Contribution of toothfish depredated on fishing lines to the energy intake of killer whales off the Crozet Islands: a multi-scale bioenergetic approach

Type Article
Date 2021-06
Language English
Author(s) Faure Johanna1, Peron Clara1, Gasco Nicolas1, Massiot-Granier Felix1, Spitz Jerome2, 3, Guinet Christophe2, Tixier Paul2, 4, 5
Affiliation(s) 1 : UA, Lab Biol Organismes & Ecosyst Aquat BOREA, MNHN, CNRS,IRD,SU,UCN, F-75005 Paris, France.
2 : La Rochelle Univ, CNRS, UMR 7372, Ctr Etud Biol Chize CEBC, F-79360 Villiers En Bois, France.
3 : La Rochelle Univ, CNRS, Observ Pelagis, UMS 3462, F-17000 La Rochelle, France.
4 : Univ Montpellier, CNRS IFREMER IRD, MARBEC, Ave Jean Monnet CS 30171, F-34203 Sete, France.
5 : Deakin Univ, Fac Sci & Technol, Sch Life & Environm Sci, 221 Burwood Highway, Burwood, Vic 3125, Australia.
Source Marine Ecology Progress Series (0171-8630) (Inter-research), 2021-06 , Vol. 668 , P. 149-161
DOI 10.3354/meps13725
WOS© Times Cited 5
Keyword(s) Marine mammals, Depredation, Bioenergetic model, Fisheries interaction, Ecosystem-based management, Top predator conservation, Dissostichus eleginoides, Orcinus orca
Abstract Fisheries modify prey availability for marine predators by extracting resources but also by providing them with new feeding opportunities. Among these, depredation, which occurs when predators feed on fish caught on fishing gear, is a behavior developed by many species as a way to acquire food through limited foraging effort. However, the extent to which depredated resources from fisheries contribute to the energetic requirements and affect the demography of depredating individuals is unknown. We investigated the contribution of Patagonian toothfish Dissostichus eleginoides depredated on longlines to the energetic requirements of killer whales Orcinus orca around the Crozet Islands (southern Indian Ocean) over the period 2007-2018. Our results indicate that during days when depredation occurred, depredating individuals fulfilled on average 94.1% of their daily energetic requirements with depredated toothfish. However, the contribution varied from 1.2 to 13.3% of the monthly energetic requirements and from 2.4 to 8.8% of the yearly energetic requirements of the total population. Together, these findings suggest that intake of depredated toothfish can be substantial at a fine scale (daily and individually), potentially leading to temporary provisioning effects and changes in predation pressures. These effects become minor (< 10%), however, when considering the full population over a whole year. The contribution of depredated fish to the annual energetic requirements of the population has increased in recent years, likely due to larger fishing quotas and greater opportunities for whales to depredate, which stresses the importance of accounting for depredation in ecosystem-based management of fishing activity.
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Faure Johanna, Peron Clara, Gasco Nicolas, Massiot-Granier Felix, Spitz Jerome, Guinet Christophe, Tixier Paul (2021). Contribution of toothfish depredated on fishing lines to the energy intake of killer whales off the Crozet Islands: a multi-scale bioenergetic approach. Marine Ecology Progress Series, 668, 149-161. Publisher's official version : https://doi.org/10.3354/meps13725 , Open Access version : https://archimer.ifremer.fr/doc/00710/82252/