Friday, February 02, 2007

Scientists looking for "Jaws"

Two New Zealand scientists are luring great white sharks from the ocean in a bid to protect the feared, but endangered species. MICHELLE SUTTON followed them on their hunt for Jaws
Clinton Duffy and Demian Chapman wait patiently for a deadly predator to appear under the water, lured by the scent of a bloody feast.

The blue-green ocean in the Papakura Channel, off Auckland, is tarnished with chunks of dead fish and a burley bag dangles from their boat. The meaty stench will drift for kilometres on the outgoing tide.

The men scan the water, squinting because of the sun that also makes waves look like dorsal fins in the distance. Silently they hope for the return of the 3.3m great white shark that turned up in 15m-deep water the day before – in a spot that is popular among fisherman. Where great whites frequently lurk, too.

On that day the monstrous fish, more than half the length of their 6m boat, appeared at Te Pirau Pt without Duffy realising it until the shark reared its bullet-point snout out of the water, only metres away.

"From the boat it looked like a giant brown submarine moving under water," says Duffy, of the 500kg great white that swam by and nudged the orange buoy with its head. The shark then picked up the burley bag and steel anchor that was tied to the two-tonne boat and swam away.

When Duffy pulled the rope towards the boat, the shark hung on and swam to the surface – its brawn giving way to curiosity; its big purple eyes watching his every movement, until it ripped the bottom of the burley bag and disappeared with the bait before it could be tagged with a pop-off satellite device.

The tiny satellite is at the crux of research being carried out by Duffy and Chapman, which is the first study of great whites in New Zealand.

The tag will track the shark's movements by measuring water depth, temperature and light levels. After six months it releases from the shark and transmits the data to an e-mail address.

First, though, the scientists must man-handle a great white; with its 300 razor teeth, pure hard muscle and the ability to kill with one inquisitive bite.

A second attempt to find a great white at Te Pirau Pt is foiled when three divers arrive. They wade into the water despite being told a great white was in the area the day before, so the search is moved to Papakura Channel.

Duffy and Chapman's methods are no different from fishermen's, they say. They even buy their bait from the same shop.

"The sharks are already there," says Duffy, "and we are merely trying to lure them to the boat."
If a shark appears it will be coaxed to the side of the boat with bait so they can get close enough to insert the tag into the back of its dorsal fin.

Failing that, they will try to harness it to the boat and take a DNA sample at the same time. They have done this before. In fact Auckland-based Duffy (42) has been chasing great whites since 1991 when he started the only data base of sightings and attacks in New Zealand.

He is also involved in a three-year project tagging great whites in the Chatham Islands.

"I started it for my own interests because I was a spear fisher and part of it was because we were always hearing stuff about them that was obviously rubbish.

"When I grew up in Wairarapa people were always saying you don't get sharks in New Zealand, but when I got out to the beach people were catching school sharks off the beach."

He advertised for sightings of great whites in the early 1990s when it was commonly thought that the species was an uncommon straggler to New Zealand waters from Australia – in recent years New Zealand has been recognised as a hot-spot for great whites. The newspaper ad was spotted by Chapman, a New Plymouth 20-year-old who later became a marine biologist like Duffy, and the pair started their shark hunting mission.

"Back in the 90s the thought was that they (great whites) were these great big clumsy sharks and they couldn't catch a seal unless it was dead," says Miami-based Chapman.

"But it has completely flipped, there's been a lot of research globally in the past 10 to 15 years."
Chapman (32) is a DNA expert – he works at the Pew Institute and discovered a shark identification test to help authorities stop the illegal fin trade – but it is Duffy who is in charge on the day we turn up.

"If I yell, don't be offended, but if something's going to happen it will happen fast," he warned, before the search started from Onehunga Wharf last weekend. Few people would argue with a man who scooped up a 1.7m blue shark from the sea off Port Taranaki last year and held it in the boat so Chapman could take a DNA sample for his research.

But even the modest expert maintains a healthy respect. Duffy would never knowingly swim with a great white, unless in a cage, nor will he watch the 1970s horror movie Jaws.

"I have swam with two seriously big bull sharks and they are just pussy cats compared to great whites. There's no other shark that compares with them."

They are relentless predators, he says, and will follow their prey after inflicting an incapacitating bite until it dies. They are curious too and will occasionally inspect novel objects such as a diver or a swimmer, but fatal attacks on humans are rare.

The only fatal attack in Taranaki, at Oakura beach, had all the characteristics of a great white despite wide-spread reports that a bronze whaler was responsible. During the January 1966 attack the shark followed its female victim to bite her a second time.

"The Taranaki fatal attack was a great white shark. I have seen the photograph of the tooth fragment removed from the victim. A bronze whaler wouldn't be capable of that bite, which severed the leg."

Early findings from their research suggests that juvenile great whites spend the majority of time in shallower waters around coastal New Zealand, particularly in the North Island. Areas such as Manukau Harbour could be a play pen for the sharks until they reach maturity. It was also where Duffy and Chapman used the first satellite tag on a great white from mainland New Zealand, last year.

The 2m-long baby was caught by Waiuku fisherman Wayne Hadley in 9m deep water and he handed over the exhausted shark.

"The fisherman didn't think it would survive," says Chapman, "so we revived the shark by tying it alongside the boat and moving slowly we pushed the water through it's gills.

"Slowly it became more feisty then we took a DNA sample and as soon as we popped the tag in that was it – it reared back up to bite my hand and missed and bit the boat."

The teeth marks remain indented along the side of the boat, not much lower than where a hand might rest.

"The shark was pretty small. The tag tracked it's movement for 24 days and during that time it mostly stayed in water 10m deep, the deepest it went was 40m."

It was a significant find in their mission to protect the rare species. Scientists say reported catches in Australia and North Atlantic have declined by up to 90 per cent, although the population in South Africa appears stable.

Survival of the young of the species is crucial to maintain the population in New Zealand which, Duffy suspects, has dwindled since the introduction of gill netting and trawling used in commercial fishing.

"It's a fairly small by-catch of great whites but it may be significant to their population."

And, says Chapman, "we may find out ways that fisherman can avoid catching them by knowing where they might be."

For now, though, they are still searching. That day on the Papakura Channel they failed to find a great white.

They say it takes about three trips before they come across one, hindered by New Zealand's vast waters. But, like their beloved great whites, the men are relentless in their hunt and will undoubtedly come back for another go.


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