A female speartooth shark gets its satellite tag

They are one of the most elusive sharks ever. Lurking in murky tropical rivers, no live adults had ever been seen before.

Now the first adult speartooth sharks (Glyphis glyphis) have been tagged and released. The tags will beamed back data to satellites in two months, revealing the first details about the endangered species.


The International Union for Conservation of Nature estimates there are 2500 individuals at most – confined to tropical river systems in Australia and Papua New Guinea. Little is known about where they go and what threats they might face.

So catching two adults was a thrill for Richard Pillans from the CSIRO, Australia’s national research organisation in Brisbane, and his colleagues.

Newborn sharks

They looked for adults at the mouth of the Wenlock river, where newborn specimens had been seen in the past. They got lucky, catching both a female and a male.

“It was a bit of a surprise to catch a male,” Pillans says. That could mean that not only are the sharks giving birth to their pups there, but they might be mating there too, he says.

Catching a male (above) also meant they could confirm the size of a fully grown shark because it had calcified genital claspers, penis-like organs, a sign of maturity. “Before that we had no idea how big they got,” Pallins says.

And at 2.3 metres long, it was the biggest specimen ever seen. The female was clearly no baby either – measuring 2.2 metres.

Until 2014, no adult speartooth sharks had ever been seen – dead or alive. But last year, scientists got hold of photographs from fishermen in Papua New Guinea, who had caught some adults, and kept some parts of the animals.

GPS tags

Each of Pallins’s catches has two satellite tags attached to their dorsal fins. One will be released in 60 days and the other in 120 days. When they do, they’ll float to the surface and beam back information to satellites about the temperature, salinity and depth of the water the sharks frequent. And GPS will record their exact location if the sharks surface.

Pallins also took a DNA sample from each shark. He says they should be able to compare that with several years of work sampling DNA from juveniles, and may help them figure out how frequently the sharks breed.

Although the juveniles only live in rivers, it’s thought the adults probably spend most of their time in marine environments, coming back to rivers just to give birth and possibly to mate. Since nobody knows where they go, conservation efforts are difficult to target.

But protecting the juveniles is at least as important, says Pallins. “During those life history stages, their total range in the dry season is something like 30 kilometres of the river,” he says. “So if there’s any threatening process that occurs in that part of the river, there’s a high change the whole population could be subject to that mortality.”

Fishing pressure

That could be anything from damming the river further up, to net-fishing, or even climate change, he says.

Speartooth sharks haven’t been seen since the mid-1980s in the Bizant river where they were first recorded, he says. “The reasons for that are most likely due to the high fishing pressure that occurred in the late 1980s. But also possibly the climatic variability – the extended drought,” he says.

The news comes just as Australia releases a recovery plan for sawfish and river sharks – including the speartooth shark.

“The information that will be gathered from the tagged sharks, including analysis of genetic samples that were collected, will provide critical information that will help to inform future recovery efforts,” says Gregory Andrews, threatened species commissioner for Australia’s department of environment.

Read more: “Chainsaw sharks: The plight of the world’s weirdest fish”

(Images: Richard Pillans)