WA shark find prompts species rethink

A male mandarin dogfish (Cirrhigaleus barbifer) shark caught off Rottnest Island. Picture: Support Our Sharks

The discovery of a species of shark never seen before in Australian waters could rewrite science, researchers say.

Shark biologist Ryan Kempster, of the University of Western Australia's Oceans Institute, said two sharks were identified as mandarin dogfish after a two-year investigation including DNA sequencing.

The rare sharks, a male just under a metre long and a pregnant female about 1.2 metres long, were caught off Rottnest Island at a depth of 430m by local recreational fisherman Steve Downs.

Mr Kempster said the species had only previously been found in waters between Indonesia and Japan, and also off New Zealand.

It's not known why the sharks were found so far from their normal habitat but the find has scientists re-evaluating their understanding of the species, including its reproduction.

"The female shark found off Rottnest had 22 unborn pups and is only the second ever-recorded specimen of a pregnant female of this species," Mr Kempster said.