Morgan Tait is the NZ Herald's police reporter.

Shark's record dive into the blue

Recently tagged male blue shark plunges 1250m off the Bay of Plenty coast in a quest for a meal of squid.

Bodhi, a blue shark, was tagged off the Coromandel Peninsula three weeks ago. Photo / Supplied
Bodhi, a blue shark, was tagged off the Coromandel Peninsula three weeks ago. Photo / Supplied

A shark broke a world record when he dived deeper than any recorded before off the coast of New Zealand this week.

Bodhi, a 2.5m male blue shark, dived 1250m deep off the Bay of Plenty coast on Tuesday, data from satellite tagging research by University of Auckland PhD student Riley Elliott has shown.

Mr Elliott tagged the shark three weeks ago off the Coromandel Peninsula as part of his study to track the habitat use and migration of blue sharks in New Zealand waters.

Bodhi is one of eight sharks monitored with tags that transmit their location to Mr Elliott's computer, but only one of two fitted with tags that also record depth and water temperature.

"This guy went from the Coromandel out into the Bay of Plenty area and went about 100km off the Bay of Plenty. There he's in 2000m of water at a big ... underwater volcano, and for some reason he realised that he wants to go down for a dive - so he went from the surface water down to the deepest recorded depth a blue shark has ever gone."

The previous record was held by a 1.8m female blue shark tagged in Portugal. She dived to 1160m.

Bodhi was probably chasing squid - 60 per cent of a blue shark's diet - when he made the dive, said Mr Elliott.

"It's unusual for sharks to dive so deep. They usually stay in the top layer of water because it isn't efficient for an animal to do that unless they're getting a reward, so that further supports the idea that it's foraging."

Mr Elliott's study was the first of its kind in NZ waters, and such finds so early on are encouraging.

"He did 90m more which isn't a great amount but the fact that he's only been tagged for about three weeks and is still in coastal waters and has recorded a depth deeper than ever recorded means he'll probably dive deeper throughout the one to three years the tag should keep giving me information."

Professor John Montgomery, Mr Elliott's supervisor and Leigh Marine Laboratory director, said the record was likely to be one of many to come from the work.

"I suspect this is the first of a number of very interesting findings that will come out of this study," he said. "There's a whole new wave of technology coming out with respect to those tags which provide really new insights into what those animals are doing and where they are."

Mr Elliott hoped his research would increase knowledge about sharks and their behaviour and aid shark conservation projects.

Record-setting shark

• 2.5m male blue shark named Bodhi.
• Satellite tagged off Castle Rock, Coromandel, three weeks ago.
• Dived 1250m deep off Bay of Plenty coast on Tuesday.
• Previous record was 1160m dived by a 1.8m female shark tagged in Portugal.

- NZ Herald

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