_CID_TOMS, Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), Institut Mines-Télécom Paris (IMT)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom Paris (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-Institut Mines-Télécom Paris (IMT)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom Paris (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL), 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), 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), Pôle STIC_AP, École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne), Centre for Integrative Ecology, Deakin University Burwood
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: Consequences; Sperm whales; Whales Orcinus orca; Changing fishing practices; Killer whales; Marine mammals; Depredation levels; Crozet; Anthropology; Populations; [SDE]Environmental Sciences; Indian; Kerguelen; Kerguelen Island; Orca; Orcinus orca; Patagonian Toothfish; Physeter macrocephalus
• Online Access: https://hal.archives-ouvertes.fr/hal-01572425; https://doi.org/10.1139/cjfas-2016-0498

International audience Depredation in longline fisheries by odontocete whales is a worldwide growing issue, having substantial socio-economic consequences for fishers as well as conservation implications for both fish resources and the depredating odontocete populations. An example of this is the demersal longline fishery operating around the Crozet Archipelago and Kerguelen Island, southern Indian Ocean, where killer whales (Orcinus orca) and sperm whales (Physeter macrocephalus) depredate hooked Patagonian toothfish (Dissostichus eleginoides). It is of great interest to better understand relationships of this modern fishery with its environment. Thus, we examined the factors influencing the decision making process of fishers facing such competition while operating on a patch. Using optimal foraging theory as the underlying hypothesis, we determined that the probability captains left an area decreases with increasing fishing success whereas, in presence of competition from odontocete whales, it increases. Our study provides strong support that fishers behave as optimal foragers in this specific fishery. Considering that captains are optimal foragers and thus aim at maximising the exploitation of the resources, we highlight possible risks for the long-term sustainability of the local ecosystems