The two adult specimens caught by CSIRO researchers at the mouth of the Wenlock River in Queensland, Australia were a male that measured 2.3 meters in length and a female that was 2.2 meters.
Until now, no one even knew how big a fully mature speartooth shark could get.
Each of the sharks was fitted with satellite tags that will collect data on the sharks’ movements, as well as the depth, salinity and temperature of the waters the sharks frequent.
Scientists with the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia’s national science agency, have caught and tagged two adult speartooth sharks (Glyphis glyphis) in a remote corner of Australia — the first time live adults of the species have ever been observed by scientists, let alone studied.
The elusive shark species, which is listed as endangered by the International Union for Conservation of Nature (IUCN), was first discovered in Australia in the Bizant River, on Cape York’s eastern side, in 1982. Only juvenile specimens have been previously observed. Until now, no one even knew how big a fully mature speartooth shark could get.
CSIRO has been researching juvenile speartooth sharks in the Wenlock River since 2006 and discovered that they are restricted to a few river systems in the Australia’s Northern Territory and Queensland states.
The two adult specimens caught by the CSIRO researchers at the mouth of the Wenlock River in Queensland were a male that measured 2.3 meters (7.5 feet) in length and a female that was 2.2 meters (7.2 feet). Each of the sharks was fitted with two satellite tags that will detach (one after 60 days, the other after 120 days), float to the surface and upload the data they’ve collected on the sharks’ movements, as well as the depth, salinity and temperature of the waters the sharks frequent.
While juvenile speartooth sharks spend the first three to six years of their life in the low-salinity river waters 40 to 80 kilometers (about 25 to 50 miles) upstream from the sea, scientists had thought that adult speartooth sharks spend most of their time in marine environments, only returning to rivers to give birth.
But the truth is that “We currently have no idea where the adults occur, all we know is that they are found in marine environments somewhere off the northern Australian coast,” CSIRO researcher Dr. Richard Pillans, who tagged the sharks together with colleagues from CSIRO and the Australia Zoo, said in a statement.
This general lack of knowledge makes conservation efforts difficult. The IUCN estimates that there are, at most, just 2500 speartooth sharks left in the world. They’ve been found in tropical river systems in Australia and Papua New Guinea, but very little else is known about where they live out their lives as adults and, therefore, what threats they are facing.
The presence of a male at the mouth of the river could possibly indicate that speartooth sharks also mate in riverine environments, for instance — a vital piece of information for conservationists to have.
“It is hoped that the information obtained from these tags will provide the first data on where adult speartooth sharks live,” Pillans added, “with this data critical to obtaining a better understanding of threats to this endangered species.”