Killer whales of the Crozet Archipelago and adjacent waters: photo-identification catalogue, population status and distribution in 2020
International audience Three forms of killer whales (Orcinus orca) occur around the subantarctic islands of the southern Indian Ocean (42-53°S; 34-74°E). The form encountered in both inshore and offshore waters, described as generalist in its feeding preferences (seals, whales, penguins and fish as...
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ftsorbonneuniv:oai:HAL:hal-03138993v1 2024-09-15T18:16:45+00:00 Killer whales of the Crozet Archipelago and adjacent waters: photo-identification catalogue, population status and distribution in 2020 Tixier, Paul Gasco, Nicolas Towers, Jared R. Guinet, Christophe Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC) La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) Biologie des Organismes et Ecosystèmes Aquatiques (BOREA) Université de Caen Normandie (UNICAEN) Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA) Bay Cetology Centre d’Etudes Biologiques de Chizé CNRS La Rochelle Université Muséum National d’Histoire Naturelle 2021 https://hal.science/hal-03138993 https://hal.science/hal-03138993/document https://hal.science/hal-03138993/file/SERAWG-03-05%20Depredation.pdf en eng HAL CCSD Centre d’Etudes Biologiques de Chizé, Centre National de la Recherche Scientifique, France hal-03138993 https://hal.science/hal-03138993 https://hal.science/hal-03138993/document https://hal.science/hal-03138993/file/SERAWG-03-05%20Depredation.pdf info:eu-repo/semantics/OpenAccess https://hal.science/hal-03138993 Centre d’Etudes Biologiques de Chizé; CNRS; La Rochelle Université; Muséum National d’Histoire Naturelle; Bay Cetology. 2021, pp.1-167 [SDE]Environmental Sciences info:eu-repo/semantics/report Reports 2021 ftsorbonneuniv 2024-07-25T23:47:37Z International audience Three forms of killer whales (Orcinus orca) occur around the subantarctic islands of the southern Indian Ocean (42-53°S; 34-74°E). The form encountered in both inshore and offshore waters, described as generalist in its feeding preferences (seals, whales, penguins and fish as prey) and known to depredate toothfish from longliners has been opportunistically photo-identified around the Crozet archipelago since the 1960s. Together with photo-identification data collected in the Prince Edward/Marion EEZ, Kerguelen EEZ and international waters, this report provides up to date information on the abundance and distribution of the Crozet killer whales. In total, 124,313 photographs taken during 2,109 encounters since 1964 were analysed, allowing for 299 individuals to be identified. Most encounters with available data were from the Crozet EEZ (1,432 from longliners, 602 from Île de la Possession) and occurred after 2003 when photo-identification was implemented in the fishery observer program. Among the 188 individuals recorded in the Crozet EEZ since 2003, 22 (12%) were also photographed in the Kerguelen EEZ, 13 (7%) in the Prince Edward/Marion EEZ and 13 (7%) in adjacent international waters. The frequently encountered subset of the Crozet killer whale population was composed of 23 social units (maternal groups), 19 of which included individuals alive in 2020. These social units ranged in size from 1 to 11 individuals with a mean (± SD) of 4 ± 3 per unit. As of June 2020 when the latest photographs included in the study were taken, abundance of this subset was 89-94 individuals. However, detailed analysis of data collected between 2005 and 2020 shows that the number of confirmed deaths (n = 51) exceeds the number of recorded births (n = 46), resulting in a 5% decrease of the population size over this period. These deaths were distributed across the population with the majority occurring in the most common sex and age classes - adult females and juveniles. Factors contributing to mortalities ... Report Killer Whale Orca Orcinus orca Killer whale HAL Sorbonne Université |
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Open Polar |
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HAL Sorbonne Université |
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ftsorbonneuniv |
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English |
topic |
[SDE]Environmental Sciences |
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[SDE]Environmental Sciences Tixier, Paul Gasco, Nicolas Towers, Jared R. Guinet, Christophe Killer whales of the Crozet Archipelago and adjacent waters: photo-identification catalogue, population status and distribution in 2020 |
