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Study finds curious case of great white sharks passing by favourite human holiday destination

Linda Silmalis, March 16, 2020 7:45AM The Sunday Telegraph

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A great white shark swimming just below the surface. Picture: iStock media_cameraA great white shark swimming just below the surface. Picture: iStock

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Human holiday-makers love the beautiful seaside town of Port Macquarie but great white sharks refuse to stay there.

This discovery by scientists could hold the key to deterring* sharks from popular Australian beaches in the future.

Researchers taking part in the New South Wales government’s five-year shark management study have discovered that great whites do not spend any time around the NSW mid-north coast town.

A special buoy* that detects sharks detected a record number of great whites swimming past, but not one stopped and spent time in the area.

The VR4G shark buoy is 500m offshore from the Port Macquarie Life Saving Club and is one of 21 buoys recording tagged shark movements along the NSW coast from Tweed Heads down to Merimbula.

media_cameraA shark monitoring buoy sitting off Lennox Head, one of 21 used in the study. It detects for sharks coming within 500m. Picture: Luke Marsden

NSW Department of Primary Industries shark biologist Dr Paul Butcher said while the buoy recorded the greatest number of sharks swimming past, the data showed none stopped by.

This compared with data from other buoys that found some sharks spent as long as a week or more in one area.

Dr Butcher said the large number of sharks swimming past the buoy suggested it could be part of a great white “corridor”.

As for why the sharks did not stay, environmental conditions such as sunlight, water temperature and currents could be to blame.

“Port Macquarie is the area which all animals appear to pass by, but don’t spend any time there,” he said.

“We don’t know why they don’t stop there.

“We have just finished collecting data and will have more information in a few weeks’ time.”

media_cameraA great white in the process of being tagged for the study.

MORE TO KNOW
The five-year shark study in NSW has tagged and tracked 469 sharks, with 450 of those still being tracked.

The researchers now understand great whites follow a coastal migration pattern, moving towards cooler waters from Queensland to Tasmania.

“We have found they move at predicted times. March to June, they begin moving north from

Tasmania and Victoria where they have spent summer. As the water cools down along our east coast, as the East Australian Current slows down, they start to move back up the coast,” Dr Butcher said.

“Then they start moving south between September and December and January.”

Some individuals broke from the pack to embark on epic solo journeys.

Longer-term tracking will help determine why these sharks are swimming off course and may also help unlock one of the bigger mysteries about the animals — where they give birth.

“Nobody knows where the east Australasian population breed. That’s one of the questions.

“A lot of our bigger animals head over to New Zealand. Over the next couple of years, we hope to see where they go. It would be a guess they breed in New Zealand but we just don’t know.”

media_cameraThe sharks in the study are caught and swim beside a boat briefly while the tracking tag can be attached, before being released.

EPIC SHARK JOURNEYS
A shark tracked in the study, named Shark 28, has been going off on his own solo epic swims around Australia, reminiscent* of how Tom Hanks’ character Forrest Gump went running across America by himself in the movie of the same name.

Since the 3m male was caught and released off South Ballina Beach, NSW in July 2016, he has covered ­almost 40,000km swimming between Queensland and WA via the Great Australian Bight.

During one 307-day swim from Queensland to WA, the shark spent 211 days hanging around The Bight.

Another solo traveller Shark 41 ventured* farther abroad.

After being tagged in Ballina in August 2016, the great white was detected in Bass Strait, Bondi, both the South Island and North Island of New Zealand, Papua New Guinea and down in sub-Antarctic waters.

Another great white known as Shark 179 also went abroad, swimming up to New ­Caledonia via New Zealand before researchers lost track of it.

The shark reappeared seven months later in sub-Antarctic waters northwest of Chatham Island.

Dr Butcher said it was not yet known why some sharks break away from their mates to embark on these epic solo journeys.

GLOSSARY

  • deterring: putting someone off something
  • buoy: floating marker
  • reminiscent: reminding us of
  • ventured: went out on a risky or daring journey

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QUICK QUIZ

  1. What are the two main things scientists know about sharks from the Port Macquarie buoy?
  2. How many sharks have been tagged? How many are still being tracked?
  3. Where do the sharks breed?
  4. Why is Tom Hanks mentioned in the story?
  5. Where did Shark 179 go?

LISTEN TO THIS STORY

CLASSROOM ACTIVITIES
1. Create an advertisement
It seems that plenty of sharks swim past Port Macquarie but they don’t stop in. While human swimmers will find this comforting to know, if sharks could read advertisements, could you convince some sharks to stop in for a visit? Design a billboard that you might place along the great white ‘corridor’ to encourage sharks to stop by. A billboard is a large advertising poster that is placed along major roads. Do some research about Port Macquarie to find things that sharks might find enticing (are there lots of juicy swimmers for them to eat?). You can make your billboard comical. Think about how you design your billboard so that it stands out to sharks swimming by. Make sure you include; a catchy heading, how to get there and why they should stop. Think about how billboards attract your attention when you’ve been on long trips.

Time: allow 30 minutes to complete this activity
Curriculum Links: English, The Arts – Visual Arts, Critical and Creative thinking

2. Extension
Where in the world are the sharks?

With the sharks being ‘tagged’, shark journeys are able to be followed and recorded by scientists. Use a map of the southern hemisphere that includes Australia and the countries around us. Use the information in the article to plot the journeys of some of the sharks indicating where they like to ‘hang out’ and where their ‘no-go zones’ are.

Time: allow 30 minutes to complete this activity
Curriculum Links: English, Humanities and Social Sciences – Geography, Science

VCOP ACTIVITY
Proper Noun Police
A proper noun is a noun that names a particular person, place or thing. It always has a capital letter.

How many proper nouns can you find within this article? Find them all and sort them into the category of name, place, time (date/month).

Can you find any proper nouns included in your writing?

What are they?

Can you sort them into their categories?

HAVE YOUR SAY: Why do you think sharks don’t stop at Port Macquarie?
No one-word answers. Use full sentences to explain your thinking. No comments will be published until approved by editors.

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