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Great White Shark eaten by super predator?
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142857 Offline
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Post: #11
RE: Great White Shark eaten by super predator?
Quote:the shark tag recorded a large temperature change from 9 degrees to 24.5 degrees

24.5 degrees is about right for tropical and subtropical coastal waters during the warmer months.

9 degrees is about right for the waters off Melbourne or Adelaide in the middle of winter.

That is a big temperature change.

A 500m dive pretty much rules out orcas, which don't dive anywhere near that deep.

** spoiler alert **









I did read in the comments that the most likely "super predator" involved would have been another, much bigger great white shark. Like many fish, great whites do eat their own kind.
06-11-2014 06:38 AM
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Alison Offline
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Post: #12
RE: Great White Shark eaten by super predator?
Western Australia shark mystery sparks bigger questions over ocean predators

October 29, 2013

What creature would be able to chase down and devour a 500 kilogram great white shark on the sea floor off Western Australia?

But as filmmakers David Riggs and Leighton De Barros began to investigate what dark fate could have befallen the ten-foot monster shark earlier this year, an even bigger mystery unfolded: why, once a year, does a rough, remote spot off the WA coast, just half a square kilometre in size, become the epicentre for a barely believable colosseum of battling marine life?

Killer whales by the dozen. Sperm whales. Giant squid. And masses of sharks, all fighting for food and supremacy. Their resultant documentary, The Search for the Ocean's Super Predator will screen early in November, and aims to answer the question of what colossal creature killed the shark, how and why.

But as Riggs explains, the bigger mystery to arise out of the film is what is to become of the area where it happened, a marine "hotspot" known as the Bremer Canyon. "It started as a film about the demise of a shark, and what could have done it - but it has opened up this huge other discovery," Riggs said. "It is a multi-species seasonal bonanza, and it happens to be on what is now recognised as a major hydrocarbon resource. It is mind boggling."

As the film, to be screened on the ABC on November 3 uncovers, the area off Bremer Bay in WA's South West is home to a natural phenomenon involving a leak from massive hydrocarbon pocket under the seabed, which fuses with the surrounding water to create an ice-like reef known as methane hydrate. This in turn sparks a food chain involving crustaceans releasing billions of nutrient-rich eggs into the desolate waters. And that food source brings with it the ocean's big boys.

"On one particular day, over a four nautical mile period, we saw in excess of 100 killer whales - it was ridiculous," Riggs says. "That is a lot of mouths to feed, so what the hell are they doing?"

To try to work that out, Riggs reached out to oil and gas company Arcadia Petroleum, which holds tenements that cover nearly 19,000 square kilometres in the area. And the company was happy to hand over its survey findings.

"They supplied me with all their observations, and the observations correlated exactly with what I had observed over the last eight years. They referred to it as the 'hotspot'," Riggs revealed. "So it definitely seems there is a link between these pressurised deep sea systems leaking, creating methane hydrate reef systems which creatures like."

That link was explored during a filming expedition involving a massive catamaran travelling 60 kilometre offshore, where footage was taken from inside an underwater canyon 4500 metres deep using camera gear requiring a cable spool weighing 3000 kilogram. On board were marine ecologist Michelle Blewitt, great white expert Rachel Robbins, and Mark Norman, an expert on the hunting behaviour of the giant squid from the Melbourne Museum. The footage that was beamed back left them all agog, despite their experience.

"You won't speak to anyone on that boat that was not flabbergasted by the intensity of life out there," Riggs said.

And having solved the original mystery of who killed the shark by the end of the film, Riggs and his collaborators are left with a bigger question.


What is to happen to the amazing summer phenomenon off WA's south-western coastline, given the uncertain future of the resources that lie below the seabed?

"It is effectively a balloon of hydrocarbon underneath the sea floor which is pressurised, and it is leaking. So what happens when you put a hole in that with an oil rig and depressurise it?" Riggs asked. "Is that going to cause this [sea life phenomena] not to happen? And if that is the case is that something worth taking notice of? I would love in 20 years for my kids to be able to go and look at this spot. That is what this is all about."

* The Search for the Ocean's Super Predator will screen on ABC 1 at 7.30pm on November 3.

AAP


8 comments so far
There's a wonderful account online about an orca lifting a great white above the ocean surface until it 'drowned'. A second GW, apparently with a tracking device fitted, observing this, then dived to an immense depth... and headed for South Africa. Orcas rock & rule! Footnote: We should welcome the American team which requested permission to tag and track GWs off our WA coast. C'mon Buzzy, convince Canberra that this free service will increase our knowledge, provide locations of inshore white sharks and alleviate tourists' anxieties... .
CommenterSV Location WA Date and time October 29, 2013, 3:29PM


Read more: http://www.watoday.com.au/environment/we...z34Gtiv500

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Is this the same article? Because I'm annoyed that it says in the article (bolded and italiced by me) that the cause has been found, only they don't say what it was! And the doco was screened in November, and on the Discovery Channel, which I don't have, so now I'll never know!

