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 Marine Biological Association (MBA) and University of Southampton predict that increased ocean temperatures will see this already endangered species driven into new habitats crossed by busy shipping lanes.
The study suggests that the co-occurrence of whale sharks and large ships could increase significantly by the end of the century compared to the present day.
Lead author Dr. Freya Womersley, Postdoctoral Research Scientist at the MBA and University of Southampton, explained, “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 shark injuries up close
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 combined with global climate models to forecast the distribution of whale sharks under different future climate scenarios.
The models indicate core habitat losses of over 50% in some national waters by 2100 under high emissions, with the greatest potential losses in Asia. On the other hand, a sustainable development scenario shows gains in core habitat, especially in Europe.
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“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, Senior Research Fellow at the University of Southampton and MBA.
The team overlaid the distribution maps with information on shipping traffic density to determine if these habitat shifts would lead whale sharks into more heavily trafficked areas, increasing the risk of ship strikes in the future.
They found that some newly suitable habitats overlapped with busy shipping routes, raising concerns about the potential impact on whale sharks. Instances included parts of the north Pacific Ocean, the eastern China Seas, and the north Atlantic Ocean.
Some areas, such as the Gulf of Mexico, saw reductions in co-occurrence, where core habitats shifted away from busy shipping routes, potentially reducing the risk of ship strikes.
Professor Sims explains, “Overall ship co-occurrence increased under all future climate scenarios, indicating a growing risk of ship strikes even with current shipping levels, let alone the projected increase 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.”
Perhaps utilizing software engineering to align whale shark migration patterns with shipping routes could help mitigate the risks posed by ship strikes.
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