The odds of being eaten by a shark

Due to my engineering background, I understand risk analysis. I do risk assessments all the time in the laboratory where I do my research. Anyone who has done a risk assessment will understand the risk matrix which sets the consequence versus the probability to determine the risk. Anything with a high probability and high consequence (i.e. death, permanent disability etc) is a no no. In fact anything with a high consequence is generally ruled out in the lab, even if the probability is unlikely.

Strangely, risk analysis is not something I consciously do in my normal life, despite the fact I do many risky things. I snowboard, mountain bike, commute by bike, I go running by myself in the dark among other things. The risk is high in many of these activities with very high consequence, as I recently found out when I gave myself a concussion falling off my mountain bike, not to mention the 4 stitches in my shoulder (which had to be scrubbed under anesthetic to get rid of the dirt…).

Overconfidence = stitches

Overconfidence = stitches

But actually, when I think about it, I actually DO assess risks constantly. When on my mountain bike, I will walk sections I am uncomfortable with or not ready for, I will slow down when trying a new trail, I take compression bandages (for snake bites), always have my phone and make sure I tell someone where I am. My fall was a result of overconfidence and doing something I knew to be pretty silly (trying a large, for me, jump). When I run by myself, I am usually with my dog who is pretty scary looking, although harmless as a kitten (maybe a bit more harmless than a kitten, those things have sharp claws while the worst Melvin would do is lick you…). I also run in well-lit and populated areas. When I snowboard I wear a helmet and try to scope out new, possibly difficult runs from the chair lift. I also wouldn’t snowboard by myself and don’t let myself get out of control while boarding.

I can’t eliminate the risk without completely stopping all the things I love, so instead I try to bring it down to an acceptable level.

On that note, a friend has recently asked me to come open ocean swimming and I am considering the possibility. She goes with experienced ocean swimmers and she recounted her first time out to me. First, they look for a rip. Not to avoid, but to use to get ‘out the back’ behind the surfers and waves. Then they swim, often from one beach to another along the headland. It. Sounds. Terrifying. But also….exhilirating. She said it is incredibly beautiful and uplifting thing to do. But like, what about sharks? I’m not going to lie, the thought is so terrifying to me I may not be able to go through with it. BUT If I think about the risk assessment matrix the probability is so low it is practically non-existant…let’s look at some facts.

There have been 202 shark attacks in NSW in the last 100 years. According to the same website, the risk of a fatal shark attack was calculated to be 1 in 292,525 (0.0003%) based on ocean use and population statistics.

In comparison, 369 people were killed in NSW in fatal car accidents in 2012. According to stats in the ‘Road Traffic Crashes in NSW, 2012’ report, this is 0.74 fatalities per 10,000 licence holders – a percentage of 0.007%, which is a 1 in 13,514 chance.

So I am 21 times more likely to die in a fatal car accident than be killed by a shark.

My calculated risk of death is therefore much higher in the drive to the beach than the swim at the beach. Numbers crunched. Logically then, if I accept the risks to drive a car, I should be able to accept the lower risk of swimming in the ocean. Logical decision making says yes.

Emotional decision making…still on the fence. Stay tuned.


2 thoughts on “The odds of being eaten by a shark

  1. Hi Jess – I just saw this post! It’s good for me to read all these stats as I have recently just had a bit of a moment of wondering ‘what am I doing again? Is it actually really dangerous to swim in the surf after all?’

    The problem is that everyone tends to freak out about sharks because the danger is talked about (esp. in movies) far out of proportion to the actual risk. It really does make you lose any perspective on the actual risk itself.

    In any case the ocean has been way too rough the last week so I’ve been swimming in the baths 🙂 I do have a few doctor friends though who like to remind me they see a lot of people come into hospital with horrific injuries from things that can (and do) happen from everyday activities like walking down stairs – the point being, you can never manage every single risk anyway.

    Still, once your mind has decided to be freaked out by something, it’s very very difficult to unfreak it using logical statistics :/ Even for scientists 🙂

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