I'll bet this gave the diver a nasty shock! Luckily it's a whale shark, the largest known fish species, which don't eat anything bigger than brine shrimp - tons and TONS of brine shrimp! It could almost swallow this guy by mistake. But not to worry, he survived.

[Image: article-0-0D191D9500000578-532_964x540.jpg]


And speaking of marine monsters, imagine you're peacefully surfing and see this:

[Image: 0.jpg]


It's one of the big ocean going crocodiles we get off the Australian coast. This one is having a light sushi lunch of whole shark.

Sign on a farm gate: "For sale - Weak old chickens going cheep".
(This post was last modified: 06-11-2014 07:54 AM by Alison.)
06-11-2014 06:55 AM
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LanguageWolf Offline
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Post: #13
RE: Great White Shark eaten by super predator?
Even if you're a shark, Australia is still trying to kill you

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06-11-2014 12:34 PM
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Luke Mauser Offline
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Post: #14
RE: Great White Shark eaten by super predator?
Rosanne Barr ate it.

History is the lies of the victors coupled with the delusions of the defeated. It is an imagined certainty created at the point where the imperfection of memory meets the inadequacy of documentation.
06-18-2014 01:48 AM
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skyblue1 Offline
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Post: #15
RE: Great White Shark eaten by super predator?
(06-18-2014 01:48 AM)Luke Mauser Wrote:  Rosanne Barr ate it.

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06-18-2014 12:54 PM
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skyblue1 Offline
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Post: #16
RE: Great White Shark eaten by super predator?
Today Show: Madison Stewart Shark Girl

20-year-old Madison Stewart started free diving with sharks when she was only seven years old. She’s dedicated the last six years of her life fighting to protect sharks. She’s debuting her first documentary Shark Girl and she came by to discuss it.

Madison Stewart said that whatever killed that Great White Shark, she wants to dive with it. She said that there has been super predators in the past, but as far as we know they’re extinct. She also said that the media likes to do with this sharks. Sharks can be eaten by other sharks. Shark Alpha could’ve just been eaten by a bigger shark. But the media dubs it a super predator.

Today: Madison Stewart Shark Fascination

Madison said that people love to fear monsters and sharks fit that description perfectly. That’s why the media is so fascinated with them. The only time we see sharks is when there’s an attack. She said that since most people don’t get to swim with sharks themselves, they believe what the media tells them.

Today Show: Madison Stewart Sharks Fear

Madison Stewart said that the only thing that scares her about sharks is that they’re disappearing. She said that she always has a level of respect for sharks and she knows they’re not harmless, but it’s like people who own dogs that look viscous to other people, but they’re not to them.

She also said that sharks are critical to the oceans. In areas where sharks were killed off, the ecosystem has collapsed. Sharks are critical to the environment and she said she wants to protect them because of that.

Today: Madison Stewart The Importance Of Saving Sharks

She got involved in conservation because sharks are disappearing around the Great Barrier Reef and it really concerns her. Shark meat is available in Australia and shark liver oil is in cosmetics. She said they’re being neglected and it’s critical we adjust our focus to them.

Sharks are one of the few animals that you can still have a wild interaction with. When you get into the ocean, all you have to protect yourself from the shark is your knowledge of them. Hundreds of people have recreational interactions with sharks on a daily basis, even though we know they’re the top predator down there.

Shark Girl premieres on the Smithsonian Channel June 15. Hunt For The Super Predator airs on the same network on June 25.

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06-18-2014 12:57 PM
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142857 Offline
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Post: #17
RE: Great White Shark eaten by super predator?
Quote:Shark meat is available in Australia

Yes it is. But only school sharks, and only sharks to a maximum size of 90cm can be sold as meat.

Normally the flesh is sold as "flake" or "boneless fillets". Years ago about 90% of the fish battered and sold as fish-and-chips was shark, because it was cheap, but these days fish can be sourced cheaper from fish farms in South East Asia (although not as good to eat).

We've had an increase in the number of big sharks in recent years in Australia, to the point where the West Australian government has controversially begun culling.

I'd say that the wholesale slaughter of sharks only for their fins by factory ships is far more worrying.
06-19-2014 08:40 AM
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LanguageWolf Offline
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Post: #18
RE: Great White Shark eaten by super predator?
[Image: image.png]


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(This post was last modified: 06-20-2014 03:05 AM by LanguageWolf.)
06-20-2014 03:02 AM
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142857 Offline
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Post: #19
RE: Great White Shark eaten by super predator?
[Image: 2%E3%83%8E-%E3%83%95-silly-human-you-can...940808.png]
02-17-2019 10:53 AM
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