Scientists found 57 animals along a 200km stretch of ocean between Queensland and New South Wales.
They warn the find – a cross between the common blacktip shark (pictured) and the Australian blacktip – could mean the animals are adapting to climate change.
Researchers in marine biology say the interbreeding is a sign the predators are adapting to warmer waters, and the discovery could have implications for the entire shark world.
Dr Jess Morgan, from the University of Queensland, told AFP: “It’s very surprising because no one’s ever seen shark hybrids before, this is not a common occurrence by any stretch of the imagination.
“This is evolution in action.”
Scientists have also warned the interbreeding could make sharks stronger – and the hybrid may eventually replace the two pure breeds.
The Australian black-tip is slightly smaller than its common cousin and can only live in tropical waters, but its hybrid offspring have been found 2,000 kilometres down the coast, in cooler seas.
“It’s enabled a species restricted to the tropics to move into temperate waters,” Morgan said.
Colin Simpfendorfer, a partner in Morgan’s research from James Cook University, said the study could could challenge traditional ideas of how sharks had and were continuing to evolve.
“And in fact, this may be happening in more species than these two,” he added.