Whale shark shipping collisions may increase as oceans warm

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Global warming could increase the threat posed to whale sharks from large ships, according to a new study published in Nature Climate Change.

Researchers from the University of Southampton and Marine Biological Association (MBA) predict that increased ocean temperatures will see this already endangered species driven into new habitats crossed by busy shipping lanes.

The study predicts that the co-occurrence of whale sharks and large ships could be 15,000 times higher by the end of the century compared to the present day.

Lead author Dr Freya Womersley, University of Southampton and MBA Postdoctoral Research Scientist said: “These shifts in the whale sharks’ habitat were most extreme under high emission scenarios. A global reshuffling could lead to core habitat losses in some areas as well as increased co-occurrence with shipping traffic as oceans warm and other variables change.”

Whale sharks, the world’s largest fish, are highly mobile and responsive to changes in temperature. Recent evidence suggests they are also particularly vulnerable to ship strikes - where large marine animals are struck and injured, often fatally, by large vessels in the global fleet.

Researchers used whale shark satellite-tracking data coupled with global climate models to project the distribution of whale sharks under three different future climate scenarios.

The models project core habitat losses of over 50% in some national waters by 2100 under high emissions (where we continue to rely heavily on fossil fuels), with the greatest potential losses in Asia. Under a sustainable development scenario (in line with the target of no more than 2°C of global warming), some areas showed a gain in core habitat, notably in Europe.

“The shifts we predict are likely to be less extreme if we are able to slow warming and mitigate climate change, suggesting that even complex, multi-factor impacts of climate change can be somewhat alleviated by our actions,” says Professor David Sims, co-author and Senior Research Fellow at the University of Southampton and MBA.

The team paired the distribution maps with information on shipping traffic density to determine if these habitat shifts would see whale sharks move into more heavily trafficked areas in future, potentially increasing the likelihood of ship strikes.

They found that some newly suitable habitats overlapped with busy shipping routes. This was the case in the US part of the North Pacific Ocean, the Japanese part of the Eastern China Seas, and the Sierra Leonian part of the North Atlantic Ocean, among many other sites globally.

Some areas, such as the Mexican part of the Gulf of Mexico, saw reductions in co-occurrence, where core habitats shifted into more coastal waters, away from the busy shipping routes in the centre of the Gulf.

Professor Sims says: “Overall ship co-occurrence increased under all future climate scenarios, even if shipping remained at current levels, rather than its anticipated expansion of up to 1,200 per cent by 2050.”

Womersley added: “We show that climate change has the potential to indirectly impact highly mobile marine species through interacting pressures of humans and the environment. This highlights the importance of factoring climate change into discussions around endangered species management.”

Climate-driven global redistribution of an ocean giant predicts increased threat from shipping is published in Nature Climate Change and is available online.

The research was supported by the UK Natural Environment Research Council (NERC) and the European Research Council (ERC) under the EU Horizon 2020 Programme.

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Contact

Steve Williams, Media Manager, University of Southampton, press@soton.ac.uk or 023 8059 3212. Maya Plass, Head of Communications, The Marine Biological Association, comms@mba.ac.uk or +44 (0)1752 426490. Notes for editors

Climate-driven global redistribution of an ocean giant predicts increased threat from shipping is published in Nature Climate Change. An advanced copy of the paper is available upon request. For Interviews with Freya Womersley please contact Steve Williams, Media Manager, University of Southampton press@soton.ac.uk or 023 8059 3212. Images are available here: https://drive.google.com/drive/folders/1NOKWdPgbCOMj9_rnDMbUideOS9w_-28C For credits see file names. Additional information

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The Marine Biological Association (MBA) is a learned society of scientists and members in 35 countries, across 5 continents. Its in-depth scientific research into the interconnected marine environment is carried out from its prestigious laboratory HQ in Plymouth, UK.

It has royal charter status for its world-leading role in marine biology research. Since 1884, the MBA has worked as a voice for the ocean and in the interests of the global marine biological community.

The MBA’s advanced knowledge has contributed to the work of several Nobel Laureates and over 170 Fellows of the Royal Society.

Discover more: www.mba.ac.uk Twitter: @thembauk

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Plymouth – Britain’s Ocean City – has been at the forefront of policy relevant marine research for more than a century. It is home to three world-leading scientific institutions (the University of Plymouth, the Marine Biological Association of the United Kingdom, and Plymouth Marine Laboratory) comprising the UK’s largest cluster of marine researchers, recognised globally in terms of publications, impact and influence. Collaborations with colleagues in 98 countries over the last five years place Plymouth at the heart of international scientific and societal advances in fields including climate change, marine pollution, and ecosystem monitoring and prediction.

 

 

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