Alongside bull sharks and great whites, tiger sharks are one of the main predatory species known to occasionally snack on humans. Their migratory habits may therefore be of some interest if you're planning to spend a lot of time in the ocean this summer. According to new research, tiger sharks regularly travel over 1000km across the Coral Sea between New Caledonia and the Great Barrier Reef. (Guess you can't blame 'em for occasionally getting the munchies.)
Tiger shark picture from Shutterstock
Over the past four years, shark research scientist Dr Jonathan Werry analysed the migratory patterns of 33 tiger sharks ranging in size between 1.54 and 3.9 metres. Using satellite tags and acoustic transmitters, Werry's team tracked the fish as they traveled across New Caledonia, the east coast of Australia and oceanic reefs in the centre of the Coral Sea.
“We found the monitored sharks utilised three dimensional activity spaces of between 503 and 2360 kmᶟ, but the range of movement varied consistently with the age and sex of the animal,” Werry said in a statement.
“When it comes to traveling long distances adult females are the primary custodians for the ‘across Coral Sea’ migrations, and this is probably driven by triennial reproductive cycles."
Females were also found to be the deepest swimmers, with one 3.7m specimen recorded at a previously unknown depth of 1136 metres below sea level. Meanwhile, juvenile females and mature males tended to stick to the isolated oceanic Chesterfield Island reef.
"Tiger sharks in our study displayed complex individual variability in both their wide-ranging migrations and localised movement patterns. Our results suggest discrete groups of tiger sharks across the Coral Sea utilise specific coral reefs incorporating nearby deep water oceanic environments...Few fish species utilize such a remarkable range of habitat in such a short amount of time."
In his report, Werry noted that coastal marine parks provide only brief protection for tiger sharks while oceanic reefs, which are vital to their ecology, are completely overlooked. It is hoped that future research will help afford tiger sharks added protections as well as improving management of shark-human interactions.
“Management strategies need to consider the wide-ranging movements of large male and female tiger sharks at the individual level, in particular when fidelity to specific coastal reefs may be consistent across groups of individuals."