Population abundance of recovering humpback whales (Megaptera novaeangliae) and other baleen whales in the Scotia Arc, South Atlantic

Baines, Mick; Kelly, Natalie; Reichelt, Maren; Lacey, Claire; Pinder, Simon; Fielding, Sophie ORCID: https://orcid.org/0000-0002-3152-4742; Murphy, Eugene ORCID: https://orcid.org/0000-0002-7369-9196; Trathan, Phil ORCID: https://orcid.org/0000-0001-6673-9930; Biuw, Martin; Lindstrøm, Ulf; Krafft, Bjørn A.; Jackson, Jennifer A. ORCID: https://orcid.org/0000-0003-4158-1924. 2021 Population abundance of recovering humpback whales (Megaptera novaeangliae) and other baleen whales in the Scotia Arc, South Atlantic. Marine Ecology Progress Series, 676. 77-94. 10.3354/meps13849

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Text Copyright © 2021 The Authors. This is the Author Accepted Manuscript of an article published in MEPS by Inter-Research. The Version of Record is available at: https://www.int-res.com/abstracts/meps/v676/p77-94/ Scotia Arc whale abundance accepted.pdf - Accepted Version Available under License Creative Commons Attribution 4.0. Download (1MB) | Preview

Abstract/Summary

Following the cessation of whaling, South Atlantic populations of humpback (Megaptera novaeangliae) and some other baleen whale species are recovering, but there has been limited monitoring of their recovery in the Scotia Arc, a former whaling epicentre and a hotspot for Antarctic krill (Euphausia superba). To inform the management of krill fisheries, up to date assessment of whale biomass and prey consumption is essential. Using a model-based approach, we provide the first estimates of whale abundance and krill consumption for South Georgia and the South Sandwich Islands, and total abundance of humpback whales across their southwest Atlantic feeding grounds, using data collected in 2019. Humpback whale abundance was estimated at 24,543 (CV = 0.26; 95% CI 14,863 – 40,528), similar to that measured in Brazil on the main wintering ground for this population. The abundance of baleen whales in South Georgia and the South Sandwich Islands, including those not identified to species level, was estimated at 43,824 (CV = 0.15; 95% CI 33,509 – 59,077). Based on the proportion of humpback whales identified during the surveys (83%), the majority of these are likely to be humpback whales. Annual krill consumption by baleen whales was estimated to be in the range 4.8 – 7.2 million tons, representing 7 - 10% of the estimated krill biomass in the region. However, there is a need to better understand feeding rates in baleen whales, and further research into this field should be a priority in order to improve the accuracy and precision of prey consumption rate estimation.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.3354/meps13849
ISSN:	0171-8630
Additional Keywords:	Humpback whale, baleen whale, abundance, krill consumption, South Georgia, South Sandwich Islands
Date made live:	15 Oct 2021 10:26 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/530411

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