On the hunt for the great white shark

22nd November 2008

Jamie Morton

A Wairarapa-born great white shark expert is at the forefront of a project that has just produced groundbreaking findings on the famous species.

Masterton-raised Clinton Duffy, today an Auckland-based marine scientist with the Department of Conservation's Aquatic and Threats Unit, said the recovery of a transponder discarded by a great white in Tonga revealed fresh information on the sharks' migratory patterns.

"The significance of the Tongan movements is that this is the first time that white sharks have ever been recorded from Tongan waters, and it confirms winter migration of Chatham Islands white sharks to the islands of the southwest Pacific is a regular and predictable behaviour."

The electric transponder, recovered from the Ha'ateiho Reef, was attached to a great white in the Chatham Islands and later popped-off near the island nation around 3000km away.

Mr Duffy, a former member of the Wairarapa Underwater Club who has been studying great whites since 1991, said he was "stoked" at the finding, which has been one of the main highlights in the DOC, NIWA and Shark-Tracker collaboration.

Scientists from these organisations have been attaching satellite tags to great whites to measure position, depth and water temperature.

The data contained in the recovered transponder will be analysed by marine scientists to trace the shark's diving behaviour and temperature preferences, and a record of light levels to roughly estimate the path it travelled.

The information may provide clues to why the sharks are travelling to Tonga, when local fisheries archives show no record of the species there.

Six great white sharks were tagged in the Chathams in April and, so far, three tags have surfaced in Tonga, but this is the only one to be recovered.

The tags appeared to have detached prematurely, and researchers hope two tags thought to still be attached will stay on until January to see if those sharks return to New Zealand waters.

The notion of great whites migrating to the tropics for summer flies in the face of the common conception that the species live only in cold coastal areas.

Mr Duffy said it was unlikely that this was just a recent pattern triggered by climate change, and had probably been occurring for millions of years.

He said another fascinating finding was the breaking of the great whites' world diving record, set by a shark travelling across the Tasman Sea en route to Australia's Great Barrier Reef.

The shark had been tagged off Stewart Island and this winter dived to an incredible depth of 1000 metres.

Mr Duffy's "fixation" with sharks began when he was just four years old.

"I was fishing with my dad at Glenburn, when a shark swam past the boat. I still remember seeing the dorsal fin and tail it's one of my most vivid memories."

His interest persisted through his days at Lansdowne Primary School "my teacher Mrs Wong bought me my first book on sharks that's how obsessed I was" and Rathkeale College.

He joined the Department of Conservation after studying at Victoria and Canterbury universities.

"As long as I can remember, I've always been fixated with them."