Great white shark's oceanic adventure

A great white shark has stunned conservationists by going on a marathon journey, probably in search of a mate. Originally tagged off the coast of South Africa, the shark was tracked by GPS on a journey all the way across the Indian Ocean to Australia and back again.

The research team thinks journeys like this must be pretty common among great whites, since they are studying a relatively small group, just 20 or so animals, and it would be very unlikely to have chanced upon totally abnormal behaviour.

The shark, a female named "Nicole" after Nicole Kidman, seems likely to have been in search of romance. The research team, drawing on expertise at the University of Cape Town and the University of Pretoria and led by Ramon Bonfil of the Wildlife Conservation Society in New York, says the trip is too long a journey to make for food, and Nicole did not linger in Australian seas.

"There's plenty of food around South Africa and she would be using too much energy to just go to Australia to feed. Of course we can't prove this at this stage, it is just a hunch," Dr. Bonfil told the BBC.

Nicole was no slouch on her journey: she travelled from Gansbaai, not too far from Cape Town, to Australia in just 99 days. Within six months, she was back home in her native waters. The round trip is a whopping 12,400 miles, and Nicole's journey is the fastest known return migration of any swimming animal, the researchers say.

Nicole was tagged in November 2003 with a pop-up archival tag. These are attached to the dorsal fin, and at a predetermined time, will detach themselves and float up to the surface.

Deon Kotze of Marine and Coastal Management (MCM), told South Africa's Independent Online: "We were really surprised. We didn't expect one of the sharks to go to Australia, and we didn't expect it to come back again. It shows how little we know about them."

DNA evidence has previously suggested that there is some exchange genetic between white shark populations of South Africa and Australia, but no behavioural evidence has been observed to support this - until now.

"It’s clear that we have only uncovered the tip of the iceberg; there is still much to learn about great white shark migrations, why and how they find their way through such vast distances, and how populations are related," Dr Bonfil said.