Publication Date:
2022-05-26
Description:
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Calderan, S., V., Black, A., Branch, T. A., Collins, M. A., Kelly, N., Leaper, R., Lurcock, S., Miller, B. S., Moore, M., Olson, P. A., Sirovic, A., Wood, A. G., & Jackson, J. A. South Georgia blue whales five decades after the end of whaling. Endangered Species Research, 43, (2020): 359-373, https://doi.org/10.3354/esr01077.
Description:
Blue whales Balaenoptera musculus at South Georgia were heavily exploited during 20th century industrial whaling, to the point of local near-extirpation. Although legal whaling for blue whales ceased in the 1960s, and there were indications of blue whale recovery across the wider Southern Ocean area, blue whales were seldom seen in South Georgia waters in subsequent years. We collated 30 yr of data comprising opportunistic sightings, systematic visual and acoustic surveys and photo-identification to assess the current distribution of blue whales in the waters surrounding South Georgia. Over 34000 km of systematic survey data between 1998 and 2018 resulted in only a single blue whale sighting, although opportunistic sightings were reported over that time period. However, since 2018 there have been increases in both sightings of blue whales and detections of their vocalisations. A survey in 2020 comprising visual line transect surveys and directional frequency analysis and recording (DIFAR) sonobuoy deployments resulted in 58 blue whale sightings from 2430 km of visual effort, including the photo-identification of 23 individual blue whales. Blue whale vocalisations were detected on all 31 sonobuoys deployed (114 h). In total, 41 blue whales were photo-identified from South Georgia between 2011 and 2020, none of which matched the 517 whales in the current Antarctic catalogue. These recent data suggest that blue whales have started to return to South Georgia waters, but continued visual and acoustic surveys are required to monitor any future changes in their distribution and abundance.
Description:
It is a pleasure to acknowledge theassistance of the following people and organisations: theGovernment of South Georgia & the South SandwichIslands for permission to use their survey data; the 2016−2017 Antarctic Circumnavigation Expedition (ACE), carriedout under the auspices of the Swiss Polar Institute and sup-ported by funding from the ACE Foundation and FerringPharmaceuticals, along with major funding for the passiveacoustic survey during ACE provided by the Swiss PolarInstitute and the Australian Antarctic Division; BárbaraGalletti Vernazzani of Centro de Conservación Cetacea,Chile, and Sonia Español-Jiménez of Fundación MERI,Chile, kindly shared their blue whale catalogues for thecomparison of photographs with those from South Georgia;Mick Baines, Lisa Ballance, Santiago Imberti, Mike Green-felder, Amy Kennedy, Bob Lamb, Stephanie Martin, MarenReichelt and Conor Ryan contributed photo-ID imagesfrom South Georgia; Tim and Pauline Carr initiated theSouth Georgia Museum sightings record, and since thenstaff and volunteers at the Museum and South GeorgiaHeritage Trust have continued to compile these data; EUBEST 2.0 Medium grant 1594, DARWIN PLUS grant 057,South Georgia Heritage Trust and Friends of South Geor-gia Island funded the 2018 and 2020 BAS surveys whichgenerated acoustic, photo-ID and sightings data; Friends ofSouth Georgia Island and South Georgia Heritage Trustprovided funding to enable the analysis of blue whaleidentification photos by P.A.O., and for the writing andpublication of this manuscript.
Keywords:
Blue whale
;
Balaenoptera musculus
;
South Georgia
;
Recovery
;
Whaling
;
Southern Ocean
Repository Name:
Woods Hole Open Access Server
Type:
Article
