Great whales will drift southward due to climate change

A new study published in the journal Ecological Indicators has investigated how climate change will impact the distribution of great whales in New Zealand waters. By using a complex modeling approach for projecting the regional range shift of blue and sperm whales by the end of the century, under different climate change scenarios, the experts argue that the suitable habitats for both species will likely shift southward as the oceans warm. 

In the most severe climate change scenario, the scientists project a 61 percent and 42 percent loss and decrease of currently suitable habitats for sperm and blue whales, respectively, particularly in New Zealand’s northern waters.

“Regardless of which of the climate change scenarios will be the reality, even the best-case scenario indicates notable changes in the distribution of suitable habitat for sperm and blue whales in New Zealand,” said study lead author Katharina Peters, a postdoctoral researcher in Animal Behavior, Population Ecology, and Evolutionary Biology at the University of Canterbury.

Due to their strong connection to the ocean, island nations such as New Zealand are highly vulnerable to the impact of climate change on marine ecosystems. For instance, sperm whales are crucial for the tourism industry and local economy. 

“The whale watch industry off Kaikoura may be at potential risk due to fewer and less reliable sightings of sperm whales off that coastline in the future,” explained study co-author Karen Stockin, an expert in Cetacean Ecology at the Massey University of New Zealand. “Such changes in sperm whale distribution would have socioeconomic impacts due to the direct and indirect reliance on the whale watching activities by the local economy.”

Moreover, blue and sperm whales are also major ecosystem engineers, fulfilling a variety of important tasks, such as facilitating the transfer of nutrients from deep waters to the surface and across different latitudes through migration. Their predicted future southward drift will most likely impact ecosystem functioning and destabilize many ecological processes in northern New Zealand.

Although this study highlights the negative impact of climate change on great whales, it also identifies habitats that may be suitable in the future for both species in the South Island and other offshore islands. 

“Such areas have the potential to serve as climate refugia for both species,” said study senior author Frédérik Saltré, a research fellow in Ecology at Flinders University. “Knowing about these areas early on provides an opportunity for their increased protection in the future, particularly when considering the placement of marine protected areas and the legislation of oil and gas exploration,” he concluded.

Image Credit: Photo courtesy DBL Wildlife

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By Andrei Ionescu, Earth.com Staff Writer