Abstract
ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 38:67-77 (2019) - DOI: https://doi.org/10.3354/esr00936 ESR Special: Marine vertebrate bycatch: problems and solutions First estimates of entanglement rate of humpback whales Megaptera novaeangliae observed in coastal Icelandic waters Charla J. Basran1,2,*, Chiara G. Bertulli3, Arianna Cecchetti4, Marianne H. Rasmussen2, Megan Whittaker5, Jooke Robbins6 1Department of Life and Environmental Sciences, University of Iceland, 101 Reykjavik, Iceland 2Húsavík Research Centre, University of Iceland, 640 Húsavík, Iceland 3Sea Watch Foundation, New Quay, Wales SA45 9NR, UK 4Biology Department, cE3c - Centre for Ecology, Evolution and Environmental Changes/Azorean Biodiversity Group, University of the Azores, Ponta Delgada, Azores 9501-855, Portugal 5Elding Adventures at Sea, 101 Reykjavik, Iceland 6Center for Coastal Studies, Provincetown, Massachusetts 02657, USA *Corresponding author: cjb2@hi.is ABSTRACT: Entanglement in fishing gear is a significant anthropogenic source of large whale injury and mortality. Although entanglements have been reported in the eastern North Atlantic, their frequency has not been previously estimated. This study used systematic scar analysis to estimate the frequency of non-lethal entanglements among individual humpback whales Megaptera novaeangliae off coastal Iceland, from 2005 through 2017. Images of the caudal peduncle and fluke insertions of 379 individuals were analyzed for wrapping injuries and notches known to be indicative of entanglement. The results indicated that at least 24.8% (n = 94, 95% confidence intervals [95% CI]: 20.5-29.1%) of individuals had a history of prior entanglement when first encountered. Depending on the metric used, the whales subsequently acquired new entanglement-related injuries at an average rate of 1.9% (95% CI: 0.6-3.2%) or 16.3% (95% CI: 3.0-29.3%) per year, with no statistically significant change over time. Furthermore, evidence suggests that at least some entanglements occurred locally. Observations of whales with gear still entangling the body confirmed the patterns of injury studied here. These results are lower than scar-based estimates from other parts of the world, but the cause of this difference requires further study. Scar-based methods underestimate the frequency of prior entanglement because some injuries heal beyond recognition, do not involve the caudal peduncle, and may occur on whales that die before they are studied. Long-term monitoring of humpback whale entanglement in Icelandic coastal waters is important for evaluating the local effects of fisheries, as well as the viability of the endangered Cape Verde breeding population. KEY WORDS: Entanglement · Humpback whales · Scar analysis · Iceland · Megaptera novaeangliae · North Atlantic Full text in pdf format PreviousNextCite this article as: Basran CJ, Bertulli CG, Cecchetti A, Rasmussen MH, Whittaker M, Robbins J (2019) First estimates of entanglement rate of humpback whales Megaptera novaeangliae observed in coastal Icelandic waters. Endang Species Res 38:67-77. https://doi.org/10.3354/esr00936 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 38. Online publication date: February 07, 2019 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2019 Inter-Research.
Highlights
Entanglement in fishing gear has been identified as one of the major anthropogenic issues faced by marine mammals, with global bycatch estimated to be in the Publisher: Inter-Research · www.int-res.comEndang Species Res 38: 67–77, 2019 and these can lead to serious consequences for both individuals and populations
Given the challenge of detecting these events in progress, injury-based studies have been used as a method of systematically assessing the frequency of entanglement interactions
The most detailed scar-based humpback whale study has been conducted in the Gulf of Maine (GoM), where the majority of individuals have scarring indicative of at least one prior entanglement in fishing gear and the frequency of nonlethal events over time has been estimated by monitoring injury acquisition and healing (Robbins & Mattila 2004, Robbins 2009, 2011, 2012)
Summary
Entanglement in fishing gear has been identified as one of the major anthropogenic issues faced by marine mammals, with global bycatch estimated to be in the Publisher: Inter-Research · www.int-res.comEndang Species Res 38: 67–77, 2019 and these can lead to serious consequences for both individuals and populations. Given the challenge of detecting these events in progress, injury-based studies have been used as a method of systematically assessing the frequency of entanglement interactions (i.e. used to identify whales that have had fishing gear attached to the body previously). Cetacean species in these studies include common minke whales Balaenoptera acutorostrata (HeldWirz 2008), North Atlantic right whales Eubalaena glacialis (Kraus 1990, Knowlton et al 2012), bowhead whales Balaena mysticetus (George et al 2017), gray whales Eschrichtius robustus (Bradford et al 2009), and humpback whales Megaptera novaeangliae (Robbins & Mattila 2001, 2004, Neilson et al 2009, Robbins 2009, 2011). The most detailed scar-based humpback whale study has been conducted in the Gulf of Maine (GoM), where the majority of individuals have scarring indicative of at least one prior entanglement in fishing gear and the frequency of nonlethal events over time has been estimated by monitoring injury acquisition and healing (Robbins & Mattila 2004, Robbins 2009, 2011, 2012)
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