The crew of a shark-spotting helicopter in South Australia has released photos of a Jaws-sized giant, sighted around 100 metres off the coast of Marino Rocks, south of Adelaide, over the weekend. The images have gone viral after the photographers estimated the animal to be close to 7 metres - which is pretty huge, considering the largest great white shark on record was closer to 6.4 metres.
"It's the biggest [I've] ever seen as a crew member in the Westpac chopper," an unnamed crew on board the helicopter told the Shark Alerts South Australia Facebook page about the sighting. "We put it down as 7 m … the photo really doesn't do it justice."
The chopper followed the shark out to deeper water, before it disappeared from sight. As you can imagine, the nearby beach was promptly evacuated.
But before you get too excited, the size of this shark is far from confirmed, and it's notoriously difficult to estimate how big a shark is from a helicopter or photos.
"The size issue from photos like this is always challenging," Colin Simpfendorfer, co-chair of the IUCN's Shark Specialist Group and a professor of marine science at James Cook University, told Sciencealert. "You can get a sense of its size, but measuring it to that sort of accuracy is always a challenge, particularly when there's very little in the way of size reference in the picture."
The Shark Alerts South Australia page claims that the crew use their 6-metre jet boat to compare the size of the shark, but there's no evidence that can be used to reliably measure the animal. "Clearly it's a big shark, there's no doubt about that, but exactly how big could be debated all day," says Simpfendorfer.
Although there's no reliable scientific evidence of sharks growing much bigger than 6 metres, Simpfendorfer admits it's not impossible, and says there's been a lot of anecdotal evidence of great whites reaching that size.
"It is possible to have a 7-metre white shark," he explains. "But it's unlikely that this animal was that large."
So how could a great white grow so big? The truth is that great white sharks actually grow and mature incredibly slowly - it's estimated that it takes males 26 years to reach sexual maturity and a length of around 4 metres. After that, their growth slows, but doesn't appear to stop… and they can keep growing for a long time.
"We know these animals live a lot longer than we previously thought. There's work in the US that suggests animals could be up to 100 years old," says Simpfendorfer. "In that situation, they probably do start to slow down their growth. The challenge for us is understanding the growth processes involved with these very big animals."
Either way, all we can reliably say is that the shark spotted in South Australia over the weekend was a big one. But if you think those photos are impressive, check out this footage of the biggest great white shark ever filmed, Deep Blue, swimming around a cage diver off the coast of Mexico. We think she's beautiful.
Deep Blue (The biggest shark ever filmed) second part
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Posted by Mauricio Hoyos Padilla on Monday, August 10, 2015