Scientists in Australia have caught and tagged two critically endangered spear tooth sharks – the first adults of the species ever seen.
The shark was discovered in the Bizant River on the eastern side of Cape York in Queensland in the far north of Australia in 1982 and juvenile have been sighted.
Australia’s peak government science agency, the CSIRO, said in a news release that ne of the sharks was a female approximately 2.2 metres in length, the other individual was a mature male of 2.3 metres in length. The previous largest recorded speartooth shark was only 189cm long.
Very little was known about the Speartooth Shark until research led by CSIRO in 2004 began to obtain a better understanding of the distribution of juveniles in a few river systems in tropical Australia.
“We’ve been conducting research into the movement and population status of juvenile Speartooth Sharks in the Wenlock River since 2006, and due to our long-term research we now know that juveniles are restricted to a few river systems in the Northern Territory and Queensland,” CSIRO researcher Dr Richard Pillans said.
“But the lack of records of adults is a key gap in our understanding of this species, which is listed as Critically Endangered by the Environment Protection and Biodiversity Conservation (EPBC) Act.”
The CSIRO gives the following summary of the sharks habits and characteristics.
The Speartooth Shark is a species of whaler shark and is often confused with bull sharks given their similar colouration and preference for riverine habitats.
The Speartooth Shark is characterised by its dark grey dorsal colouration, a large second dorsal fin and narrow spear-like teeth in the lower jaw which is where it gets its name from.
The Speartooth Shark gives birth to live young with the juveniles thought to be born at the mouths of a few rivers systems in northern Australia.
Once born, the young are completely self-reliant and move upstream where they spend the next three to six years about 40km to 80km from the river mouth in water of reduced salinity.
During the annual monsoon, juveniles move downstream to avoid the influx of freshwater but move back upstream once freshwater flows ease and salinity returns to their preferred range.
Bill Condie is a science journalist based in Adelaide, Australia.
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