By Stephen Beech via SWNS
Endangered whale sharks are at greater risk from potentially deadly shipping collisions due to global warming, warns new research.
The largest living fish species – that can grow to more than 60 feet long – are at more serious threat from large ships due to warming oceans, say scientists.
Researchers from the University of Southampton and Marine Biological Association (MBA) predict that increased ocean temperatures will see the already endangered species driven into new habitats crossed by busy shipping lanes.
The study was published in the journal Nature Climate Change. 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 now.
Lead author Dr. Freya Womersley, of the University of Southampton, 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.”
Scientists say whale sharks are highly mobile and responsive to changes in temperature.
But recent evidence suggests they are also “particularly vulnerable” to ship strikes – where large marine animals are struck and injured, often fatally, by large vessels.
Researchers used whale shark satellite-tracking data along with global climate models to project the distribution of whale sharks under three different future climate scenarios.
The models project core habitat losses of more than 50% in some national waters by 2100 under current emissions – 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.
Study co-author Professor David Sims said: “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.”
The researchers paired the distribution maps with information on shipping traffic density to determine if habitat shifts would see whale sharks move into busier shipping areas in future, potentially increasing the likelihood of collisions.
They found that some newly suitable habitats overlapped with busy shipping routes including 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.
Some areas, including 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 middle of the Gulf.
Sims, Senior Research Fellow at the University of Southampton and MBA, said: “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% by 2050.”
Dr. 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.”
