Up in the air: drone images reveal underestimation of entanglement rates in large rorqual whales
Entanglement in fishing gear is a significant threat to many cetaceans. For the 2 largest species, the blue whale Balaenoptera musculus and the fin whale B. physalus, reports of entangled individuals are rare, leading to the assumption that entanglements are not common. Studies of interaction with f...
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Inter-Research
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ftdoajarticles:oai:doaj.org/article:e30b7851de5c4eaa8b91f73b6ae25a3a 2023-05-15T15:36:24+02:00 Up in the air: drone images reveal underestimation of entanglement rates in large rorqual whales C Ramp D Gaspard K Gavrilchuk M Unger A Schleimer J Delarue S Landry R Sears 2021-01-01T00:00:00Z https://doi.org/10.3354/esr01084 https://doaj.org/article/e30b7851de5c4eaa8b91f73b6ae25a3a EN eng Inter-Research https://www.int-res.com/abstracts/esr/v44/p33-44/ https://doaj.org/toc/1863-5407 https://doaj.org/toc/1613-4796 1863-5407 1613-4796 doi:10.3354/esr01084 https://doaj.org/article/e30b7851de5c4eaa8b91f73b6ae25a3a Endangered Species Research, Vol 44, Pp 33-44 (2021) Zoology QL1-991 Botany QK1-989 article 2021 ftdoajarticles https://doi.org/10.3354/esr01084 2022-12-31T05:37:06Z Entanglement in fishing gear is a significant threat to many cetaceans. For the 2 largest species, the blue whale Balaenoptera musculus and the fin whale B. physalus, reports of entangled individuals are rare, leading to the assumption that entanglements are not common. Studies of interaction with fisheries in other species often rely on the presence of scars from previous entanglements. Here, scar detection rates were first examined in humpback Megaptera novaeangliae, fin and blue whales using standard vessel-based photo-identification photographs collected between 2009 and 2016 in the Gulf of St. Lawrence, Canada. We then examined aerial images of fin whales collected with a drone in 2018 and 2019 and compared both methods. Entanglement rates were 6.5% for fin and 13.1% for blue whales using photo-identification images of individuals. Prominent scarring was observed around the tail and caudal peduncle, visible only when animals lifted those body sections above water when diving. For the small subset of pictures which captured the entire caudal peduncle, entanglement rates ranged between 60% for blue and 80% for fin whales. This result was similar to the 85% entanglement rate estimated in humpback whales. The assessment of aerial-based photography yielded an entanglement rate of 44.1 to 54.7% in fin whales. Scars were always around the peduncle, often the tail, rarely the dorsal fin and never around the pectoral fins, while the mouth cannot be examined from above. Thus, in species that do not regularly expose their tail or peduncle, aerial imagery is the preferred method to quantify entanglement rates by assessment of scars. Article in Journal/Newspaper Balaenoptera musculus Blue whale Fin whale Megaptera novaeangliae Directory of Open Access Journals: DOAJ Articles Canada Rorqual ENVELOPE(-62.311,-62.311,-65.648,-65.648) Endangered Species Research 44 33 44 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Zoology QL1-991 Botany QK1-989 |
spellingShingle |
Zoology QL1-991 Botany QK1-989 C Ramp D Gaspard K Gavrilchuk M Unger A Schleimer J Delarue S Landry R Sears Up in the air: drone images reveal underestimation of entanglement rates in large rorqual whales |
topic_facet |
Zoology QL1-991 Botany QK1-989 |
description |
Entanglement in fishing gear is a significant threat to many cetaceans. For the 2 largest species, the blue whale Balaenoptera musculus and the fin whale B. physalus, reports of entangled individuals are rare, leading to the assumption that entanglements are not common. Studies of interaction with fisheries in other species often rely on the presence of scars from previous entanglements. Here, scar detection rates were first examined in humpback Megaptera novaeangliae, fin and blue whales using standard vessel-based photo-identification photographs collected between 2009 and 2016 in the Gulf of St. Lawrence, Canada. We then examined aerial images of fin whales collected with a drone in 2018 and 2019 and compared both methods. Entanglement rates were 6.5% for fin and 13.1% for blue whales using photo-identification images of individuals. Prominent scarring was observed around the tail and caudal peduncle, visible only when animals lifted those body sections above water when diving. For the small subset of pictures which captured the entire caudal peduncle, entanglement rates ranged between 60% for blue and 80% for fin whales. This result was similar to the 85% entanglement rate estimated in humpback whales. The assessment of aerial-based photography yielded an entanglement rate of 44.1 to 54.7% in fin whales. Scars were always around the peduncle, often the tail, rarely the dorsal fin and never around the pectoral fins, while the mouth cannot be examined from above. Thus, in species that do not regularly expose their tail or peduncle, aerial imagery is the preferred method to quantify entanglement rates by assessment of scars. |
format |
Article in Journal/Newspaper |
author |
C Ramp D Gaspard K Gavrilchuk M Unger A Schleimer J Delarue S Landry R Sears |
author_facet |
C Ramp D Gaspard K Gavrilchuk M Unger A Schleimer J Delarue S Landry R Sears |
author_sort |
C Ramp |
title |
Up in the air: drone images reveal underestimation of entanglement rates in large rorqual whales |
title_short |
Up in the air: drone images reveal underestimation of entanglement rates in large rorqual whales |
title_full |
Up in the air: drone images reveal underestimation of entanglement rates in large rorqual whales |
title_fullStr |
Up in the air: drone images reveal underestimation of entanglement rates in large rorqual whales |
title_full_unstemmed |
Up in the air: drone images reveal underestimation of entanglement rates in large rorqual whales |
title_sort |
up in the air: drone images reveal underestimation of entanglement rates in large rorqual whales |
publisher |
Inter-Research |
publishDate |
2021 |
url |
https://doi.org/10.3354/esr01084 https://doaj.org/article/e30b7851de5c4eaa8b91f73b6ae25a3a |
long_lat |
ENVELOPE(-62.311,-62.311,-65.648,-65.648) |
geographic |
Canada Rorqual |
geographic_facet |
Canada Rorqual |
genre |
Balaenoptera musculus Blue whale Fin whale Megaptera novaeangliae |
genre_facet |
Balaenoptera musculus Blue whale Fin whale Megaptera novaeangliae |
op_source |
Endangered Species Research, Vol 44, Pp 33-44 (2021) |
op_relation |
https://www.int-res.com/abstracts/esr/v44/p33-44/ https://doaj.org/toc/1863-5407 https://doaj.org/toc/1613-4796 1863-5407 1613-4796 doi:10.3354/esr01084 https://doaj.org/article/e30b7851de5c4eaa8b91f73b6ae25a3a |
op_doi |
https://doi.org/10.3354/esr01084 |
container_title |
Endangered Species Research |
container_volume |
44 |
container_start_page |
33 |
op_container_end_page |
44 |
_version_ |
1766366753434107904 |