Adapt to new habitats or face extinction – that’s the ultimatum Australia’s critically endangered whitefin swellshark could be forced to face, should the predicted changes in the ocean stay their current course as a direct impact of climate change.

Should shifts in ocean chemistry and increasing ocean temperatures continue on the trajectory currently mapped out by scientists, a team of marine researchers from the University of Plymouth have warned that up to 70% of currently suitable habitats for the species could be lost within the next 75 years. 

A species of catshark found in the deeper waters just off Australia’s south and east coasts, the whitefin swellshark (the Cephaloscyllium albipinnum) has been considered to be Critically Endangered for a number of years, due – largely – to declines attributed to overfishing.

While many details about the species, including the precise population numbers, are still uncertain, what is known is that this already endangered species could be facing a substantially heightened vulnerability, if the right action to mitigate climate change impacts aren’t taken now.

Using a range of computer modelling, which accounted for the species’ favoured habitats and forecast ocean conditions, researchers at the University of Plymouth found that up to 70% of currently suitable habitats will be lost over the next 75 years.

There is predicted to be an area within the Great Australian Bight that could offer whitefin swellshark populations refuge, with favourable ocean conditions and sources of the food they need to survive.

However, the issue is that – based on current knowledge of the species’ whereabouts – these sharks (which can grow to around 1.1 metres long) – may need to move to anywhere between 70km and 1,100km in order to reach their potential new home.

Further to this, it’s likely they won’t be the only species seeking refuge in the area. In fact, it’s anticipated that a number of other marine species will also likely be forced to migrate polewards, towards these new havens, as they look to leave areas impacted by climate change.

“Most people will probably have never seen them, but whitefin swellsharks are an incredibly pretty species. However, despite them being listed as critically endangered, we actually know very little about their behaviour given its habitats are deep in the ocean,” said Kerry Brown, marine biology and oceanography graduate at the University of Plymouth, and lead author on the study.

“What we do know is that they have been on our planet for a very long time, so will have had to adapt to changes in their environment before. However, the threat to their future survival now is very real unless we take urgent steps to protect them.” 

Writing in the journal PeerJ, the researchers say the vulnerability of the species to the future effects of climate change is clear. Despite this, researchers believe there is still cause for hope – this being that Australia is one of the world’s more proactive nations when it comes to implementing conservation measures and management strategies, such as marine protected areas.

“We have seen species move into different areas of the ocean in the past, so that offers some sense of hope for the whitefin swellshark. And the marine protected areas along the Australian coast are certainly a positive factor, although whether they are in the right place for this particular species is another matter,” said Dr Robert Puschendorf, associate professor in conservation biology at the University of Plymouth. 

“However, it does show the authorities in the region have the willingness and means to take action. The challenges faced by this – and other – species are now very different to what they may have encountered in the past, when you consider there are now very few parts of the planet that humans haven’t damaged in some way.

“But our study shows we are potentially in a position where we can do something about it.”

The full study – Brown and Puschendorf: Future climate-driven habitat loss and range shift of the Critically Endangered whitefin swellshark – is published in the scientific journal, PeerJ.

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