Scientists keep tags on great whites

Four great white sharks have been satellite-tagged for the first time in New Zealand waters.

DoC marine ecologist Clinton Duffy took part in the project near the Chatham Islands to help solve mysteries that surround the life of one of the ocean's most fearsome predators.

The project was carried out with the help of scientists from the Wildlife Conservation Society and the National Institute of Water and Atmospheric Research.

Researchers hope to use the tags to gather information on the sharks' migration routes and habits.

"White sharks are difficult to study because of their naturally low abundance, large size and mobility," Mr Duffy said. "This technology provides us with a window into their lives for the first time."

Similar studies have shown the great white covers huge distances, travelling from California to Hawaii.

The tags will collect information about the depth, temperature and light levels of the water through which the animals travel. They detach on preset dates of between three and six months and float to the surface where they broadcast data to scientists via satellite.

Mr Duffy said the project was one of the experiences of his life.

"I've never seen them up that close and personal and it's something I won't forget in a hurry, they are really impressive animals."

Thanks to two local fishermen, Tim Gregory-Hunt and Kina Scollay - a paua diver who survived a great white attack east of the Chatham Islands in 1995 - finding the sharks over the two-day trip earlier this month was relatively easy. Every day the researchers saw between one and four great whites, ranging in size from 3.2m and 4m.

The only disappointment was the female great white that got away, refusing to be tempted near enough to the boat to be tagged. "She was as big as a bus," said Mr Duffy.

The scientists attracted the sharks with tuna bait tied to ropes, slowly reeling the bait near the boat so they could poke dart-shaped tags into the creatures' backs.

Conservationists have become concerned that the great white is in decline through game fishing and commercial harvesting.