Diving behaviour of albatrosses: implications for foraging ecology and bycatch susceptibility

• Published in: Marine Biology
• Main Authors: Bentley, L. K., Kato, Akiko, Ropert‐coudert, Yan, Manica, A., Phillips, Richard A.
• Other Authors: Department of Zoology Cambridge, University of Cambridge UK (CAM), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), 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)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: [SDE]Environmental Sciences; Bird Island
• Online Access: https://hal.science/hal-03144206; https://hal.science/hal-03144206/document; https://hal.science/hal-03144206/file/s00227-021-03841-y.pdf; https://doi.org/10.1007/s00227-021-03841-y

International audience Diving is an ecologically important behaviour that provides air-breathing predators with opportunities to capture prey, butthat also increases their exposure to incidental mortality (bycatch) in commercial fisheries. In this study, we characterisedthe diving behaviour of 26 individuals of three species, the black-browed albatross Thalassarche melanophris, grey-headedalbatross T. chrysostoma and light-mantled albatross Phoebetria palpebrata, breeding at Bird Island, South Georgia. Individualswere tracked using Global Location Sensor (GLS)-immersion loggers and time-depth recorders (TDRs) and, for twospecies, Global Positioning System (GPS) loggers. Although the TDRs recorded 589 dives (defined in this paper as submersion> 1 m), average dive depths and durations were just 1.30–1.49 m and 2.5–3.3 s, respectively, for the three species. Inaddition, many individuals (22% of black-browed, 20% of grey-headed, and 57% of light-mantled albatrosses; total n = 9, 10and 7 individuals, respectively) did not dive at all. Most dives occurred at the distal end of foraging trips and were rare duringthe commuting phase. No dives took place in darkness, despite long periods spent on water at night. The limited and shallowdive activity contrasts with impressions from a previous study using capillary-tube depth gauges (which are less accuratethan TDRs) and has implications for the susceptibility of albatrosses to bycatch on longlines. This study provides furthersupport for regulations requiring night setting and increased sink rates of baited hooks to help mitigate albatross bycatch.