At Norfolk Island Airport the signs say “welcome to paradise”.
asserted
signs → say → paradise
The super-sized tiger sharks that live here must surely agree.
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that → live → ?
In the pristine waters around this South Pacific outcrop, 1400 kilometres from the Australian mainland, the tiger sharks grow fat on juicy mutton birds and beef offal.
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sharks → grow → birds
They roam freely across thousands of kilometres from New Zealand to New Caledonia, with the occasional jaunt to the Great Barrier Reef.
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They → roam → Reef
And left unmolested by humans, they grow to a ripe old age.
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they → leave → age
And that’s even before a proposal by the federal government to expand the area of marine sanctuary around Norfolk and Lord Howe islands.
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that → ’ → islands
The median length of a Norfolk tiger was 4 metres, in a Flinders University study of 35 tagged sharks.
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length → tag → sharks
Professor Charlie Huveneers at Flinders University, an ecologist specialising in shark research, says the Norfolk Island tiger sharks are extremely large.
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sharks → specialise → research
Since his paper in Marine Environmental Research last year, scientists have also studied large tiger sharks in the Maldives, but Huveneers says the Norfolk population is remarkable for having so many in a small area, without the influence of wildlife tour operators using food-based attractants.
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population → study → attractants
“The primary reasons for these tiger sharks being so large is likely because they are old individuals which had the opportunity to grow to these large sizes,” Huveneers says.
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Huveneers → have → sizes
“These sharks would have also needed the right nutrition to grow and their time around Norfolk Island likely facilitated the consumption of nutritious prey.
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time → need → prey
The reason many Norfolk Island locals point to is the offal chute at Headstone Bay.
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locals → point → Bay
There are free-range cattle all over the island, but nowhere to dispose of the carcasses without poisoning the groundwater, given the island is just eight square kilometres.
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island → be → groundwater
The skin and offcuts often get dumped down a chute into the ocean and the tiger sharks devour the beef from underneath.
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sharks → dump → beef
Tien Dat Do, 28, a nurse who moved from Vietnam to Norfolk Island about nine months ago, goes rock fishing four or five times a week.
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who → move → fishing
Headstone is his favourite fishing spot on the island, and he sees the chute used at least weekly.
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chute → see → island
Do has seen the remains of up to four cows dumped into the water, and the tiger sharks demolish it all within half an hour to an hour.
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sharks → see → hour
“They smash from the bottom and when they finish the bottom, they keep going until there’s nothing left,” Do says.
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Do → smash → bottom
Huveneers and the team used biochemical tracers from the muscle of tiger sharks to find out what they ate.
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they → use → what
Only about 5 per cent of their diet was identified as organic waste from livestock.
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cent → identify → livestock
Seabirds, including wedge-tailed shearwaters known colloquially as mutton birds, made up 70 per cent of their diet.
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Seabirds → include → diet
Twenty per cent consisted of turtles, sea snakes and fish.
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cent → consist → turtles
The tiger sharks like to hang out in Headstone Bay regardless of the organic waste disposal, acoustic underwater monitoring found.
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monitoring → like → disposal
Huveneers says this could be because it is where the largest shearwater colonies are found on Norfolk Island, with the offal being incidental.
uncertain
offal → say → Island
The researchers also found that dusky and Galapagos whaler sharks visited Norfolk Island’s fishing piers at various times of day, especially in the afternoons when fishers clean their catch along the piers and throw the scraps into the water.
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fishers → find → water
The tiger sharks are around Norfolk mostly between October and April, satellite tracking found, while dusky and Galapagos whalers remain there year round.
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whalers → find → October
Tracking found that nearly nine out of 10 tiger sharks across multiple seasons returned to Norfolk Island at least once.
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sharks → find → Island
One intrepid individual tiger shark swam between New Caledonia, the Great Barrier Reef, Norfolk Island, the Chesterfield Islands, and New Zealand, at least 17,000 km in 468 days.
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shark → swim → days
Luke Fitzpatrick, 30, takes tourists out fishing in his charter boat, but uses a more resilient aluminium boat to do the shark tagging with Huveneers and the scientists.
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Fitzpatrick → take → Huveneers
“We catch them and they get them up to the side of the boat and then they put a couple of ropes and hoses around them so it doesn’t hurt them and then they put the tags in their fins,” Fitzpatrick says.
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Fitzpatrick → catch → fins
“They’ve got a tape measure that goes from its head to its fins, one person each end.
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that → get → fins
They’re pretty cool creatures, the big ones.
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They → ’re → ?
It does not surprise Fitzpatrick or anyone else on Norfolk Island that their sharks are bigger than anywhere else in the world.
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sharks → surprise → world
It seems everyone who grew up there has their “you’re gonna need a bigger boat”, or Jaws, moment.
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you → seem → moment
“We were just drifting, and a great white hit the boat like a seal,” Greenwood says.
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Greenwood → drift → seal
“It hit the back of the boat, nearly tipped us out.
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It → hit → us
It still had enough momentum after glancing off the boat that it was airborne beside the boat.
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it → have → boat
We thought it’s going to be hurt and take off.
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it → think → ?
“No, it landed, turned around on a dime, came back and hit the boat again.
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it → land → boat
At this point, we were terrified and just got out of there.”
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we → terrify → point
…and 9 more, not listed.
The Aporia
