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A truly collaborative effort, the researchers combined data collected by different research projects that span over almost two decades and resulted in very detailed information on the movements of 115 sharks monitored, with some of these individuals tracked over up to 4.5 consecutive years. The results were mindboggling, finding that the movement patterns of each biological group (juvenile females, juvenile males, and adult females) were correlated with different gradients of water temperatures. Adult males were not included due to not having enough tagged individuals. “Climate change is raising the water temperatures, consequently, it is moving the thermal gradients where not only tiger sharks but also their prey like to live in. Our projections indicate that this rise in water temperatures is likely to expand tiger shark suitable habitats towards the east coast of Tasmania over the next decade,” said Niella. Juvenile and adult females are expected to spend more time in the northern region, while juvenile male distribution is moving southwards due to ocean warming and redistribution of their prey.

The data also shows that tiger sharks are expected regularly as far south as the coast of Tasmania (a over 400 miles or about a 670 km shift southwards) by 2030. “If tiger sharks start spending more time further south the east coast of Australia in the future, they might start competing with other species (like white sharks) for resources. This may have consequences for tiger sharks themselves, but also broader ecosystemic impacts, such as food web restructuring by increasing predation pressures upon lower trophic level species,” commented Niella. “Besides, this southward shift can raise concerns regarding management of shark bite interactions, since tiger sharks are one of the species mostly involved in these incidents (together with white and bull sharks) and this is the most densely populated part of Australia.”