Great White Shark Tagged Off New Zealand Sets Record For Deepest Ever Known Dive

March 31, 2010

Shark
The world of technology and advanced electronics continues to help shed light in all of the marine sciences.

A recent press release issued by the New Zealand-based National Institute of Water and Atmospheric Research (NIWA) reports that a New Zealand great white shark that they had tagged has set a world record for the deepest ever known dive of 1200 meters (3,937 feet).

“A big shark called ‘Shack’, the biggest shark we have tagged, at 4.8 metres (15.75-ft), has set the world’s deepest great white shark dive record,” says NIWA Principal Scientist, Malcolm Francis. “And he made several other very deep dive records between 1000 and 1200 metres while crossing the ocean. Prior to this, we had recorded several at around 1000 metres, so it’s quite a substantial extension.”

Migratory Sharks

New Zealand scientists tagged Shack and 24 other great white sharks with electronic “pop-up” tags at Stewart and Chatham Islands, over a five year period. The high-tech tag records location, depth and temperature, and releases itself after a pre-determined time, usually 6–9 months, to transmit its data via satellite.

Of the 25 tagged sharks, four tags came off within the first two weeks. Movement tracks could be determined for nineteen sharks, and only one of those stayed near the tagging site the whole time; ‘Kara’, a big female shark, stayed near Stewart Island to Fiordland. The other 18 headed towards warmer tropical waters.

“Before we started this work, five years ago, it was thought that great white sharks were cold water animals. But it seems the great white sharks are taking tropical winter holidays, departing New Zealand between April and September, for somewhere warmer. The maximum distance migrated was 3300 km,” says Francis. One shark returned to its Chatham Islands tagging site after spending 6 months at Norfolk Island.

“Our sharks don’t cross the equator; so far our tagged animals have only gone as far north as 17 degrees south, north of New Caledonia,” says Francis.

They take long migratory trips making deep dives as they go. They can travel 150 km a day and it takes them just three weeks to get to Australia.

Great white sharks experience a huge range of water temperatures between 3 and 27 degrees Celsius.

Pop-up Tags

Tagging a shark is not an easy process.

“We have to attract them to the boat, with a berley of tuna oil and minced tuna. Then we use a long pole that has a needle tip on it. The tag has a monofilament nylon leader with a barbed plastic anchor on it. The anchor slides over the needle tip, which is injected under the skin of the shark with the pole,” says Department of Conservation (DOC) scientist Clinton Duffy.

“When the shark is close enough and at (hopefully) the right angle, we use the pole to stab the anchor into the muscle below the dorsal fin as it swims by,” says Duffy. “Lots of patience is needed because usually the shark is moving around, its back is exposed only for a short amount of time and the dorsal fin is out of reach.”

After nearly a year, the tag releases itself from the tether, floats to the ocean surface and starts sending the data via satellite, to France. “If the tag itself is recovered after washing ashore, we are able to extract much more high resolution data from it. So far, we have recovered 6 of our tags from the Pacific Ocean. These “pop-up” tags cost $5000 each, and they have a return to sender message on them.

“The tag leaders have a small guillotine on them, which can cut through the monofilament nylon, and release the tag if it goes too deep,” Says Duffy.

For more information about this great white shark program, read the entire article on the National Institute of Water and Atmospheric Research (NIWA) website.