For the first time, scientists have documented unique individual personalities in Port Jackson sharks, a nocturnal, egg-laying species of bullhead shark found along the coast of southern Australia.

Biologists from the Macquarie University observed measurable and consistent differences in the way individual Port Jackson sharks responded to various stressors and foreign environs.

They detailed these individual personality differences in the Journal of Fish Biology.

"Over the past few decades, personality research has shown that nearly 200 species of animals demonstrate individual personality," lead study author Evan Byrnes said in a news release. "Personality is no longer considered a strictly human characteristic, rather it is a characteristic deeply engrained in our evolutionary past."

Researchers introduced individual sharks to new habitat, measuring how quickly individual sharks emerged from the dens and into foreign territory. They also subjected each shark to handling stress and measured how quickly they recovered once released back into the water.

The sharks that best managed the stress of relocation also recovered the quickest from handling stress.

"We are excited about these results because they demonstrate that sharks are not just mindless machines," said Culum Brown, associate professor of biology at Macquarie. "Just like humans, each shark is an individual with its unique preferences and behaviors."

Researchers say their findings may have implications for wildlife managers and conservationists.

"If each shark is an individual and doing its own thing, then clearly managing shark populations is much more complicated than we previously thought," Brown said.