By Marina Trajkovich, ABC<\/p>\n
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\nGrey nurse shark populations along Australia’s east coast have steadily increased.
\nPhoto: ABC \/ David Harasti\n<\/p>\n
Grey nurse shark numbers along Australia’s east coast are on the rise, in “rare good conservation news” for the critically endangered species often dubbed “the labradors of the sea”.<\/p>\n
David Harasti from the New South Wales Department of Primary Industries said the often misunderstood species was crucial for the ocean’s ecosystem and harmless to humans.<\/p>\n
“It’s one of the more placid sharks, they come and look at you really inquisitively, they follow you around,” he said.<\/p>\n
“They’re a very ferocious-looking shark with big pointy teeth, but they’re not known to bite people.”<\/p>\n
Growing to more than three metres in length, grey nurses became the first shark species in the world to be protected in 1984.<\/p>\n
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Photo: ABC \/ David Harasti\n<\/p>\n
Harasti said that while there was no accurate population estimate for the time, divers and researchers raised the alarm after noting their decline.<\/p>\n
“Divers went actively searching for grey nurse sharks, and where they used to find dozens, they could only find a handful,” he said.<\/p>\n
New research from the NSW Department of Primary Industries (DPI) and the CSIRO shows the population is slowly bouncing back.<\/p>\n
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Photo: ABC \/ David Harasti\n<\/p>\n
“The adult population is now estimated to be around 1,500 along the east coast and rising,” Harasti said.<\/p>\n
“It’s increasing around five percent a year, so this is a really good thing.<\/p>\n
“This is one of our first good news marine stories for a threatened species.”<\/p>\n
Harasti said the study used genetic modelling to estimate population size, including techniques involving “sneaking up on the sharks” to collect samples at crucial dive and aggregation sites.<\/p>\n
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Photo: ABC \/ David Harasti\n<\/p>\n
“Quite often, underwater, you’re contorting your body to get these samples,” he said.<\/p>\n
“The results back up what divers have been noticing in the wild.”<\/p>\n
Accurate population picture<\/p>\n
CSIRO principal research scientist Toby Patterson said getting an accurate sense of endangered populations was crucial for conservation work.<\/p>\n
“The popular view is that it’s easy to see how numbers are going – the reality is it’s quite hard to get that fundamental data,” he said.<\/p>\n
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Photo: ABC \/ David Harasti\n<\/p>\n
Patterson said the CSIRO was also looking to use catch-and-release tagging methods like smart drum lines on more animals and species.<\/p>\n
“We’ve used it on white sharks, sawfish in the north, river sharks and also terrestrial animals in Australia,” he said.<\/p>\n
“That then supports better decision making, better management responses, and to work out where funding and resources are most needed.”<\/p>\n
Threat remains<\/p>\n
University of the Sunshine Coast researcher Ross Dwyer said while the results of the study were exciting, there was still work to be done.<\/p>\n
“These results are really promising, it shows the population does seem to be increasing, but the numbers are still very low,” he said.<\/p>\n
“The genetic testing is exciting, but it’s still in its infancy and needs to be corroborated.”<\/p>\n
Dwyer said grey nurse sharks were slow to reproduce and remained vulnerable to both recreational and commercial fishing.<\/p>\n
He said more research into aggregation sites would inform new green zones, and called for divers to submit sightings and photographs to research projects like Spot a Shark.<\/p>\n
“Particularly those spot patterns on their sides \u2026 that allows us to get a better understanding of shark interactions with fishing gear and how sharks are faring in terms of population numbers,” he said.<\/p>\n