topic_facet |
[SDE]Environmental Sciences |
description |
International audience Three forms of killer whales (Orcinus orca) occur around the subantarctic islands of the southern Indian Ocean (42-53°S; 34-74°E). The form encountered in both inshore and offshore waters, described as generalist in its feeding preferences (seals, whales, penguins and fish as prey) and known to depredate toothfish from longliners has been opportunistically photo-identified around the Crozet archipelago since the 1960s. Together with photo-identification data collected in the Prince Edward/Marion EEZ, Kerguelen EEZ and international waters, this report provides up to date information on the abundance and distribution of the Crozet killer whales. In total, 124,313 photographs taken during 2,109 encounters since 1964 were analysed, allowing for 299 individuals to be identified. Most encounters with available data were from the Crozet EEZ (1,432 from longliners, 602 from Île de la Possession) and occurred after 2003 when photo-identification was implemented in the fishery observer program. Among the 188 individuals recorded in the Crozet EEZ since 2003, 22 (12%) were also photographed in the Kerguelen EEZ, 13 (7%) in the Prince Edward/Marion EEZ and 13 (7%) in adjacent international waters. The frequently encountered subset of the Crozet killer whale population was composed of 23 social units (maternal groups), 19 of which included individuals alive in 2020. These social units ranged in size from 1 to 11 individuals with a mean (± SD) of 4 ± 3 per unit. As of June 2020 when the latest photographs included in the study were taken, abundance of this subset was 89-94 individuals. However, detailed analysis of data collected between 2005 and 2020 shows that the number of confirmed deaths (n = 51) exceeds the number of recorded births (n = 46), resulting in a 5% decrease of the population size over this period. These deaths were distributed across the population with the majority occurring in the most common sex and age classes - adult females and juveniles. Factors contributing to mortalities ... |
author2 |
Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC) La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) Biologie des Organismes et Ecosystèmes Aquatiques (BOREA) Université de Caen Normandie (UNICAEN) Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA) Bay Cetology Centre d’Etudes Biologiques de Chizé CNRS La Rochelle Université Muséum National d’Histoire Naturelle |
format |
Report |
author |
Tixier, Paul Gasco, Nicolas Towers, Jared R. Guinet, Christophe |
author_facet |
Tixier, Paul Gasco, Nicolas Towers, Jared R. Guinet, Christophe |
author_sort |
Tixier, Paul |
title |
Killer whales of the Crozet Archipelago and adjacent waters: photo-identification catalogue, population status and distribution in 2020 |
title_short |
Killer whales of the Crozet Archipelago and adjacent waters: photo-identification catalogue, population status and distribution in 2020 |
title_full |
Killer whales of the Crozet Archipelago and adjacent waters: photo-identification catalogue, population status and distribution in 2020 |
title_fullStr |
Killer whales of the Crozet Archipelago and adjacent waters: photo-identification catalogue, population status and distribution in 2020 |
title_full_unstemmed |
Killer whales of the Crozet Archipelago and adjacent waters: photo-identification catalogue, population status and distribution in 2020 |
title_sort |
killer whales of the crozet archipelago and adjacent waters: photo-identification catalogue, population status and distribution in 2020 |
publisher |
HAL CCSD |
publishDate |
2021 |
url |
https://hal.science/hal-03138993 https://hal.science/hal-03138993/document https://hal.science/hal-03138993/file/SERAWG-03-05%20Depredation.pdf |
genre |
Killer Whale Orca Orcinus orca Killer whale |
genre_facet |
Killer Whale Orca Orcinus orca Killer whale |
op_source |
https://hal.science/hal-03138993 Centre d’Etudes Biologiques de Chizé; CNRS; La Rochelle Université; Muséum National d’Histoire Naturelle; Bay Cetology. 2021, pp.1-167 |
op_relation |
hal-03138993 https://hal.science/hal-03138993 https://hal.science/hal-03138993/document https://hal.science/hal-03138993/file/SERAWG-03-05%20Depredation.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1810454748651847680 |