A more accurate shark attack risk
"I like my odds. It's more likely I'll get struck by lighting, so I'm not really worried", says a swimmer in San Francisco interviewed after a white shark was captured on video attacking a sea lion right next to Alcatraz. All over the place you can read about that the risk of dying from a shark attack is 1 in 3.75 million, and how this compares favourably versus dying from being struck by lighting (1 in 79.000), falling (1 in 218), flu (1 in 63), stroke (1 in 24), cancer (1 in 7), etc… (Source: Florida Museum of Natural History))
Taking a larger timeframe and worldwide data (the odds above were using US data), I come up with this:
- 70 shark attacks per year worldwide (Note 1), or 5250 over a 75 year lifetime. With a worldwide population of 7 billion, the odds of being attacked by a shark is 1 in 1.3 million.
- 5.9 fatal shark attacks per year worldwide (Note 1), or 442 over a 75 year lifetime. With a worldwide population of 7 billion, there is the odds of dying from a shark attack is 1 in 15 million.
However, 1 in 15 million is NOT the odds if you are an ocean swimmer in San Francisco. As opposed to other causes of death, the risk is not evenly distributed among the total population. The odds above are misleading, since the vast majority of the population has 0 risk of being attacked by a shark. The risk is fully concentrated on those individuals that swim/surf/dive in waters where Great Whites (and Tiger and Bull sharks) frequent.
So, what’s the risk of dying from a shark attack if you are a San Francisco ocean swimmer?
- Over a 75 year lifetime, there will be 232 shark attacks in CA, 23 of them fatal (Note 1)
- Over a 75 year lifetime, there will be 4.3 shark attacks to SF swimmers, 1 of them fatal (Note 3).
- There are 1750 ocean swimmers in SF (Note 4), so these individuals (including myself) have a 1 in 1750 chance of dying from a shark attack over their 75 year lifetime (or, put it another way, 1 SF swimmer would die every 75 years from a shark attack).
The numbers will vary depending on many other factors and assumptions, but the main point is that anybody can die from a heart attack, a fall, cancer, etc. But only those that swim in oceans with white, tiger and bull sharks, are vulnerable to dying from a shark attack. As an ocean swimmer in SF, it is safe to say that the odds of dying from a shark attack are closer to 1 in 1750 than the 1 in 3.75 million_ being advertised out there. So, contrary to what the Alcatraz swimmer said, he is actually much more likely to die from a shark attack (one in a handful of thousands) than from being struck by lighting (1 in 79.000).
Note 1: In the 10 years between 2005 and 2014, 702 worldwide shark attacks, of which 31 were in CA (4.4%). 59 fatal WW attacks, of which 3 were in CA (5%). https://www.flmnh.ufl.edu/fish/sharks/statistics/Act.htm
Note 2: Between 1926 and 2014 4.3% of shark attacks in CA and 10% of fatal attacks in CA took place in SF. http://www.flmnh.ufl.edu/fish/sharks/statistics/gattack/mapca.htm
Note 3: Between 1900 and 2009, 43% of shark attacks were to swimmers and bathers. https://www.flmnh.ufl.edu/fish/sharks/statistics/Act.htm
Note 4: Assuming that there are 1750 regular ocean swimmers in SF… assuming that 80% of the 1100 Dolphin Club members and 80% of the 1100 (?) SERC members are regular swimmers