Climate change pushes whales to forage further

Embargoed until: Publicly released: 2023-02-28 10:18

Australia; New Zealand; Pacific; International

© Zoltan BAGOSI, some rights reserved (CC-BY-NC)

Tohorā (southern right whales) are searching further north and south for food across the Southern Ocean. The researchers say the changes happened over the past 30 years, after a long period of "remarkable consistency" in whale feeding ranges dating back to the 1700s. The researchers say the change is likely driven by climate-associated changes in the availability of krill and other small crustaceans which tohorā feed on.

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From: PNAS

Climate change and foraging ranges of southern right whales

Researchers report the effects of whaling and climate change on southern right whales since 1792. Variations in large marine predator populations can provide insight into long-term environmental changes in the Southern Ocean. However, long-term data on marine predators in this remote region are limited. Solène Derville, Emma Carroll, and colleagues analyzed recent and long-term variations in distributions of southern right whales (Eubalaena australis) based on carbon and nitrogen isotope composition measurements and historical whaling data. The authors compared isotopic compositions of 1,002 skin samples from six genetically distinct E. australis populations collected from 1994 to 2020 with models of the Southern Ocean isotopic baseline, accounting for seasonal and regional variation, to estimate the foraging range of each E. australis. Since 1994, E. australis populations have shifted their foraging grounds in the south Atlantic and southwest Indian oceans from high to low latitudes and slightly shifted their foraging grounds in the southwest Pacific Ocean to high latitudes. These shifts in E. australis foraging correspond with contemporary changes in prey distributions. Analysis of 2,614 whale-catch records from 1792 to 1968 suggests that historical E. australis foraging grounds were largely stable in midlatitudes. According to the authors, the results suggest that climate change has driven recent shifts in E. australis distribution and could help identify priority areas for conservation.

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conference: PNAS

Research:Paper

Organisation/s: University of Auckland, See paper for full list of author affiliations.

Funder: Sample collection and analysis were funded by the Charles University Grant Agency (1140217), Dyer Island Conservation Trust, Great White House, Kleinbaai, ExxonMobil, Total, and Eni in South Africa; the Department of Environment, Land, Water, and Planning, Victoria; Department of Natural Resources and Environment, Tasmania; and the Australian Marine Mammal Centre (AMMC), Australia. Sample collection in New Zealand was funded by the following: 1995 to 1998 Auckland Islands field seasons—the Whale and Dolphin Conservation Society, the US Department of State (Program for Cooperative US/NZ Antarctic Research), the Auckland University Research Council, and the NZ Marsden Fund; 2006 to 2009 Auckland Islands field seasons—Winifred Violet Scott Estate Research Grant Fund, Australian Antarctic Division, Marine Conservation Action Fund, Blue Planet Marine NZ Ltd., Holsworth Wildlife Research Endowment, New Zealand Ministry of Foreign Affairs, DOC, South Pacific Whale Research Consortium, National Geographic, and Brian Skerry Photography; 2020 Auckland Islands field work—Royal Society Te Apārangi Rutherford Discovery Fellowship to E.L.C., Live Ocean, Lou and Iris Fisher Charitable Trust, and the University of Auckland—Waipapa Taumata Rau (2020 field season); and mainland samples—DOC. Analysis of New Zealand and Australian samples was funded by the AMMC, a Newton Fellowship from the Royal Society of London, Marie Curie Fellowship, and the University of Auckland. Funding for satellite tracking in Argentina was provided by Instituto Aqualie (Brazil), the National Oceanic and Atmospheric Administration (NOAA) of the United States, the International Whaling Commission (IWC), and Wildlife Conservation Society. Satellite tracking in South Georgia was funded by the Darwin Plus initiative (DPLUS057), with additional funding support from the South Georgia Heritage Trust, Friends of South Georgia Island, World Wide Fund for Nature (WWF) UK, and EU BEST 2.0 Medium Grant 1594. Isoscape analysis was funded by an International Whaling Commission— Southern Ocean Research Partnership grant. C.J.S. was supported by the Deutsche Forschungsgemeinschaft (project no. 445549720). P.H.O. was supported by the Brazilian National Research Council (Conselho Nacional de Desenvolvimento Científico e Tecnológico—CNPq numbers 477611/2004-4 and 144064/98-7) and World Wildlife Fund (WWF-Brazil). L.O. was supported by the Brazilian National Council for Scientific and Technological Development, Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) that provided the research productivity grant nos. 303813/2011-3, 308650/2014-0, 310621/2017-8, and 315361/2021-2.

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