The Basics: Sharks live in every ocean in the world, and some species can also survive in freshwater rivers and lakes. No-one knows the size of the world shark population for certain, but best estimates put it at around 1.5 billion. In addition to our five senses they have electro-reception, allowing them to detect the small electrical fields generated when muscles move: the bigger the movement (eg, the flopping of a wounded creature), the stronger the signal.
Shark count: The more than 500 species range from the 20cm dwarf lantern shark to the 12-18m whale shark. A quarter of shark species are now in danger of extinction.
“We’re in their domain and it’s like going into a lion’s cage. If you jump in the cage then one day your number’s gonna come up.”
– Mick Fanning, Australian surfer after escaping a shark attack
7 per cent
Percentage of shark population killed by humans annually, on average.
0.00000008 per cent
Percentage of human population killed by sharks annually, on average.
Tweets about comedy-horror telemovie Sharknado 3: Oh Hell No! on its July 2015 premiere.
How Dangerous Are They?
From 2005 to 2014, sharks made 701 recorded attacks on humans. Of these, 59 or 8% were fatal, with most occurring in the US (409 attacks, 6 fatal) but Australia recording the most fatalities (123 attacks, 15 fatal).
Their ability to detect smells in water is a tad overhyped, but it’s still impressive. New research shows they can’t detect a drop of blood diluted in the equivalent of an Olympic-sized swimming pool – but they could in a backyard-sized pool. And their nostrils operate separately so they can precisely pinpoint the direction of a smell’s origin.
Humans kill perhaps 100 million sharks a year, with fished species including porbeagle, angel shark, spiny dogfish and gummy shark. The real number might be much higher because of shark finning. Tens of millions are taken purely for their fins – often cut off the still-living animal, which is then dumped back in the sea to drown or be eaten alive by predators it can no longer evade.
“Mosquitoes kill 50,000 times as many people [as sharks], but if there’s a TV channel that features Mosquito Week, I haven’t heard about it.”
Bill Gates, philanthropist entrepreneur
Why are the Fins Taken?
Shark-fin soup has been a high-status delicacy in China for a millennium. A growing Asian middle-class greatly increased demand, but in recent years conservation campaigning, trade bans in various countries, and the flow-on effects from a 2012 Chinese government austerity ban on serving the soup at official functions significantly reduced that demand. There’s still a way to go, however.
How Can I Reduce My Risks?
Don’t swim, dive or surf alone; don’t swim in murky water; don’t assume the presence of dolphins or porpoises means sharks are absent; don’t wear shiny jewellery – light reflecting off it can resemble fish scales; avoid the water at dusk, dawn and night, when sharks are more active and hard to spot; and avoid schooling fish or where people are fishing.