Lead investigator Dr Samantha Reynolds from Murdoch University’s Harry Butler Institute used three future climate change scenarios from CMIP6 climate models to investigate how ocean warming could affect the overall health and distribution of the world's largest marine ectotherm. 

Using biotelemetry, animal-borne electronic tags, Dr Reynolds and her research team were able to assess how temperatures can affect a whale shark’s behaviours and movements.  

Results of the study showed the warming climate would increase metabolic rates and energy needs of the whale shark, while simultaneously depleting its food sources. 

With the species already categorised as endangered, Dr Reynolds said it was imperative to understand the risk human behaviour poses on its longevity and wellbeing. 

“Whale sharks have been around for millions of years, but now, thanks to humans, they are endangered,” Dr Reynolds said. 

I want to make sure that we protect and conserve them so that they continue to fulfil their important role in the world’s oceans, and future generations can experience the wonder of swimming with the world’s biggest fish.”  

Dr Reynolds’ research identified ocean temperatures at Indian Ocean whale shark aggregations may rise 4.9°C by the year 2100. This will increase whale sharks’ metabolic rate and energy needs.  

The increased temperatures will also decrease zooplankton - the whale shark’s main source of food. 

Dr Reynolds said a pivotal message she hoped to convey through her research was that the repercussions of human behaviour on the world’s oceans are severe. 

She said the time for action was now and that the study would help prompt this action.  

“I hope that my research can help to guide protection and conservation of whale sharks, but also help people to understand that humans are having huge impacts on the world’s oceans, from the smallest organisms to the biggest fish in the sea,” she said. 

“We need to minimise our detrimental impacts and find ways to have positive impacts on our planet.”