Scientists believe whale sharks could live well beyond 80 years of age. (ABC North West: Andrew Seabourne)
Scientists are hoping to shed new light on the age of Western Australia’s whale shark population in a world first study.
CSIRO researchers have been collecting genetic samples from the animals, a method previously only used on humans and humpback whales.
The project is taking place at the world-heritage-listed Ningaloo Reef, a known feeding hotspot for whale sharks.
CSIRO senior scientist Richard Pillans said, although the animals were well known to the general public, a lot of mystery still surrounded their behaviour and population size.
Scientists hope their methods might one day be able to reveal the secrets of other endangered animals. (ABC North West: Andrew Seabourne)
“Whales sharks are probably one of the longest-living sharks … there are estimates of sharks up to 80 years old and they possibly live a lot longer than that,” he said.
“But in order to work out how many there are we need this age information that we currently don’t have.”
“It will be a massive breakthrough — not only being able to see how old they are — but also how many whale sharks there are in the population.”
Dr Pillans said they hoped to collect 100 genetic samples this year.
“For humans, it’s really easy to know how old we are because we have a birthday every year,” he said.
“But for sharks, in order to run a population model to find out how many there are, we need information about how long they live for — so what their lifespan is.”
“We’re collecting tissue samples every year, so that we test the same individual years apart and so we’ve got a baseline then that we know the animals are a year older each time we collect a sample.”
Securing future populations
Whale sharks are currently listed as an endangered species and are protected in Australia.
But Dr Pillans said they were not so lucky in other parts of the world.
“In Australia we’re lucky that they’re protected and there are very few threats, but whale sharks unfortunately do go to countries where they are killed by people for food,” he said.
“If we can understand how many there are we can start to know if the population is stable, if it’s going up or going down, and if it is going down then we can work with other countries around the world to address that.”
Whale sharks are the world’s largest fish and possibly the oldest. (ABC North West: Andrew Seabourne)
Hopes to apply method to more wildlife
The trial is part of the CSIRO’s Ningaloo Outlook program, which conducts monitoring and studies on the region’s environment and wildlife.
It is hoped that if this genetic ageing trial is successful the method could be applied to other species.
“We don’t know how old turtles are and so if we can prove that it works on sharks we can then apply it to other, mainly threatened and endangered, species,” Dr Pillans said.
“If we want to know how many turtles or how many whale sharks there are we need information on how old they are, so it’s a critical gap in our knowledge of these animals.”