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Basking shark sub-surface behaviour revealed by animal-towed cameras

While biologging tags have answered a wealth of ecological questions, the drivers and consequences of movement and activity often remain difficult to ascertain, particularly marine vertebrates which are difficult to observe directly. Basking sharks, the second largest shark species in the world, agg...

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Autores principales: Rudd, Jessica L., Bartolomeu, Tiago, Dolton, Haley R., Exeter, Owen M., Kerry, Christopher, Hawkes, Lucy A., Henderson, Suzanne M., Shirley, Marcus, Witt, Matthew J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8318306/
https://www.ncbi.nlm.nih.gov/pubmed/34320007
http://dx.doi.org/10.1371/journal.pone.0253388
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author Rudd, Jessica L.
Bartolomeu, Tiago
Dolton, Haley R.
Exeter, Owen M.
Kerry, Christopher
Hawkes, Lucy A.
Henderson, Suzanne M.
Shirley, Marcus
Witt, Matthew J.
author_facet Rudd, Jessica L.
Bartolomeu, Tiago
Dolton, Haley R.
Exeter, Owen M.
Kerry, Christopher
Hawkes, Lucy A.
Henderson, Suzanne M.
Shirley, Marcus
Witt, Matthew J.
author_sort Rudd, Jessica L.
collection PubMed
description While biologging tags have answered a wealth of ecological questions, the drivers and consequences of movement and activity often remain difficult to ascertain, particularly marine vertebrates which are difficult to observe directly. Basking sharks, the second largest shark species in the world, aggregate in the summer in key foraging sites but despite advances in biologging technologies, little is known about their breeding ecology and sub-surface behaviour. Advances in camera technologies holds potential for filling in these knowledge gaps by providing environmental context and validating behaviours recorded with conventional telemetry. Six basking sharks were tagged at their feeding site in the Sea of Hebrides, Scotland, with towed cameras combined with time-depth recorders and satellite telemetry. Cameras recorded a cumulative 123 hours of video data over an average 64-hour deployment and confirmed the position of the sharks within the water column. Feeding events only occurred within a metre depth and made up ¾ of the time spent swimming near the surface. Sharks maintained similar tail beat frequencies regardless of whether feeding, swimming near the surface or the seabed, where they spent surprisingly up to 88% of daylight hours. This study reported the first complete breaching event and the first sub-surface putative courtship display, with nose-to-tail chasing, parallel swimming as well as the first observation of grouping behaviour near the seabed. Social groups of sharks are thought to be very short term and sporadic, and may play a role in finding breeding partners, particularly in solitary sharks which may use aggregations as an opportunity to breed. In situ observation of basking sharks at their seasonal aggregation site through animal borne cameras revealed unprecedented insight into the social and environmental context of basking shark behaviour which were previously limited to surface observations.
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spelling pubmed-83183062021-07-31 Basking shark sub-surface behaviour revealed by animal-towed cameras Rudd, Jessica L. Bartolomeu, Tiago Dolton, Haley R. Exeter, Owen M. Kerry, Christopher Hawkes, Lucy A. Henderson, Suzanne M. Shirley, Marcus Witt, Matthew J. PLoS One Research Article While biologging tags have answered a wealth of ecological questions, the drivers and consequences of movement and activity often remain difficult to ascertain, particularly marine vertebrates which are difficult to observe directly. Basking sharks, the second largest shark species in the world, aggregate in the summer in key foraging sites but despite advances in biologging technologies, little is known about their breeding ecology and sub-surface behaviour. Advances in camera technologies holds potential for filling in these knowledge gaps by providing environmental context and validating behaviours recorded with conventional telemetry. Six basking sharks were tagged at their feeding site in the Sea of Hebrides, Scotland, with towed cameras combined with time-depth recorders and satellite telemetry. Cameras recorded a cumulative 123 hours of video data over an average 64-hour deployment and confirmed the position of the sharks within the water column. Feeding events only occurred within a metre depth and made up ¾ of the time spent swimming near the surface. Sharks maintained similar tail beat frequencies regardless of whether feeding, swimming near the surface or the seabed, where they spent surprisingly up to 88% of daylight hours. This study reported the first complete breaching event and the first sub-surface putative courtship display, with nose-to-tail chasing, parallel swimming as well as the first observation of grouping behaviour near the seabed. Social groups of sharks are thought to be very short term and sporadic, and may play a role in finding breeding partners, particularly in solitary sharks which may use aggregations as an opportunity to breed. In situ observation of basking sharks at their seasonal aggregation site through animal borne cameras revealed unprecedented insight into the social and environmental context of basking shark behaviour which were previously limited to surface observations. Public Library of Science 2021-07-28 /pmc/articles/PMC8318306/ /pubmed/34320007 http://dx.doi.org/10.1371/journal.pone.0253388 Text en © 2021 Rudd et al https://creativecommons.org/licenses/by/4.0/This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Rudd, Jessica L.
Bartolomeu, Tiago
Dolton, Haley R.
Exeter, Owen M.
Kerry, Christopher
Hawkes, Lucy A.
Henderson, Suzanne M.
Shirley, Marcus
Witt, Matthew J.
Basking shark sub-surface behaviour revealed by animal-towed cameras
title Basking shark sub-surface behaviour revealed by animal-towed cameras
title_full Basking shark sub-surface behaviour revealed by animal-towed cameras
title_fullStr Basking shark sub-surface behaviour revealed by animal-towed cameras
title_full_unstemmed Basking shark sub-surface behaviour revealed by animal-towed cameras
title_short Basking shark sub-surface behaviour revealed by animal-towed cameras
title_sort basking shark sub-surface behaviour revealed by animal-towed cameras
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8318306/
https://www.ncbi.nlm.nih.gov/pubmed/34320007
http://dx.doi.org/10.1371/journal.pone.0253388
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