A mako shark's excellent adventure

CLIO FRANCIS
Last updated 12:53 07/01/2013

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The last few months have been busy for Carol the mako shark.

After spending spring in Fiji, October near the Coromandel Peninsula and November off the East Coast she opted to celebrate Christmas Day in the Cook Strait.

At the moment she's making quick time towards Kaikoura.

So much is known of Carol's holiday plans because she is being tracked by The New Zealand National Institute of Water and Atmospheric Research (Niwa) which is conducting research on mako sharks, funded by the Ministry for Primary Industries.

To date, Carol - who was named after a researcher's mother - has travelled more than 13,300 kilometres in seven months, averaging 60km a day and exceeding 100km a day during some parts of her migration.

Scientists have been tracking Carol, a 1.8-metre mako, using a satellite reporting tagging device known as a SPOT tag.

This was attached to Carol in the Bay of Islands six months ago and is providing scientists with remarkable and previously unknown details of the timing and long-distance migratory movements of this species.

Niwa principal scientist Dr Malcolm Francis said Carol was about four or five years old.

"Its absolutely amazing for us," he said.

"It's the first mako shark we've tagged with fancy technology like this. This tag has just given us some incredible data."

The SPOT tag is revealing that Carol is spending a lot of time at the ocean's surface, reporting her location to the satellite several times daily.

"Conventional plastic identification tags tell us little about the timing of mako shark movements, the route that they take or distance travelled," Francis said.

One of the most intriguing discoveries from the data was that Carol had opted to cut short her trip to Fiji, spending only a couple of weeks there before returning to New Zealand.

"The fact that she went to Fiji and came back straight away is interesting," he said.

"We thought she'd go up there and spend winter there. We had a feeling they'd be much more seasonal migrators."

Tagging mako sharks will help identify the geographical range of New Zealand sharks, and how they mix with makos from other parts of the Pacific Ocean.

This information is important for determining mako stock structure, which is fundamental for assessing stock status. Tagging will also help determine how long makos remain in New Zealand waters.

This tagging study is being carried out in collaboration with Dr Mahmood Shivji at the Guy Harvey Research Institute at Nova Southeastern University in Florida, which is funding the electronic tags and Argos satellite time.

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The mako shark is the fastest of the world's shark species and found in waters all around New Zealand. They can weigh up to half a tonne and their diet usually consists of schooling fish and squid.

Mako sharks, targeted for their highly-prized fins and their good-quality flesh, are listed as "vulnerable" on the International Union for Conservation of Nature list of threatened species.

You can check out Carol's track here

- © Fairfax NZ News

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