Beachgoers in Australia fled the water this past weekend after a massive great white shark was spotted just off the Adelaide coast. Rumoured to be seven metres (23ft) long – roughly the same size as Jaws' famed fictional beast, "Bruce" – the fish has become the latest media sensation. But there's a problem here: this shark was almost certainly not seven metres long. 

The largest scientifically measured white shark caught in Western Australia measured just 6.1 metres. To put things into perspective, that shark was caught the same year Frankie Goes To Hollywood told the world to "Relax" for the first time: 1984. That's how infrequently such large great whites appear. 

"In the 18 years I have worked with white sharks, the largest shark we have measured was 5.5 metres out of thousands of sightings," says marine biologist Dr Alison Kock

The shark was seen by aerial surveyors, who reportedly used a nearby boat to gauge the animal's length. 

"Sizing these ocean giants can be tricky," explains Kock. "This is because objects underwater are magnified or distorted, because white sharks are notably much bulkier than other sharks, and let's not forget that the excitement of seeing such an incredible animal probably contributes to interpreting the estimation."

Reports of bigger white sharks have surfaced over the years. One individual, caught near Australia's Kangaroo Island in 1987, was estimated at over seven metres long, as was another caught that same year off the Malta coast. Bigger still, an alleged eight-metre specimen was reported near Mallorca in 1969 – but in each of these cases, the accuracy of the claim was questioned by scientists, who eventually issued new size estimates for these sharks. Thanks to known relationships between fin height and body length, the supersized Mallorca shark, for example, is now thought to have been 6 and 6.42 metres long. 

Deep Blue interacts with divers in Guadalupe. Image: Maurico Hoyos Padilla/Facebook 

Even the famed "Deep Blue", one of the largest great whites ever caught on camera, falls within this range. 

"However unlikely, it is not impossible that seven metre giants are out there," adds Kock. "And seeing evidence for one would be pretty awesome." If the estimates were accurate, the Australian sighting would be right up there in the big leagues, but we're not bringing out the record books just yet.

In any case, it's important to note great white sharks are highly migratory, and the animal is unlikely to stay in the area for long. Regardless of size, the animal poses little threat to swimmers, and its appearance is not evidence to support claims that sharks are flocking to the area because of surfing season. 

"There are large schools of fish moving through our waters at this time of year," Surf Life Saving chief executive Clare Harris said in a statement.

What we're seeing is simply a healthy fish, in its typical habitat, following its typical food source. 


Top header image: kqedquest/Flickr